Revised Manuscript 8/7/12 Click here to view linked References

1 2 3 4 5 The Dalradian rocks of the northern Grampian 6 7 Highlands of Scotland 8 9 10 A.G. Leslie, S. Robertson, M. Smith, C.J. Banks, J.R. Mendum and 11 D. Stephenson 12 13 A. Graham Leslie British Geological Survey, Murchison House, West 14 Mains Road, Edinburgh EH9 3LA. 15 Steven Robertson (deceased) formerly British Geological Survey, 16 Edinburgh. 17 Martin Smith British Geological Survey, Murchison House, West 18 Mains Road, Edinburgh EH9 3LA. 19 20 Christopher J. Banks Slumberger Information Solutions, Ashley 21 House, Pitmeddden Road, Dyce, Aberdeen AB21 0DP; formerly 22 Department of Earth Sciences and Geography, Keele University. 23 John R. Mendum British Geological Survey, Murchison House, West 24 Mains Road, Edinburgh EH9 3LA. 25 * David Stephenson British Geological Survey, Murchison House, 26 West Mains Road, Edinburgh EH9 3LA. 27 [email protected] 28 0131 650 0323 29 30 * Corresponding author 31 32 Keywords: 33 Geological Conservation Review 34 Northern Grampian Highlands 35 Dalradian Supergroup 36 Lithostratigraphy 37 38 Structural geology 39 Metamorphism 40 41 42 ABSTRACT 43 44 The Northern Grampian Highlands are dominated by the outcrop of the 45 Grampian Group, together with infolds and structural outliers of 46 Appin Group strata and inliers of pre-Dalradian ‗basement‘, 47 consisting of Badenoch Group metasedimentary rocks. The south- 48 eastern limit of this mountainous region corresponds with the 49 regionally continuous Grampian Group-Appin Group boundary, which in 50 the south is marked by a high-strain zone corresponding to the 51 Boundary Slide of some authors. The more arbitrary southern 52 boundary runs north-west from Blair Atholl along the A9 road and 53 then westwards to Fort William. 54 The Neoproterozoic-age Grampian Group siliciclastic succession 55 accumulated during several transgressive and regressive cycles in 56 multiphase ensialic rift basins. The Badenoch Group constitutes 57 the crystalline floor to those basins and had experienced 58 amphibolite-facies metamorphism, migmatization, gneissification and 59 deformation between c. 840–800 Ma, prior to deposition of the 60 Dalradian strata. In contrast, evidence for only 470–450 Ma 61 62 63 64 65 1 2 3 4 Caledonian orogenic events is found at higher structural levels in 5 the Grampian and Appin group successions. Locating and 6 understanding the nature of the contact between the basement 7 gneisses and the Dalradian cover sequence has long been a major 8 challenge of Highland geology. Recent research has argued that not 9 only is a rift-basin architecture evident from the patterns of 10 Neoproterozoic stratigraphy, but also that it played a significant 11 role in influencing the geometry of the superimposed Caledonian 12 deformation, with the basin infill buttressed against its margins 13 or intrabasinal ‗highs‘. 14 The GCR sites in this region preserve important evidence of cover- 15 basement relationships, patterns of punctuated deposition, and 16 onlapping sequences. The effects of both pre-Caledonian and 17 Caledonian deformation and metamorphic events are also well 18 represented. Despite the deformation and metamorphism, spectacular 19 sedimentary structures are visible at several of the GCR sites and 20 there is evidence of the earliest recorded glacigenic sediments in 21 the Neoproterozoic rocks of the British Isles. 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 2 3 4 5 1 INTRODUCTION 6 7 A.G. Leslie 8 9 The Northern Grampian Highlands are dominated by a widespread and 10 thick succession of Neoproterozoic siliciclastic deposits referred 11 12 to as the Grampian Group (Figure 1). Most interpretations of the 13 regional geological relationships have suggested that the strata 14 were deposited upon an orogenic unconformity, now largely obscured 15 by a zone of ductile shearing at or near the base of the group 16 (Piasecki and van Breemen, 1979b, 1983; Piasecki, 1980; Piasecki 17 and Temperley, 1988a and references therein). These 18 interpretations were based upon structural and metamorphic 19 contrasts recognized between rocks referred to an older ‘Moine-like’ 20 crystalline basement of probable Grenvillian age and termed the 21 ‘Central Highland Division’, and a cover sequence referred to as the 22 ‘Grampian Division’ or Grampian Group. The basement rocks apparently 23 underwent amphibolite-facies migmatization, gneissification and 24 deformation prior to deposition of the cover sequence. While 25 lithologically similar to the Moine Supergroup of the Northern 26 Highlands, and formerly termed the ‘Younger Moine’, the Grampian 27 Group was included within the Dalradian Supergroup by Harris et al. 28 (1978) on the basis of the apparent stratigraphical, structural and 29 30 metamorphic continuity south-east of the Great Glen Fault in the 31 Grampian Terrane (Harris et al., 1994; Stephenson and Gould, 1995; 32 Strachan et al., 2002). Locating and understanding the nature of 33 the contact between the rocks of the Northern Highlands and 34 Grampian terranes has long been a major challenge of Highland 35 geology. 36 An alternative model viewed the rocks of the Northern Grampian 37 Highlands as part of a single stratigraphical succession in which a 38 regional metamorphic front separates the supposed basement and 39 cover sequences (Lindsay et al., 1989). Such a model was not 40 however supported by more-recent radiometric studies that confirmed 41 the existence of Neoproterozoic tectonothermal events (c. 840–800 42 Ma) in parts of the Northern Grampian Highlands (Noble et al., 43 1996; Highton et al., 1999), even though only Caledonian orogenic 44 events (470–450 Ma) are known at higher levels in the Dalradian 45 succession. Such a paradox, whereby comparable studies recognized 46 discrete tectonothermal events in different parts of an apparently 47 48 continuous stratigraphical succession, but were unable to separate 49 or define the limits of these events, continues to be one of the 50 key problems in Highland geology. 51 A lithostratigraphical framework has been erected for the Grampian 52 Group in the western and south-western parts of the Northern 53 Grampian Highlands, despite the problems of correlation across 54 major structures, polymetamorphism and the absence of 55 biostratigraphical control (Glover and Winchester, 1989; Glover et 56 al., 1995; Key et al., 1997). Those authors described an evolving 57 depositional basin in which marine and locally terrestrial 58 deposition occurred within multiphase ensialic rift basins, during 59 several transgressive and regressive cycles (Glover et al., 1995; 60 Glover and McKie, 1996). Smith et al. (1999) extended the 61 62 63 64 65 1 2 3 4 lithostratigraphical approach and integrated detailed mapping with 5 geophysical modelling to define a series of basin-bounding 6 structures in the Northern Grampian Highlands (Figure 2). Current 7 research continues to refine and improve the understanding of this 8 depositional framework (Banks and Winchester, 2004; Banks, 2005; 9 Banks et al., 2007). 10 The Grampian Group sediments were deposited in NE- to SW-trending 11 12 marine basins formed during a major phase of Neoproterozoic 13 rifting. These basins extended rapidly and accumulated up to 5 km 14 of turbiditic deposits, possibly within 20–30 Ma (Ryan and Soper, 15 2001). Later thermal subsidence is suggested by the regional 16 development of shallow marine-shelf environments and could have 17 occupied a similar length of time. The margins to these basins are 18 characterized by lateral facies and thickness changes, 19 stratigraphical omission and onlap relationships of both Grampian 20 and Appin group strata onto a basement of predominantly gneissose 21 rocks that records the older, pre-Caledonian tectonothermal 22 history. Stratigraphical relationships are summarized in Figure 3, 23 which is based largely upon Smith et al. (1999). 24 Smith et al. (1999) and Robertson and Smith (1999) argued that the 25 basin architecture thus determined is not only reflected in the 26 patterns of Neoproterozoic sedimentation, as would be expected, but 27 also played a significant role in predetermining the geometry of 28 the superimposed orogenic deformation in the Northern Grampian 29 30 Highlands. For example, the Geal-charn–Ossian Steep Belt has been 31 re-interpreted by those authors to reflect buttressing of basin 32 infill against the architecture of the basin margins or any 33 intrabasinal ‗highs‘. Such analysis of preserved ‗cover-basement‘ 34 relationships led Smith et al. (1999) to propose that a significant 35 stratigraphical and sedimentological break does indeed exist at the 36 base of Grampian Group, much in the manner originally suggested by 37 Piasecki (1980). Although there is presently insufficient 38 structural or metamorphic evidence to prove an orogenic 39 unconformity beyond all reasonable doubt, geochronological data do 40 confirm the presence of Precambrian events in the basement rocks 41 that have not been recognized in the cover. The basement rocks were 42 referred to informally as the Dava and Glen Banchor successions in 43 publications and on Geological Survey maps of the period 1999 to 44 2010, but have now been united formally as the Badenoch Group, with 45 Dava and Glen Banchor subgroups. 46 The GCR sites described within this paper (Figure 1) preserve 47 48 important evidence from locations where ‗cover-basement‘ 49 relationships, and the pattern of punctuated deposition and 50 onlapping relationships within the Appin Group, are preserved. 51 There are examples of the lithostratigraphical sequence in the 52 Grampian Group and evidence of the earliest recorded glacigenic 53 sediments in the Dalradian succession. Caledonian and pre- 54 Caledonian deformation and metamorphic events are similarly well 55 represented. A broad outline of current thinking and the 56 geological sequence of events is provided below. 57 58 59 60 61 62 63 64 65 1 2 3 4 1.1 Badenoch Group 5 6 Sedimentary structures and way-up criteria are lacking in these 7 metasedimentary gneisses and only the most-recent research has 8 attempted to erect any level of internal stratigraphy (Robertson 9 and Smith, 1999; Smith et al., 1999). The Glen Banchor Subgroup is 10 identified in the cores of large-scale antiformal structures in the 11 12 Glen Banchor and Kincraig districts (Figure 1) (see the An Suidhe 13 and Blargie Craig GCR site reports); comparable strata between 14 Tomatin and Lochindorb are assigned to the Dava Subgroup (see The 15 Slochd GCR site report). In broad terms, both the Dava and Glen 16 Banchor subgroups comprise a structurally undivided lower unit of 17 banded psammite, micaceous psammite and subordinate semipelite, and 18 an upper unit of more-varied lithologies including quartzite, 19 siliceous feldspathic psammite, micaceous psammite and schistose 20 banded semipelite. The lithological associations are consistent 21 with deposition in shallow marine environments. 22 23 1.1.1 Knoydartian orogenic events 24 25 Piasecki (1980) and Piasecki and van Breemen (1979a, 1983) 26 identified a suite of deformed pegmatites emplaced within rocks now 27 assigned to the Badenoch Group and from which they obtained c. 750 28 Ma Rb-Sr muscovite ages (see the An Suidhe GCR site report). These 29 30 pegmatites are located within ductile shear-zones associated with 31 progressive modification and grain-size reduction of gneissose 32 fabrics within the host migmatites. The pegmatites were thought to 33 have formed during, and hence to date, an episode of ductile 34 shearing. They were correlated with c. 750 Ma ‘older’ pegmatites 35 from the Northern Highlands Terrane and were thought to have formed 36 during the Knoydartian Orogeny. However, the Rb-Sr isotope ratios 37 have been variably reset by Caledonian tectonothermal activity 38 (Hyslop and Piasecki, 1999), so that a spectrum of ages from c. 700 39 to 500 Ma has been obtained from the same pegmatites, resulting in 40 ambiguous relationships that frustrate any single unifying 41 interpretative model. 42 Hyslop (1992) and Hyslop and Piasecki (1999) have confirmed the 43 temporal link between syntectonic metamorphic growth and pegmatite 44 segregation within the ductile shear-zones, while U-Pb analyses of 45 monazites from two large pegmatites at A‘ Bhuideanaich and 46 Lochindorb have yielded high-precision ages of 808 +11/-9 Ma and 47 48 806 ± 3 Ma respectively (Noble et al., 1996). Monazites from the 49 matrix of the mylonitic host to the Lochindorb pegmatite yielded an 50 age of 804 +13/-12 Ma. These results confirmed a phase of monazite 51 growth, and by implication pegmatite formation, contemporaneous 52 with metamorphic recrystallization and growth in the host mylonites 53 at c. 806 Ma, lending support to the earlier Rb-Sr studies. U-Pb 54 dating of single zircon grains within kyanite-grade migmatites 55 within The Slochd GCR site yielded an age of 840 ± 11 Ma and this 56 has been interpreted as dating high-grade metamorphism and 57 migmatization during an orogenic event that can be correlated with 58 the Knoydartian Orogeny (Highton et al., 1999). 59 60 61 62 63 64 65 1 2 3 4 1.1.2 Basement–cover relationships 5 6 A major orogenic break at or near the base of the Grampian Group 7 was first proposed by Piasecki and van Breemen (1979b, 1983), 8 Piasecki (1980), and Piasecki and Temperley (1988a). The original 9 lines of evidence presented by Piasecki and his coworkers centred 10 upon apparent structural and metamorphic contrasts between what is 11 12 now essentially the Badenoch Group and the Grampian Group. 13 Alternative hypotheses to explain those contrasts have invoked 14 metamorphic fronts (Lindsay et al., 1989) or as yet unrecognized 15 orogenic unconformities in the Appin or Argyll groups (Highton et 16 al., 1999). Previous attempts to test for an orogenic unconformity 17 were hampered by confusion over the significance and regional 18 extent of migmatitic and gneissose rocks in large areas of unmapped 19 ground. With much of the area now resurveyed by the British 20 Geological Survey (BGS), and a coherent stratigraphical framework 21 established, many of the earlier problems are diminished. The 22 distribution and development of gneissose and migmatitic textures 23 is largely compositionally controlled and cannot therefore be used 24 as a discriminant between cover and basement. Semipelite and 25 compositionally suitable psammite of both the Badenoch Group and 26 the Grampian and Appin groups,could have developed such textures 27 during peak metamorphic, upper amphibolite-facies conditions (see 28 the Lochan Uaine GCR site report). Any model attempting to explain 29 30 relationships in the Northern Grampian Highlands should therefore 31 take account of the nature of the stratigraphical framework, the 32 structural and metamorphic evidence for any break, and any evidence 33 for an isotopic break. 34 35 1.1.3 Stratigraphical framework 36 37 Critical localities in Glen Banchor, Speyside and Lochindorb are 38 largely unaffected by intense Caledonian deformation and preserve 39 unconformable and overstep relationships of Grampian and Appin 40 group rocks onto the Badenoch Group (Smith et al., 1999; Robertson 41 and Smith, 1999), thus providing evidence for a significant 42 stratigraphical break near the base of the Grampian Group. 43 Examples of the nature of these relationships are described under 44 the An Suidhe, Blargie Craig and Aonach Beag and Geal-charn GCR 45 site reports. Since the true base of the Grampian Group has not 46 been identified within the Northern Grampian Highlands, the 47 48 magnitude of this stratigraphical break is uncertain. 49 50 1.1.4 A structural and metamorphic break? 51 52 Rocks of the Badenoch Group are intensely recrystallized, preserve 53 no sedimentary structures and commonly contain intrafolial 54 isoclinal folds that deform the first foliation (usually a 55 gneissosity). The overlying Grampian Group rocks are variably 56 recrystallized, structurally less complex and commonly preserve 57 sedimentary structures; the first foliation, usually a schistosity, 58 deforms bedding. Observations such as these imply a structural 59 break, and thus support the original thesis of Piasecki (see the An 60 Suidhe GCR site report), but this difference is difficult to detect 61 62 63 64 65 1 2 3 4 where both successions are migmatitic or highly deformed. Regional 5 metamorphic studies do not detect a break (Phillips et al., 1999) 6 but this could reflect either the intensity of the Caledonian 7 overprint and/or the likelihood that the Badenoch Group rocks, if 8 already dehydrated during an earlier metamorphic event, would have 9 been essentially unreactive (e.g. Yardley and Valley, 1997). 10 11 12 1.1.5 An isotopic break? 13 14 Evidence for a Neoproterozoic (Knoydartian) tectonothermal event 15 has so far only been reported from within the Badenoch Group; rocks 16 assigned to the Grampian Group do not record this event. In 17 addition, as yet unpublished BGS data draw a further distinction 18 between the Grampian Group and the Badenoch Group in as much as the 19 latter contain complex monazite populations whose ages span c. 20 1200-450 Ma, while Grampian Group rocks contain relatively simple 21 monazites that record only Caledonian (470–450 Ma) events. 22 Taken all together, the above lines of evidence indicate a 23 significant break in sedimentation near the base of the Grampian 24 Group in the Northern Grampian Highlands. The rocks of the 25 Badenoch Group are therefore thought to form a ‗Moine like‘ 26 metasedimentary basement, which was affected by a ‗Knoydartian‘ 27 event prior to the deposition of the overlying Grampian Group. The 28 possibility that it is the Badenoch Group, rather than the Grampian 29 30 Group that might more easily share affinities with the Moine 31 Supergroup and thus establish linkages across the Great Glen Fault, 32 requires further geochemical, provenance and structural studies. 33 34 1.2 Grampian Group lithostratigraphy and basin 35 evolution 36 37 Flaggy psammitic metasedimentary rocks older than the Appin Group 38 were originally regarded as ‘Younger Moine’ (Johnstone, 1975) and 39 were known by such local names as the Struan Flags in Perthshire, 40 the Eilde Flags in Argyllshire and the Central Highland ‘Granulites’ 41 over much of the Northern Grampian Highlands. Based upon apparent 42 stratigraphical, structural and metamorphic continuity in the 43 Grampian Terrane, Harris et al. (1978) extended the then tripartite 44 Dalradian Supergroup downwards to include such lithologies, which 45 were all assigned to a new Grampian Group. A number of constituent 46 subgroups and formations were proposed by Winchester and Glover 47 48 (1988) and the lithostratigraphical relationships were synthesized 49 by Harris et al. (1994) and Stephenson and Gould (1995). 50 Since then, application of the techniques of basin analysis to the 51 lithostratigraphy of the Northern Grampian Highlands has made 52 important contributions to an evolutionary model for the Grampian 53 and Appin group depocentre in that region (Glover et al., 1995; 54 Smith et al., 1999; Robertson and Smith, 1999). Three main 55 lithofacies associations have been recognized and interpreted as 56 representing distinct phases of early- and syn-rift extension 57 followed by a protracted period of post-rift thermal subsidence. 58 Modelling of basin subsidence curves, using the method developed by 59 Ryan and Soper (2001), has indicated that both the syn-rift and 60 post-rift phases might each have lasted c. 30 Ma. Thus defined, 61 62 63 64 65 1 2 3 4 the Grampian Group is believed to record the initiation of late- 5 Neoproterozoic extension and basin development. However Prave 6 (1999), in contrast, has re-interpreted the Grampian Group as 7 detritus that was shed, post-806 Ma, from a Knoydartian orogenic 8 terrane as molasse or flysch deposits. 9 The timing of deposition of the Grampian and Appin groups is not 10 well constrained and is the subject of some current debate; the 11 12 general consensus is that the base of the Grampian Group is 13 unlikely to be older than c. 750 Ma. That consensus is supported 14 by chemostratigraphical data derived from Grampian and Appin group 87 86 15 metalimestones, all of which have Sr/ Sr isotope ratios greater 16 than 0.7064 (Thomas et al., 2004). Comparing that data with the 17 calibration of chemostratigraphy for global Neoproterozoic 18 carbonates (Melezhik et al., 2001) implies that precipitation of 19 the original carbonate must have occurred less than c. 750 Ma ago 20 and possibly even from as little as 670 Ma ago. 21 The lithostratigraphy of the Grampian Group that forms the basis 22 for the following outline is known in detail only for the area now 23 referred to as the Corrieyairack Basin (Figure 2; Smith et al., 24 1999). The true base of the Grampian Group is not exposed; the 25 oldest unit is the Glenshirra Subgroup (Figure 3), which has never 26 been found in undisturbed primary contact with rocks of the 27 underlying Badenoch Group. 28 29 30 1.2.1 Glenshirra Subgroup 31 32 The Glenshirra Subgroup comprises stacked thinning-upward sequences 33 of immature feldspathic psammite and beds of metaconglomerate, the 34 latter increasing in abundance up section and up dip towards the 35 Great Glen Fault. The type locality is in the inlier formed by the 36 Glenshirra Dome, around the upper reaches of the River Spey 37 (Haselock et al., 1982; Okonkwo, 1988; Banks and Winchester, 2004). 38 There it is represented by the Garva Bridge Psammite Formation, 39 locally with a distinctive Gairbeinn Pebbly Psammite Member in its 40 upper part (see the Garva Bridge GCR site report). Closer to the 41 Great Glen Fault, the subgroup is represented by the Glen Buck 42 Pebbly Psammite Formation in several smaller inliers, such as the 43 one traversed by the River E GCR site. The faulted inlier between 44 Loch Lochy and Fort Augustus exposes a succession of psammites and 45 metaconglomerates over 2000 m thick, which includes minor dolomitic 46 metalimestone and graphitic pelite (Parson, 1982; May and Highton, 47 48 1997). This inlier is separated from the overlying Corrieyairack 49 Subgroup by the Eilrig Shear-zone, a zone of mylonites up to 1.0 km 50 thick (Phillips et al., 1993), and high-strain zones are also seen 51 elsewhere at that junction, as in the Lochan Uaine GCR site. 52 In this subgroup, abundant sedimentary structures, including 53 convolute lamination, trough cross-bedding and ripple lamination, 54 together with rare hummocky cross-stratification indicate 55 deposition by traction currents in shallow marine environments 56 subject to storms. Parts of the subgroup might represent 57 fluviatile deposits, and Banks and Winchester (2004) interpreted 58 the whole association as alluvial fan and shallow water sediments 59 deposited within a SE-thinning fan–delta clastic wedge. They 60 considered the sedimentary environment to be so different from the 61 62 63 64 65 1 2 3 4 overlying sub-marine slope setting of the overlying Corrieyairack 5 Subgroup to warrant elevation of the Glenshirra Subgroup to group 6 status. However, this suggestion has not become generally accepted 7 and has not been adopted in this special issue. 8 Seams of magnetic heavy minerals are common. Progressive 9 thickening and coarsening of the strata westwards, combined with 10 the pebble compositions (mainly granite and vein-quartz with rare 11 12 amphibolite, psammite and quartzite), imply the presence of a basin 13 margin to the west or north-west, with an exposed hinterland of 14 mature crust beyond, perhaps composed of older Proterozoic rocks 15 similar to parts of the Rhinns Complex of Islay. 16 17 1.2.2 Corrieyairack Subgroup 18 19 The base of the overlying Corrieyairack Subgroup is marked by a 20 distinctive and regionally widespread succession of semipelite and 21 striped semipelite and psammite, which corresponds to basin-wide 22 flooding and the start of widespread subsidence and rift-related 23 extension. Locally, as at Kincraig, a heterogeneous succession of 24 muscovite-rich semipelites interbedded with calcsilicate rocks, 25 thin quartzites and metacarbonate rocks marks the base of the 26 subgroup (see the An Suidhe GCR site report). Such rocks probably 27 represent a condensed basin-margin facies reflecting deposition on, 28 or adjacent to, an uplifting high. 29 30 A near-complete sequence through the main rift cycle is preserved 31 within the western part of the basin, around Loch Laggan and in 32 Glen Roy (Figure 3; Smith et al., 1999; Banks, 2005). The basal 33 semipelitic facies (the Coire nan Laogh Semipelite Formation) is 34 overlain by c. 4 km of siliciclastic strata (the Loch Laggan 35 Psammite Formation), deposited by prograding turbidite complexes 36 (see the Rubha Magach GCR site report). Variations in sediment 37 supply and source area and the depositional processes are best 38 documented for the Loch Laggan-Glen Roy area (Glover and 39 Winchester, 1989; Key et al., 1997). Bouma sequences are well 40 represented within the main depocentre around Loch Laggan and Glen 41 Doe, while graded bedding is reflected as ‗saw-tooth‘ bed profiles 42 over most of the outcrop. Inferred bottom structures are extremely 43 rare but there is no lack of way-up criteria. 44 The overlying Ardair Semipelite Formation records a reduction in 45 sand-grade sediment supply and development of shelf conditions 46 along the basin margins. Turbidite deposition apparently continued 47 48 unabated in the putative basin centre, while lateral facies changes 49 into striped semipelite and psammite indicate more marginal 50 settings. A return to sand-dominated turbidites (the Creag 51 Meagaidh Psammite Formation) marks deposition in extensive 52 turbidite fan-lobe systems, derived from the north-west and 53 extending southwards and eastwards into shelf environments in the 54 Glen Roy and Drumochter areas (Glover et al., 1995). Rapid local 55 facies variations and thickness variations indicate active 56 tectonism at this time and, together with progressive overstep onto 57 an interbasin high in the Glen Banchor area (see the Blargie Craig 58 and Aonach Beag and Geal-charn GCR site reports), permit the 59 tracing of outlines of former basin margins (Glover et al., 1995; 60 Robertson and Smith, 1999). 61 62 63 64 65 1 2 3 4 1.2.3 Glen Spean Subgroup 5 6 The turbiditic rocks in the upper part of the Corrieyairack 7 Subgroup are overlain conformably by lithological associations with 8 well-preserved sedimentary structures that indicate deposition in 9 shallow marine environments. Such shelf areas were subjected to 10 tidal influences and sea-level fluctuations that resulted in 11 12 intensive sediment recycling and winnowing of the underlying 13 turbiditic rocks. The successions reflect reduced subsidence and 14 relative tectonic stability, which have been interpreted as 15 indicative of a post-rift thermal subsidence phase at this time 16 (Glover et al., 1995). 17 On the south-western and south-eastern margins of the 18 Corrieyairack Basin, sediments prograded into the basin from the 19 north-west and south-east and complex diachronous and lateral 20 facies relationships are common (Key et al., 1997). The Allt 21 Mhainisteir and Aonach Beag and Geal-charn GCR sites both lie on 22 the south-eastern margin, within the Geal-charn–Ossian Steep Belt, 23 and contain Glen Spean Subgroup strata. The northern part of the 24 Strath Tummel Basin is dominated by the Gaick Psammite Formation, 25 which was 1–2 km thick before deformation and has been repeated by 26 a stack of recumbent F2 folds (Leslie et al., 2006). It must 27 contribute significantly to the great thickness of Grampian Group 28 strata in this basin revealed by geophysical modelling (Smith et 29 30 al., 1999). The southern part of the Strath Tummel Basin is 31 covered by GCR sites described by Treagus et al. (2013). Farther 32 north, in the Cromdale Basin, psammites and quartzites of the Glen 33 Spean Subgroup are well represented. There, the top part of the 34 subgroup is dominated by thick quartzite formations, originally 35 channel-dominated quartz-rich sands, which extend from the Hills of 36 Cromdale to the Banff coast near Cullen, where they form the 37 western end of the Cullen to Troup Head GCR site (see Stephenson et 38 al., 2013b). 39 40 1.3 Appin Group lithostratigraphy and overstep 41 42 The Appin Group is characterized generally by consistency of 43 sediment supply into low-energy (open to lagoonal) marine 44 environments; many of its constituent formations can be correlated 45 along some 280 km of strike length, despite significant lateral 46 facies and thickness variations and local unconformable 47 48 relationships. Sedimentation occurred in a régime of progressive 49 lithospheric stretching in which listric synsedimentary growth 50 faults apparently constrain the architecture of NE-trending basins 51 (Hickman, 1975; Litherland, 1980; Anderton, 1985; see Stephenson et 52 al., 2013a). In the Northern Grampian Highlands, Appin Group rocks 53 record progressive overstep and onlap onto a substrate of rifted 54 Grampian Group rocks as stretching and subsidence proceeded. 55 56 1.3.1 Lochaber Subgroup 57 58 The basal Lochaber Subgroup conformably succeeds the Grampian Group 59 in the Central and Northern Grampian Highlands as alternating 60 successions of siliceous psammite and quartzite with minor 61 62 63 64 65 1 2 3 4 semipelite, pelite and rare metacarbonate units (Glover et al., 5 1995; Key et al., 1997). Such strata record the persistence of 6 relatively shallow marine environments from Grampian Group times; 7 the geometry of the basin architecture established earlier 8 continued to exert a strong influence (Robertson and Smith, 1999; 9 Smith et al., 1999). A general pattern for the Lochaber district 10 in the Central Grampian Highlands has offshore sediments 11 12 interbedded with tidally dominated quartzites that thicken to the 13 south-west. The nearshore sediments are interpreted as extending 14 away from a coastline to the north and are a reflection of periodic 15 basin shoaling events (Glover and McKie, 1996). To the north-east, 16 around Loch Laggan, comparable sediments in the Geal-charn–Ossian 17 Steep Belt underlie the glacigenic Kinlochlaggan Boulder Bed 18 (Treagus, 1969, 1981; Evans and Tanner, 1996). 19 Upper parts of the Lochaber Subgroup record a period of renewed 20 rifting with gradual deepening and widespread marine transgression, 21 as is represented by the Leven Schist Formation. Laminated pale- 22 grey schistose pelites account for up to 1200 m of strata in the 23 Central Grampian Highlands (Harris et al., 1994) but elsewhere this 24 formation is absent or is represented by thin local correlatives 25 (see the Aonach Beag and Geal-charn and Allt Mhanisteir GCR site 26 reports). Such dramatic variations have been attributed to 27 significant intrabasinal footwall uplift, reflecting continuing 28 basin development (Glover et al., 1995; Robertson and Smith, 1999). 29 30 31 1.3.2 Ballachulish Subgroup 32 33 Metasedimentary rocks of the overlying Ballachulish Subgroup record 34 the further effects of major marine transgression and widespread 35 thermally driven subsidence. There is a progressive development of 36 shallow shelf, tidally influenced sedimentation and anoxic lagoonal 37 environments in the Northern Grampian Highlands as elsewhere across 38 the Dalradian outcrop (Anderton, 1985). The regional pattern of 39 widespread stability and relatively uniform subsidence for the 40 lower formations of the subgroup is interrupted locally by 41 stratigraphical excision and the more sporadic distribution of the 42 upward-coarsening, deltaically influenced Appin Quartzite 43 (Litherland, 1980). A return to interbedded semipelite, 44 calcsilicate rock and metalimestone (the Appin Phyllite and 45 Limestone Formation) indicates renewed transgression and deepening. 46 In the Geal-charn-Ossian Steep Belt, the distinctive Appin 47 48 Quartzite Formation is absent; correlatives of the Appin Phyllite 49 and Limestone Formation overstep onto underlying Lochaber Subgroup 50 lithologies, and across the entire Grampian Group, to rest directly 51 on the Glen Banchor Subgroup (see the Blargie Craig and Aonach Beag 52 and Geal-charn GCR site reports). This overstep has been 53 attributed to a combination of non-deposition and erosion on a 54 long-standing intrabasinal ‘high’ (Robertson and Smith, 1999). 55 56 1.4 Caledonian deformation 57 58 The mushroom-like structure resulting from the divergent facing of 59 the major folds in the South-western and Central Grampian Highlands 60 encouraged the idea of a fundamental ‗root-zone‘ beneath the Loch 61 62 63 64 65 1 2 3 4 Awe Syncline in early structural models (Sturt, 1961; Rast, 1963). 5 Various geometries and locations for the extension of this root- 6 zone into the Northern Grampian Highlands have been debated 7 (Harris, 1963; Roberts and Treagus, 1979; Bradbury et al., 1979), 8 with attention focussed latterly on the the Geal-charn-Ossian Steep 9 Belt. Thomas (1979, 1980) interpreted this fold-complex as a 10 ‗root-zone‘ for the emergence of the SE-facing structures of the 11 12 Atholl Nappe that lies beneath the Boundary Slide. The NW-facing 13 nappes identified in Lochaber formed a similar architecture 14 emerging to the north-west during the earlier phases of Caledonian 15 compression. Other workers, whilst recognizing the existence of 16 the steep belts, regarded them as late developments in the 17 deformation sequence and rejected any connection with a primary or 18 fundamental root-zone (Hall in Fettes et al., 1986; Krabbendam et 19 al., 1997). Smith et al. (1999) and Robertson and Smith (1999) 20 made a genetic link between the location of the major Caledonian 21 structural features in the Northern Grampian Highlands and the pre- 22 existing architecture of the Dalradian depositional basins. 23 Despite the differences in overall models to explain the 24 distribution of the major fold-complexes in the Northern Grampian 25 Highlands and the debate surrounding pre-Caledonian orogenesis in 26 the Badenoch Group, there is a general consensus with regard to the 27 pattern of Caledonian fabric development and metamorphism (Thomas, 28 1979; Smith et al., 1999). The Caledonian metamorphic peak is 29 30 broadly coincident with the second fabric or foliation, that 31 typically being a crenulation of a pre-existing schistosity or 32 cleavage that has affected the bedding. There is however more 33 debate with regard to the development of the later third or fourth 34 fabrics, which are commonly more localized in the intensity of 35 their development. 36 37 1.4.1 Folds beneath the Boundary Slide: the Atholl 38 Nappe 39 40 Along the A9 road section, which forms the southern boundary of the 41 Northern Grampian Highlands as described in this special issue, 42 Thomas (1979, 1980) argued that the Grampian Group strata are 43 disposed in a large-scale, isoclinal F1 fold termed the Atholl 44 Nappe. This structure lies beneath the Boundary Slide and the Tay 45 Nappe, is disposed in the form of a broad arch called the 46 Drumochter Dome (see the A9 and River Garry GCR site report in 47 48 Treagus et al., 2013). However, Treagus (1987) has suggested that 49 there is no need to invoke a separate Atholl Nappe below the Tay 50 Nappe and hence that there is no need to invoke considerable 51 movement on the Boundary Slide in order to excise an intervening 52 right way-up limb. 53 The nature of the Drumochter Dome has also been the subject of 54 some controversy. Thomas (1979, 1980) argued that it is an early 55 structure but the work of Lindsay et al. (1989) has shown that D2 56 axial planes and cleavages are folded across the dome, which is 57 consequently now generally accepted as a later structure, possibly 58 D4. Over most of the dome the strata were originally represented 59 as flat-lying and inverted; however, a recent BGS survey across the 60 Gaick region in the north-eastern part of the dome has shown that 61 62 63 64 65 1 2 3 4 bedding is generally right-way-up in a SSE-facing system of F2 5 recumbent folds, geometrically similar to the original concept of 6 the Atholl Nappe (Leslie et al., 2006). 7 8 1.4.2 The Geal-Charn–Ossian Steep Belt 9 10 To the north-west of the Drumochter Dome, a 4 km-wide zone in which 11 12 all the fold limbs and axial planes are near vertical, forms a 13 complex of upward-facing isoclines (Figure 4) (see the Aonach Beag 14 and Geal-charn GCR site report). This is the Geal-charn–Ossian 15 Steep Belt of Thomas (1979), which can be traced for some 40 km from 16 south-west of Loch Ossian, through Aonach Beag and Geal-charn, to 17 Kinloch Laggan. In the Aonach Beag–Geal-charn area, three major 18 slide-zones are recognized, which commonly form steep boundaries 19 between Grampian Group and Appin Group strata. The steep belt 20 includes, on its north-west side, the Kinlochlaggan Syncline which 21 has long been regarded as a major isoclinal primary fold (Anderson, 22 1947b, 1956; Smith, 1968; Treagus, 1969). 23 To the south-west, the Geal-charn-Ossian Steep Belt may be aligned 24 approximately with the axial plane trace of the F1 Loch Awe 25 Syncline, although the Rannoch Moor and Etive granitic plutons 26 intervene, making direct correlation difficult. Both structures 27 appear to mark a fundamental structural divide between NW-facing F1 28 folds on one side (i.e. the Islay Anticline and other primary 29 30 structures such as the Appin Syncline) and SE-facing F1 folds on 31 the other (i.e. the Atholl, Glen Orchy and Tay nappes). 32 Consequently, Thomas (1979) proposed that the Geal-charn-Ossian 33 Steep Belt constitutes a root-zone, lying directly below the Loch 34 Awe Syncline, from which all of the fundamental F1 nappes of the 35 Grampian Highlands have diverged (see the Ben Alder GCR site 36 report). 37 38 1.4.3 Strathspey and the Monadhliath mountains 39 40 The phases of Caledonian deformation in this region are broadly 41 comparable to those established to the south and south-west in 42 fold-complexes that affect the higher structural and 43 stratigraphical levels of the Grampian Terrane. A detailed study 44 of the area around Kincraig, coupled with reconnaissance mapping 45 and traversing over much of the Monadhliath area between Lochindorb 46 and Kingussie, led to the first detailed comparison of structures 47 48 and the development of ideas, promoting a ‘basement-cover’ 49 relationship and the presence of an orogenic unconformity (Piasecki 50 and van Breemen, 1979b; Piasecki, 1980). 51 However, Lindsay et al. (1989) summarized structural studies that 52 strengthened belief in common elements of a Caledonian structural 53 history traced with some confidence from the Boundary Slide at 54 Blair Atholl, along the A9 road section and across the Drumochter 55 Dome to Strathspey. In the latter area, stratigraphical way-up 56 evidence becomes less reliable as tectonic strain and the degree of 57 migmatization intensify. However, tectonic fabric relationships 58 have been traced north and south-west from Aviemore into 59 Strathnairn and the Corrieyairack area, and comparable fabrics are 60 recognized both in the Grampian Group and in the structurally 61 62 63 64 65 1 2 3 4 underlying, highly migmatized rocks that are now assigned to the 5 Badenoch Group. As previously discussed, current structural, 6 metamorphic and isotope data are still insufficient to prove the 7 existence of any orogenic unconformity beyond doubt, but recent 8 detailed mapping in the region by the British Geological Survey has 9 confirmed the existence of a significant stratigraphical and 10 sedimentological break between the two sequences (Smith et al., 11 12 1999). 13 14 2 AN SUIDHE, KINCRAIG 15 (NH 810 050–NH 827 063) 16 17 M. Smith 18 19 20 2.1 Introduction 21 22 The lithological, metamorphic and structural correlation of the 23 lowest Dalradian rocks of the Northern Grampian Highlands with the 24 Moine Supergroup of the Northern Highlands has long been the 25 subject of considerable debate (see reviews by Harris et al., 1994; 26 Stephenson and Gould, 1995). Of particular importance is the 27 evidence for a major orogenic break at or near the base of the 28 Grampian Group (Piasecki and van Breeman, 1979b, 1983). Recent 29 30 radiometric studies have confirmed the existence of Neoproterozoic 31 (800–750 Ma) tectonothermal events within both the Moine and the 32 oldest rocks of the Northern Grampian Highlands (Noble et al., 33 1996; Highton et al., 1999), yet in the higher Grampian, Appin and 34 Argyll group rocks of the Dalradian succession, only Palaeozoic 35 (470–450 Ma) Caledonian events are known (e.g. Rogers and Pankhurst, 36 1993, Smith et al., 1999). Comparable dating studies now recognize 37 discrete tectonothermal events and it remains one of the key issues 38 of Highland geology to define the limits of these events. 39 The GCR site at An Suidhe, north-west of Kincraig on Speyside 40 (Figure 5), forms part of the original evidence cited by Piasecki 41 (1980) for the existence of an orogenic unconformity, largely 42 obscured by a zone of ductile shearing termed the Grampian Shear- 43 zone or Slide. He recognized an apparent structural and 44 metamorphic contrast between an older crystalline basement (his 45 ‗Central Highland Division‘) and a cover sequence (his ‗Grampian 46 Division‘). The Central Highland Division was believed to be of 47 48 possible Grenvillian age (c. 1000 Ma) and to have experienced 49 amphibolite-facies migmatization, gneissification and deformation 50 prior to the deposition of the ‗Grampian Division‘. Rb-Sr whole- 51 rock and mineral (muscovite) ages from pegmatitic granites within 52 the intervening shear-zone also provided key evidence for 53 deformation and metamorphism of both the basement rocks and the 54 lower parts of the cover sequence, initially by Knoydartian events 55 (c. 800–750 Ma) and then by Grampian events (c. 470–450 Ma). 56 Importantly, the site is also the type area for a distinctive 57 heterogeneous succession of metasedimentary and meta-igneous rocks 58 including semipelite, psammite, quartzite, metalimestone and 59 amphibolite. This succession, termed the Kincraig Formation, forms 60 the local base to the Grampian Group and separates grey micaceous 61 62 63 64 65 1 2 3 4 psammite from variably gneissose and sheared psammite, semipelite 5 and quartzite typical of the sub-Grampian Group basement. The 6 Grampian Shear-zone and dated pegmatites lie beneath this 7 sucession, wholly within the sub-Grampian Group basement. These 8 strata and their contacts, which are well exposed on the SE-facing 9 glaciated crags, small quarries and stream sections south of An 10 Suidhe summit, lie in the core and north-eastern limb of a major 11 12 refolded fold termed the Leault Antiform (Figure 5). They preserve 13 a variety of tectonic fabrics and metamorphic textures. Despite 14 this complex deformation, sedimentary structures are recognizable 15 within the basal Grampian Group rocks. 16 The area was mapped and described briefly during the primary 17 geological survey of the Highlands (Hinxman and Anderson, 1915), 18 but the first detailed description of the area was provided by 19 Piasecki (1980). A useful map and brief descriptions of the 20 outcrops are also included in an excursion guide (Piasecki and 21 Temperley, 1988b). Recent mapping at the 1:10 000 scale by the 22 present author is included in the BGS 1:50 000 Sheet 74W (Tomatin, 23 2004). 24 25 2.2 Description 26 27 28 29 2.2.1 Lithostratigraphy 30 31 The three main lithostratigraphical units distinguished in the An 32 Suidhe area are, in upward succession, the Glen Banchor Subgroup of 33 the Badenoch Group, the Kincraig Formation and the Loch Laggan 34 Psammite Formation (Smith et al., 1999) (Figure 6). The Kincraig 35 Formation was previously assigned to the Ord Ban Subgroup by 36 Winchester and Glover (1988), but this and the Loch Laggan 37 Formation now represent the oldest strata assigned to the 38 Corrieyairack Subgroup of the Grampian Group in the Speyside 39 district. 40 The Glen Banchor Subgroup, equivalent to the basement rocks of 41 Piasecki (1980), forms a series of low exposures south-west of 42 Kincraig House and in the birch woods around the Leault Burn 43 (Figure 5). It comprises variably gneissose to locally migmatitic 44 and schistose semipelite, psammite with subordinate siliceous 45 psammite, quartzite (the Blargie Quartzite Member of the Craig 46 Liath Psammite Formation) and pelite with lenses of pale-brown to 47 48 cream coloured calcsilicate rock. 49 The structurally lowest unit, lying within the core of the Leault 50 Antiform (Figure 5), is a segregated dark schistose semipelite to 51 pelite with thin ribs of quartzite and calcsilicate rock grading 52 outwards into striped garnet-muscovite-kyanite-fibrolite-bearing 53 semipelite and psammite. Where these rocks are strongly sheared, 54 lenticular ribbons of silvery muscovite, quartz-feldspar augen and 55 plates and veins of quartz are common, particularly towards the 56 contact with the overlying siliceous psammite and quartzite. This 57 overlying Blargie Quartzite Member, is a distinctive white to pale- 58 brown well-jointed feldspathic and migmatitic quartzite with 59 abundant microcline; it is interlayered with banded gneissose 60 psammite and rare thin lenses of semipelite. Generally 15–25 m 61 62 63 64 65 1 2 3 4 thick, it can be traced throughout the area as a series of ice- 5 scoured ‗crag-and-tail‘ exposures and it forms a low cliff along 6 the northern bank of the Leault Burn at NH 8194 0602. Abundant 7 minor folds, some intrafolial, in the quartzite are picked out by 8 concordant bands of leucosome and provide evidence for the earliest 9 phase of deformation in these rocks. Strongly flattened and 10 segregated micaceous psammites within the Blargie Quartzite Member 11 12 have been worked locally as walling stone (e.g. at NH 8200 0604). 13 The overlying and structurally uppermost strata of the basement 14 rocks comprise a striped sequence of medium-grained biotite- and K- 15 feldspar-bearing psammite and semipelite interlayered in varying 16 proportions. 17 Immediately north of Badden Cottage (NH 8251 0616), a thin unit of 18 phyllonitic semipelite is developed along the contact between 19 semipelite and psammite; it hosts a thin sheet (0.5 m) of foliated 20 pegmatitic granite with rotated and recrystallized augen of quartz, 21 feldspar and prophyroblasts of garnet and muscovite. These 22 pegmatitic granites, hosted by sheared striped psammite and 23 semipelite, are interpreted to have formed by strain-induced syn- 24 tectonic recrystallization within the Grampian Shear-zone (Hyslop 25 and Piasecki, 1999). 26 The overlying Kincraig Formation forms the lowest strata assigned 27 to the Grampian Group in the area and comprises in upward 28 succession, calcsilicate rock, quartzite, metalimestone and 29 30 schistose calcareous semipelite (Figure 6). A 30–50 m-thick sill 31 of massive to banded garnetiferous amphibolite obscures the base of 32 the formation everywhere and intrudes the underlying rocks locally. 33 However, evidence for the deposition of the Kincraig Formation onto 34 gneissose psammite can be seen elsewhere in Speyside; in a fault- 35 bounded block at Ord Ban (NH 895 085), on A‘ Bhunanaich (NH 787 36 090) and at NH 759 291, 2.5 km south of Glenkyllachy Lodge. 37 Banding, 5–15 mm thick, in the amphibolite is defined by variations 38 in the amount of amphibole, plagioclase and clinozoisite. The 39 remainder of the formation, up to 50 m in thickness, is well 40 exposed in the lower crags north-west of Kincraig House (e.g. 41 between NH 8221 0624 and NH 8210 0641) and a near-complete section 42 through the upper contact is exposed above the metalimestone 43 quarries around NH 8209 0641. At least two beds of coarsely 44 crystalline brown-weathering metalimestone are present. They 45 appear as a series of laterally discontinuous pods and megaboudins, 46 2–3 m thick and up to 40 m in length, wrapped by the main 47 48 foliation; they have been quarried as a source of lime (Figure 7). 49 The Loch Laggan Psammite Formation is well exposed on the south- 50 facing flanks and along the north-trending summit ridge of An 51 Suidhe. The basal facies, approximately 20–30 m thick, comprises 52 medium- to locally coarse-grained, schistose to weakly gneissose 53 semipelite with thin ribs (2–7 cm thick) of micaceous and quartzose 54 psammite in a regular alternating sequence. These striped beds 55 (‗rhythmites‘ of Piasecki, 1980) are intruded by a swarm of late- 56 to post-tectonic veins of granite and related quartzofeldspathic 57 pegmatite. Upslope, they pass gradationally into thicker bedded 58 biotite-, quartz- and plagioclase-bearing psammite with thin beds 59 and partings of semipelite bearing pods of calcsilicate rock. A 60 repetitive bed-scale variation in grain size and mica content 61 62 63 64 65 1 2 3 4 defines original grading cycles. Combined with evidence for 5 lateral bed amalgamation and channelling, these data indicate that 6 the section is right way up and consistently youngs away from the 7 underlying Glen Banchor Subgroup. 8 9 2.2.2 Structure and Metamorphism 10 11 12 The An Suidhe GCR site lies within the southern part of a large 13 structural window. The oldest rocks (the Glen Banchor Subgroup) 14 are exposed in the core of this window and contain evidence of an 15 early phase of deformation (D1) associated with amphibolite-facies 16 metamorphic conditions (M1). An early gneissosity (S1), formed by 17 solid-state recrystallization and probably mimetic on the original 18 compositional layering, is defined in semipelite and psammite by 19 coarse-grained mica foliae (melanosomes), which enclose lenticular 20 quartzofeldspathic segregations (leucosomes). The original 21 compositional banding (S0) might be represented within rare 22 intrafolial minor folds but in general, recrystallization and 23 deformation has destroyed the primary fabric. 24 The overlying Grampian Group strata display evidence for three 25 episodes of deformation (D2, D3 and D4), which also occurred under 26 amphibolite-facies conditions (M2). Bedding (S0), defined by 27 variations in quartz and mica content, is overprinted by the main 28 penetrative schistosity (S2), which in turn forms the second fabric 29 30 in the Glen Banchor Subgroup rocks. S2, identified by shape- 31 aligned biotite, quartz and plagioclase, varies from parallel to S0 32 to oblique (locally up to 15°) and is axial planar to a series of 33 gently inclined SW-verging tight minor folds in the Loch Laggan 34 Psammite Formation. On the northern limb of the Leault Anticline, 35 S2 is parallel to or steeper than S0, whereas on the southern limb 36 S2 is consistently shallower than S0 indicating local overturning. 37 S3 is a steeply inclined to asymmetrical SW-verging crenulation 38 cleavage that affects all the strata and is related to the 39 formation of a broad NW-trending antiformal dome structure and 40 sideways-facing minor folds, verging consistently to the south- 41 west. The youngest deformation visible in the area (D4) is 42 expressed as a series of weak open upright antiforms and synforms 43 and associated crenulation fabric that trends north–south and 44 refolds all the earlier structures. 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 2 3 4 The presence of the Grampian Shear-zone is indicated by a series 5 of narrow zones (a few tens of metres wide) of distributed ductile 6 shear that anastomose throughout the upper parts of the Glen 7 Banchor Subgroup. These zones have gradational boundaries with the 8 enclosing lithologies and are identified by a marked grain-size 9 reduction. The S1 gneissosity is reworked into a fine-grained 10 mylonitic and phyllonitic foliation that wraps around subelliptical 11 12 augen and porphyroblasts of plagioclase and muscovite. A suite of 13 distinctive foliated pegmatitic granite veins (up to 0.5 m thick) 14 are developed impersistently within the zones of most-intense 15 strain. 16 17 2.3 Interpretation 18 19 Piasecki (1980) originally proposed that the Glen Banchor Subgroup 20 rocks had experienced amphibolite-facies metamorphism and three 21 separate episodes of deformation prior to the deposition of the 22 Grampian Group. He argued that the unconformity subsequently became 23 the focus for ductile shear strain whose effects appear to have 24 decreased with increasing distance from the contact. Both the 25 cover and basement rocks were then deformed by a further three 26 episodes of deformation associated with medium- to low-grade 27 amphibolite- to greenschist-facies metamorphism. This complex 28 history has not been substantiated by subsequent dating studies and 29 30 the recent survey by the British Geological Survey. 31 The evidence for an orogenic unconformity can be described in 32 terms of two lines of evidence, stratigraphical omission and 33 tectonometamorphic history. At An Suidhe, the absence of any 34 recognizable strata of the basal Grampian Group (Glenshirra 35 Subgroup), combined with the shallow marine environments 36 represented by the Kincraig Formation, imply a major 37 stratigraphical hiatus, with the development of a shallow marine 38 shelf upon basement. The evidence for an extra phase of 39 deformation (the S1 gneissosity) in the Glen Banchor Subgroup, 40 which is absent from the overlying Grampian Group strata, indicates 41 a structural/metamorphic break and is further supported by two 42 independent radiometric studies. 43 Firstly, statistical analysis of major- and trace-element data 44 effectively discriminates the An Suidhe metalimestone pods from 45 Appin Group equivalents and establishes their distinctive nature 46 within the Dalradian Supergroup (Thomas and Aitchison, 1998). 47 87 86 48 However, Sr/ Sr isotopic ratios of the carbonate in these 49 metalimestones, which are thought to largely reflect those of the 50 coeval seawater, are consistent with those of younger Appin Group 87 86 51 and Islay Subgroup metacarbonate rocks. Sr/ Sr in seawater is 52 known to have changed with time and a comparison with published 53 data for limestones of Neoproterozoic age from elsewhere in the 54 world constrains the depositional age of the An Suidhe 55 metalimestones to be less than c. 800 Ma. Hence, on this evidence, 56 the base of the Grampian Group in this area is younger than 800 Ma 57 and possible significantly less (Thomas et al., 2004). Thus the 58 Kincraig Formation was deposited after the Glen Banchor Subgroup 59 rocks were affected by Knoydartian tectonothermal events. 60 61 62 63 64 65 1 2 3 4 Secondly, elsewhere in the Kincraig area, foliated pegmatitic 5 granite veins and their phyllitic host rock within the Grampian 6 Shear-zone have yielded Rb-Sr muscovite ages in the range 718 ±19 7 Ma to 573 ± 13 Ma (Piasecki, 1980) and U-Pb ages on monazite of 808 8 ± 11 Ma (Noble et al., 1996). Reworking of both the earlier 9 mylonitic and gneissose fabrics and the granitic veins by F2 folds 10 (e.g. at NH 8175 0567) indicates that the Glen Banchor Subgroup was 11 12 affected by a ductile tectonothermal event prior to D2, which is 13 the first phase of deformation recorded by the overlying Grampian 14 Group. The relative age of the mylonitic fabric in the Grampian 15 Shear-zone and hence the ages of monazite from the sheared 16 pegmatite, and whether these formed syntectonically in the host 17 rock to the S2 fabric of the Grampian Group, remains to be 18 clarified. Unpublished studies (BGS, 2000) indicate that monazites 19 in basement strata are complex, yielding both Precambrian and 20 Palaeozoic ages, whereas those in the cover only record Palaeozoic 21 events. 22 Cumulatively, these lines of evidence support the hypothesis of an 23 orogenic unconformity with Precambrian tectonothermal events 24 restricted to the basement. 25 26 2.4 Conclusions 27 28 The An Suidhe, Kincraig GCR site is a key section in the Northern 29 30 Grampian Highlands, where the relationships between pre-Dalradian 31 basement rocks (now termed the Glen Banchor Subgroup of the 32 Badenoch Group) and their cover (now assigned to the Corrieyairack 33 Subgroup of the Grampian Group) were first documented. The contact 34 between the two successions is obscured by a basic intrusion and 35 the relationships were controversial for many years. However, 36 recent detailed work on the lithostratigraphy, structure, 37 metamorphism, isotope geochemistry and age dating suggests that the 38 original cover-basement interpretation was correct and that the 39 contact represents not just a stratigraphical and/or structural 40 hiatus, but a major orogenic unconformity of national, if not 41 international importance. 42 Amphibolite-grade metasedimentary rocks of the ‗basement‘ Glen 43 Banchor Subgroup are variably gneissose and locally migmatitic. 44 They preserve at least one phase of deformation that is not seen in 45 the cover rocks and are cut by a major shear-zone that contains 46 syntectonic pegmatitic granites, forming part of a suite whose U-Pb 47 48 radiometric ages record an 800–750 Ma Precambrian (Knoydartian) 49 tectonothermal event. 50 The basal part of the Grampian Group records the encroachment over 51 the basement of a distinctive shallow marine sequence with 52 metalimestones, and sedimentary way-up evidence confirms that the 53 succession youngs away from the basement. 87Sr/86Sr isotopic ratios 54 in the metalimestones are consistent with post c. 800 Ma seawater 55 and hence support the field evidence that deposition of the 56 Grampian Group entirely post-dated the Knoydartian Event. 57 58 59 60 61 62 63 64 65 1 2 3 4 3 THE SLOCHD 5 (NH 836 257–NH 833 240–NH 842 240) 6 7 M. Smith 8 9 10 11 3.1 Introduction 12 13 The Slochd is one of the key localities described by Piasecki and 14 Temperley (1988b) as representative of the gneissose and migmatitic 15 basement rocks that stratigraphically and structurally underly the 16 Dalradian Supergroup. These authors postulated the existence of an 17 orogenic unconformity, but in most places where it is exposed, the 18 apparent junction was interpreted as being obscured by a zone of 19 ductile shearing, which they termed the Grampian Shear-zone or 20 Slide (see the An Suidhe GCR site report). Crucially, at The 21 Slochd, Piasecki and Temperley (1988b) presented evidence of an 22 undeformed contact between older crystalline basement (their 23 ‘Central Highland Division’) and its cover sequence (their ‗Grampian 24 Division‘). The basement was considered to be of possible 25 Grenvillian age (c. 1000 Ma) and to have experienced amphibolite- 26 facies migmatization, gneissification and deformation prior to the 27 deposition of the ‘Grampian Division’. This was in agreement with 28 evidence from the Grampian Shear-zone to the south, where Rb-Sr 29 30 whole-rock and mineral (muscovite) ages from pegmatitic granite 31 veins indicated that the basement rocks, and possibly the lower 32 parts of the cover sequence, preserve the record of two 33 tectonothermal events, namely the Knoydartian (c. 840–750 Ma) and 34 the Grampian (c. 470–450 Ma). The evidence for an undeformed 35 unconformity at The Slochd is no longer accepted, but the overall 36 premise of an orogenic unconformity has been substantiated by 37 subsequent work. 38 The Slochd GCR site includes the A9 road section described by 39 Piasecki and Temperley (1988b) and extends for 1.5 km southwards, 40 via scattered exposures and stream sections to the west of the 41 railway line (Figure 8). The site is dominated by moderate to 42 strongly gneissose, migmatitic psammite (Figure 9), semipelite and 43 quartzite, which were assigned to what is now termed the Dava 44 Subgroup of the Badenoch Group by Smith et al. (1999). These 45 strata are locally in sheared contact with grey micaceous striped 46 psammites and semipelites of uncertain stratigraphical affinity. 47 48 These were considered by Piasecki and Temperley (1988b) and Highton 49 et al. (1999) to be correlatable with the Grampian Group on 50 lithological and textural grounds. One possibility is that they 51 are equivalent to the Kincraig Formation at the An Suidhe GCR site. 52 The contacts between the two main lithostratigraphical units are 53 poorly exposed and are marked by a series of narrow N–S-trending 54 zones of blastomylonite and phyllitic semipelite and psammite that 55 locally host distinctive sheets of quartzofeldspathic pegmatite. 56 Podiform lenses of metagabbro and amphibolite are distinctive and 57 widespread throughout the site. The rocks have moderately to 58 steeply dipping foliations and occur in a broad zone of map-scale 59 reclined folds (F2) that have been refolded about N–S-trending axes 60 of later upright folds (F3). They preserve a variety of tectonic 61 62 63 64 65 1 2 3 4 fabrics and amphibolite-grade metamorphic textures. Highton (1992) 5 and Highton et al. (1999) have proposed a model of tectonic 6 interleaving or imbrication to account for the disposition of the 7 various lithologies. 8 The area was first mapped during the primary geological survey of 9 the Highlands (Hinxman and Anderson, 1915) and was resurveyed at 10 the 1:10 000 scale as part of the BGS 1:50 000 Sheet 74W (Tomatin, 11 12 2004). The resurvey included a ground-based magnetometer survey, 13 which was carried out to detect the extent of the shear-zones and 14 host lithologies (Leslie et al., 1999). A brief description of the 15 geology and a useful sketch of the A9 roadcut (cf. Figure 10b) are 16 included in an excursion guide (Piasecki and Temperley, 1988b). 17 18 3.2 Description 19 20 The Dava Subgroup, equivalent to the ‘Central Highland Division’ of 21 Piasecki and Temperley (1988a) and the ‘Central Highland Migmatite 22 Complex’ of Stephenson and Gould (1995) and Highton (1999), 23 comprises variably gneissose to locally strongly migmatitic 24 semipelite, psammite with subordinate siliceous psammite, quartzite 25 and pelite with lenses of pale-brown to cream-coloured calcsilicate 26 rock. It is divided into the Slochd Psammite, Creag Bhuidhe 27 Semipelite and Beinn Breac Psammite formations (Figure 8). The 28 complete absence of sedimentary structures in these rocks precludes 29 30 the determination of the stratigraphical relationships and inhibits 31 detailed interpretation of the regional structure. Parts of the 32 Dava Subgroup, mainly the Beinn Breac Psammite appear to be similar 33 lithologically to the Glen Banchor Subgroup farther to the south at 34 Kincraig and in Glen Banchor but detailed correlations have yet to 35 be established. 36 The Slochd Psammite Formation dominates the eastern part of the 37 GCR site and forms the core to a major reclined fold. This unit is 38 exposed at the south-eastern end of the A9 roadcut (Figure 10a). 39 Its upper contacts are poorly exposed or faulted (as in the 40 roadcut) but are marked by narrow zones of ductile shear and are 41 assumed to be highly tectonized. The formation is dominated by 42 coarse-grained, cream to pinkish-yellow gneisosse feldspathic 43 psammite (Figure 9). It is commonly strongly migmatitic and 44 contains monzogranite leucosomes, which coalesce locally into 45 discordant veins and sheets of gneissose granite up to 10 cm in 46 thickness. Zircons extracted from various parts of this rock (at 47 48 NH 8380 2520) have yielded U-Pb ages that indicate new zircon 49 growth at 840 ± 11 Ma (Highton et al., 1999). Thin bands of 50 semipelite occur sporadically and thicken locally into mappable 51 units, as in the railway cutting at NH 8418 2405. 52 The Creag Bhuidhe Semipelite Formation crops out north of the A9 53 around Carn nam Bain-tighearna and in stream sections south of Torr 54 Mor (Figure 8). It is a medium- to coarse-grained gneissose 55 biotite and muscovite semipelite that is spectacularly 56 migmatititic, with a well-developed stromatic texture defined by 57 layers of tonalitic leucosome and bound by screens of biotitic 58 melanosome. All of the original texture in these rocks has been 59 destroyed by metamorphic processes. 60 61 62 63 64 65 1 2 3 4 The Beinn Breac Psammite Formation is exposed in crags south of 5 Torr Mor (e.g. at NH 8319 2454 and NH 8311 2365). It is composed 6 of grey medium- to coarse-grained banded micaceous psammite and 7 psammite, variably gneisosse with bands of siliceous psammite and 8 quartzite. Interbedded units of semipelite and impure quartzite 9 and pods of calcsilicate rock are common, particularly towards the 10 contacts with the Creag Bhuidhe Semipelite Formation. The contact 11 12 with the Creag Bhuidhe Semipelite Formation is marked by a 13 prominent band of feldspathic and migmatitic quartzite, locally 14 interbanded with semipelite and micaceous psammite. This unit, 15 which can be traced around the western limb of the fold structure, 16 is lithologically similar to the Blargie Quartzite of the Kincraig 17 and Glen Banchor districts. 18 The structurally, and probably the stratigraphically, highest 19 strata are mainly bound tectonically by zones of ductile shear. 20 These strata comprise interlayered and striped, non- to weakly 21 gneissose, grey micaceous psammite and semipelite with lenses of 22 calcsilicate rock. The central section of the A9 roadcut provides 23 a section through the northern part of a thin shear-bounded unit 24 (Figure 10b). The main exposures within the GCR site are west of 25 the railway line at NH 8403 2418 and south-west of Torr Mor in the 26 Allt Ruighe an-t sabhail (NH 837 242). Together these strata form 27 the easternmost outcrops of a series of shear-bounded lenses of 28 non-gneissose striped psammitic and semipelitic units that 29 30 elsewhere contain beds of quartzite. The semipelitic component is 31 segregated, dark and interlayered with thin ribs of quartzite and 32 calcsilicate rock grading outwards into striped garnet-muscovite- 33 kyanite-fibrolite-bearing banded semipelite and psammite. 34 Muscovite porphyroblasts up to 6 cm in diameter are common and 35 weather proud locally to impart a knobbly appearance to the rock. 36 These strata host pegmatitic granite veins and, where strongly 37 sheared, contain common lenticular ribbons of quartz-feldspar augen 38 and veins of quartz, particularly towards the contact with the 39 adjacent quartzite. 40 At the north-west end of the A9 roadcut, a thin bed of quartzite 41 intervenes between the above strata and the Creag Bhuidhe 42 Semipelite. This unit can be traced for 1.3 km southwards before 43 pinching out tectonically. It comprises pinkish orange to grey, 44 well-jointed feldspathic quartzite, interlayered with banded 45 gneissose psammite and rare thin lenses of semipelite, up to 5 cm 46 thick. All contacts between these lithologies and the Slochd 47 48 Psammite and Creag Bhuidhe Semipelite formations are sheared and 49 are marked by fine-grained bands of mylonite and phyllonite. The 50 evidence of grading in these rocks described by Piasecki and 51 Temperley (1988b) has not been confirmed by the recent BGS survey. 52 Scattered outcrops of podiform dark-green metagabbro are a common 53 distinctive feature of the Slochd area (Highton, 1992; Wain, 1999). 54 These bodies, up to 50–70 m in length and 20 m in width, are hosted 55 by all the main lithologies and are elongated within the main 56 foliation. They are medium to coarse grained and commonly preserve 57 relict ophitic textures and schistose amphibolitic margins. The 58 largest mass (250 × 60 m) occurs 800 m south-east of Torr Mor at NH 59 8394 2456 and is cut by late quartzofeldspathic pegmatite. The 60 metagabbros are envisaged to have been emplaced after the peak of 61 62 63 64 65 1 2 3 4 regional metamorphism and migmatization but before the main D2 5 shearing event. 6 Late-stage post-tectonic pegmatitic granite veins, thin sheets of 7 microdiorite and felsitic minor intrusions cross-cut all the rocks 8 of the GCR site. Bands of biotite amphibolite and hornblende 9 schist in the A9 roadcut, reported by Piasecki and Temperley 10 (1988b), are re-interpreted here as foliated sheets of microdiorite 11 12 intruded along contacts and deformed by late-Caledonian events. 13 The Slochd GCR site lies within a NW-trending deformation zone 14 dominated by SW-verging reclined folds and fabrics and termed the 15 Foyers–Cairngorm Lineament by Smith et al. (1999). The local 16 structure is dominated by a map-scale F2 fold, cored by the Slochd 17 Psammite, that has been refolded by an upright N-S-trending F3 fold 18 into a classic hook interference structure. In the absence of 19 facing and fabric evidence it is not known if the early fold is 20 antiformal or synformal. All of the rocks contain evidence of an 21 early phase of deformation (D1) associated with amphibolite-facies 22 metamorphic conditions. An early gneissosity (S1), formed by 23 solid-state recrystallization and probably mimetic on the original 24 compositional layering, is preserved within rare intrafolial minor 25 folds. The main deformation (D2) formed large-scale, shallowly 26 plunging, tight to isoclinal reclined folds and reworked the 27 earlier gneissose foliation. Minor folds have S2 axial stretching 28 and mineral lineations, which plunge consistently at low angles to 29 30 the north-north-west. Shearing and reworking along fold limbs and 31 lithological boundaries were widespread locally, producing an 32 intense S2 shear fabric. All earlier structures were then reworked 33 and overprinted by an upright crenulation associated with the later 34 open F3 folds. All three structural events took place under middle 35 to upper amphibolite-facies metamorphic conditions. Unlike at the 36 An Suidhe GCR site, no difference in tectonic histories of the 37 postulated cover and basement rocks has been identified. 38 The Grampian Shear-zone is indicated by a series of narrow zones 39 (a few metres wide) of distributed ductile shear that anastomose 40 along or close to the main lithological contacts of the Dava 41 Subgroup with the non-gneissose banded ‗cover‘ lithologies. These 42 zones, which have gradational boundaries with the enclosing 43 lithologies, are identified by a marked grain-size reduction and 44 the reworking of the S1 gneissosity into fine-grained mylonitic, 45 blastomylonitic and phyllonitic foliations that wrap subelliptical 46 augen and porphyroblasts of plagioclase and muscovite. South-west 47 48 of Bracklettermore, at NH 8374 2285, a distinctive flaggy unit of 49 semipelite hosts a thin (0.2 m) foliated vein of beryl-bearing 50 pegmatitic granite with rotated and recrystallized augen of quartz 51 and feldspar and porphyroblasts of garnet and muscovite. This vein 52 is comparable to others observed at the An Suidhe and Blargie Craig 53 GCR sites and is interpreted to have formed by strain-induced syn- 54 tectonic recrystallization and to record an early phase of 55 deformation that took place between 800 Ma and 750 Ma (Hyslop and 56 Piasecki, 1999). 57 58 59 60 61 62 63 64 65 1 2 3 4 3.3 Interpretation 5 6 The Slochd GCR site exhibits a series of outcrops of high-grade 7 metasedimentary strata and meta-igneous rocks whose early history 8 has been destroyed by at least two high-grade tectonothermal 9 events. Little grain-size, bed-form or other sedimentary evidence 10 is preserved by which one could determine the environment of 11 12 deposition of these rocks. The stratigraphical correlations of the 13 ‘basement’ and ‘cover’ strata are unconfirmed but, by comparison with 14 sections elsewhere in the Northern Grampian Highlands, correlations 15 with the Glen Banchor Subgroup or Grampian Group are possible. If 16 the non-gneissose strata are the lateral equivalent of the Kincraig 17 Formation (Corrieyairack Subgroup), then a break in sedimentation 18 is implied by the absence of any recognizable strata of the 19 Glenshirra Subgroup at the base of the Grampian Group. 20 Alternatively, the non-gneissose strata could represent a 21 distinctive facies of the basement Dava Subgroup that has not been 22 recorded elsewhere. 23 Piasecki (1980) was the first to propose that an orogenic 24 unconformity separates what are now known as the Dava Subgroup and 25 Grampian Group strata. In the absence of clear evidence he 26 proposed, not unreasonably, that the unconformity became the focus 27 of ductile shear with the strain effects appearing to decrease with 28 increasing distance from the contact. Crucial to this argument was 29 30 the reported evidence in the Slochd A9 roadcut for an unconformable 31 contact between migmatitic rocks (of the Slochd Psammite Formation) 32 and overlying non-gneissose strata, and for the preservation of 33 inverse grading in the latter. However, neither of these features 34 has been confirmed by recent BGS surveys. The intensity of 35 recrystallization and deformation during amphibolite-grade 36 metamorphism has obliterated all early sedimentary structures and 37 ductile deformation fabrics and has blurred original contact 38 relations between the lithological units. The apparent striking 39 textural contrasts between individual psammite units at The Slochd 40 is a reflection of their bulk composition rather than of different 41 tectonometamorphic histories. Thus microcline-rich feldspathic 42 psammites of the Slochd Psammite Formation preferentially develop 43 gneissose and migmatitic textures, in contrast to more-plagioclase- 44 rich units of the ‗cover‘ strata, which are comparatively 45 unreactive and remain non-gneissose. 46 The timing of the various deformation and metamorphic events is 47 48 also unclear. Peak amphibolite-facies metamorphism and development 49 of gneissose and migmatitic fabrics is interpreted to have occurred 50 at c. 840 Ma (Highton et al., 1999). These fabrics were then 51 strongly reworked in the Grampian Shear-zone and deformed during 52 D2, whose age may be constrained, by analogy with dated monazites 53 at Lochindorb (Noble et al., 1996), to have occurred at c. 800 Ma. 54 However, the relationship of the dated monazites at Lochindorb and 55 elsewhere to the regional D2 foliation, which is recorded in 56 Grampian Group strata, and to the mylonitic fabrics in the Grampian 57 Shear-zone, has not been confirmed and continues to be the subject 58 of debate. Thus, unlike at the An Suidhe GCR site, there is no 59 structural or metamorphic evidence at The Slochd to support an 60 orogenic unconformity between any of the lithological units. There 61 62 63 64 65 1 2 3 4 is however mounting evidence from elsewhere in the region that 5 Piasecki (1980) and Piasecki and Temperley (1988b) were correct in 6 their overall interpretation, even though some of their detailed 7 evidence has not been substantiated. 8 9 3.4 Conclusions 10 11 12 The Slochd GCR site has played an important historical role in the 13 development of ideas regarding the structural and stratigraphical 14 relationships of the basal Dalradian strata of the Northern 15 Grampian Highlands. It includes one of the first documented 16 examples of a possible cover–basement relationship for the 17 Dalradian, but much of the original evidence has not been confirmed 18 by recent surveys. Although the roadcut is easily accessible, the 19 strata are highly disturbed by later faulting and evidence for an 20 ‘unconformity’ is problematical. However, sheared contacts with 21 syntectonic granitic veins between gneissose and non-gneissose 22 strata are present and, as is the case elsewhere in the region 23 (e.g. the An Suidhe GCR site), these could represent shearing along 24 an original unconformity in what has been referred to regionally as 25 the Grampian Shear-zone. 26 Migmatitic metasedimentary rocks of the Dava Subgroup of the 27 Badenoch Group have provided the first radiometric evidence from 28 south-east of the Great Glen Fault of new zircon growth during the 29 30 Precambrian Knoydartian Event (c. 840 Ma). They clearly form an 31 older basement to non-gneissose strata, which are tentatively 32 assigned to the Grampian Group, although their exact 33 stratigraphical relationships remain to be established. 34 35 4 LOCHAN UAINE 36 (NH 611 224–NH 613 228) 37 38 M. Smith 39 40 41 4.1 Introduction 42 43 Locating and understanding the nature of the contact between the 44 rocks of the Northern Highlands and Grampian terranes has long been 45 a major challenge of Highland geology (Harris et al., 1994; 46 Strachan et al., 2002). In particular the junction and 47 48 relationship between the Moine and Dalradian supergroups and the 49 correlation of their tectonothermal histories, has provided a focus 50 of study for many eminent geologists for over a century. Despite 51 this attention, the junction remains elusive and interpretations 52 are based on educated guesswork or model-driven hypotheses. 53 The Lochan Uaine GCR site is situated south of Dunmaglass Mains 54 farm in the headwaters of the River Farigaig in Strath Errick 55 (Figure 11). Its importance stems from the original belief that it 56 represents a candidate for the missing junction between the Moine 57 and Dalradian successions. The site contains excellent examples of 58 highly contrasting rock types and clear, easily accessible 59 exposures of their contacts. Migmatitized and gneissose 60 semipelites are juxtaposed across a zone of relatively high strain 61 62 63 64 65 1 2 3 4 against variably gneissose psammite and quartzite containing 5 abundant sedimentary structures. The sedimentary structures 6 confirm that that the psammites and quartzites are everywhere 7 structurally and stratigraphically below the semipelite. The 8 contact zone is a zone of high strain but is distinctly different 9 from the Grampian Shear-zone as described at The Slochd and An 10 Suidhe GCR sites in that it lies along the common limb linking two 11 12 major fold structures and it does not contain deformed pegmatitic 13 granite veins, quartz veining, pods of garnet amphibolite or books 14 of muscovite. 15 The nature of the contact between these two contrasting rock types 16 was first described in the Strath Errick area in an abstract by 17 Harris et al. (1981), who noted the presence of a zone of strong 18 deformation marked by platy quartzite. They considered the contact 19 to be a modified unconformity between the ‗Newer Moine‘ rocks, 20 which pass upwards into the Dalradian, and an ‗Old Moine‘ basement. 21 Highton (1986) provided a more-detailed description and re- 22 interpreted the contact zone as a ductile thrust carrying the 23 ‗older‘ migmatites over younger Dalradian metasedimentary rocks. 24 The primary survey of the area was completed in 1989 by P Haselock 25 under contract to BGS (1:10 000 Sheet NH62SW), and this was 26 included in the BGS 1:50 000 Sheet 73E (Foyers, 1996). 27 28 29 4.2 Description 30 31 Within the Lochan Uaine area, the contrasting lithologies can be 32 studied in the craggy outcrops around the summit and eastern flanks 33 of Beinn Mheadhoin (NH 6045 2175) and on Garbhal Mor (NH 6260 34 2344). Their contact relations are best observed in the prominent 35 meltwater channel and jokallhaup basin, which includes Lochan 36 Uaine, between NH 6122 2276 and NH 6124 2257. The rocks, all at 37 amphibolite-facies metamorphic grade, dip steeply eastwards and are 38 overturned locally. A series of map-scale reclined folds (F2) 39 trend north-west–south-east and are refolded about N-S-trending axes 40 of later upright folds (F3). 41 Two lithostratigraphical units have been defined. The 42 stratigraphically and structurally lowest strata are represented by 43 the variably gneissose Gairbeinn Pebbly Psammite Member of the 44 Garva Bridge Psammite Formation in the Glenshirra Subgroup (Smith 45 et al., 1999). These are the lowest strata recognized in the 46 Grampian Group and form a geochemically distinct metasedimentary 47 48 unit across the Northern Grampian Highlands (Haselock, 1994; Banks 49 and Winchester, 2004). The uppermost and younger lithological 50 unit, the Ruthven Semipelite Formation, comprises intensely 51 migmatized semipelite with thin units of psammite and calcsilicate 52 rock. This unit was considered to be older by early workers, and 53 was correlated with the Moine rocks of the Northern Highlands 54 Terrane, mainly on textural grounds and the presence of additional 55 deformation phases. However, it is now correlated with the Coire 56 nan Laogh and Kincraig formations which together form the basal 57 units of the Corrieyairack Subgroup (Smith et al., 1999). 58 The Gairbeinn Pebbly Psammite Member comprises medium-grained, 59 typically grey- to pink-weathering psammite and micaceous psammite, 60 with subordinate quartzite and distinctive thin pebbly units. It 61 62 63 64 65 1 2 3 4 is comparable to the strata described at the River E GCR site. In 5 thin section the psammites are dominated by plagioclase, K- 6 feldspar, quartz and mica. Highton (1986) separated the pebbly and 7 magnetite-bearing rocks of Beinn Mheadhoin from the variably 8 gneissose psammites on Garbhal Mor (his Can Ban Psammite), largely 9 on the basis of degree of metamorphic recrystallization. However, 10 subsequent recognition of pebbly bands and sedimentary structures 11 12 on Garbhal Mor and on the nearby hills of Carn Poullachie and Carn 13 Ban, has confirmed a correlation with the Beinn Mheadhoin outcrop 14 and this suggests that the development of gneissose textures was 15 controlled by intra-formational variations in bulk chemistry. 16 Bedding is generally 5–20 cm but locally up to 50 cm thick and is 17 defined by variations in grain size, the proportion of mica and by 18 magnetite-rich laminae. Semipelite is rare but bands up to 0.4 m 19 thick were noted by Highton (1986). Evidence for stratigraphical 20 younging is common and includes graded bedding, cross-bedding, 21 small-scale ripple drift and flaser lamination, ripple lamination, 22 convolute lamination and slump folds (Figure 12). Younging is 23 everywhere towards the contacts with the structurally overlying 24 semipelite. Laterally impersistent pebble beds, up to 30 cm thick, 25 are seen immediately south of Lochan Uaine at NH 6117 2241 and on 26 Garbhal Beag (NH6224 2418). The clasts, up to 10 cm in diameter 27 and composed of microcline and quartz-feldspar aggregates, are 28 dispersed within the matrix of the rock but are sufficiently 29 30 abundant locally for the rock to be clast supported. The pebble 31 beds and heavy-mineral seams contain magnetite, titanite and 32 epidote. These impart a detectable magnetic signature to the 33 formation and have been used to map out its outcrop throughout the 34 district (e.g. Haselock and Leslie, 1991) (Figure 11). Farther to 35 the north-east, on Garbhal Mor at NH 621 238 and on the hill of 36 Carn Ban, the formation is variably gneissose with units containing 37 abundant granitic segregations rimmed by biotite-rich selvidges. 38 Highton (1986), Haselock and Gibbons (1990) and the summary of 39 geology accompanying the BGS 1:50 000 Sheet 73E (Foyers, 1996) have 40 all described a transitional junction between the two formations 41 south of Garbhal Mor at NH 6225 2274 (Figure 11). The transition 42 is marked by the incoming of bands of siliceous psammite, passing 43 upwards into interbanded impure quartzite and psammite; the 44 proportion of semipelite decreases but thin seams of semipelite are 45 still present up to 200 m from the contact. Individual units of 46 quartzite reach 50 m in thickness locally. Elsewhere in the area, 47 48 the contact relations are less clear due to the focussing and 49 overprint of ductile shear along the contact zone. However, 50 despite the high strain and resultant attenuation, the transitional 51 nature of the junction has now been well established by several 52 authors and major excision of strata along the line of the shear- 53 zone is unlikely. 54 The Ruthven Semipelite Formation is characterized by medium- to 55 coarse-grained gneissose and migmatitic semipelite and pelite. 56 Rare thin units of psammite, layers of calcsilicate rock and 57 variations in the frequency of quartzofeldspathic segregations 58 define original lithological variation. In thin section the 59 semipelite contains the assemblage biotite, muscovite, quartz, 60 garnet and plagioclase. Pelites containing kyanite, fibrolite and 61 62 63 64 65 1 2 3 4 K-feldspar are recorded elsewhere in the district. At Lochan 5 Uaine, the formation is spectacularly exposed in large boulders at 6 the southern end of the loch and in the crags to the east (e.g. at 7 NH 6128 2275). The migmatites are stromatic (lit-par-lit) and 8 comprise quartzofeldspathic leucosomes, up to 10 cm thick, 9 surrounded by screens of biotite and muscovite. Layering, commonly 10 accentuated by effects of later deformation, becomes more schistose 11 12 locally. No sedimentary structures have been observed. 13 The metasedimentary rocks at Lochan Uaine are affected by three 14 phases of deformation and associated amphibolite-grade 15 metamorphism. An early tectonic event produced a near-bedding- 16 parallel foliation in the psammites, which is transitional into the 17 coarser grained migmatitic fabrics in the micaceous psammite and 18 the semipelite. Earlier workers separated these two fabrics into 19 two distinct events, with the gneissosity predating the foliation 20 (Harris et al., 1981; Highton, 1986). In the Gairbeinn Pebbly 21 Psammite Member this early fabric, probably a composite of S0 and 22 S1, is defined by aligned micas. The main D2 deformation produced 23 a series of NW-trending steep to reclined folds with steep NE- 24 dipping axial planes, a strong axial planar crenulation cleavage in 25 the hinge-zones and transposition of the earlier gneissoity. An 26 antiform-synform pair controls the disposition of lithologies and 27 the early fabrics at the GCR site and the common limb, which runs 28 close to Lochan Uaine, is strongly attenuated and faulted. Garnets 29 30 within the semipelite show two-stage growth, typically with 31 inclusion-free rims around a core rich in quartz and magnetite. 32 The final and weakest phase of deformation (D3) produced regional 33 upright tight N-S-trending folds with an axial planar crenulation 34 overprint; these features are not well developed at the GCR site. 35 At Lochan Uaine, the boundary between the Gairbeinn Pebbly 36 Psammite Member and Ruthven Semipelite Formation lies on the right 37 way-up limb of the F2 fold-pair and is marked by a zone of 38 deformation previously termed the Lochan Uaine or Gairbeinn slide 39 (Highton, 1986; Haselock and Gibbons, 1990). Haselock and Gibbons 40 (1990) correlated this structure with a slide-zone that marks the 41 upper boundary of the Glenshirra Subgroup with younger rocks 42 throughout the western part of the Northern Grampian Highlands. 43 The zone of deformation is well exposed in the crags at the 44 northern and southern ends of Lochan Uaine, where the transition 45 from feldspathic pebbly psammite to pelite occurs over a distance 46 of c. 2 m. It is marked by platy psammite and quartzite and by 47 48 schistose semipelite in which the original bedding and coarse 49 gneissose fabrics have been obliterated and transposed into the 50 main shear fabric. Highton (1986) described the progressive 51 deformation of pebbles and sedimentary structures that define a 52 strain gradient consistent with simple-shear and minimal horizontal 53 extension. Above the contact, the rapid fall off in strain and the 54 presence of ribboned quartz grains in thin section led Highton 55 (1986) to interpret these rocks as the products of a ductile thrust 56 or zone of decollement, synchronous with D2 in the gneissose 57 semipelites and with his first deformation in the psammites. A 58 shape fabric in the pebbly bands, together with mineral fabrics, 59 defines a lineation that plunges gently to the north. This is 60 progressively re-orientated into steep plunges in the shear-zone. 61 62 63 64 65 1 2 3 4 Shear-sense indicators have not been recorded, although Highton 5 (1986) noted an anticlockwise sense of rotation from augen of 6 restite grains and muscovite in the semipelite. The BGS 1:10 000 7 Sheet indicates a top-to-the-west sense of shear, though the basis 8 for this interpretation is not clear. 9 10 11 4.3 Interpretation 12 13 The startling contrast between the Gairbeinn Pebbly Psammite Member 14 and Ruthven Semipelite Formation, as highlighted by a variety of 15 features including sedimentary environment, metamorphic fabric and 16 structural history, has led previous workers to consider the Lochan 17 Uaine GCR site as a candidate for the elusive Moine–Dalradian 18 contact, a zone of major ductile thrusting or a local zone of 19 attenuation on the common limb between two major folds. 20 In sedimentary terms, the presence of superb sedimentary 21 structures and grain-size variation with local development of 22 pebble bands indicates high-velocity, rapid rates of sedimentation 23 for the Gairbeinn Pebbly Psammite Member. The psammites are 24 texturally and mineralogically immature and this, combined with the 25 nature of the sedimentary structures, indicates deposition within 26 an alluvial to shallow marine environment (Banks and Winchester, 27 2004). The pebbly beds might indicate shallow marine fan-type 28 deposits whilst the presence of slump folds suggests liquifaction 29 30 and rapid sedimentation. Regionally, the Gairbeinn Pebbly Psammite 31 is interpreted as having been deposited within a SE-thining fan- 32 delta clastic wedge (Banks and Winchester, 2004). The presence of 33 clasts and pebbles suggest proximity to an uplifted block of 34 granitoid basement (Smith et al., 1999). 35 In contrast, the Ruthven Semipelite Formation formed in a wholly 36 marine environment and passes stratigraphically upwards into a 37 thick sequence of rift-related turbiditic metasedimentary rocks. 38 The base of the formation, like the Coire nan Laogh Semipelite 39 Formation elsewhere (see the Garva Bridge GCR report), represents 40 an important sequence boundary and defines the base of the 41 Corrieyairack Subgroup (Banks and Winchester, 2004; Banks, 2005). 42 This base is marked by the transitional unit of interbedded 43 quartzite and semipelite seen on Garbhal Mor and at Lochan Uaine. 44 Superficially the two formations appear to record distinct 45 metamorphic histories, with a major gneiss-forming event preserved 46 in the semipelites but not in the psammites in which bedding is 47 48 commonly well preseserved. This has now been re-interpreted as a 49 response to differences in primary composition. During 50 deformation, the plagioclase-bearing psammites on Beinn Mheadhoin 51 were essentially unreactive and thus preserve their original 52 primary structures, whereas the stratigraphically equivalent K- 53 feldspar-bearing micaceous psammites and semipelites on Garbhal Mor 54 developed gneissose and migmatitic fabrics. Similarly the mica- 55 rich pelites of the Ruthven Semipelite Formation were readily 56 migmatized during deformation and metamorphism. On this basis the 57 strata on either side of the postulated shear-zone share a common 58 tectonothermal history and hence there is no evidence for an 59 orogenic unconformity as was proposed by Harris et al. (1981). 60 61 62 63 64 65 1 2 3 4 The nature of the contact and the amount of translation across the 5 shear-zone remain debateable. If the correlation of the psammites 6 on Beinn Mheadhoin and Garbhal Mor is accepted then there is little 7 requirement for a significant break, and the deformation zone can 8 be explained in terms of attenuation along major rheological 9 contrasts on the long limb of a fold during the D2 event. Shear- 10 zones propagating on minor F2 fold limbs were noted by Highton 11 12 (1986) in Strathnairn and are common throughout the Northern 13 Grampian Highlands. Alternatively, if stratigraphical excision is 14 envisaged then the shear-zone, with a presumed top-to-the-west 15 sense of movement, contravenes the first rule of thrusting as it 16 brings younger rocks over older. 17 18 4.4 Conclusions 19 20 Interest in the Lochan Uaine GCR site was first aroused because the 21 exposed contact between two distinctly different metasedimentary 22 units, one gneissose and the other non-gneissose with good 23 sedimentary structures, was thought to be a possible junction 24 between the Moine and Dalradian successions. Subsequent 25 contrasting interpretations of the contact have varied from an 26 unconformity overprinted by a shear-zone, to a thrust and, more 27 recently, to a zone of attenuation along the long limb of an F2 28 fold. Such variance highlights the need for care in the 29 30 interpretation of stratigraphical contacts and metamorphic fabrics 31 in such lithologies. This historical site now provides an 32 exceptional example of how contrasts in physical properties and 33 differences in bulk-rock chemistry can produce markedly different 34 looking rocks. 35 Superbly exposed psammites and quartzites with abundant 36 sedimentary structures (the Gairbeinn Pebbly Psammite) young 37 upwards towards a transitional contact with strongly migmatitic 38 semipelite (the Ruthven Semipelite). The two units share a common 39 tectonothermal history and both are now assigned to the Grampian 40 Group of the Dalradian. During the main phase of deformation (D2), 41 rheological contrasts across the contact zone have provided the 42 focus for ductile strain to produce platy, mylonitic fabrics along 43 the long limbs of major fold structures. 44 45 5 BLARGIE CRAIG 46 47 (NN 587 938–NN 608 955) 48 49 M. Smith and S. Robertson 50 51 52 5.1 Introduction 53 54 The Blargie Craig GCR site contains one of two recently discovered 55 exposures, where there is evidence for the existence of an 56 unconformity separating Grampian and Appin group Dalradian strata 57 from an underlying crystalline basement of Moine-like affinity. 58 The major break in sedimentation that this represents is critical 59 to the elucidation of both the geometry of Dalradian sedimentary 60 basins in the Northern Grampian Highlands and their subsequent 61 62 63 64 65 1 2 3 4 deformation during the Caledonian Orogeny (Harris et al., 1994; 5 Smith et al., 1999; Strachan et al., 2002). Additionally, the site 6 preserves features of the Grampian Shear-zone. 7 Variably gneissose rocks at Blargie Craig that have been deformed 8 in the Grampian Shear-zone (previously termed the Blargie Slide), 9 are cut by veins of pegmatitic granite that have yielded 10 radiometric ages of c. 750 Ma. These have been interpreted as 11 12 recording a Neoproterozoic deformation episode (Temperley, 1990). 13 The recognition of Neoproterozoic deformation here and elsewhere in 14 the Northern Grampian Highlands has been fundamental to the 15 delineation of a series of inliers of older ‗basement‘ to the 16 Dalradian ‗cover‘, previously referred to as the Central Highland 17 Division (Piasecki, 1980), the Central Highland Migmatite Complex 18 (Stephenson and Gould, 1995) or the Glen Banchor and Dava 19 successions (Smith et al., 1999). Those 'successions' have now 20 been formalized as subgroups of the Badenoch Group. The Blargie 21 Craig GCR site includes part of the Laggan Inlier, which is the 22 largest and most southerly of these ‗basement‘ inliers. 23 The basement–cover interpretation did not gain widespread 24 acceptance; Lindsay et al. (1989) considered that a ‗metamorphic 25 front‘ separated the purported basement from its ‗cover‘ and 26 thereby envisaged a single continuous Dalradian succession. More 27 recently however, Smith et al. (1999) and Robertson and Smith 28 (1999) have shown that the lower part of the Dalradian, namely the 29 30 Grampian Group and parts of the Appin Group were deposited 31 unconformably on a pre-Dalradian sedimentary succession, which is 32 now exposed in upstanding interbasin ‗highs‘. The Laggan Inlier 33 exposes one of these ‗highs‘ and is comparable to the Kincraig 34 Inlier, which includes the An Suidhe GCR site. 35 The GCR site includes a wide range of lithologies, which are well 36 exposed in glaciated SE-facing crags and small cliffs rising to an 37 elevation of 750 m in the upper Spey Valley (Figure 13a). A 38 consistent sub-parallel outcrop pattern, steep to vertical strata 39 and large-scale, upright, tight to isoclinal folds with highly 40 attenuated limbs indicate that the site lies within the NE-trending 41 deformation zone termed the Geal-charn–Ossian Steep Belt (see 1.4.2 42 in Introduction). The youngest strata are assigned to the Appin 43 Group and include metalimestone and quartzite, amphibolite and 44 semipelite. In many places across the Grampian Highlands (e.g. 45 Kinlochleven, Bridge of Brown), these strata rest conformably on 46 psammite and semipelite of the Grampian Group. In contrast, in the 47 48 lower ground around Coull Farm, south-west of Blargie Craig, 49 glaciated mounds and roches moutonées preserve Appin Group strata 50 resting unconformably on the older Glen Banchor Subgroup, with no 51 intervening zone of shearing or high strain. In this area, the 52 Grampian Shear-zone, including the dated pegmatitic granite veins, 53 occurs wholly within the Glen Banchor Subgroup rocks. 54 The regional geology of the area was described briefly by Anderson 55 (1956) and Temperley (1990) and a description of Blargie Craig is 56 included in an excursion guide (Piasecki and Temperley, 1988b). 57 The primary survey of the area was completed between 1996 and 1999 58 (BGS 1:10 000 sheets NN59NE, NN59SE, NN69NW and NN69SW) and is 59 included in the BGS 1:50 000 Sheet 63E (Dalwhinnie, 2002) but, 60 other than the maps, little information has been published. This 61 62 63 64 65 1 2 3 4 site report is based upon the authors‘ observations and 5 acknowledges numerous discussions with J.R. Mendum. 6 7 5.2 Description 8 9 The GCR site extends from Coul Farm north-eastwards for about 3 km 10 to Gergask Craig and includes key sections at Blargie Craig and 11 12 Coull Farm (Figure 13a). 13 The site contains three principal lithostratigraphical units 14 (Figure 13a). The oldest comprises variably gneissose interbanded 15 semipelites, psammites and quartzites of the Glen Banchor Subgroup. 16 These are separated from grey flaggy non- to weakly-gneissose 17 psammites and semipelites of the Corrieyairack Subgroup of the 18 Grampian Group to the north-west by a narrow outcrop of semipelite, 19 quartzite, amphibolite and metalimestone assigned to the Aonach 20 Beag Semipelite and Coire Cheap formations of the Appin Group 21 (Robertson and Smith, 1999). The effects of recrystallization 22 during amphibolite-facies metamorphism have largely obliterated the 23 original sedimentary textures in the older rocks and no way-up 24 evidence has been found in the Glen Banchor Subgroup. In the 25 Grampian and Appin group rocks, bedding profiles and rare 26 sedimentary structures provide reliable younging evidence. Within 27 the GCR site, the Appin Group strata young consistently away from 28 the Glen Banchor Subgroup strata (Figure 13b). 29 30 In its type area, farther north-east in Glen Banchor, the Glen 31 Banchor Subgroup comprises four informal units, all of which are 32 present in the area around Blargie Craig. These units are similar 33 to lithologies described at the An Suidhe and The Slochd GCR sites 34 but detailed correlations have yet to be established. The 35 structurally lowest unit is the Creag an Loin Psammite, which is 36 exposed south of the River Spey around Dalchully House (NN 5945 37 9375). It comprises medium- to coarse-grained gneissose and 38 migmatized interbanded psammite and semipelite. Granitic 39 leucosomes of quartz and feldspar are sheathed with biotite-rich 40 melanosomes imparting a stromatic texture. The semipelite is 41 biotite, mucovite and garnet bearing. In Glen Banchor, these 42 strata are in conformable contact with the An Stac Semipelite, e.g. 43 on Sron Mor na h-Uamhaidh (NN 638 977). The An Stac Semipelite, 44 clearly displayed in cliff sections at Gergask Craig (NN 6121 9535) 45 and north of Blargie (NN 6008 9512), consists of medium-grained 46 gneissose muscovite-and-garnet-bearing semipelite with thin ribs of 47 48 quartzite and calcsilicate rock and is intensely veined by granite 49 and quartzofeldspathic pegmatite. Banding is defined by rare bands 50 of dark-grey micaceous psammite. Close to contacts with adjacent 51 units, the semipelite is finer grained, interbanded with micaceous 52 psammite and more schistose in appearance. It contains the 53 assemblage, garnet-muscovite-kyanite-fibrolite and, where strongly 54 sheared, for example near Coul Farm and on Blargie Craig, it has 55 lenticular ribbons of silvery muscovite, quartz-feldspar augen and 56 plates and veins of quartz. This unit everywhere hosts the 57 pegmatitic granite veins that characterize the Grampian Shear-zone. 58 The structurally highest unit in the Glen Banchor Subgroup is the 59 Creag Liath Psammite, comprising K-feldspar-bearing medium-grained 60 gneissose banded psammite and siliceous psammite. Minor 61 62 63 64 65 1 2 3 4 lithologies include quartzite. Porphyroblasts of microcline up to 5 0.5 cm in diameter are common and impart a pebbly appearance to the 6 rock and along joint faces. A minor but very distinctive unit of 7 gneissose feldspathic quartzite, referred to as the Blargie 8 Quartzite Member, generally occurs at the lower boundary of the 9 Creag Liath Psammite Formation, although thin developments of this 10 lithology are also noted within the An Stac Semipelite Formation. 11 12 The quartzite is typically white to pale brown, well jointed, 13 feldspathic and migmatitic with abundant microcline and thin 14 interbeds of banded gneissose psammite and rare semipelite. 15 Elongate irregular lensoid bodies of medium-grained amphibolite are 16 developed sporadically throughout the Glen Banchor Subgroup. They 17 are generally a few tens of metres in diameter but can reach up to 18 100 m in length e.g. at Blargie Farm (NN 6018 9465). 19 The Grampian Group strata include metasedimentary rocks assigned 20 to the Loch Laggan Psammite, Ardair Semipelite and Creag Meagaidh 21 Psammite formations of the Corrieyarack Subgroup, which are poorly 22 exposed to the north-west of the site e.g. in the Allt Tarsuinn Mor 23 (NN 5873 9622) and Allt Tarsuinn Beag (NN 5840 9530). These strata 24 comprise, in varying proportions, well-bedded blocky grey psammite 25 with thin semipelite and ribs of calcsilicate rock. Grading 26 profiles defined by weathering of muscovite-rich semipelite bands 27 indicate a consistent regional sense of right way-up and 28 stratigraphical younging away from the underlying Glen Banchor 29 30 Subgroup. The Rubha na Magach GCR site report contains further 31 descriptions of these lithologies. 32 The youngest strata in the Blargie area are assigned to the Aonach 33 Beag Semipelite and Coire Cheap formations of the Appin Group on a 34 combination of lithological and geochemical criteria (see 35 ‗Interpretation‘). They are in mappable continuity with strata 36 farther west, which include the Kinlochlaggan Boulder Bed and 37 Quartzite and are of undoubted Appin Group affinities (see the Allt 38 Mhainisteir and Kinloch Laggan Road GCR site reports) (Evans and 39 Tanner 1996; Robertson and Smith 1999). The Aonach Beag Semipelite 40 Formation is dominated by interbanded rusty-weathering schistose 41 semipelite and micaceous psammite but also includes blocky white 42 quartzite and quartzose psammites, some of which are pebbly. 43 Concordant thin sheets of garnet amphibolite are abundant, 44 particularly close to the boundary with the Glen Banchor Subgroup. 45 At NN 5915 9524, a small outcrop of metacarbonate rock, 46 calcsilicate rock and semipelite is well exposed in and around 47 48 three small quarries where limestone has previously been extracted. 49 These rocks are assigned to the Coire Cheap Formation on the basis 87 86 50 of their whole-rock geochemistry and Sr/ Sr initial isotopic 51 ratios, which are consistent with younger Appin and Argyll group 52 metacarbonate rocks (Thomas et al., 1997; Thomas et al., 2004). 53 Minor exposures of white quartzite occur in the vicinity of the 54 contact with the Aonach Beag Semipelite Formation. The quartzite, 55 which might be the Kinlochlaggan Quartzite Formation, is only a few 56 metres thick compared with up to 160 m seen at the Allt Mhainisteir 57 GCR site. 58 The contacts between the above strata are generally poorly exposed 59 and are commonly highly attenuated by deformation. However, north 60 of Coul Farm (at NN 5870 9425) the critical contact between Appin 61 62 63 64 65 1 2 3 4 Group and Glen Banchor Subgroup strata is well exposed in a series 5 of roche moutonée exposures (Figure 14). A sharp and concordant 6 boundary separates striped gneissose psammite with micaceous 7 laminae and thin layers of quartzose psammite of the Creag Liath 8 Psammite from schistose semipelite and micaceous psammite with 9 abundant garnet amphibolite sheets of the Aonach Beag Semipelite 10 Formation. Thin calcsilicate layers occur at the contact. The 11 12 outcrop of this contact is repeated a number of times by upright 13 isoclinal folds (Figure 13b) and is also well exposed some 5 km to 14 the north-east at Margie na Craig in upper Glen Banchor (NN 6202 15 9780). 16 Zones of high ductile strain typical of the Grampian Shear-zone 17 are present within the An Stac Semipelite c. 30–40 m below the 18 unconformity at the locality described above. Similar features are 19 also well exposed at Blargie Craig along the contact between the An 20 Stac Semipelite and the Blargie Quartzite (Paisecki and Temperley, 21 1988b). As at the An Suidhe and The Slochd GCR sites, the Grampian 22 Shear-zone is characterized by the progressive attenuation of 23 lithologies with transposition into parallelism of all lithological 24 and structural features. Mylonites are also present and exhibit 25 grain-size reduction and segregation of quartz into subconcordant 26 ‗plates‘ together with the development of tabular garnets. 27 Porphyroblasts of quartz, K-feldspar, muscovite and garnet have 28 grown within the zones of quartz ‗plates‘. Thin sheets and thicker 29 30 veins of pegmatitic granite are developed within the high-strain 31 zones and Rb-Sr dates on muscovite books within these indicate ages 32 of c. 750 Ma (Piasecki and van Breemen, 1983). 33 Throughout the GCR site the lithological layering, axial surfaces 34 of folds and associated tectonic fabrics are coplanar due to 35 deformation within the Geal-charn–Ossian Steep Belt (Robertson and 36 Smith, 1999). Overall the structure is one of a syncline–anticline 37 pair with numerous parasitic folds on the limbs, many with sheared 38 long limbs. The main gneissosity of the Glen Banchor Subgroup 39 strata probably reflects an early compositional variation and is in 40 places deformed by isoclinal folds, some of which are rootless. 41 This gneissosity and the early bedding fabrics (S0) of the Grampian 42 and Appin group strata are overprinted, transposed and re- 43 orientated into the main S2 foliation, which is axial planar to the 44 numerous minor tight to isoclinal folds that are commonly seen in 45 exposures. An upright S3 crenulation records the final deformation 46 event to have affected all strata. Mineral assemblages, 47 48 particularly in the semipelitic strata, indicate that both the 49 early gneissosity and the S2 deformation occurred under 50 amphibolite-facies metamorphic conditions. 51 52 5.3 Interpretation 53 54 Blargie Craig, originally recognized for the preservation of high- 55 strain lithologies and features of the Grampian Shear-zone 56 (Piasecki and van Breemen, 1983; Piasecki and Temperley, 1988b), 57 can now be placed in a wider lithological and structural context. 58 Following the completion of the primary survey, the lithologies of 59 the Laggan Inlier and its surrounding strata can now be fitted into 60 the regional framework. On the BGS 1:50 000 Sheet 63E (Dalwhinnie, 61 62 63 64 65 1 2 3 4 2002), definite Grampian Group strata are spatially separated from 5 an older basement succession by a heterolithic sequence containing 6 quartzites and metalimestones (Figure 13b). This sequence has 7 lithological similarities to the Kincraig Formation of the 8 Corrieyairack Subgroup at the An Suidhe GCR site. Accepting such a 9 correlation would place an emphasis and focus on the Aonach Beag 10 Slide as an important discontinuity or thrust structure juxtaposing 11 12 basement rocks against a thin cover of upward-facing and locally 13 overturned basal Grampian Group strata (Figure 13b). However, the 14 quartzites are distinctively thicker and whiter in colour and the 15 semipelites are rusty weathered and less segregated than those in 16 the Kincraig Formation and, most significantly, the metalimestones 17 have chemical signatures consistent with those in the Appin Group 18 (Thomas et al., 1997). The sequence was therefore assigned to the 19 Appin Group by Robertson and Smith (1999). 20 If the above correlation is accepted, then there is good evidence 21 along the north-western margin of the Laggan Inlier for major 22 stratigraphical omission across an unconformity between the Appin 23 Group strata and an older ‗basement‘. Although less clearly 24 evidenced than at the An Suidhe GCR site, due to the intensity of 25 the regional deformation, the basement Glen Banchor Subgroup strata 26 are affected by a gneiss-forming event prior to deposition of the 27 Grampian and Appin groups and thus the contact is an orogenic 28 unconformity. The actual plane of the unconformity, as exposed 29 30 north of Coul Farm, is unremarkable. There is no evidence for an 31 angular discordance, or for conglomerates at the base of the 32 younger succession. But across the contact, some 5–6 km of 33 Grampian Group strata are absent. Structurally, there is no 34 evidence (i.e. down-dip lineations, mylonites, veining etc) for the 35 contact being a major thrust. High ductile strains associated with 36 the Grampian Shear-zone are preserved only within Glen Banchor 37 Subgroup strata. 38 Regionally the Blargie Craig GCR site lies within the Geal-charn– 39 Ossian Steep Belt. On the basis of opposing facing directions, 40 Thomas (1979) originally interpreted this major structure as a 41 primary root-zone to the major nappes of the Central and Northern 42 Grampian Highlands. It forms the boundary between two contrasting 43 structural domains, with primary upright structures to the north- 44 west and recumbent folding to the south-east and has been re- 45 interpreted as a zone of partitioned strain, where shortening 46 during the Caledonian Orogeny was focused along an intrabasinal 47 48 high (Smith et al., 1999; Robertson and Smith, 1999). The steep 49 belt has overprinted and transposed all minor structures and 50 fabrics within all strata. Evidence cited by Piasecki (1980) from 51 elsewhere in the Northern Grampian Highlands, which suggests that 52 the Glen Banchor Subgroup rocks experienced a more-complex 53 tectonothermal history, is difficult to confirm, although the 54 presence of an early gneisossity contrasting with the preservation 55 of bedding in Grampian Group strata supports a tectonic break. The 56 Grampian Shear-zone, as at other GCR sites, is represented by thin 57 zones of enhanced ductile strain and fluid-enhanced metamorphism 58 and mineral growth within the Glen Banchor Subgroup only. The 59 timing of fabric-forming events, as evidenced by zircon and 60 61 62 63 64 65 1 2 3 4 monazite growth, is uncertain and remains to be proven 5 conclusively. 6 7 5.4 Conclusions 8 9 The Laggan Inlier, represented by the Blargie Craig GCR site, is 10 possibly unique in the Proterozoic record of Scotland in that it 11 12 preserves one of the few recorded exposures of the contact between 13 a ‘basement’ of essentially Moine-like rocks and a ‘cover’ of Grampian 14 and Appin group metasedimentary rocks. The stratigraphical 15 omission of more than 5 km of Grampian Group strata is interpreted 16 as resulting from non-deposition on an intrabasinal high during 17 Neoproterozoic rifting events (post 800–750 Ma). Subsequent 18 deformation during the Grampian Event of the Caledonian Orogeny 19 (470–450 Ma) partitioned strain between the basin and its margin. 20 The site therefore highlights the challenges involved in 21 identifying primary lithological, orogenic and structural relations 22 in a zone of intense strain in which all fabrics have been 23 transposed into a common upright orientation. 24 This GCR site is representative of the basement Glen Banchor 25 Subgroup of the Badenoch Group and preserves excellent examples of 26 the key lithologies of both this and its Dalradian cover. Sheets 27 of pegmatitic granite within the Grampian Shear-zone have yielded 28 key radiometric dates, which were crucial in the initial 29 30 identification of the older basement. 31 If the Badenoch Group successions described in The Slochd, An 32 Suidhe, and Blargie Craig GCR site reports are to be correlated 33 with the Moine Supergroup of the Northern Highlands Terrane, then 34 the present understanding of their contact with Dalradian strata 35 could question the validity of identifying separate Northern 36 Highlands and Grampian terranes. 37 38 6 RIVER E 39 (NH 541 150–554 136) 40 41 C.J. Banks 42 43 44 6.1 Introduction 45 46 The River E, which flows from the Monadhliath Mountains into the 47 48 south end of Loch Mhor, some 4 km south-east of Foyers, contains 49 excellent exposures of Grampian Group strata. The river section 50 provides a transect across the Glen Buck Pebbly Psammite Formation 51 of the Glenshirra Subgroup, exposed as a structural inlier in the 52 core of an upright F2 anticline (Figure 15). Clean-washed 53 exposures of feldspathic pebbly psammites, psammites and less 54 abundant pelites, exhibit abundant well-preserved sedimentary 55 structures, a rarity in this part of the Northern Grampian 56 Highlands due to ubiquitous metamorphism and deformation (see also 57 the Rubha na Magach and Garva Bridge GCR site reports). Slumped 58 horizons, load casts, rip-up clasts, trough and tabular cross- 59 lamination, planar lamination, grading and dewatering structures 60 are all preserved due to low strain in the hinge-zone of the major 61 62 63 64 65 1 2 3 4 fold (Figure 16). Indeed, the detail exhibited allows 5 palaeoenvironmental interpretations to be made with a resolution 6 comparable to that in undeformed Phanerozoic successions. 7 The base of the Glen Buck Pebbly Psammite Formation is nowhere 8 exposed and hence its relationship with postulated basement rocks 9 of the Badenoch Group is unknown. The upper contact, with 10 schistose semipelite and micaceous psammite of the Corrieyairack 11 12 Subgroup, defines the inlier but it is not exposed in the river 13 section described here (see the BGS 1:50 000 Sheet 73E (Foyers, 14 1996). Where seen, the contact is sharp, but it is strongly 15 deformed by a ductile shear-zone that exploited competency 16 contrasts between lithologies of the Corrieyairack and Glenshirra 17 subgroups. 18 On the BGS 1:50 000 Sheet 73E (Foyers, 1996) the rocks of the 19 inlier were included within the Gairbeinn Pebbly Psammite 20 Formation, now reassigned to member status within the Garva Bridge 21 Psammite Formation (see the Lochain Uaine and Garva Bridge GCR site 22 reports). However, a recent re-interpretation of the relationships 23 indicates a correlation with the Glen Buck Pebbly Psammite 24 Formation to the south-west (Banks and Winchester, 2004; Banks, 25 2005). 26 27 6.2 Description 28 29 30 An estate track provides easy access and the best sections occur in 31 the River E, east and north of the ruins at NH 5556 1370. The most 32 common lithology within the Glen Buck Pebbly Psammite Formation is 33 a medium-grained feldspathic psammite that occupies c. 75% of the 34 river section. Scattered angular clasts of quartz and/or K- 35 feldspar form less than 5% of the rock. This lithology varies in 36 colour from salmon pink (reflecting oxidation of iron minerals), 37 through cream (quartzose lithologies) to dark grey (more micaceous 38 lithologies). 39 These beds of feldspathic psammite have a lens, sheet or wedge 40 morphology up to 50 cm in thickness (Figure 16a). They display 41 excellent tabular and trough lamination with multiple re-activation 42 surfaces. Cross-laminated beds commonly have a pebbly lag or heavy 43 mineral concentration at their base (Figure 16b). Sets usually 44 attain c. 0.1 - 0.15 m in thickness with co-sets c. 0.2 - 0.3 m 45 thick. Ripple cross-lamination is very common and occurs at the 46 top of cross-laminated beds of psammite or pebbly psammite. 47 o 48 Psammite beds at NH 546 136 preserve low-angle (<10 ) cross-sets 49 with migration directions opposite to the surrounding background 50 tabular cross-laminae. Some rare beds thin and display a reduction 51 in clast abundance and size in a direction opposite to foreset 52 migration. 53 Common erosional scour-and-fill structures are developed at the 54 base of the feldspathic psammite units and have a deep (c. 0.05 m) 55 and narrow (c. 0.1 m) morphology with intraclasts scattered 56 throughout the scour fill. Well-developed examples occur at NH 57 5445 1410. A variety of load casts, flame structures, sand 58 volcanoes and injection structures are well developed; good 59 exposures of injection structures can be viewed at NH 5445 1410 60 (Figure 16c). 61 62 63 64 65 1 2 3 4 Pebbly psammite occupies approximately 25% of the section, and is 5 commonly matrix supported, with granule- to pebble-sized clasts of 6 single mineral grains (K-feldspar or quartz) or of 7 quartzofeldspathic aggregates, which are rarely pegmatitic. The 8 clasts are always angular, which might reflect either original 9 immature depositional texture or the synmetamorphic overgrowth of 10 detrital grains. The pebbly psammites can be divided into two 11 12 groups–beds that are internally massive (disorganized) and beds 13 that show well-developed sedimentary structures (organized). 14 Massive beds of pebbly psammite tend to form sharp, parallel-sided 15 sheets between 0.1 and 1.0 m thick, with erosive bases. Bed tops 16 may show cross-stratification, indicating later reworking. Some 17 thicker units show inverse grading from granule- to pebble-sized 18 clasts (NH 5463 1363). These massive sheets are stacked and 19 interbedded with organized beds of pebbly psammite (Figure 17). 20 Organized pebbly psammite beds are discontinuous laterally and 21 have lensoid morphologies. They can have gradational lower 22 contacts with more-massive pebbly sheets (Figure 17). Intricate 23 tabular and trough cross-stratification is well preserved. Cross- 24 strata form co-sets c. 0.1 - 0.3 m thick with sets ranging from 25 0.05 - 0.1 m thick (NH 5463 1363). 26 Semipelite forms a very minor constituent of the River E 27 succession. Where developed, it is rarely extensive, either 28 laterally or vertically. It most commonly occurs as micaceous 29 30 drapes on psammitic cross-laminae or as thicker lenses between 31 psammitic macroforms. No internal sedimentary fabric or texture is 32 preserved in this lithology as a consequence of coarse-grained 33 recrystallization during regional metamorphism. 34 Slumped bedding forms a relatively minor, but locally important, 35 component of the stratigraphical succession described here. 36 Beautifully preserved, contorted and folded slumped layers up to 2 37 m thick occur at NH 5460 1367. These slump folds occur within 38 layers that are demonstrably stratabound by planar beds; the slump 39 structures have no systematic axial trend and are disharmonic to 40 the regional fabric. 41 42 6.3 Interpretation 43 44 The metasedimentary rocks exposed within the River E inlier, are 45 interpreted as having been deposited within alluvial and fluvial 46 environments. The assemblages of sedimentary structures indicate 47 48 that two depositional processes were dominant: sediment gravity 49 flows (debris flows and slumps) and traction currents. 50 Disorganized and massive, matrix-supported pebbly psammite sheets 51 indicate deposition by cohesive debris flows (Miall, 1992). Rare 52 inverse grading suggests that significant dispersive pressures 53 (probably from grain collision) operated within these flows (the 54 density-modified-grain flow of Lowe, 1976). Flows eroded the 55 underlying substrate but were gradational with, and reworked by, 56 stream flows as is suggested by the development of cross-lamination 57 in pebbly sheet tops. 58 Sediment gravity flows are also represented by slumped units. 59 These indicate failure and collapse of a topographical high (a bank 60 or cliff) perhaps by fluvial undercutting. The intensity and 61 62 63 64 65 1 2 3 4 ductile nature of the slumped folding suggest that these sediments 5 were unlithified and water saturated when this occurred. 6 Well-developed tabular and trough cross-lamination within 7 organized pebbly psammite and psammite indicate deposition by 8 traction currents. Considering the palaeo-grain size of the 9 sediment, these traction currents would have been almost certainly 10 subaqueous; no indication of aeolian processes has been found. The 11 12 dominance of tabular cross-stratification indicates the common 13 accretion of straight-crested ripples and dunes. The rarer 14 occurence of trough cross-bedding is the result of higher velocity 15 flows creating more-linguoid ripples and lunate dunes (Allen, 16 1963). Weaker, dilute traction currents are indicated by 17 developments of ripple lamination within non-pebbly units. The 18 unidirectional nature of the tabular cross-sets indicates a 19 consistent migration direction of these fluvial sand bodies, which 20 could be either downstream or lateral. Rare low-angle cross-sets 21 with palaeocurrents opposite to the general trend indicate the 22 development of antidunes, where standing waves promote upstream 23 migration of bedforms. 24 Common scour-and-fill structures suggest very high current 25 velocities eroding the substrate. Deep, narrow scours and 26 intraclast-rich scour-fills suggest coarse bedload abrasion rather 27 than fluid erosion of the substrate (Collinson and Thompson, 1988). 28 Rapid deposition onto a water-saturated substrate is recorded by 29 30 common dewatering structures. 31 The pebbly and feldspathic psammites exposed in the River E 32 therefore represent a variety of lateral and downstream accretion 33 architectural elements (sensu Miall, 1985). However, due to poor 34 lateral continuity of exposure away from the river section, three- 35 dimensional control on the geometry of these sand bodies is 36 difficult to establish. 37 The pebbly deposits are interpreted as longitudinal gravel bars, 38 point bars, thoroughly reworked debris flows or sheet-flood 39 deposits. The non-pebbly deposits represent a spectrum of sand 40 bars, sand waves, dunes and ripples. Some of these non-pebbly 41 psammite beds represent point bars as is suggested by lateral 42 grain-size reduction in the opposite direction to palaeocurrents. 43 Palaeocurrents reflect lateral migration of bars, whilst lateral 44 grain-size reduction indicates flows becoming weaker up the bar 45 (Miall, 1992). 46 The quartz-K-feldspar-dominated clast population indicates that 47 48 both the debris flows and the river systems were fed from a 49 quartzofeldspathic gneissose or granitic hinterland. 50 51 6.4 Conclusions 52 53 This near-continuous section in the River E exhibits some of the 54 most spectacular Neoproterozoic sedimentary structures in Britain. 55 Here, feldspathic pebbly psammites crop out in the core of an 56 upright F2 antiform, where the amount of strain is far less than is 57 usual in the Northern Grampian Highlands, preserving excellent 58 examples of sedimentary slumping, load casts, rip-up clasts, trough 59 and tabular cross-lamination, planar lamination, grading and 60 dewatering structures. 61 62 63 64 65 1 2 3 4 The strata are representative of the Glenshirra Subgroup, the 5 lowest division of the Grampian Group and the detailed evidence at 6 this site indicates that the original sediments were deposited 7 within continental alluvial and fluvial environments. Traction 8 deposition of a mixed sandy and gravely bedload took place in 9 braided river systems. This palaeoenvironment was subject to 10 influx of debris flows that introduced coarse clastic sediment 11 12 sourced from a nearby quartzofeldspathic gneissose or granitic 13 terrane. 14 15 7 GARVA BRIDGE 16 (NN 524 953) 17 18 S. Robertson 19 20 21 7.1 Introduction 22 23 The environs of Garva Bridge, in the upper catchment of the River 24 Spey, are the type area for the Glenshirra Subgroup, the oldest 25 part of the Dalradian Supergroup. The sedimentological detail 26 preserved at this GCR site in the lower stretch of the Allt Coire 27 Iain Oig, together with the lithological features observed in the 28 surrounding area, are highly pertinent to interpretations of basin 29 30 evolution for the lower part of the Grampian Group. 31 The Glenshirra Subgroup crops out in a near-circular inlier 2 32 covering approximately 30 km and informally referred to as the 33 Glenshirra Dome (Figures 18, 19). This dome dominates the outcrop 34 pattern in the north-west corner of the BGS 1:50 000 Sheet 63E 35 (Dalwhinnie, 2002). It is cut by The Allt Crom Complex in the 36 north-east and by the Corrieyairack Pluton in the south-west. The 37 stratigraphy was originally described by Haselock et al. (1982), 38 who recognized four formations in the north of the dome, and 39 Okonkwo (1988) who recognized two formations in the south. Recent 40 detailed surveying has replaced these with a single formation, the 41 Garva Bridge Psammite Formation, containing a distinctive pebbly 42 psammite (the Gairbeinn Pebbly Psammite Member). Haselock and 43 Leslie (1992) demonstrated the distinctively strong magnetic nature 44 of the Gairbeinn Pebbly Psammite Member and used that 45 characteristic to help define lithological boundaries in unexposed 46 ground. Any discrepancies between the published map and the 47 48 earlier studies result largely from previously unrecognized fold 49 repetition. 50 The boundary between the Garva Bridge Psammite Formation and the 51 overlying Coire nan Laogh Semipelite Formation of the Corrieyairack 52 Subgroup was recognized as a zone of high strain referred to as the 53 Gairbeinn Slide (Haselock et al., 1982; Okonkwo, 1988). However, 54 recent investigations have concluded that the high strain is 55 focused at the boundary between contrasting lithologies within a 56 conformable succession (Smith et al., 1999). Comparative 57 geochemical studies (Haselock, 1984) and sedimentological analysis 58 (Glover et al., 1995; Glover, 1998; Banks and Winchester, 2004) 59 have emphasized the distinctive immature fluviatile to shallow- 60 marine nature of the Glenshirra Subgroup, which is in sharp 61 62 63 64 65 1 2 3 4 contrast to the deeper marine, turbiditic nature of the succeeding 5 Corrieyairack Subgroup. Banks and Winchester (2004) identified 6 this change in sedimentary environment as a sharp sequence 7 boundary, recording a major reorganization of basin architecture. 8 They considered this to be so significant as to warrant elevation 9 of the Glenshirra sequence from subgroup to group status. However, 10 this has not been adopted in this special issue. 11 12 13 7.2 Description 14 15 The Garva Bridge Psammite Formation consists mainly of psammite 16 with lesser amounts of micaceous psammite and thin beds of 17 semipelite. The formation is well exposed in the north bank 18 tributaries to the River Spey, including the Allt Coire Iain Oig 19 and Allt a’ Ghamnha, and in hillside exposures around Gairbeinn (NN 20 46 98). On Creag Mhor (NN 488 974) the succession is relatively 21 more micaceous with common thin beds of semipelite. The base of 22 the formation is not exposed and therefore the 2 km observed 23 thickness provides a minimum estimate only. The following detailed 24 descriptions are based largely on those of Glover (1998). 25 The formation comprises two lithological associations; a psammite 26 association that occurs near the base of the succession and a 27 heterolithic association of psammite, micaceous psammite and 28 semipelite. The heterolithic association is dominant and, while it 29 30 occurs both above and below the psammite association, it broadly 31 overlies the psammite association; the relationships are well 32 exposed in the Allt Coire Iain Oig section (NN 519 979 to NN 524 33 949), which includes the designated Garva Bridge GCR site at NN 524 34 953. 35 Rocks of the psammite association are typically pink and range 36 from well bedded with cross-bedding in the Allt a‘ Ghamnha section 37 (NN 491 958 to NN 483 975), to massive and, in places, flaggy and 38 coarse grained with increasing deformation and recrystallization in 39 the Allt Coire Iain Oig (NN 519 979 to NN 524 949). In the Allt a‘ 40 Ghamnha, where the association is approximately 500 m thick, 41 individual gently lensoid psammite bodies up to several metres 42 thick are stacked vertically and are inferred to overlap laterally. 43 Each psammite body is made up of a number of cross-bedded sets 44 arranged into thinning upwards packages. Tectonic flattening has 45 greatly reduced intersection angles, both at set-bounding surfaces 46 such that cross-bedding is not prominent and at psammite body 47 48 boundaries (Glover, 1998). 49 The heterolithic association in the Allt Coire Iain Oig shows 50 interdigitation of psammite, micaceous psammite and semipelite on 51 centimetre to metre scales (Figure 20a). Sedimentary structures 52 are widely preserved in spite of the metamorphic recrystallization, 53 largely as a result of original mud drapes which, as thin 54 semipelitic or pelitic selvedges, now accentuate relict bedding 55 structures. Psammite-dominated parts of the association show 56 small-scale cross-bedding and planar bedding, ripple cross- 57 lamination and local features thought to be hummocky cross- 58 stratification. Feldspar augen are interpreted as metamorphic 59 overgrowths on originally smaller detrital grains. In the muddier 60 parts of the association, sharp-based white or pale-grey psammites 61 62 63 64 65 1 2 3 4 pass gradually upwards and downwards into progressively more- 5 micaceous (originally muddier) lithologies in stacked metre-scale 6 cycles. The gradual change occurs through a series of sharp-based 7 thin and medium beds (3 to 50 cm). These show a variety of 8 sedimentary structures including ripple cross-lamination and cross- 9 bedding, scour and gutter casts, convolute laminations and local 10 normally graded bedding. 11 12 The Gairbeinn Pebbly Psammite Member is restricted to the north- 13 western part of the Glenshirra Dome and is best seen on the slopes 14 of Gairbeinn (NN 464 985). The member is lithologically similar to 15 the remainder of the formation but also includes coarser grained 16 beds, which become pebbly towards the top of the formation (Figure 17 20b). The pebbles are composed entirely of quartz and, whilst now 18 significantly flattened, are interpreted to have been originally up 19 to 3 cm in diameter. Pebbles occur within beds of micaceous 20 psammite and less commonly in psammite, with bed thickness 21 typically less than 0.3 m but locally up to 1 m. Pebbly beds 22 typically account for 10% of the member. 23 The Garva Bridge Psammite Formation thickens markedly towards the 24 north-west. This is largely a result of the much greater thickness 25 of the psammite association and is enhanced by the spatial 26 restriction of the pebbly psammite member referred to above. The 27 heterolithic association generally overlies the psammite 28 association, albeit with some possible interdigitation in the 29 30 south-east. 31 The contact between the Gairbeinn Pebbly Psammite Member and the 32 overlying Coire nan Laogh Semipelite Formation is almost 33 continuously exposed along the eastern slopes of Gairbeinn (NN 462 34 986). Within 60 m of the contact, the Gairbeinn Pebbly Psammite is 35 platy with both intense flattening and elongation of pebbles down 36 dip to the north-west. The base of the Coire nan Laogh Semipelite 37 Formation is represented by an abrupt change to schistose to 38 gneissose semipelite with quartzofeldspathic layers and lenses up 39 to a few millimetres across. A few lenses of quartzite occur in 40 the lower few metres of the formation, but otherwise the semipelite 41 is homogeneous. The upper parts of the formation are marked by an 42 increase in the proportion of psammite layers. These form the 43 lower parts of composite psammite-semipelite beds which reflect 44 graded bedding. The incoming of psammite layers marks a 45 progressive transition into the overlying dominantly psammitic Loch 46 Laggan Psammite Formation (see the Rubha na Magach GCR site 47 48 report). 49 Deformation and amphibolite-facies metamorphic recrystallization 50 are variably intense. The succession is generally the right way 51 up, although SE-verging small-scale fold structures are present 52 locally, and a SW-closing and SE-verging medium-scale reclined 53 fold-pair in the Creag Mhor area (NN 486 970) repeats part of the 54 succession. 55 Structures related to three phases of deformation can be 56 recognized across the area. An intense schistosity is developed 57 parallel to bedding planes in micaceous lithologies during the D1 58 phase and, although no discrete F1 folds have been recognized, this 59 bedding-parallel schistosity is crenulated in the hinge-zone of F2 60 folds. The majority of the minor F2 folds have a consistent south- 61 62 63 64 65 1 2 3 4 easterly vergence; where abundant as on Creag Mhor, the F2 folding 5 is accompanied by intense crenulation of the S1 schistosity. These 6 crenulations, and a rodding in quartzofeldspathic segregations, 7 give rise to a prominent L2 lineation; the dominant planar 8 schistosity is probably in reality a composite D1-D2 structure and 9 lies parallel to lithological layering. The shape of the 10 Glenshirra Dome is controlled by a major antiformal F3 fold. Minor 11 12 open folds of probable D3 age occur at NN 4936 9660 and 13 intersecting crenulations occur in many semipelite exposures. 14 Distinguishing S2 and S3 crenulations is however difficult due to 15 the variable orientation of the S2 axial surfaces and the lack of 16 any significant development of a crenulation cleavage in either the 17 D2 or the D3 phase of deformation. 18 19 7.3 Interpretation 20 21 A combination of lithological associations, bedforms and 22 sedimentary structures, albeit modified by deformation and 23 metamorphic recrystallization, allow an interpretation of the 24 depositional environment of the Glenshirra Subgroup. Cross-bedding 25 within the psammite association demonstrates that these strata were 26 deposited largely from traction-dominated currents. The stacking 27 of sandstone bodies, each comprising thinning upward sets, is 28 consistent with deposition as bedforms and barforms within a 29 30 fluvial setting. The absence of intervening primary mud deposition 31 suggests little preservation of overbank material. This could have 32 been due either to a braided-river environment or the lack of 33 vegetation available in the Neoproterozoic to bind overbank 34 material. 35 The variety of sedimentary structures in the heterolithic 36 association, including ripple cross-lamination and cross-bedding, 37 scour and gutter casts, hummocky cross-stratification, convolute 38 laminations and local normally graded bedding point to deposition 39 in a shallow-marine storm-influenced environment. The cleaning and 40 muddying upward cycles are interpreted as having been controlled by 41 changes in relative sea level (Glover, 1998). 42 The depositional environment of the Gairbeinn Pebbly Psammite 43 Member cannot be well constrained because of the absence of well- 44 preserved sedimentary structures. It is inferred to have been 45 dominantly fluvial, with the muddy pebbly rocks possibly the 46 product of mass flow rather than traction (Glover, 1998). 47 48 The overall geometry of the depositional basin (Figure 21) can be 49 inferred from the gross disposition and thickness of the 50 lithological associations outlined in Figure 19. A number of 51 features suggest that the north-western part of the dome represents 52 a more-proximal environment. These include a greater thickness of 53 both the psammite association and of the succession as a whole. 54 Additionally, the Gairbeinn Pebbly Psammite Member is only present 55 in the north-west, whereas the heterolithic association is dominant 56 in the south-east. These observations reflect a lateral facies 57 change from dominantly fluvial in the north-west to shallow-marine, 58 storm-dominated facies in the south-east. 59 The overall evolution of the Glenshirra Subgroup is interpreted as 60 a gradual north-westwards backstepping of fluvial facies and a 61 62 63 64 65 1 2 3 4 concomitant increase in the distribution of shallow-marine 5 sedimentation (Glover, 1998) with a renewed phase of more-extensive 6 fluvial deposition close to the top of the formation. 7 The abrupt change from psammites that represent fluvial deposits 8 to semipelite derived from muddy sediments at the base of the Coire 9 nan Laogh Semipelite Formation, is interpreted as representing a 10 major basin-flooding event (Banks and Winchester, 2004). This 11 12 starved the basin of coarse clastic material and led to the 13 deposition of offshore mud. Progressive basin deepening led to the 14 onset of deposition by turbidity currents in the upper part of the 15 formation. Quartz-rich lenses near the base of the semipelite may 16 represent reworking of the underlying originally sandy deposits in 17 an offshore environment. 18 19 7.4 Conclusions 20 21 The Garva Bridge GCR site represents the original type-area for the 22 Glenshirra Subgroup and preserves evidence relating to the 23 depositional environment and basin geometry of the lowest exposed 24 part of the Dalradian succession. The combination of lithological 25 associations and sedimentary structures in the Garva Bridge 26 Psammite Formation demonstrate that fluvial sediments passed 27 laterally to the south-east into shallow-marine, storm-influenced 28 sediments. Through time, the area of fluvial deposition back- 29 30 stepped towards the north, to be replaced by more-extensive 31 shallow-marine deposition. A major flooding event marked by an 32 abrupt change of lithology at the base of the Coire nan Laogh 33 Semipelite Formation cut off the sand-grade sediment supply. This 34 was probably related to basin deepening, which resulted in the 35 onset of deposition from turbidity currents. 36 37 8 RUBHA NA MAGACH 38 (NN 4603 8495–NN 4660 8522) 39 40 C.J. Banks 41 42 43 8.1 Introduction 44 45 The Grampian Group rocks that underlie much of the Northern 46 Grampian Highlands have been divided by Harris et al. (1994) into 47 48 the Glenshirra (oldest), Corrieyairack and Glen Spean (youngest) 49 subgroups. The Corrieyairack Subgroup attains its greatest 50 thickness (c. 5.5 km) in the area surrounding Loch Laggan (Figure 51 22). Smith et al. (1999) postulated that this might represent the 52 depocentre of an intercratonic rift basin, which they termed the 53 Corrieyairack Basin. 54 Clean water-washed sections on the north shore of Loch Laggan at 55 Rubha na Magach, provide some of the most informative exposures of 56 the Loch Laggan Psammite Formation, which account for some 3.6 km 57 thickness of the Corrieyairack Subgroup. Details of primary 58 sedimentological features are commonly preserved in the micaceous 59 psammites and semipelites of this formation, despite simple upright 60 F2 folding and the effects of metamorphic recrystallization under 61 62 63 64 65 1 2 3 4 amphibolite-facies conditions (c. 500–600°C, 5–8 kbar, Phillips et 5 al., 1999). Sedimentological analysis of excellent exposures in an 6 area of low tectonic strain at Rubha na Magach allows 7 characterization of the depositional systems for the postulated 8 basin depocentre. 9 The exposures at Rubha na Magach (NN 4618 8492) were first 10 described by Winchester and Glover (1988), who noted the 11 12 extraordinarily detailed preservation of such sedimentary 13 structures as cross-bedding, rip-up clasts and convolute bedding. 14 Subsequent descriptions by Glover (1989) and by Glover and 15 Winchester (1989) incorporated palaeo-environmental 16 interpretations. A useful field description with maps and 17 photographs was provided by Winchester and Glover (1991). The site 18 is included within BGS 1:50 000 Sheet 63E (Dalwhinnie, 2002). 19 20 8.2 Description 21 22 The Loch Laggan Psammite Formation comprises grey psammite and 23 micaceous psammite with subordinate thin semipelite. These 24 lithologies occur in the form of massive and graded beds. The 25 graded bedding and several observation of cross-lamination indicate 26 that the formation is the right way up. 27 The most-informative localities can be seen on the Rubha na Magach 28 promontory (NN 4618 8492) and at a lochside exposure 300 m to the 29 30 east at NN 4653 8516. Both exposures lie on the south-east limb of 31 the F2 Laggan Antiform; bedding and a bedding-parallel foliation

32 dip at c. 60° to the south-east and bedding is the right way up. 33 Measured logs of both exposures are provided in Figure 23. A 34 heterolithic association of interbedded psammite, micaceous 35 psammite, and dark micaceous psammite with semipelite is exposed. 36 Beds commonly have tabular, parallel-bedded forms and are laterally 37 persistent on the scale of the exposures. Coarse-grained 38 metamorphic recrystallization of the semipelitic component has 39 resulted in scant preservation of sedimentary detail so that it is 40 only possible to infer that it is likely to represent original 41 mudstone. In contrast, the micaceous psammite has well-preserved 42 and commonly very intricate sedimentary structures (Figure 24). 43 The most-common sedimentary structure is normal grading. 44 Recrystallization during metamorphism has affected the mineralogy 45 and grain size so that original grading is defined by an upward 46 increase in mica content. Psammitic beds consequently have a 47 48 pseudo-coarsening-upward appearance as they grade into semipelite. 49 Most psammitic beds have graded tops but some massive psammite does 50 occur. A discontinuous planar lamination is also very common and 51 is usually confined to the micaceous psammites. 52 Climbing ripple (ripple-drift) cross-lamination is beautifully 53 preserved in the micaceous psammites at Rubha na Magach (Figure 54 24a). Both stoss-side preservation (so that cross-laminae are 55 continuous) and stoss-side erosion surfaces are preserved. Packets 56 of cross-laminae are commonly c. 10 cm thick and occur at discrete 57 horizons in individual beds. As with the planar lamination, these 58 are most commonly found in the micaceous psammites. 59 Convolute lamination can be viewed where thick psammite beds 60 overlie originally planar-laminated micaceous psammite (Figure 61 62 63 64 65 1 2 3 4 24b). Rare beds of micaceous psammite with convolute lamination 5 show bulbous basal projections thought to be load structures (best 6 seen at NN 4653 8516). Such structures are only very rarely 7 preserved in the Loch Laggan Psammite Formation, any such basal 8 projections typically having been removed by shearing along bedding 9 surfaces during folding. 10 Low-angle scours that cut off the underlying sedimentary 11 12 structures occur in a number of places and many beds have a very 13 sharp base. The scours are also marked in places by lines of rip- 14 up clasts. Small rip-up clasts, 5-10 cm long and several 15 centimetres thick, have been found at NN 4618 8492. The clasts are 16 usually of dark micaceous psammite or semipelite within more- 17 psammitic beds. Some clasts show original lamination, twisted 18 concordantly with the shape of the clast. These are usually seen 19 at the interface between two psammite or micaceous psammite beds 20 suggesting that significant amounts of bed amalgamation might have 21 occurred. 22 Okonkwo (1985) noted a common repetitive sequence of sedimentary 23 structures, similar to that reported by Bouma (1962) for the 24 deposits of turbidity currents. Okonkwo (1985) described a basal 25 massive sandy layer overlain in turn by a lower planar laminated 26 horizon, then a cross-laminated horizon, then an upper planar 27 laminated horizon and finally by a mud corresponding respectively 28 to the Ta, Tb, Tc, Td and Te divisions of the Bouma sequence 29 30 (Bouma, 1962). 31 Two principal lithofacies associations are present at Rubha na 32 Magach and are shown in the sedimentary logs of Figure 23. The 33 first consists of thick-bedded massive psammite, micaceous psammite 34 and thin semipelite, forming complete Bouma (i.e. Ta–e) and base- 35 missing Bouma (i.e. Tb–e, Tc–e, Td–e) sequences. These have very 36 well-developed sedimentary structures and are well graded. The 37 second lithofacies consists of thin-bedded micaceous to highly 38 micaceous psammite interbedded with more-thickly developed 39 semipelite. This second lithofacies usually shows planar 40 lamination and good grading. Taken together, the two lithofacies 41 form c. 15 m-thick packages. The thick-bedded lithofacies 42 association commonly shows a crude thinning and fining upwards into 43 the thinner bedded one. 44 These localities have several other notable features. Prominent 45 white calcsilicate pods, originally diagenetic calcareous 46 concretions, have the assemblage garnet-hornblende-clinozoisite- 47 48 andesine-quartz, thus indicating that amphibolite-facies conditions 49 were attained during regional metamorphism (Winchester, 1974). The 50 metasedimentary rocks are cut by several suites of pegmatitic veins 51 and felsic dykes (the Loch Laggan Vein-complex), some of which are 52 quite spectacular, as in the road cuttings at NN 4760 8615 and NN 53 4721 8593. 54 55 8.3 Interpretation 56 57 The abundant sedimentary structures in the psammites and micaceous 58 psammites suggest deposition by high-energy, fast-flowing and 59 turbulent currents. In contrast, the semipelitic lithologies 60 suggest a quieter environment of deposition dominated by the 61 62 63 64 65 1 2 3 4 settling out of suspended fine sediment. These interpretations, 5 along with the identification of Bouma sequences, support the 6 interpretation of Okonkwo (1985), that these sediments were 7 deposited by turbidity currents. 8 The grain size of the original sediment (sand to mud grade) and 9 the sedimentary structures present are consistent with a turbidity 10 current origin. The thicker bedded, coarser grained lithofacies 11 12 association represents relatively high-density, sand-laden 13 turbidity currents and possible tractional processes. As these 14 high-density turbidity currents could scour the existing substrate 15 and deposit sand on top of it, the resultant beds are sharp based 16 and commonly show amalgamation with the underlying sand beds. 17 Rapid deposition is suggested at Rubha na Magach by scouring, rip- 18 up clasts and convoluted lamination. The overlying, thinner bedded 19 and muddier lithofacies association was deposited by much less- 20 dense turbidity flows. Between periods of turbidity flow, periods 21 of quiescence allowed sediment to fall out of suspension and form a 22 silt or mud layer (now semipelite). 23 Glover (1989) and Glover et al. (1995) assigned these 24 metasedimentary rocks to more-specific turbidite elements (sensu 25 Mutti and Normark, 1987) and concluded that the Loch Laggan 26 Psammite Formation represents an inner fan channel system. Mutti 27 and Normark (1987), comparing multiple examples of ancient and 28 modern turbidite successions, decribed similar lithofacies 29 30 associations to the Loch Laggan Psammite Formation in channel 31 systems where erosional and depositional processes took place. 32 Such channels acted as conduits for powerful high-density turbidity 33 currents, such as those inferred here for the thicker lithofacies 34 association in the Loch Laggan Psammite Formation. More-dilute and 35 less-powerful flows dominated the inter-channel areas. Inter-flow 36 times were marked by a laterally persistent mud blanket 37 (semipelite). Thus, in broad agreement with Glover et al. (1995), 38 the lithofacies associations observed at Rubha na Magach are 39 interpreted here as inner fan in-channel- and channel-related 40 deposition. The complex channel systems were of mixed erosional– 41 depositional type. 42 43 8.4 Conclusions 44 45 Rubha na Magach is a nationally important site for its excellent 46 exposures of Neoproterozoic turbiditic sequences in the Grampian 47 48 Group. These are the most-instructive exposures of the Loch Laggan 49 Formation, the dominant formation of the Corrieyairack Subgroup and 50 are particularly important in developing an understanding of the 51 overall palaeo-environment of the basin depocentre, which was 52 situated in the Loch Laggan area. The more-typical complex 53 deformation and metamorphism of the Northern Grampian Highlands are 54 less well developed here, enabling the application of 55 sedimentological techniques that are more readily applied to 56 undeformed Phanerozoic successions. 57 A vertical sequence of sedimentary structures, comparable with 58 that of Bouma (1962), is well preserved. This consists of a basal 59 massive division (Ta) overlain in turn by a lower planar-laminated 60 division (Tb), a cross-laminated division (Tc), an upper planar- 61 62 63 64 65 1 2 3 4 laminated division (Td) and is capped by semipelite (mud, Te). The 5 preservation of rip-up clasts, scours and the sharp-based nature of 6 the beds indicate that these turbiity currents were of very high 7 density and it is concluded that the Loch Laggan Psammite Formation 8 was deposited by turbidity currents in a sub-marine channel system. 9 10 11 9 KINLOCH LAGGAN ROAD A86 12 (NN 5440 8975–NN 5500 8980) 13 14 S. Robertson 15 16 17 9.1 Introduction 18 19 A number of boulder beds interpreted to be of glacial origin have 20 been recognized within the Grampian Highlands. Their significance 21 lies not only in their record of the Earth’s past glacial history 22 but also in their potential value as chronostratigraphical markers. 23 The thickest and most extensively developed is the Port Askaig 24 Tillite, which can be traced from the type area on the Isle of 25 Islay, north-eastwards through Perthshire and into the North-east 26 Grampian Highlands (see the Garvellach Isles, Tempar Burn and 27 Muckle Fergie Burn GCR site reports in Tanner et al., 2013a, 28 Treagus et al., 2013 and Stephenson et al., 2013b respectively). 29 30 Other boulder beds are much more restricted in their geographical 31 occurrence. The Kinloch Laggan road section contains the type 32 locality for the Kinlochlaggan Boulder Bed. Here, adjacent 33 lithologies allow the stratigraphical position of the boulder bed 34 to be determined and the excellent glacially smoothed exposures 35 have prompted some re-assessment of the nature of the deposit. The 36 results of recent mapping by the British Geological Survey on 1:50 37 000 Sheet 63E (Dalwhinnie, 2002) have traced lenticular occurrences 38 of boulder bed to the south-west along the west-north-west limb and 39 around the hinge of the major Kinlochlaggan Syncline (see the 40 Aonach Beag and Geal-charn GCR site report). 41 The Kinlochlaggan Boulder Bed was first recognized and interpreted 42 as glacial in origin by Treagus (1969). The unit occurs within a 43 sequence of quartzites, pelites and metacarbonate rocks that were 44 attributed by Treagus to the lower part of the ‗Ballachulish 45 succession‘ of the Dalradian. The succession was thought to occur 46 within the core of the Kinlochlaggan Syncline and to be surrounded 47 48 by older rocks of the ‗Moine Series‘ (Anderson, 1947b, 1956; Smith, 49 1968), the latter now assigned to the Grampian Group. Subsequent 50 work has generally assigned the boulder bed more precisely to the 51 Lochaber Subgroup of the Appin Group (Thomas, 1979; Treagus, 1981; 52 Robertson and Smith, 1999). However, Piasecki and Temperley 53 (1988a) equated the succession at Kinloch Laggan, including the 54 boulder bed, with the ‗Ord Ban Subgroup‘, now the Kincraig 55 Formation at the base of the Corrieyairack Subgroup of the Grampian 56 Group. At the opposite extreme, Evans and Tanner (1996) suggested 57 that the boulder bed is equivalent to the Port Askaig Tillite at 58 the base of the Islay Subgroup of the Argyll Group. 59 60 61 62 63 64 65 1 2 3 4 9.2 Description 5 6 The type locality for the Kinlochlaggan Boulder Bed is a small 7 roche moutonnée beside the A86 road at Kinloch Laggan (NN 548 897) 8 (Figure 25). The boulder bed occurs within a near-vertical, NNE- 9 striking succession of quartzite, semipelite, metacarbonate-rock 10 and calcsilicate rock exposed on the west-north-west limb of the 11 12 upright Kinlochlaggan Syncline (Anderson, 1947b). 13 The boulder bed consists of a sequence, over 20 m thick, of 14 quartzite and psammite. The north-western part comprises 7 m of 15 massive pebbly quartzose psammite or quartzite that is apparently 16 unbedded apart from some poorly developed micaceous partings and 17 colour lamination. Clasts are relatively abundant, poorly sorted, 18 matrix supported and unevenly distributed (Figure 26). Treagus 19 (1969, 1981) recognized ‗several thousand stones‘ per square metre 20 within the size range 3 to 30 mm. Most clasts are less than 3 cm 21 long and many are less than 1 cm with only 20 counted in the range 22 8 to 10 cm. Treagus reported that approximately 75% of the 23 ‗stones‘ are of alkali granite with the remainder being quartzite, 24 pelite or semipelite. Numerous pink feldspars could be either 25 clasts or porphyroblasts, whereas quartz-feldspar aggregates are 26 thought to be clasts. Numerous weathered-out hollows on exposed 27 surfaces are thought to indicate former positions of clasts. One 28 clast of semipelite is 9 cm long and 1.5 cm across and contains two 29 30 tectonic fabrics, the later of which is parallel to both the long 31 axis of the clast and the fabric in the host quartzite. Only one 32 large boulder is present. This is 40 cm by 16 cm, subrounded and 33 composed of granite. It contains a foliation parallel to both the 34 long axis of the boulder and the fabric in the host quartzite. 35 The clast-bearing lithology is succeeded to the south-east by 6 m 36 of non-pebbly psammite and then by 7 m of psammite containing 37 scattered clasts that are lithologically similar to those in the 38 first unit. Only 6 clasts in the size range 8 to 10 cm have been 39 recognized; smaller 3 to 30 mm clasts are more abundant but widely 40 scattered. Treagus (1969) reported traces of bedding lamination 41 and that the bedding planes are deformed locally in the matrix 42 beneath some of the clasts. Thin granite veins cross-cut the 43 second clast-bearing unit. 44 The contacts between the boulder bed and the adjacent lithologies 45 are not exposed in the road section. The nearest exposures of the 46 Kinlochlaggan Quartzite Formation are 60 m away to the west, 47 48 forming the prominent cliffs behind Kinloch Laggan village hall and 49 smaller exposures on the roadside. There are no exposures in the 50 intervening ground. However, 16 km to the south-west, both in 51 Coire Cheap (NN 4176 7566) and near Aonach Beag (NN 4554 7375), the 52 boulder bed is seen to be conformable with the quartzite. 53 Furthermore, preserved cross-bedding in the Coire Cheap area 54 clearly shows that the quartzite underlies the boulder bed. 55 At Kinloch Laggan, the Kinlochlaggan Quartzite comprises 150-200 m 56 of massive white quartzite with bedding defined only by variations 57 in colour. Large, white to pink feldspar crystals are a widespread 58 feature. Two subangular granitic clasts 15 mm long occur in 59 roadside exposures at NN 5459 8976. Younging evidence is sparse 60 61 62 63 64 65 1 2 3 4 and is confined to possible examples of cross-bedding, which do not 5 give a conclusive answer. 6 The quartzite is well exposed and forms numerous glacially 7 smoothed surfaces on the hillside along strike to the north-east. 8 Vertical faces at NN 556 906 show prominent gently plunging rodding 9 lineations. Some surfaces show two slightly oblique linear 10 structures, an earlier rodding lineation, which is co-axial with 11 12 the large-scale folds such as the Kinlochlaggan Syncline, and a 13 later lineation marked by the hinges of small-scale crenulations or 14 corrugations. 15 The Kinlochlaggan Quartzite overlies a dominantly semipelitic unit 16 referred to as the Aonach Beag Semipelite Formation. The contact 17 between the semipelite and the quartzite is gradational through a 18 zone of interbedded quartzite and semipelite that is well exposed 19 on the hillslope to the north-west of Kinloch Laggan around NN 551 20 904. The contact between the lowest exposed part of the semipelite 21 and the Grampian Group to the north-west is interpreted as a slide 22 (Figure 25). However, to the south-west, in the Coire Cheap area, 23 the contact is locally conformable and transitional (Robertson and 24 Smith, 1999). 25 To the east of the boulder bed, the overlying succession is 26 dominated by metacarbonate rocks, calcsilicate rocks and 27 semipelites assigned to the Coire Cheap Formation. Amphibolite 28 sheets are widespread. The nearest exposures to the boulder bed, 29 30 less than 10 m away across strike, occur in a small disused 31 limestone quarry. On the west wall of this quarry, 32 stratigraphically closest to the boulder bed, 1 m of schistose 33 biotite-muscovite semipelite is succeeded to the east by 34 approximately 1 m of biotite semipelite composed of biotite, 35 plagioclase, quartz, clinozoisite and accessory tourmaline. Some 36 20 to 30 cm of vein quartz separates this from c. 16 m of 37 metacarbonate rock. The lowest part of the metacarbonate rock is 38 pale grey and contains both dolomite and calcite. The remainder is 39 massive, coarsely crystalline and grey-blue with brown-weathering 40 surfaces. Micaceous partings separate metre-thick units of 41 metacarbonate rock. Brown-weathering upstanding ribs, resulting 42 from a greater abundance of calcsilicate minerals, show tight to 43 isoclinal folds with a strong co-axial ribbing lineation. 44 Approximately 1 m of rusty-weathering biotite semipelite occurs on 45 the east wall of the quarry. A second quarry immediately to the 46 east contains 13 m of metacarbonate rock that is lithologically 47 48 similar to the bulk of the first quarry. Farther to the east, 49 schistose semipelite to pelite contains a 3 m-wide sheet of garnet 50 amphibolite; the garnets are largely replaced by feldspar. 51 52 9.3 Interpretation 53 54 The Kinlochlaggan Boulder Bed has been interpreted as glacial in 55 origin on the basis of the occurrence of matrix-supported 56 extrabasinal granite clasts, and the unbedded psammite units 57 containing the clasts were originally interpreted as tillites 58 (Treagus 1969, 1981). However, the quartz-rich and mica-poor 59 character of the sequence indicates that it was derived from a 60 relatively mature sandy sediment, more typical of a clastic water- 61 62 63 64 65 1 2 3 4 lain origin than a subglacial till. The immediately underlying 5 quartzites of the Kinlochlaggan Quartzite are likely to have 6 originated on a shallow marine shelf. Therefore the extrabasinal 7 clasts are best interpreted as ice-rafted dropstones, a feature 8 supported by the apparent deformed bedding lamination beneath some 9 clasts reported by Treagus (1969). These features are preserved in 10 spite of intense folding and metamorphic recrystallization at 11 12 kyanite to sillimanite grade. 13 The boulder bed occurs within a heterogeneous succession of 14 semipelites, quartzites and metacarbonate rocks, which 15 stratigraphically overlies the Grampian Group. Therefore the 16 suggested correlation with the ‗Ord Ban Subgroup‘ (now the Kincraig 17 Formation at the base of the Corrieyairack Subgroup) is untenable. 18 The boulder bed occurs above and in stratigraphical continuity with 19 the Aonach Beag Semipelite Formation and Kinlochlaggan Quartzite 20 Formation. Collectively, these two units are lithologically 21 similar to the Loch Treig Schist and Quartzite Formation, which 22 forms the lower part of the Lochaber Subgroup in the Loch Treig 23 area to the south-west of this GCR site (Key et al., 1997). The 24 boulder bed is therefore assigned to the Lochaber Subgroup of the 25 Appin Group (Figure 27). The overlying metacarbonate-bearing 26 succession of the Coire Cheap Formation, which is separated from 27 the boulder bed by some 10 m of unexposed strata, has no 28 correlative in the Loch Treig area. However, there are 29 30 similarities in terms of the lithologies and the geochemistry of 31 the metacarbonate rocks with the upper part of the Ballachulish 32 Subgroup in the Schiehallion area, which represents the closest 33 Appin Group rocks to the south (Thomas et al., 1997). Such a 34 correlation requires that the upper part of the Lochaber Subgroup 35 and the lower part of the Ballachulish Subgroup are absent from the 36 Kinloch Laggan area (Robertson and Smith, 1999). The much more- 37 extensive Port Askaig Tillite occurs at the base of the Islay 38 Subgroup, stratigraphically well above the metacarbonate-bearing 39 successions of the Ballachulish Subgroup. 40 41 9.4 Conclusions 42 43 The Kinloch Laggan Road GCR Site contains the type locality for the 44 Kinlochlaggan Boulder Bed, which represents one of a number of 45 boulder beds containing extrabasinal clasts within the Dalradian 46 succession. The clasts of granite, together with quartzite, 47 48 semipelite, pelite and feldspar are interpreted as dropstones from 49 floating ice rather than being derived from till beneath a grounded 50 ice-sheet. The boulder bed occurs within a conformable 51 stratigraphical succession that can be correlated with the Lochaber 52 Subgroup of the Appin Group. It lies beneath a significant intra- 53 Appin Group unconformity in the local succession where the upper 54 parts of the Lochaber and lower parts of the Ballachulish Subgroup 55 are absent. The site is of national importance in demonstrating 56 the earliest recorded glacial influence within the Dalradian. When 57 combined with the Port Askaig Tillite and the boulder beds in the 58 upper parts of the Dalradian, it demonstrates a repeated glacial 59 influence during Neoproterozoic and Early Palaeozoic times. 60 61 62 63 64 65 1 2 3 4 10 ALLT MHAINISTEIR 5 (NN 546 861–NN 524 847) 6 7 S. Robertson 8 9 10 11 10.1 Introduction 12 13 The Allt Mhainisteir and Allt Liath nam Badan river sections, in 14 the Ardverikie Forest area south of Loch Laggan, contain a near- 15 continuous section through the lithologically diverse Kinlochlaggan 16 succession of the Appin Group (Figure 28). The Kinlochlaggan 17 succession is separated from the Grampian Group lying 18 stratigraphically beneath it by spectacular shear-zones and 19 tectonic slides, with resulting local omission of lithological 20 units. Nevertheless, strain is low in places and this GCR site 21 provides the framework against which to place elements of the 22 succession recorded elsewhere in the Kinloch Laggan district (see 23 for example the Aonach Beag and Geal-charn GCR site report). 24 The Allt Mhainisteir GCR site lies within the Geal-charn–Ossian 25 Steep Belt, a major composite D1 synclinal structure focussed upon 26 the Kinlochlaggan Syncline (Thomas, 1979; Robertson and Smith, 27 1999) (Figures 30, 31). Details of the stratigraphical and 28 structural architecture of the steep belt are included in the 29 30 report for the Aonach Beag and Geal-charn GCR site, which lies some 31 10–12 km to the south-south-west of the Allt Mhainisteir. The 32 steep belt comprises a narrow, elongate zone of steeply dipping, 33 varied lithologies of the Kinlochlaggan succession, which include 34 metalimestone, kyanite semipelite, quartzite and the Kinlochlaggan 35 Boulder Bed (see the Kinloch Laggan Road GCR site report). These 36 lithologies contrast markedly with the surrounding psammites and 37 semipelites of the Grampian Group. The Allt Mhainisteir GCR site 38 also includes gneissose ‗basement‘ rocks belonging to the Glen 39 Banchor Subgroup of the Badenoch Group (Smith et al., 1999). In 40 addition, a well-exposed section through the NNE-trending 41 Inverpattack Fault-zone reveals both early ductile and later 42 brittle deformation 43 The results of new mapping in the area by the British Geological 44 Survey are represented on the 1:50 000 Sheet 63E (Dalwhinnie, 45 2002). 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 2 3 4 10.2 Description 5 6 Within the area of the GCR site there are three major 7 tectonostratigraphical units (Figure 28); the Kinlochlaggan 8 succession occupying the core of the Kinlochlaggan Syncline is 9 bound to both the east and west by Grampian Group psammites. The 10 boundaries are defined by high-strain ductile shearing expressed as 11 12 tectonic slides, the Allt Mhainisteir Slide to the east of the 13 Kinlochlaggan succession and the northward continuation of the 14 Aonach Beag Slide to the west. Rocks of the Glen Banchor Subgroup 15 crop out in the eastern part of the GCR site, where they are 16 juxtaposed against the Grampian Group by the Inverpattack Fault. 17 18 10.2.1 Lithologies east of the Allt Mhainisteir Slide 19 20 Grampian Group rocks assigned to the Creag Meagaidh Psammite 21 Formation of the Corrieyairack Subgroup are well exposed in the 22 lower part of the Allt Mhainisteir section, immediately west of the 23 Inverpattack Fault-zone (NN 544 859). A succession of graded beds, 24 typically 20 cm thick, are composed dominantly of psammite in which 25 thin micaceous bed tops represent original muddier sediment. The 26 rocks dip steeply to the south-east but young to the west towards 27 the trace of the Kinlochlaggan Syncline; hence they are inverted. 28 The published BGS 1:50 000 sheet indicates that rocks of the Appin 29 30 Group, Sron Garbh Semipelite Formation extend north-north-eastwards 31 from the valley of the Allt Cam (NN 50 78) towards an unexposed 32 section at NN 542 859 in the Allt Mhainisteir, to the west of the 33 outcrop just described. The formation is very well exposed on Sron 34 Garbh (NN 514 814) and on the ice-scoured slopes between Sron Garbh 35 and Meall na Brachdlach (NN 518 824). Across these locations, the 36 formation comprises almost entirely gneissose magnetite semipelite 37 with rare gradations towards micaceous psammite. The outcrop width 38 ranges from at least 750 m immediately north-east of Sron Garbh to 39 less than 200 m 5.5 km to the north-east around NN 538 856. The 40 formation is not exposed north of the Allt Mhainisteir and has been 41 interpreted as a local facies development within the Kinlochlaggan 42 succession (Robertson and Smith, 1999). The formation is 43 juxtaposed against the Creag Meagaidh Formation in the north and 44 east of its outcrop, with no intervening older elements of the 45 Kinlochlaggan succession (Figure 27). Although contacts are not 46 clearly exposed, loose debris in the form of regolith can be traced 47 48 across the boundary near Meall na Brachdlach. No highly strained 49 material can be seen; the contacts are therefore regarded as 50 preserving the original depositional relationships and hence 51 provide evidence of onlap of the Sron Garbh Semipelite Formation 52 onto the underlying Grampian Group (Robertson and Smith, 1999). 53 Returning to the river section, the next exposures to the north- 54 west (at NN 5371 8559) comprise further graded psammites that are 55 also assigned to the Creag Meagaidh Formation, albeit a rather 56 coarser grained lithology than that seen to the east. At NN 5351 57 8541, abundant close folds deforming the lithological banding are 58 particularly well seen. The folds die out over short distances 59 along their axial surfaces but a coarse schistosity, axial planar 60 to the folds and strongly oblique to the bedding, is prominent even 61 62 63 64 65 1 2 3 4 where there are no folds. Remnants of graded bedding are locally 5 recognizable, although the increase in grain size due to 6 metamorphism has modified most primary features. 7 Over the 80 m that intervenes between the last locality and the 8 Allt Mhainisteir Slide, the folds become progressively tighter with 9 the local development of discontinuities along fold limbs. Some of 10 these discontinuities host metamorphic quartzofeldspathic 11 12 segregations. Within 30 m of the slide (at NN 5343 8535) isoclinal 13 folds, some of which are rootless, are exposed in the bed of the 14 Allt Mhainisteir (Figure 29). Quartzofeldspathic leucosomes and 15 thin pegmatitic veins up to 1 cm thick are also present within the 16 pervasive gneissose foliation. At NN 5339 8532, the slide contact 17 is marked by an abrupt change from flaggy psammite and micaceous 18 psammite of the Creag Meagaidh Psammite Formation to the Aonach 19 Beag Semipelite Formation of the Kinlochlaggan succession, which 20 here comprises micaceous psammite and psammite with 10 cm-thick, 21 brown-weathering schistose semipelites and concordant homogeneous 22 to banded amphibolites. 23 24 10.2.2 Grampian Group lithologies west of the 25 Kinlochlaggan succession and the Aonach Beag Slide 26 27 The Aonach Beag Slide is not exposed in the Allt Liath nam Badan 28 but a continuous section through the contact of the Kinlochlaggan 29 30 succession with the Grampian Group is exposed nearby at NN 522 851 31 on the eastern slope of Meall Each. There, a medium-scale 32 asymmetrical fold hinge preserves a low-strain area in the Creag 33 Meagaidh Psammite Formation. The main tectonic fabric is at a high 34 angle to bedding. Graded beds, typically up to 10 to 15 cm (and 35 locally 30 cm) thick, range from massive psammite to micaceous 36 psammite with thin semipelitic tops. The stratigraphy youngs to 37 the east towards a slide that forms the contact with the 38 Kinlochlaggan succession. Much of the Creag Meagaidh Psammite 39 Formation to the west is flaggy and strongly attenuated with very 40 tight or isoclinal folds. Gneissose semipelites and psammites of 41 the Inverlair Psammite Formation form a unit a few tens of metres 42 thick adjacant to the trace of the Aonach Beag Slide (NN 526 852). 43 To the east of the slide, schistose to platy semipelite with some 44 psammite and abundant amphibolite represent the Aonach Beag 45 Semipelite Formation of the Kinlochlaggan succession. 46 47 48 10.2.3 The Kinlochlaggan succession in the Allt 49 Mhainisteir and Allt Liath nam Badan 50 51 The Kinlochlaggan succession comprises a heterogeneous association 52 of quartzite, schistose to gneissose semipelite, micaceous 53 psammite, metacarbonate rock, calcsilicate rock and abundant 54 amphibolite. The succession is represented by three formations in 55 the area of this GCR site. 56 The oldest formation, the Aonach Beag Semipelite Formation, is 57 well exposed in the Allt Liath nam Badan between NN 5240 8475 and 58 NN 5260 8490. It comprises a mixed succession of interlayered 59 schistose and commonly platy semipelite and micaceous psammite with 60 ribs of psammite. At NN 5251 8487, more than 18 m of massive and 61 62 63 64 65 1 2 3 4 locally gneissose psammite with streaked-out feldspar megacrysts 5 occurs between flaggy schistose semipelite and fissile, intensely 6 deformed psammite and micaceous psammite. Amphibolites, many of 7 which carry garnet, account for less than 5% to over 30% of any 8 particular exposure and occur in concordant sheets ranging from 9 less than 1 cm to 100 cm thick. Quartz seams and lenses together 10 with coarse-grained quartzofeldspathic lenses are widely developed. 11 12 Quartzites, which are a prominent feature of the upper part of the 13 formation both to the south-west (see the Aonach Beag and Geal- 14 charn GCR site report) and to the north-east, are not present here. 15 The Aonach Beag Semipelite Formation is overlain by the 16 Kinlochlaggan Quartzite Formation. The contact is not exposed in 17 this section, although elsewhere it is gradational, with either an 18 increase in the proportion of interbedded quartzite or a change to 19 more-psammitic lithologies. The formation is very well exposed in 20 the Allt Liath nam Badan around NN 5267 8492 and close to its 21 confluence with the Allt Mhainisteir around NN 5312 8513, where 22 pebbly layers and relics of cross-bedding can be seen. It 23 comprises massive white quartzite up to 160 m thick (see also the 24 Kinloch Laggan Road GCR site report). No representative of the 25 Kinlochlaggan Boulder Bed has been recognized in this section. At 26 NN 5271 8491, the quartzite is cut by an amphibolite lens, at least 27 35 m thick and probably less than 100 m long. This amphibolite has 28 a sharp contact with the quartzite. 29 30 The Kinlochlaggan Quartzite Formation is overlain abruptly by the 31 Coire Cheap Formation in the Allt Liath nam Badan at NN 5280 8505; 32 pale-coloured metacarbonate rock occurs close to the base of the 33 Coire Cheap Formation at this contact. Here, the Sron Garbh 34 Semipelite Formation is absent, most likely as the result of 35 original depositional variations rather than the effect of any 36 tectonic excision. The Coire Cheap Formation is dominated by 37 semipelite but is distinguished by the presence of calcsilicate 38 rocks and metacarbonate rocks (e.g. at NN 5290 8507). The latter 39 range up to 45 m in outcrop width. 40 Between NN 5318 8516 and the Allt Mhainisteir Slide, each of the 41 three constituent formations of the Kinlochlaggan succession are 42 present in the stream section. However, relationships are 43 complicated by a combination of faulting, very tight folds that 44 repeat the succession, and a stratigraphically attenuated 45 succession. The Aonach Beag Semipelite Formation is approximately 46 25 m thick adjacent to the Aonach Beag Slide (compared with 170 m 47 48 on the opposite limb of the Kinlochlaggan Syncline), and the 49 Kinlochlaggan Quartzite is only 5 m thick at NN 5335 8527 and 7 m 50 thick at NN 5323 8516 where it crops out in an antiformal closure. 51 The Coire Cheap Formation is marked by metacarbonate-rock units up 52 to 6 m thick. At NN 5327 8518, metacarbonate rock contains pods of 53 cross-cutting pegmatite and is separated by 1 m of micaceous 54 psammite from gneissose semipelite with leucosomes up to 1 cm 55 across and 2 cm-long kyanites. 56 57 10.2.4 The Inverpattack Fault 58 59 The Inverpattack Fault is well exposed in the Allt Mhainisteir 60 around NN 5454 8591, where it juxtaposes Grampian Group lithologies 61 62 63 64 65 1 2 3 4 against the Glen Banchor Subgroup. East of the fault and into the 5 River Pattack (NN 546 861), small- to medium-scale asymmetrical and 6 chevron folds (several metres in amplitude) occur together with 7 fractures, many of which dip steeply to the west. Some fold limbs 8 are truncated by the fractures, whereas in other examples 9 semipelitic lithologies are crumpled and crenulated adjacent to 10 discontinuities. The geometry of crumple folds suggests that 11 12 displacement across the fractures has a normal sense (i.e. 13 downthrow to the west). Microdiorite dykes cut some folds, whereas 14 a dyke at NN 5461 8612 might be deformed by a fold; other dykes are 15 deformed in fracture-zones. 16 A zone of mixed cataclasitic and mylonitic rock at least 8 m 17 across crops out to the west of the folded and fractured zone (NN 18 5456 8592), deforming interbanded psammite and semipelite that is 19 cut by microdiorite and pegmatitic dykes. The rock is typically 20 dark grey, fissile, friable and very fine grained, with the 21 foliation typically inclined at 70° to the east-south-east. It 22 contains porphyroclasts of psammitic and pegmatitic lithologies up 23 to 10 cm across that are wrapped by the foliation. In thin 24 section, numerous angular to subrounded quartz and plagioclase 25 grains and bent biotite flakes form both monominerallic and lithic 26 clasts within a very fine-grained foliated groundmass in which 27 larger clasts are cemented by carbonate minerals. Deformation 28 might also post-date emplacement of the microdiorite dykes, as 29 30 microdiorite clasts are thought to occur within the zone. Both 31 anastomosing shear fabrics (S-C fabrics) and tails developed on 32 porphyroclasts indicate a sinistral reverse sense of displacement 33 (i.e. downthrow to the west). Immediately to the west, the 34 cataclasite-mylonite zone is succeeded by 90 m of brecciated 35 psammite. The psammite forms massive exposures, which on close 36 examination consist of angular psammite fragments within a 37 psammitic matrix. Thin zones of mylonite and discontinuities, some 38 of which are gently inclined, occur throughout this brecciated 39 zone, all of which has been recemented and is therefore cohesive. 40 41 10.3 Interpretation 42 43 The Kinlochlaggan succession strata are preserved in the core of 44 the Kinlochlaggan Syncline in the centre of the Geal-charn–Ossian 45 Steep Belt (Figures 30, 31). The contacts with the underlying 46 Grampian Group are affected by high-strain ductile shearing, with 47 48 the Aonach Beag Slide marking the boundary in the west and the Allt 49 Mhainisteir Slide acting similarly in the east. Grampian and Appin 50 group rocks share a common deformational history. Good evidence 51 for increasingly high non-co-axial strain as each of the slide 52 contacts is approached is preserved in the lithostratigraphy. 53 However strain is sufficiently low in places for the essential 54 stratigraphical continuity of the sequence to be maintained. 55 The Lochaber Subgroup, Sron Garbh Semipelite Formation, resting 56 directly on the Grampian Group, Creag Meagaidh Psammite Formation 57 east of the Allt Mhainisteir Slide, represents a local facies 58 development within the Kinlochlaggan succession. In the absence of 59 any highly strained material at the contact this relationship is 60 interpreted to mean that the original depositional relationships 61 62 63 64 65 1 2 3 4 are preserved. Since distinctive older elements of the 5 Kinlochlaggan succession are not present here e.g. the 6 Kinlochlaggan Quartzite Formation, such details constitute an 7 important part of the overall evidence for onlap relationships and 8 the complex depositional framework in Appin Group times proposed 9 for the region now disposed within the Geal-charn–Ossian Steep Belt 10 by Robertson and Smith (1999) (see the Aonach Beag and Geal-charn 11 12 GCR site report). 13 The Inverpattack Fault is one of a number of NNE-trending faults 14 that link major NE-trending transcurrent faults in the Northern 15 Grampian Highlands. It links the Markie Fault and the Ericht– 16 Laidon Fault and cuts across the trace of the Geal-charn–Ossian 17 Steep Belt. The fault separates the Grampian and Appin groups of 18 the Dalradian from the older Glen Banchor Subgroup of the Badenoch 19 Group, which is exposed on the east side of the steep belt. The 20 microfabric relationships in the fault rocks are consistent with 21 the left-lateral displacement of lithological units across the 22 fault; c. 2.5 km of sinistral offset is observed farther north (NN 23 58 96). Observed fault fabrics display evidence for both early 24 brittle–ductile deformation and later brittle faulting, 25 demonstating the likely long-lived nature of this fault system. 26 27 10.4 Conclusions 28 29 30 The Allt Mhainisteir GCR site provides a coherent c. 4 km-long 31 traverse across the Geal-charn–Ossian Steep Belt, which here 32 includes a distinctive succession of metalimestone, quartzite, 33 semipelite and amphibolite known as the Kinlochlaggan succession. 34 This provides the most-complete correlative framework for other 35 sections within the steep belt. Despite the presence of high 36 ductile strain on both the north-west and the south-east sides of 37 the Kinlochlaggan succession, Grampian Group psammites can be seen 38 to young consistently towards it. Hence the Kinlochlaggan 39 succession lies stratigraphically above the Grampian Group and can 40 be readily assigned to the Appin Group. Local stratigraphical 41 omissions in both the Grampian and Appin group successions provide 42 evidence for the punctuated nature of the depositional record in 43 this sector of the Dalradian basin. 44 This GCR site also provides a well-exposed section through the 45 Inverpattack Fault, revealing a complex history of ductile and 46 brittle deformation associated with one of the sinistral strike- 47 48 slip faults that have a major effect upon the outcrop pattern in 49 the Northern Grampian Highlands, and whose effects must be 50 compensated for in any attempt to reconstruct a depositional 51 framework for the region. 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 2 3 4 11 AONACH BEAG AND GEAL-CHARN 5 (NN 454 735–NN 470 747 and NN 475 761–NN 497 746) 6 7 S. Robertson, J.R. Mendum and A.G. Leslie 8 9 10 11 11.1 Introduction 12 13 The Aonach Beag and Geal-charn GCR site provides one of the best 14 cross-sections through the zone of sheared and tightly folded, 15 steeply dipping metasedimentary rocks termed the Geal-charn-Ossian 16 Steep Belt. Exposures around Aonach Beag (NN 457 743) and in the 17 NE-facing corries of Coire Cheap (NN 476 754) and Coire Sgòir (NN 18 487 747) provide an excellent near three-dimensional section across 19 this complex zone. The site includes a number of spectacularly 20 developed ductile shear-zones or slides and associated isoclinal 21 folds, elegantly first described by Thomas (1979). The 22 stratigraphy, structure and metamorphism of the area have been most 23 recently re-assessed by Robertson and Smith (1999), and details are 24 incorporated within the BGS 1:50 000 Sheet 63E (Dalwhinnie, 2002), 25 this report draws extensively upon that work. 26 The Geal-charn-Ossian Steep Belt comprises a narrow zone of 27 steeply dipping rocks that can be traced north-eastwards for more 28 than 50 km from Aonach Beag (Figures 18 and 30). A varied 29 30 association of lithologies, including metacarbonate rock, kyanite- 31 bearing pelite and semipelite, quartzite and the Kinlochlaggan 32 Boulder Bed, occur in the core of the steep belt and are 33 collectively referred to as the Kinlochlaggan succession in the 34 Appin Group (Robertson and Smith, 1999). These lithologies 35 contrast markedly with the surrounding psammites and semipelites of 36 the Grampian Group. 37 To the west of the steep belt, in the Loch Laggan-Glen Roy area, 38 the Grampian Group succession is at least 8 km thick (Key et al., 39 1997). There the sand- and silt-dominated succession is divided 40 into three subgroups, which broadly reflect their depositional 41 environment; the fluvial and shallow marine Glenshirra Subgroup is 42 overlain by deeper water sediments of the Corrieyairack Subgroup 43 that were deposited largely from turbidity currents. These are 44 overlain in turn by the shallow marine to estuarine Glen Spean 45 Subgroup in a basin-shoaling succession. The overlying Appin Group 46 represents an overall transgressive system with a silt- and mud- 47 48 dominated succession contrasting with the mainly sandy Glen Spean 49 Subgroup. 50 To the south-east of the steep belt, much of the Grampian Group is 51 assigned to the Fara Psammite Formation of the Strathtummel 52 succession. It is less well known than the succession of the Loch 53 Laggan–Glen Roy area, although it was described by Thomas (1979, 54 1980). Robertson and Smith (1999) made only tentative correlations 55 with the Corrieyairack Subgroup. Gneissose rocks of the Glen 56 Banchor Subgroup, which are thought to form a basement to the 57 Grampian Group (Robertson and Smith, 1999), extend partway along 58 the south-east side of the steep belt from the north-east to within 59 12 km of this GCR site. They are exposed on the eastern side of 60 the Allt Mhainisteir GCR site. 61 62 63 64 65 1 2 3 4 11.2 Description 5 6 The site is remote and mountainous. Aonach Beag (1116 m) and Geal- 7 charn (1107 m) form a dramatic ridge to the north-west of the Ben 8 Alder massif. Coire Cheap and Coire Sgòir both face north-east 9 along the continuation of that ridge (Figure 32). A 10 lithostratigraphical column for the area within and west of the 11 12 steep belt is shown in Figure 27. Within the GCR site, Grampian 13 Group rocks form the flanks of the steep belt whereas the Appin 14 Group rocks occupy the core in the Kinlochlaggan Syncline and 15 related folds. The broad disposition of these lithologies is 16 illustrated in the cross-section (Figure 31). 17 18 11.2.1 Structural setting of the steep belt 19 20 The Geal-charn-Ossian Steep Belt is defined as a zone of steeply 21 inclined rocks (dips of over 60°) up to 4 km wide (Robertson and 22 Smith, 1999). The overall attitude of lithological layering, the 23 axial surfaces of isoclinal folds and associated tectonic fabrics 24 are approximately coplanar. 25 The Grampian Group in the Loch Laggan area, north-west of the 26 steep belt, has an apparently simple structural history. Strata in 27 the Loch Laggan-Glen Roy area are generally moderately to steeply 28 inclined, with a preponderance of upright early structures (Key et 29 30 al., 1997). An early schistosity, steeper than bedding, occurs in 31 semipelitic rocks and in the micaceous tops to graded beds. This 32 is modified in places by a steeply inclined crenulation. Minor 33 folds are rare and strain is generally low, as is indicated by the 34 widespread preservation of sedimentary structures (e.g. Glover et 35 al., 1995). 36 The structural history is more varied to the south-east of the 37 steep belt. A large area of gently inclined, albeit strongly 38 flattened, rocks with recumbent early folds, extends for several 39 tens of kilometres east of Kinloch Laggan to beyond Dalwhinnie 40 (Robertson and Smith, 1999). In this area, the Glen Banchor 41 Subgroup of the Badenoch Group preserves a protracted 42 tectonothermal history in which an early gneissose foliation is 43 deformed by at least one generation of isoclinal folds. That early 44 gneissose foliation is deformed by shear-zones with associated 45 syntectonic veins of quartz and quartzofeldspathic pegmatite 46 yielding Rb-Sr muscovite ages of c. 750 Ma (Piasecki and van 47 48 Breemen, 1983). In contrast, much of the adjacent eastern outcrop 49 of Grampian Group strata shows evidence of only a relatively simple 50 history. A single bedding-parallel schistosity is pervasive and is 51 the result of strong flattening strain. Small-scale recumbent and 52 asymmetrical folds are rare over a large area of the Grampian Group 53 outcrop between the steep belt and the A9 road section north of 54 Drumochter and no large-scale folds have been recognized to date. 55 An upright open crenulation is developed locally. In contrast, 56 Thomas (1979) recorded that the Ben Alder area preserves evidence 57 of major changes in facing of early recumbent structures south-east 58 of the Geal-charn-Ossian Steep Belt (see the Ben Alder GCR site 59 report). The model proposed by Thomas (1979) has early SE-facing 60 61 62 63 64 65 1 2 3 4 nappe structures refolded by two further phases of folding, with 5 the major nappes divergent from the upward-facing steep belt. 6 The steep belt separates these contrasting north-western and 7 south-eastern structural domains (Figure 31). A progressive 8 increase in inclination of strata into the steep belt from the 9 north-west culminates in a zone, mostly less than 2 km wide, where 10 inclination is over 75°. The south-eastern margin of the steep 11 12 belt is more abrupt with steeply inclined and near flat-lying rocks 13 closely juxtaposed. 14 The intensity and complexity of deformation within the steep belt 15 is striking when compared with patterns to the north-west and 16 south-east. Robertson and Smith (1999) recognized three main 17 phases of deformation in the steep belt, which broadly equate with 18 those described by Thomas (1979). The first phase produced large- 19 scale tight to isoclinal folds with amplitudes of several 20 kilometres and a penetrative axial planar schistosity. This 21 deformation resulted in extreme attenuation of fold limbs and the 22 development of slides. Adjacent to the slides, there is a marked 23 decrease in the wavelength and increase in frequency of tight to 24 isoclinal folds with minor dislocations on some fold limbs (see 25 also the Allt Mhainisteir GCR site report). The main dislocations 26 are generally marked by zones with intense platy fabrics, varying 27 in width from about a metre up to 20 m. Both small- and large- 28 scale dislocations generally show excision of strata with only rare 29 30 repetition. 31 The first phase structures were modified and attenuated during a 32 second phase of close to isoclinal folding. In the north, the 33 first and second phase structures are co-axial and coplanar and 34 therefore difficult to distinguish but in the southern part of the 35 steep belt (e.g. around this GCR site), the second deformation is 36 less intense and is oblique to the first phase. Thus, interference 37 structures are widely developed and in psammites a coarse secondary 38 biotite foliation is commonly discordant to the first fabric. Re- 39 activation of some of the slide-zones is indicated by 40 intensification of the second fabric, which is rotated into 41 parallelism with the first. Elsewhere, the slide-zones are clearly 42 cut by the coarsely spaced biotite fabric. Kyanite-grade 43 metamorphism developed during the second phase of deformation. 44 Later in this phase, fluid movements along the sheared and deformed 45 zones of high strain resulted in local sillimanite replacement of 46 kyanite (Phillips et al., 1999). 47 48 The overall geometry of the steep belt is that of a major upright 49 synform (Figure 31). The facing and vergence of small- and medium- 50 scale structures indicates that much of the structural pattern 51 developed during second-phase tightening and intensification of 52 earlier first-phase structures. Few significant changes in the 53 large-scale pattern of fold vergence occurred during the second 54 phase and primary facing relationships were largely preserved from 55 the onset of deformation in the steep belt. The most important 56 major fold structure, the Kinlochlaggan Syncline, constrains the 57 main outcrop of the Kinlochlaggan succession to a zone generally 58 less than 1 km wide. Critical exposure of the fold hinge can be 59 traced in detail on the south-west ridge of Aonach Beag (NN 454 60 735) (Figure 30). The Aonach Beag Slide lies on the western limb 61 62 63 64 65 1 2 3 4 of the syncline (Thomas, 1979). This important dislocation has the 5 same lateral extent as the main syncline and defines the north- 6 western limit of the Kinlochlaggan succession. South-east of the 7 trace of the main syncline, the Cheap slides separate the 8 Kinlochlaggan Syncline from the Sron Garbh anticlinal fold-complex 9 and associated slides to the east (Figures 30). The Kinlochlaggan 10 succession is also present within parts of this latter fold 11 12 complex, the eastern limit of which is defined by the Sgòir Slide, 13 which was first recognized as separating contrasting 14 stratigraphical successions by Thomas (1979). The Cheap and Sgòir 15 slides die out gradually farther to the north-east. 16 The second phase folds are refolded by sporadically developed 17 third phase structures. These occur primarily close to the eastern 18 edge of the steep belt, although they are also prominent around 19 Aonach Beag (NN 458 742) where they have nucleated on the earlier 20 folds. Open to close SE-verging folds are typical, with axial 21 planes inclined moderately or steeply to the east-south-east. 22 Crenulation cleavages are developed in semipelite but are generally 23 confined to fold hinges. The absence of penetrative fabrics, even 24 in the tightest folds, and of new metamorphic mineral growth or 25 recrystallization, readily distinguishes the third phase 26 structures. 27 28 29 11.2.2 Grampian Group lithostratigraphy 30 31 Within this GCR site, the units of the Grampian Group range from 32 near-undeformed sequences with well-preserved sedimentary 33 structures to migmatitic gneissose and highly sheared equivalents. 34 The stratigraphy is summarized in Figure 27. 35 The Creag Meagaidh Psammite Formation comprises thin- to medium- 36 bedded psammite and micaceous psammite with little lithological 37 variation; the field appearance is largely controlled by the degree 38 of strain. On the cliffs of Sgòr Iutharn (NN 490 744), the 39 formation is generally preserved in a low-strain state (Figure 32). 40 Beds are typically 10 to 15 cm thick and are rarely 25 to 30 cm. 41 These mostly comprise grey to white, rather massive feldspathic 42 psammite that grades into thin (mostly less than 3 cm) micaceous 43 psammite, semipelite or even pelite. The local presence of sharp 44 bases and gradations in the tops of the beds into more-micaceous 45 lithologies is considered to reflect primary graded bedding. 46 Differential erosion across these graded units produces distinctive 47 48 ‗sharks teeth‘ profiles with preferential weathering inwards of the 49 more-micaceous tops. High-strain areas are very flaggy to fissile 50 with fine-scale (several millimetres) interbanding of platy 51 psammite and micaceous psammite. 52 The Creag Meagaidh Formation is overlain stratigraphically by the 53 Clachaig Semipelite and Psammite Formation and in places by the 54 Inverlair Psammite Formation. The boundary with the latter is 55 tectonic (the Sgòir slides)–see below. 56 The Clachaig Semipelite and Psammite Formation comprises a varied 57 succession dominated by semipelite. On the north-east ridge of 58 Sgòr Iutharn, the Lancet Edge (NN 495 746), the Clachaig Formation 59 forms the core of an isoclinal syncline (?F1) on the eastern edge 60 of the steep belt. Here there is a transitional contact with the 61 62 63 64 65 1 2 3 4 underlying psammite of the Creag Meagaidh Formation. The basal 5 part of the Clachaig Formation is a massive, coarsely foliated, 6 garnetiferous biotite-rich semipelite and pelite with minor thin 7 beds of micaceous psammite. Higher in the succession, quartzose 8 and feldspathic psammite beds are seen within thin- to medium- 9 bedded semipelite, micaceous psammite and feldspathic psammite. 10 Spectacular minor folds and refolded folds are present. Minor 11 12 calcsilicate-rock lenses occur in these lithologies. 13 The Inverlair Psammite Formation is particularly well seen around 14 Coire Cheap (Figure 30) in massive exposures showing transitions 15 from psammite to micaceous psammite on scales ranging from a few 16 centimetres to a metre or so (e.g. around NN 478 755). Micaceous 17 psammite beds are typically only a few centimetres thick. 18 Boundaries are commonly subtle as a result of extensive 19 recrystallization and grain coarsening, a characteristic feature of 20 this formation. The formation is generally gneissose, particularly 21 the micaceous psammites, which carry a coarsely spaced fabric 22 within leucosomes that are pegmatitic in places. 23 On the north-west side of the steep belt, the degree of 24 gneissification and deformation increases towards the Aonach Beag 25 Slide and related ductile dislocation structures (Figure 30). The 26 psammite is correspondingly more massive and gneissose with 27 interbanded quartzite units in places. The slide-zone is marked by 28 lithologies from the Inverlair Psammite Formation and Aonach Beag 29 30 Semipelite Formation interleaved in an imbricate zone. Immediately 31 north of a small col on the north-north-west ridge of Aonach Beag 32 at NN 452 751, notably striped migmatitic psammite and subsidiary 33 semipelite show abundant segregation veins, tight folding and a 34 gently ENE-plunging quartz-rodding lineation. These rocks lie 35 within a slide-zone structurally just below the main Aonach Beag 36 Slide that is exposed on the ridge. 37 Folded gneissose, and locally migmatitic, psammites and minor 38 semipelites of the Inverlair Psammite Formation also occur 39 extensively in the north-western part of Coire Sgòir (NN 485 750), 40 east of the Kinlochlaggan succession in the core of the steep belt. 41 The sequence is tightly folded and is cut by several ductile slide- 42 zones (the Sgòir slides, Figure 31); slivers of the Aonach Beag 43 Semipelite Formation (including amphibolite) occur in this high- 44 strain zone. Contacts with folded and locally sheared psammite of 45 the Clachaig, Creag Meagaidh and Aonach Beag formations are all 46 steeply inclined ductile slides. Units of foliated gneissose 47 48 semipelite, quartzite and quartzose psammite also occur locally. 49 50 11.2.3 Appin Group lithostratigraphy 51 52 Within the steep belt, the boundary of Grampian Group rocks with 53 those of the overlying Appin Group is generally tectonic and is 54 marked by platy zones of interbanded psammite and quartzite. These 55 are seen spectacularly at NN 477 756 in Coire Cheap (the Cheap 56 slides). However, transitional stratigraphical boundaries are also 57 preserved in Coire Cheap to the west of Aisre Ghobhainn (NN 478 58 753) and locally north-west of Aonach Beag (NN 45 74). At the 59 former locality, psammite and gneissose micaceous psammite pass 60 into platy micaceous psammite with quartz segregations and then 61 62 63 64 65 1 2 3 4 schistose semipelite and micaceous psammite of the Aonach Beag 5 Semipelite Formation. 6 The Aonach Beag Semipelite Formation is well developed on the 7 north-west ridge of Aonach Beag (NN 457 743) and in Coire Cheap (NN 8 478 752), where the transitional boundary with the Grampian Group 9 Inverlair Psammite Formation reveals the lowest parts of the 10 formation. The formation dominantly comprises semipelite but 11 12 contains progressively more psammite in its upper part. Units of 13 tremolitic rock and thin white quartzites occur in the lower part. 14 Abundant amphibolite sheets generally lie parallel to bedding but 15 are discordant locally. These range from 15 cm to several metres 16 thick, and are generally thicker adjacent to the overlying 17 Kinlochlaggan Quartzite Formation and to thicker psammite units. 18 The Kinlochlaggan Quartzite Formation comprises massive white 19 quartzite with large, locally prominent, white to pink feldspar 20 crystals. Partings in the quartzite, which probably reflect 21 bedding, are typically 5 to 60 cm apart and are controlled locally 22 by micaceous psammite layers up to 2 cm thick. The feldspars are 23 up to 5 mm long and are either scattered or are concentrated within 24 layers, indicating a clastic origin. The formation has an outcrop 25 width of between 5 and 160 m, a range that probably reflects both 26 tectonic attenuation and original variation in depositional 27 thickness. South-west of Aonach Beag (NN 455 740), in the hinge- 28 zone of the Kinlochlaggan Syncline, the quartzite is 100 to 120 m 29 30 thick, is well exposed in clean crags and exhibits only minor 31 deformation. Pink feldspar clasts are scattered throughout 32 individual white to pale-grey packets of dominantly quartz sand 1 33 to 20 cm thick. Minor coarser grained bases to these units are 34 seen and in places more-micaceous tops are present. Grading shows 35 that the formation youngs and faces upwards. No cross-bedding has 36 been recorded here. However, minor cross-bedding and small-scale 37 slump folds can be seen in the craggy exposures on the north-west 38 ridge of Geal-charn at NN 4715 7563 and in exposures farther north- 39 east at NN 4798 7667. In the central part of the steep belt, to 40 the west of Coire Cheap (NN 475 750), outcrop of the formation is 41 repeated up to three times by upright isoclinal folding. Pebbly 42 layers, 1 to 10 cm thick with rounded quartz and feldspar pebbles 43 up to 6 mm across, occur in the quartzite in Coire Cheap at NN 474 44 753. Amphibolites, typically up to 2 m thick, are widespread and 45 are commonly concentrated at the margins of the formation; examples 46 in Coire Cheap and south-west of Aonach Beag are locally discordant 47 48 and are clearly dykes. 49 The Kinlochlaggan Boulder Bed (see also the Kinlochlaggan Road GCR 50 site report) is represented on the west wall of Coire Cheap (NN 51 4776 7566), by massive grey psammite containing scattered granite 52 clasts up to 5 cm across and with a few discontinuous slightly 53 micaceous layers. This occurrence has a gradational boundary over 54 20 or 30 cm with the underlying quartzite, is approximately 2 m 55 thick and forms a lens about 20 m long. The lensoid nature is 56 considered to be representative of the other occurrences in the 57 region, thereby accounting for the discontinuous nature of the 58 ‗boulder bed‘. 59 To the west of and stratigraphically upwards from the 60 Kinlochlaggan Quartzite Formation in Coire Cheap, a 20 m-thick 61 62 63 64 65 1 2 3 4 mixed unit of metacarbonate rock, calcsilicate rock, micaceous 5 psammite and garnet amphibolite represents an attenuated Coire 6 Cheap Formation. This is succeeded by a c. 100 m-thick semipelite 7 unit forming the prominent peak of Sron Gharbh (NN 473 754). The 8 semipelite is characteristically dark grey, homogeneous and 9 generally schistose, with widespread scattered small garnets; 10 quartzofeldspathic segregations are rare whereas quartz 11 12 segregations are widespread. This semipelite is not recognized 1 13 km to the north-east in the Allt Coire Cheap section but can be 14 traced south-westwards into Coire na Coichille (NN 469 750) where 15 it apparently lenses out; it is apparently a local facies 16 development (Robertson and Smith, 1999). Kyanite-bearing 17 semipelite occurs at the western boundary of the semipelite in 18 Coire Cheap, and is succeeded to the west (at NN 4754 7588) by 16 m 19 of flaggy, platy, very fine-grained, grey micaceous psammite. 20 This platy psammite marks the return to a heterogeneous succession 21 of semipelite, calcsilicate rock and metacarbonate rock, all cut by 22 amphibolite sheets, which extends north-eastwards from Aonach Beag 23 (NN 455 740) through superb exposures in Coire Cheap and Allt Coire 24 Cheap, the type area for the Coire Cheap Formation. The 25 semipelitic units are gneissose and/or kyanite-rich in parts and 26 locally they are graphitic. In Coire Cheap, the micaceous psammite 27 referred to above is succeeded to the west by fine-grained platy 28 micaceous psammite with thin quartzite ribs interbanded with thin 29 30 layers (up to 1 m) of calcsilicate rock and metacarbonate rock. 31 Lines of solution hollows up to a few metres deep, along with some 32 resurgence and limited along-strike exposures might represent 33 unexposed metacarbonate rocks. Locally (e.g. at NN 4740 7571), 34 rusty-weathering micaceous psammite is cut by discordant 35 amphibolite sheets up to 3 m thick. The discordance with 36 schistosity in the micaceous psammite is up to 30° and the 37 amphibolite is unfoliated. Rather fine-grained margins could 38 reflect original chills, whereas relics of ophitic texture and 39 blue-green amphibole are preserved in the central parts of the 40 sheets. At NN 4717 7541, graphitic schist with partially replaced 41 kyanite occurs in loose blocks; contacts with adjacent lithologies 42 are not exposed. 43 In the west wall of the corrie (NN 473 755), the graphitic schist 44 is succeeded by c. 45 m of thinly bedded, cream- to buff-weathering 45 metacarbonate rock, referred to as the Coire Cheap Limestone. The 46 metacarbonate rock appears particularly thick here; no major fold 47 48 closures have been identified but there are tight internal minor 49 folds. A few amphibolite sheets and pods up to 2 to 3 m across 50 occur, mostly near the western boundary. Farther west the 51 metacarbonate rock is succeeded by c. 5 m of platy calcsilicate 52 rock with thin beds of metacarbonate rock and then by a 50-70 m- 53 thick gneissose kyanite semipelite referred to as the Coire Cheap 54 Kyanite Gneiss. Kyanite is abundant throughout this unit and 55 commonly comprises some 25% of the rock. Much of the kyanite is 56 coarse (over 1 cm and rarely up to 5 cm long) and although many 57 crystals are randomly arranged, some show subhorizontal alignment 58 on the steep schistosity surfaces. A few garnet amphibolite layers 59 up to 30 cm thick are present. The kyanite gneiss is succeeded to 60 the north-west by a thin metacarbonate-rock layer in the corrie 61 62 63 64 65 1 2 3 4 wall and then by approximately 20 m or so of rusty-weathering 5 micaceous psammite with some layers of semipelite. The latter 6 contain tourmaline and relics of kyanite largely replaced by 7 muscovite. This is succeeded in turn in the corrie wall by several 8 metres of calcsilicate rock, which is in contact to the west with 9 the Kinlochlaggan Boulder Bed and the Kinlochlaggan Quartzite 10 Formation. The repetition of the underlying Kinlochlaggan 11 12 Quartzite indicates that the trace of the Kinlochlaggan Syncline is 13 crossed in Coire Cheap; the most likely place for the closure is in 14 either the semipelite unit on Sron Garbh or in the Coire Cheap 15 Limestone, although there is no obvious repetiton of the 16 surrounding lithologies. This indicates either original facies 17 changes or structural dislocation preferentially on one limb of the 18 structure. Facies changes over short distances seem more likely 19 given the significant lateral changes in the succession within a 20 kilometre as indicated by the succession in the Allt Coire Cheap 21 and to the south-west in Coire na Coichille. 22 23 11.3 Interpretation 24 25 26 11.3.1 Stratigraphical relationships 27 28 The Kinlochlaggan succession has generally been interpreted as an 29 30 upward-facing succession within the core of the Geal-charn-Ossian 31 Steep Belt, with the Grampian-Appin group boundary modified locally 32 by sliding (Hinxman et al., 1923; Anderson, 1947b, 1956; Smith, 33 1968; Treagus, 1969, 1997; Thomas, 1979). However, Evans and 34 Tanner (1996, 1997) speculated that the Kinlochlaggan succession 35 contains an allochthonous, inverted and downward-facing upper Appin 36 Group–lower Argyll Group stratigraphy, separated from the Grampian 37 Group by a major structural discontinuity. In marked contrast, 38 Piasecki and Temperley (1988b) equated the Kinlochlaggan succession 39 with semipelites and metalimestones at the base of the Grampian 40 Group that are exposed at Kincraig and Ord Ban (see the An Suidhe 41 GCR site report). 42 In the steep belt, a gradational stratigraphical boundary is 43 preserved locally between the Grampian Group and the Aonach Beag 44 Semipelite Formation; the latter must therefore lie at the base of 45 the Appin Group. The Kinlochlaggan Quartzite Formation is in 46 stratigraphical succession above the Aonach Beag Semipelite 47 48 Formation and, while the boundary between the Kinlochlaggan 49 Quartzite and Coire Cheap formations is marked locally by c. 70 cm 50 of platy psammite, this is not thought to represent a major 51 tectonic discontinuity. The Kinlochlaggan Boulder Bed occurs 52 locally in lenticular form on top of the Kinlochlaggan Quartzite 53 Formation and cannot on that basis be correlated with the Port 54 Askaig Tillite (basal Islay Subgroup) and its equivalents. 55 The Aonach Beag Semipelite Formation is lithologically similar to 56 the Loch Treig Schist and Quartzite Formation of the Glen Roy 57 district, which also lies stratigraphically on top of the Grampian 58 Group and is assigned to the Lochaber Subgroup. The Kinlochlaggan 59 Quartzite Formation is lithologically similar to the Binnein 60 Quartzite Formation in the Loch Leven area and hence it too is 61 62 63 64 65 1 2 3 4 assigned to the Lochaber Subgroup. The Sron Garbh Semipelite 5 Formation is correlated with the Leven Schist Formation of the Glen 6 Roy district on the basis of lithological similarities, 7 particularly its magnetic character, and its stratigraphical 8 position. It is therefore assigned to the upper part of the 9 Lochaber Subgroup although the correlation is tentative (Robertson 10 and Smith, 1999). 11 12 Pale metalimestone in the Coire Cheap Formation, located above the 13 Kinlochlaggan Quartzite, has a geochemical signature typical of the 14 middle part of the Ballachulish Subgroup, while the remainder of 15 the metalimestones have geochemical signatures similar to Blair 16 Atholl Subgroup metalimestones elsewhere in the Grampian Highlands 17 (Thomas, 1995; Thomas et al., 1997; Thomas and Aitchison, 1998). 18 These correlations indicate that well-known segments of the Appin 19 Group stratigraphy are missing from the exposed sections at this 20 site. There is no representative of the Appin Quartzite and the 21 uppermost parts of the Lochaber Subgroup are also absent. It is 22 not known whether this is the result of non-deposition or erosion. 23 Any erosion must have pre-dated deposition of the upper parts of 24 the Ballachulish Subgroup, since this rests without a major 25 structural discontinuity on the Kinlochlaggan Quartzite. 26 Significant facies changes and thickness changes have been reported 27 in the Appin Group in the South-west Grampian Highlands with 28 possible uplift and erosion at the time of deposition of the Appin 29 30 Quartzite (Litherland, 1970, 1980), supporting such 31 interpretations. 32 Robertson and Smith (1999) argued that within the steep belt as a 33 whole, component parts of the Kinlochlaggan succession show major 34 onlap relationships. North of Laggan (NN 600 965), stratigraphical 35 relationships show the progressive overstep of the Kinlochlaggan 36 succession onto the Creag Meagaidh and Ardair formations and 37 ultimately directly onto the Glen Banchor Subgroup. For 10 km 38 along strike to the north-east of the River Spey, the entire 39 Grampian Group is absent on the eastern limb of the Kinlochlaggan 40 Syncline. This therefore represents one of the most significant 41 stratigraphical breaks in the Grampian Highlands, but nowhere is it 42 marked by an angular discordance or by exposed conglomerates. 43 Based upon the regional stratigraphical considerations, Robertson 44 and Smith (1999) argued for an original basin architecture in which 45 the Glen Banchor Subgroup occured in a structural ‗high‘ that 46 formed the eastern wall of a west-facing basin during deposition of 47 48 the Grampian Group and continued to influence depositional systems 49 throughout Appin Group time. Metalimestones of the Blair Atholl 50 Subgroup are the youngest parts of the sequence to overstep the 51 Glen Banchor ‗high‘. 52 53 11.3.2 Structural framework 54 55 Thomas (1979) interpreted the Geal-charn-Ossian Steep Belt as a 56 fundamental root-zone because the major recumbent folds on opposite 57 sides of the steep belt face in opposite directions i.e. to the 58 north-west on the north-west side and to the south-east on the 59 south-east side (see Stephenson et al., 2013a, fig 10a). In 60 contrast, Temperley (1990) argued for a late structural development 61 62 63 64 65 1 2 3 4 for the steep belt with folding and shearing superimposed upon a 5 zone that had already experienced a protracted tectonothermal 6 history. 7 The overall geometry of the steep belt is that of a major upright 8 synform (Figure 31). The facing and vergence of small- and medium- 9 scale structures indicates that much of the structural pattern 10 developed during the first deformation phase, with few significant 11 12 changes in architecture resulting from the subsequent deformation 13 (Figure 4); the vergence of second-phase folds shows no large-scale 14 systematic changes across the belt (Smith et al., 1999). The steep 15 belt forms the boundary between contrasting structural domains with 16 primary upright structures to the north-west and recumbent folding 17 to the south-east. The original orientation of the structures in 18 the steep belt has previously been envisaged as either upright 19 (Anderson, 1947b, 1956; Thomas, 1979, 1980) or recumbent 20 (Temperley, 1990; Evans and Tanner, 1996). 21 On the basis on the overall structural geometry and the 22 stratigraphical relationships, Robertson and Smith (1999) argued 23 that the Geal-charn-Ossian Steep Belt is a major composite 24 synclinal structure focussed upon the Kinlochlaggan Syncline. 25 According to their model, the steep belt originated as a primary 26 feature located at the eastern margin of a major west-facing 27 sedimentary basin in which more than 8 km of Grampian Group 28 sediment had been deposited. This basin was adjacent to an 29 30 intrabasin structural ‗high‘ composed mainly of gneissose 31 metasedimentary rocks of the Glen Banchor Subgroup and acting as 32 the local basement to the Grampian and Appin group rocks. Major 33 unconformities recognized at more than one stratigraphical level 34 reflect onlap of the basin successions onto the ‗high‘. 35 The primary major upright folds and associated slides of the steep 36 belt developed when considerable shortening was focused along the 37 basin margin during the Caledonian Orogeny (Figure 4). The 38 deformation patterns were interpreted by Robertson and Smith (1999) 39 as the result of buttressing and inversion of the depositional 40 sequence against the more-rigid upstanding structural ‗high‘. A 41 similar origin has been suggested for the upright Stob Ban–Craig a‘ 42 Chail Synform which reflects deformation of the western edge of 43 both the deep water Corrieyairack Subgroup basin and Appin Group 44 half grabens (Glover et al., 1995). 45 46 47 11.4 Conclusions 48 49 The Aonach Beag and Geal-charn GCR site is of national importance 50 for the way in which the complex Caledonian deformation pattern in 51 a crucial central area of the Grampian Highlands can be related to 52 the original geometry and subsequent development of early Dalradian 53 sedimentary basins. 54 The site preserves excellent exposures of the stratigraphical 55 relationships between the local Kinlochlaggan succession of the 56 Appin Group and the underlying Grampian Group in a regional zone of 57 steeply dipping rocks known as the Geal-charn–Ossian Steep Belt. 58 The mountainous nature of the site is such that truly three- 59 dimensional observations can be made of the structural geometry of 60 the steep belt, which includes the complex upward-facing 61 62 63 64 65 1 2 3 4 Kinlochlaggan Syncline and other complementary tight folds in its 5 core. 6 The Geal-charn–Ossian Steep Belt occurs at the boundary between 7 contrasting structural and stratigraphical domains. Distinct but 8 coeval sedimentary successions in each domain responded in 9 fundamentally different ways to later deformation, with primary 10 upright structures to the west and recumbent structures to the 11 12 east. The steep belt is a zone of primary major upright folds with 13 associated slides, developed on severely attenuated fold limbs as 14 originally stated by Thomas (1979). However, it is not a root-zone 15 to divergent nappes as envisaged by Thomas, nor is it the product 16 of a late monoform or late upright shearing as proposed by 17 Temperley (1990). It occurs at the eastern margin of a thick 18 composite sedimentary basin where deformation was focused against a 19 footwall ‗high‘. Subsequent deformation was then influenced by the 20 distribution of half-graben fills and intrabasinal ‗highs‘. 21 22 12 BEN ALDER 23 (NN 477 722–NN 483 722 and NN 495 733–NN 499 708) 24 25 A.G. Leslie and C.J. Banks 26 27 28 29 12.1 Introduction 30 31 The Ben Alder GCR site comprises the whole of the eastern flank of 32 the mountain (Figure 33, 34), from Garbh Coire (NN 498 715) to 33 Coire na Lethchois (NN 502 734), together with the western corrie 34 of Coire Labhair (NN 483 722). Its national importance arises from 35 the architecture of large-scale polyphase folding of a varied 36 Grampian Group metasedimentary succession, adjacent to the Geal- 37 charn–Ossian Steep Belt that is exposed in the Aonach Beag and 38 Geal-charn GCR site. 39 The summit of Ben Alder stands at 1148 m in the midst of an 40 extensive plateau with much ground above 970 m, some 10 km from the 41 nearest 4-wheel-drive track and 15 km from the nearest road. The 42 cliffs on the north-western flank and in the imposing eastern 43 corries are over 200 m high. The remote and mountainous nature of 44 the terrain has no doubt led to the paucity of geological 45 investigations. The area was originally surveyed by the Geological 46 Survey, who identified a number of ‗sharp folds‘ whose ‗true nature 47 48 and value are unknown‘, deforming ‗quartz-biotite-granulites of the 49 Moine Series‘. It was concluded that it was ‗impossible to 50 decipher the structure of the Ben Alder plateau‘ (Carruthers in 51 Hinxman et al., 1923). Thomas (1979) provided the first detailed 52 account of the country between Loch Ericht and Loch Treig, which 53 includes the great corries on the north-east face of Geal-charn 54 (the Aonach Beag and Geal-charn GCR site) and those of Ben Alder. 55 Much of the structure relevant to the Ben Alder area is represented 56 on the BGS 1:50 000 Sheet 63E (Dalwhinnie, 2002), although this GCR 57 site lies along strike to the south-west, entirely within the 58 adjacent Sheet 54E (Loch Rannoch). 59 Thomas (1979, 1980) recognized major changes in facing across 60 early recumbent structures affecting a ‗Moine‘ succession in the 61 62 63 64 65 1 2 3 4 Ben Alder area to the south-east of the Geal-charn-Ossian Steep 5 Belt. He regarded the area as critical to any understanding of 6 potential stratigraphical and structural linkages between the NW- 7 facing nappes that had by then been recognized in the Loch Leven 8 district (Treagus, 1974; Roberts, 1976) and the SE-facing nappes of 9 Glen Orchy (Thomas and Treagus, 1968), Strathtummel (Thomas, 1980) 10 and the Southern Highlands (Harris et al., 1976; Bradbury et al., 11 12 1979). The model proposed by Thomas (1979) had major nappes 13 diverging to the north-west and south-east from either side of the 14 upward-facing Geal-charn-Ossian Steep Belt, which in effect acted 15 as a fundamental root-zone (see Stephenson et al., 2013a, fig. 16 10a). In the Ben Alder area, the early SE-facing nappe structures 17 were refolded by two further phases of folding. 18 Robertson and Smith (1999) examined many of the critical sections 19 across the Geal-charn–Ossian Steep Belt in Coire Cheap and Coire 20 Sgòir. That work essentially confirmed the presence of Appin Group 21 lithostratigraphy in the core of the upward-facing Kinlochlaggan 22 Syncline (F1) and the importance of ductile slide structures in 23 Coire Cheap, Coire Sgòir and on Aonach Beag. Three main 24 penetrative deformation phases were recognized; the resultant 25 structures and fabrics equate broadly with those described by 26 Thomas (1979), while recognizing that the strict timing of 27 deformation might be diachronous in structural domains across the 28 region. The facing and vergence of small- and medium-scale 29 30 structures is such that the structural pattern must have developed 31 to a large extent during the first main deformation, there being 32 few significant changes in secondary-phase fold vergence across the 33 steep belt. Robertson and Smith (1999) thus regarded the steep 34 belt as a zone of primary major upright folds with associated 35 slides developed on severely attenuated fold limbs, as originally 36 stated by Thomas (1979). 37 38 12.2 Description 39 40 The following description is drawn largely from the maps and 41 comments within publications by Thomas (1979, 1980), supplemented 42 where appropriate by more-recent work by the British Geological 43 Survey, mainly on the adjacent 1:50 000 Sheet 63W (Dalwhinnie, 44 2002) (Robertson and Smith, 1999). The most-recent BGS work (2005– 45 2006) extended that re-assessment southwards onto the Ben Alder 46 massif itself and will rationalize the regional stratigraphical 47 48 relationships within current understanding of the Grampian Group 49 (c.f. Banks, 2005). The structural chronology referred to here is 50 that of Thomas (1979). 51 Thomas (1979) referred to a ‗Moine succession‘ rich in strongly 52 striped and banded schistose semipelite and psammite, interleaved 53 with much thicker units of schistose pelite and gneissose psammite. 54 A few pods and lenses of calcsilicate rock occur throughout. These 55 lithologies are likely to be assigned eventually to the sequence of 56 Grampian Group formations recognized within Sheet 63E (Dalwhinnie, 57 2002) immediately to the north and by Banks (2005); namely the 58 Coire nan Laogh Semipelite Formation, Creag Dhubh Psammite 59 Formation, Pitmain Semipelite Formation and the Gaick Psammite 60 Formation. 61 62 63 64 65 1 2 3 4 Thomas (1979, 1980) considered that the upright pattern of folds 5 in the Geal-charn-Ossian Steep Belt is transformed to the south- 6 east, over 2-3 km across strike, into broadly recumbent nappe 7 structures, which have been refolded by second and third generation 8 upright structures (Figure 35) that he termed the ‗Ben Alder 9 folds‘. Details of the distribution and suggested way up of this 10 sequence are reproduced in Figure 34; Figure 36 is a structural 11 12 profile extending south-eastwards from the Geal-charn-Ossian Steep 13 Belt through Ben Alder (both after Thomas, 1979). 14 The Sgòir Slide lies along the south-east margin of the steep 15 belt. This slide lies on the north-western limb of the F1 Coire 16 Sgòir Anticline and is marked by tight folding, migmatization, and 17 loss of good bedding features. The slide juxtaposes Inverlair 18 Psammite Formation rocks to the north-west against folded, strained 19 and mobilized Creag Dhubh Psammite Formation in the south-east 20 (referred to as the Creag Meagaidh Psammite on BGS Sheet 63E). 21 Earlier slide structures are affected by refolding locally and, at 22 a larger scale, the Coire Sgòir Anticline and the structurally 23 lower level F1 Coire Labhair Syncline are re-orientated across the 24 trace of the F3 Lancet Edge Antiform, so that the upright axial 25 surfaces of both folds adjacent to the steep belt become NW-dipping 26 to the south-east, across the trace of the F3 fold. 27 In the upright core of the Coire Labhair Syncline, where it 28 crosses Lancet Edge (NN 495 745), are pelites, banded semipelites 29 30 and psammites, which have been assigned to the Clachaig Semipelite 31 and Psammite Formation by Robertson and Smith (1999) (see also BGS 32 Sheet 63E). Thomas (1979) mapped these schistose semipelites and 33 pelites from Lancet Edge along the trace of the Coire Labhair 34 Syncline, south across the Bealach Dubh and then south-westwards 35 through the crags to Coire Labhair, where the syncline closure is 36 very well exposed in the south face of the corrie (NN 481 722). At 37 this point, schistose psammites are revealed in the core of the 38 fold; semipelite and pelite on the lower limb extend eastwards 39 across much of the summit plateau of Ben Alder and the cliffs and 40 crags farther to the east around Garbh Coire (NN 500 715). 41 The closure of the complementary F1 Ben Alder Anticline is less 42 clear and is dependent upon assessment of lithological repetition 43 eastwards towards Coire na Lethchois and Garbh-choire Beag (Figure 44 34). Thomas (1979) placed the closure on the cliffs just south of 45 Garbh-choire Beag (NN 501 724), within a unit of schistose 46 psammite. From there, a repetition of the semipelite and pelite 47 48 formations mapped at the Bealach Dubh is shown northwards from the 49 closure towards Coire na Lethchois (NN 503 734). From Garbh-choire 50 Beag the Ben Alder Anticline was traced west and then north across 51 the northern flank of the summit massif of Ben Alder to the crags 52 at NN 497 734; here too the closure is within schistose psammite 53 with schistose semipelite and pelite to the west and east on 54 opposite limbs. 55 According to Thomas (1979), the major change in trend of the F1 56 Ben Alder Anticline occurs across the trace of the NE-trending F2 57 Ben Alder Antiform; the latter structure was identified in cross- 58 section in the cliffs in Garbh-choire Beag (NN 503 726). The 59 complementary F2 Ben Alder Synform is less clear, being ‗barely 60 61 62 63 64 65 1 2 3 4 exposed‘ in a section around NN 509 730, above the hanging valley 5 of the Bealach Beithe. 6 Rather symmetrical open F3 folds, which deform both the D1 and D2 7 structures, are present as a fold-pair in Coire na Lethchois (NN 8 501 734) (the Coire na Lethchois Antiform and Synform) and as more- 9 asymmetrical folds stepping down to the north-west on the southern 10 edge of the Bealach Dubh (NN 498 737) (the Bealach Dubh Synform) 11 12 and on Lancet Edge (NN 496 745) (the Lancet Edge Antiform). These 13 are open to tight folds with a crenulation cleavage developed 14 locally, especially in the hinge areas. 15 South of the Garbh Coire Fault (NN 497 715), Thomas (1979) 16 recorded that several F1 isoclines become truly recumbent over the 17 broad symmetrical hinge of the F3 Coire na h‘Iolaire Antiform (NN 18 513 705), so that in general terms the attitude of the earliest 19 isoclinal folds is upright in the steep belt to the north-west and 20 recumbent on the Ben Alder massif and to the south-east. 21 22 12.3 Interpretation 23 24 Thomas (1979, 1980) described local successions of what is now 25 termed the Grampian Group from both the Ben Alder area and farther 26 to the south-east across Strath Tummel. Tentative correlations, in 27 the area of Sheet 63E (Dalwhinnie), of the psammite and semipelite 28 successions immediately south-east of the steep belt with the 29 30 Corrieyairack Subgroup succession of the Loch Laggan–Glen Roy area 31 (Robertson and Smith, 1999) have been further rationalized by Banks 32 (2005). 33 Thomas‘ succession for the Ben Alder area comprised three 34 psammite-dominated, and two semipelite-and-pelite-dominated units. 35 Whilst Robertson and Smith (1999) recorded a strikingly similar 36 sequence for their Grampian Group lithostratigraphy in the steep 37 belt, detailed correlation is an ongoing concern. Adopting the 38 most-recent analysis of Grampian Group lithostratigraphy (Banks, 39 2005) will mean, for example, that the pelite, banded semipelite 40 and psammite in the core of the Coire Labhair Syncline should be 41 correlated with the Pitmain Semipelite Formation, and the younger 42 schistose psammites should be correlated with the Gaick Psammite. 43 Banded and graded schistose psammites that enclose these two 44 formations are correlated with the Creag Dhubh Psammite Formation. 45 Establishing the lithostratigraphical succession on Ben Alder, and 46 hence the structural architecture, was apparently more 47 48 problematical than it was in the steep belt (Thomas, 1979). This 49 was largely due to the apparent lack of sedimentary structures and 50 evidence of younging, compounded by the superimposition of 51 polyphase folding on a major scale. More-recent work farther to 52 the north and north-west, notably on Loch Laggan side and in Glen 53 Roy has recognized sedimentary rocks of the Corrieyairack Subgroup 54 that were deposited in deep water, largely by turbidity currents 55 (see the Rubha na Magach GCR site report). These are overlain in 56 turn by the Glen Spean Subgroup, which represents a basin-shoaling 57 succession from shallow marine to estuarine (Glover and Winchester, 58 1989; Glover et al., 1995; Glover and McKie, 1996). Such 59 documentation of the stratigraphy and sedimentary history has 60 transformed understanding of the Grampian Group depositional 61 62 63 64 65 1 2 3 4 record. The lithostratigraphy of the Ben Alder massif is now known 5 to straddle the boundary between the Corrieyairack and Glen Spean 6 subgroups of the Grampian Group, with the Pitmain Semipelite 7 Formation deposited on the flooding surface that defines the base 8 of the Glean Spean Subgroup. 9 The Ben Alder GCR site is centred upon the northern part of the 10 Ben Alder massif where Thomas (1979) recorded his evidence for D2 11 12 and D3 refolding of the primary nappe structure on the south-east 13 flank of the steep belt. The earliest folds were considered to 14 change from an upward-facing, upright form in the steep belt to 15 more-recumbent SE-facing structures, (ultimately downwards-facing 16 to the south-east) as they were traced south-eastwards away from 17 the steep belt, across the Drumochter Dome and into the Atholl 18 Nappe-complex in the footwall of the Boundary Slide in the Blair 19 Atholl district (see 1.4.1 in Introduction). The NW-facing 20 structures in the Appin and Lochaber districts were represented as 21 a ‗mirror-image‘ emerging from the steep belt to the north-west. 22 Thus the Geal-charn-Ossian Steep Belt was envisaged as a root-zone 23 to both the SE-facing and the NW-facing nappes of the Central 24 Grampian Highlands. 25 In this scenario, Thomas regarded the Drumochter Dome as an F2 26 structure (Thomas, 1979, figure 6). However, Lindsay et al. (1989) 27 demonstrated that S2 axial planes and cleavages are folded across 28 the dome, which is consequently now generally accepted as a later 29 30 structure, possibly F3 as originally proposed by Roberts and 31 Treagus (1977c, 1979) for the related domes of Glen Orchy and Glen 32 Lyon or F4 of other authors. Thomas (1980, 1988) regarded the 33 Meall Reamhar Synform of the Blair Atholl district as the F1 34 closure of the SE-facing Atholl Nappe but in the light of work by 35 Treagus (1987, 2000) this fold is now regarded as an F2 structure. 36 The most-recent structural interpretations of the Grampian 37 Highlands emphasize the importance of the D2 deformation (rather 38 than D1) in relation to the generation of the major nappes 39 (Krabbendam et al., 1997; Treagus, 1987, 2000) and it seems likely 40 that a similar modification of the structural chronology of the 41 polyphase folding displayed on the Ben Alder massif will be 42 appropriate, with the major recumbent folds essentially D2 in age 43 rather than D1. However, the presence of F1 folds of significant 44 magnitude cannot be discounted at this stage. 45 Robertson and Smith (1999) broadly agreed with Thomas (1979) on 46 the structural architecture within the steep belt but dismissed the 47 48 idea of a root-zone for emergent nappes. Instead they argued that 49 the steep belt forms the boundary between contrasting structural 50 domains, with primary upright structures to the north and west and 51 recumbent folding to the south and east (Figure 31). In this 52 model, the steep belt itself is believed to have formed at the 53 eastern margin of a major Grampian Group basin with partitioned 54 (and possibly diachronous) deformation patterns interpreted to be 55 the result of buttressing of the sedimentary rocks of the basin 56 against a rigid upstanding block of ‗basement‘ to the east composed 57 of the Glen Banchor Subgroup (see the Aonach Beag and Geal-charn 58 GCR site report). In this respect, the steep belt would have a 59 similar origin to the upright Stob Ban-Craig a‘Chail Synform, which 60 reflects deformation of the western edge of both the deep water 61 62 63 64 65 1 2 3 4 Corrieyairack Subgroup basin and Appin Group half grabens (Glover 5 et al., 1995). Current syntheses of the structure of the Central 6 Grampian Highlands do not therefore invoke the D1/D2 ‗fountain of 7 nappes‘ emanating in opposing directions from a root-zone as was 8 envisaged (Thomas, 1979) in earlier structural models (see 9 discussion in 1.4 in Introduction). 10 11 12 12.4 Conclusions 13 14 The area around Ben Alder has been central to debates concerning 15 the existence or otherwise of a root-zone for the regional nappe- 16 complexes of the Central Grampian Highlands. It was believed that 17 the nappes were ‘squeezed out’ on both sides of a zone of steeply 18 dipping rocks, now called the Geal-charn–Ossian Steep Belt, which 19 is well exposed in the adjacent Aonach Beag and Geal-charn GCR 20 site. This in effect created a mushroom-shaped ‘fountain’ of nappes 21 in which individual nappes were separated by ductile dislocations 22 termed slides. Away from the steep belt to the south-east the 23 primary F1 nappes became highly inclined, SE-facing, and all of the 24 structures were subsequently refolded by more-upright folds of at 25 least two generations (F2 and F3), resulting in the observed 26 pattern of recumbent structures. 27 The Ben Alder GCR site is situated on the south-east side of the 28 steep belt and has been crucial to any interpretation of the steep 29 30 belt and of the nappes between there and the Boundary Slide at 31 Blair Atholl. This in turn is fundamental to theories for the 32 origin and evolution of the Grampian nappe-complexes in general. 33 The most recent published work has emphasized the influence of the 34 original depositional framework of the Grampian Group sediments, 35 and in particlar the basin geometry, on the subsequent structural 36 architecture. Hence the Geal-charn–Ossian Steep Belt is no longer 37 regarded as a root-zone to the major nappes and has been attributed 38 to compression of the sediments against a basement ‗high‘ that 39 forms the basin margin, with the SE-facing nappes attributable 40 largely to the D2 deformation phase. The ongoing debate will 41 continue to draw heavily upon evidence from the Ben Alder area, 42 emphasizing still further the national importance of the Aonach 43 Beag to Geal-charn and Ben Alder GCR sites. 44 45 46 47 ACKNOWLEDGEMENTS 48 49 This regional paper is the combined work of 6 authors, many of 50 whom, in addition to their own site descriptions, have made 51 valuable comments on other aspects of the work. Sadly, Steve 52 Robertson died during the early stages of preparation of the 53 Dalradian GCR and his contributions have been completed by M. 54 Smith. Steve made major contributions to his own areas of the 55 Dalradian outcrop and to our overall understanding of Grampian 56 Highland geology. 57 The paper has been compiled by A.G. Leslie and has been edited by 58 D. Stephenson. The GCR editor was P.H. Banham and the referee was 59 M.R.W. Johnson, who also provided valuable editorial suggestions. 60 The project was cofunded by the Joint Nature Conservation Committee 61 62 63 64 65 1 2 3 4 (JNCC) and the British Geological Survey (BGS) and has been managed 5 by N.V. Ellis for JNCC and D.J. Fettes and M. Smith for BGS. 6 The initial site selection and site documentation for the 7 Dalradian block of the Geological Conservation Review was by S.J. 8 Moorhouse. Since then, much new mapping and refined interpretation 9 has taken place, and the site list has been revised, firstly by 10 J.E. Treagus and subsequently through a panel consisting of R. 11 12 Anderton, A.L. Harris, J.R. Mendum, J.L. Roberts, P.W.G. Tanner, R. 13 Threadgould and J.E. Treagus. The necessary amendments to the GCR 14 documentation were greatly facilitated by R. Wignall (for Scottish 15 Natural Heritage). 16 K.M. Goodenough and S.W. Horsburgh assisted with preliminary 17 drafts of key maps and all diagrams were drafted for publication by 18 S.C. White (JS Publications, Newmarket) and K.J. Henderson (BGS, 19 Edinburgh). Photographs were scanned and prepared by B.M. McIntyre 20 (BGS, Edinburgh). Photographs from the BGS collection are 21 reproduced by kind permission of the Director, BGS © Natural 22 Environment Research Council; all rights reserved (PR/23–27). 23 Several of the principal authors of the Dalradian GCR have been 24 involved in the writing of other reviews of the Dalradian of 25 Scotland and, inevitably, sections of introductory text have been 26 adapted and updated from their contributions to those earlier 27 works. In particular, sections have been adapted from a chapter in 28 The Geology of Scotland (Strachan et al., 2002) and from a recent 29 30 review of the evolution of the north-east margin of Laurentia 31 (Leslie et al., 2008). The original sources of many key diagrams 32 taken from these and other works are acknowledged in their 33 captions. 34 The first complete draft of the Dalradian GCR was submitted to the 35 JNCC in June 2009. In 2010, the JNCC terminated its involvement in 36 Earth Science conservation and abandoned its contractual agreements 37 to publish the remaining GCR volumes. So, the authors are greatly 38 indebted to Diarmad Campbell, Chief Geologist Scotland for the BGS, 39 for funding the drafting of remaining figures and to the 40 Geologists‘ Association and Elsevier, for ensuring that this volume 41 is published as a Special Issue of their Proceedings. We are 42 particularly grateful to Neil Ellis of the JNCC for his efforts to 43 secure a new publisher and to Professor James Rose, Editor in Chief 44 of the PGA, for making it all happen. 45 Finally, on behalf of all of the site authors, we would like to 46 record our thanks to the owners and managers of land and quarries 47 48 who have allowed access to the sites, either during previous work 49 or specifically for the GCR exercise. 50 51 REFERENCES 52 53 Agrell, S. O. (1942) 1. A petrological investigation of the 54 adinoles at Dinas Head, Cornwall. 2. A petrofabric study of the 55 Ben Vuroch granite and the adjacent schists in Perthshire. 56 Unpublished PhD thesis, University of Cambridge. 57 Ahmed-Said Y. and Tanner P. W. G. (2000) P-T conditions during 58 emplacement, and D2 regional metamorphism, of the Ben Vuirich 59 Granite, Perthshire, Scotland. Mineralogical Magazine, 64, 737–53. 60 61 62 63 64 65 1 2 3 4 Ague, J.J. & Baxter, E.F., 2007. Brief thermal pulses during 5 mountain building recorded by Sr diffusion in apatite and 6 multicomponent diffusion in garnet. Earth and Planetary Science 7 Letters, 261, 500-516. 8 Allen, J. R. L. 1963. The classification of cross stratified units 9 with notes on their origin. Sedimentology, 2, pp. 93-114. 10 Allison, A. (1933) The Dalradian succession in Islay and Jura. 11 Quarterly Journal of the Geological Society, London, 89, 125–44. 12 Allison, A. 1941. Loch Awe succession and tectonics-Kilmartin- 13 Tayvallich-Danna. Quarterly Journal of the Geological Society, 14 London, 96, 423–49. 15 Allison, I., May, F and Strachan, R.A. (1988) An Excursion guide to 16 the Moine Geology of the Scottish Highlands. Scottish Academic 17 Press for Edinburgh Geological Society and Geological Society of 18 Glasgow. 19 Alsop, G.I. and Hutton, D.H.W. (1990) A review and revision of 20 Dalradian stratigraphy in central and southern Donegal, Ireland. 21 Irish Journal of Earth Sciences, 10, 181–98. 22 Alsop, G.I., Prave, A.R., Condon, D.J. and Phillips, C.A. (2000) 23 Cleaved clasts in Dalradian conglomerates: possible evidence for 24 Neoproterozoic compressional tectonism in Scotland and Ireland? 25 Geological Journal, 35, 87–98. 26 Amos, B.J. (1960). The geology of the Bowmore district, Islay. 27 Unpublished PhD thesis, University of London, Imperial College. 28 Anderson, E M. (1923). The geology of the schists of the 29 Schiehallion district. Quarterly Journal of the Geological Society 30 of London, 79, 423–45. 31 Anderson, E M. (1951) The Dynamics of Faulting. (Second edition). 32 (Edinburgh: Oliver and Boyd.) 33 Anderson, J. G. C., (1942) The stratigraphical order of the 34 Dalradian schists near the Highland Border in Angus and 35 Kincardineshire. Transactions of the Geological Society of 36 Glasgow, 20, 223–37. 37 Anderson, J.G.C. (1947a) The geology of the Highland Border, 38 Stonehaven to Arran. Transactions of the Royal Society of 39 Edinburgh, 61, 479–515. 40 Anderson, J.G.C. (1947b) The Kinlochlaggan Syncline, southern 41 Inverness-shire. Transactions of the Geological Society of 42 Glasgow, 21, 97–115. 43 Anderson, J.G.C. (1948) Stratigraphic nomenclature of Scottish 44 metamorphic rocks. Geological Magazine, 85, 89–96. 45 Anderson, J.G.C (1956). The Moinian and Dalradian rocks between 46 Glen Roy and the Monadhliath Mountains, Inverness-shire. 47 Transactions of the Royal Society of Edinburgh, 63, 15–36. 48 Anderton, R. (1974) Middle Dalradian sedimentation in Argyll, with 49 particular reference to the Jura quartzite, Scarba conglomerate 50 and Craignish phyllites. Unpublished PhD thesis, University of 51 Reading. 52 Anderton, R. (1975) Tidal flat and shallow marine sediments from 53 the Craignish Phyllites, Middle Dalradian, Argyll, Scotland. 54 Geological Magazine, 112, 337–40. 55 Anderton, R. (1976) Tidal-shelf sedimentation: an example from the 56 Scottish Dalradian. Sedimentology, 23, 429–58. 57 Anderton, R. (1977) The Dalradian rocks of Jura. Scottish Journal 58 of Geology, 13, 135–42. 59 Anderton, R. (1979) Slopes, submarine fans and syn-depositional 60 sedimentology of parts of the Middle and Upper Dalradian in the 61 62 63 64 65 1 2 3 4 S.W. Highlands of Scotland. In The British Caledonides - Reviewed 5 (eds. Harris, A. L., Holland, C. H. and Leake, B. E.), Geological 6 Society, London, Special Publications, 8. 7 Anderton, R. (1980). Distinctive pebbles as indicators of Dalradian 8 provenance. Scottish Journal of Geology, 16, 143–52. 9 Anderton, R. (1982) Dalradian deposition and the late Precambrian - 10 Cambrian history of the N Atlantic region: a review of the early 11 evolution of the Iapetus Ocean. Journal of the Geological Society 12 of London, 139, 421–31. 13 Anderton, R. (1985) Sedimentation and tectonics in the Scottish 14 Dalradian. Scottish Journal of Geology, 21, 407–36. 15 Anderton, R. (1988) Dalradian slides and basin development: a 16 radical interpretation of stratigraphy and structure in the SW and 17 Central Highlands of Scotland. Journal of the Geological Society 18 of London, 145, 669–78. 19 Arndt, N.T. and Nisbet, E.G. (editors) (1982) Komatiites. George 20 Allen and Unwin, London. 21 Ashcroft W.A., Kneller B.C., Leslie, A.G. and Munro M. (1984) Major 22 shear zones and autochthonous Dalradian in the northeast Scottish 23 Caledonides. Nature, London 310, 760–2. 24 Ashworth, J.R. (1972) Migmatites of the Huntly-Portsoy area, north- 25 east Scotland. Unpublished PhD thesis, University of Cambridge. 26 Ashworth, J.R. (1975) The sillimanite zones of the Huntly–Portsoy 27 area in the north-east Dalradian, Scotland. Geological Magazine, 28 112, 113–224. 29 Ashworth, J.R. (1976) Petrogenesis of migmatites in the Huntly– 30 Portsoy area, north-east Scotland. Mineralogical Magazine, 40, 31 661–82. 32 Ashworth, J.R. (1979) Comparative petrography of deformed and 33 undeformed migmatites from the Grampian Highlands of 34 Scotland. Geological Magazine, 116, 445–56. 35 Astin, T.R. and Rogers, D.A. (1991) ‗Subaqueous shrinkage cracks‘ 36 in the Devonian of Scotland re-interpreted. Journal of Sedimentary 37 Petrology, 61, 850–9. 38 Atherton, M.P. (1977) The metamorphism of the Dalradian rocks of 39 Scotland. Scottish Journal of Geology, 13, 331–70. 40 Atherton, M.P., and Brotherton, M.S. (1972) The composition of some 41 kyanite-bearing regionally-metamorphosed rocks from the Dalradian. 42 Scottish Journal of Geology, 8, 203–13. 43 Atherton, M.P. and Ghani, A.A. (2002) Slab breakoff: a model for 44 Caledonian, Late Granite syn-collisional magmatism in the ortho- 45 tectonic (metamorphic) zone of Scotland and Donegal. Lithos, 62, 46 65–85. 47 48 Bailey, E.B. (1910) Recumbent folds in the schists of the Scottish 49 Highlands. Quarterly Journal of the Geological Society of London, 50 66, 586–620. 51 Bailey, E. B. 1913. The Loch Awe Syncline (Argyllshire). Quarterly 52 Journal of the Geological Society of London, 69, 280–307. 53 Bailey, E.B. (1917) The Islay anticline (Inner Hebrides). Quarterly 54 Journal of the Geological Society of London, 72, 132–64. 55 Bailey, E.B. (1922) The structure of the South West Highlands of 56 Scotland. Quarterly Journal of the Geological Society of London, 57 78, 82–131. 58 Bailey, E.B. (1925) Perthshire tectonics: Loch Tummel, Blair 59 Atholl and Glen Shee. Transactions of the Royal Society of 60 Edinburgh, 53, 671–98. 61 62 63 64 65 1 2 3 4 Bailey, E.B. (1930) New Light on Sedimentation and Tectonics. 5 Geological Magazine, 67, 77. 6 Bailey, E.B. (1934) West Highland tectonics: Loch Leven to Glen 7 Roy. Quarterly Journal of the Geological Society of London, 90, 8 462–523. 9 Bailey, E.B. (1938) Eddies in mountain structure. Quarterly Journal 10 of the Geological Society of London, 94, 607–25. 11 Bailey, E B. (1953). Facies changes versus sliding: Loch Leven, 12 Argyll. Geological Magazine, 90, 111–13. 13 Bailey, E.B. (1960) The geology of Ben Nevis and Glencoe and the 14 surrounding country. (2nd edition). Memoir of the Geological 15 Survey of Great Britain, Sheet 53 (Scotland). 16 Bailey, E.B., and McCallien, W. (1937). Perthshire tectonics: 17 Schiehallion to Glen Lyon. Transactions of the Royal Society of 18 Edinburgh, 59, 79–118. 19 Bailey, E B, and MacGregor, M. 1912. The Glen Orchy Anticline, 20 Argyllshire. Quarterly Journal of the Geological Society of 21 London, Vol. 68, 164–179. 22 Bailey, E.B., and Maufe, H.B. (1916) The geology of Ben Nevis and 23 Glen Coe and the surrounding country. (1st edition). Memoir of the 24 Geological Survey of Great Britain, Sheet 53 (Scotland). 25 Bain, J.A., Briggs, D.A. and May, F. (1971) Geology and 26 mineralogical appraisal of an extensive talc-magnesite deposit in 27 the Shetlands. Transactions of the Institute of Mining and 28 Metallurgy, 80, B77–B84. 29 Baker, A.J. (1985) Pressures and temperatures of metamorphism in 30 the eastern Dalradian. Journal of the Geological Society of 31 London, 142, 137–48. 32 Baker, A.J. (1987) Models for the tectonothermal evolution of the 33 eastern Dalradian of Scotland. Journal of Metamorphic Geology, 5, 34 101–18. 35 Baker, A.J., and Droop, G.T.R. (1983) Grampian metamorphic 36 conditions deduced from mafic granulites and sillimanite–K- 37 feldspar gneisses in the Dalradian of Glen Muick, Scotland. 38 Journal of the Geological Society of London, 140, 489–97. 39 Baldwin, C.T. and Johnson, H.D. (1977) The Dalradian rocks of 40 Lunga, Luing and Shuna. Scottish Journal of Geology, 13, 143–54. 41 Banks, C. J. (2005). Neoproterozoic Basin Analysis: a combined 42 sedimentological and provenance study in the Grampian Group, 43 Central Highlands, Scotland. Unpublished PhD Thesis, University of 44 Keele. 45 Banks, C.J. (2007) Exceptional preservation of sedimentary 46 structures in metamorphic rocks: an example from the upper 47 Grampian Group, Creag Stalcair, Perthshire. Scottish Journal of 48 Geology, 43, 9–14. 49 Banks, C.J. and J.A. Winchester (2004). Sedimentology and 50 stratigraphic affinities of Neoproterozoic coarse clastic 51 successions, Glenshirra Group, Inverness-shire Scotland. Scottish 52 Journal of Geology 40, 159–174. 53 Banks, C.J., Smith, M., Winchester, J.A., Horstwood, M.S.A., Noble, 54 S.R. and Ottley, C.J. (2007) Provenance of intra-Rodinian basin- 55 fills: the lower Dalradian Supergroup, Scotland. Precambrian 56 Research, 153, 46-64. 57 Barreiro, B.A. (1998) U-Pb systematics on zircon from the Keith and 58 Portsoy granites, Grampian Highlands, Scotland. NERC Isotope 59 Geosciences Laboratory Report Series No. 132. 60 61 62 63 64 65 1 2 3 4 Barrow, G. (1893) On an intrusion of muscovite-biotite gneiss in 5 the south-east Highlands of Scotland, and its accompanying 6 metamorphism. Quarterly Journal of the Geological Society of 7 London, 49, 330–58. 8 Barrow, G. (1904) Moine gneisses of the east central Highlands and 9 their position in the Highland sequence. Quarterly Journal of the 10 Geological Society of London, 60, 400–44. 11 Barrow, G. (1912) On the geology of Lower Deeside and the southern 12 Highland border. Proceedings of the Geologists’ Association, 23, 13 274–90. 14 Barrow G. and Cunningham Craig E.H. (1912) The geology of the 15 districts of Braemar, Ballater and Glen Clova. Memoir of the 16 Geological Survey of Great Britain, Sheet 65 (Scotland). 17 Barrow, G, Grant Wilson, J S, and Cunningham Craig, E H. (1905). 18 The geology of the country around Blair Atholl, Pitlochry and 19 Aberfeldy. Memoir of the Geological Survey of Great Britain, Sheet 20 55 (Scotland). 21 Basahel, A.N. (1971) The Dalradian stratigraphy and structure of 22 southern Islay, Argyll. Unpublished PhD thesis. University of 23 Liverpool. 24 Batchelor, R.A. (2011) Geochemistry of Torridonian tuffs and 25 contemporary phosphorites; potential for correlation of 26 Torridonian sequences in NW Scotland. Scottish Journal of Geology, 27 47, 133-142. 28 Baxter, E.F., Ague, J.J. and Depaolo, D.J. (2002) Prograde 29 temperature-time evolution in the Barrovian type-locality 30 constrained by Sm/Nd garnet ages from Glen Clova, Scotland. 31 Journal of the Geological Society, London, 159, 71–82. 32 Beddoe-Stephens B. (1990) Pressures and temperatures of Dalradian 33 metamorphism and the andalusite-kyanite transformation in the 34 northeast Grampians. Scottish Journal of Geology 26, 3–14. 35 Bell, A. M. (1981) Vergence: an evaluation. Journal of Structural 36 Geology, Volume 3, 197–202. 37 Bendall, C.A. (1995). A geochronological, structural and 38 metamorphic study of rocks from the central and SW Dalradian of 39 Scotland. Unpublished PhD thesis, University of Manchester 40 Bentley, M.R. (1986) The tectonics of Colonsay, Scotland. 41 Unpublished PhD thesis, University of Wales, Aberystwyth. 42 Bentley, M.R. (1988). The Colonsay Group. In Winchester, J.A (ed.) 43 Later Proterozoic stratigraphy of the Northern Altlantic Regions. 44 Blackie and Son Ltd., London, 119–30. 45 Bentley, M.R., Maltman, A.J., and Fitches, W.R. (1988) Colonsay 46 and Islay: a suspect terrane within the Scottish 47 Caledonides. Geology, 16, 26–8. 48 Bingen B., Demaiffe D. and van Breemen O. (1998) The 616 Ma old 49 Egersund basaltic dyke swarm, SW Norway, and late Neoproterozoic 50 opening of the Iapetus Ocean. Journal of Geology, 106, 565–74. 51 Bingen, B., Griffin, W.L. Torsvik, T.H. and Saeed, A. (2005) Timing 52 of late Neoproterozoic glaciation on Baltica constrained by 53 detrital zircon geochronology in the Hedmark Group, south-east 54 Norway. Terra Nova, 17, 250–58. 55 Bliss, G.M. (1977) The micropalaeontology of the Dalradian. 56 Unpublished PhD thesis, University of London, Imperial College. 57 Bluck, B.J. (1983) Role of the Midland Valley of Scotland in the 58 Caledonian Orogeny. Transactions of the Royal Society of 59 Edinburgh: Earth Sciences, 74, 119 –136. 60 61 62 63 64 65 1 2 3 4 Bluck, B.J. (1984) Pre-Carboniferous history of the Midland Valley 5 of Scotland. Transactions of the Royal Society of Edinburgh: Earth 6 Sciences, 75, 275–95. 7 Bluck, B.J. (2000) ‗Where ignorance is bliss ‗tis a folly to be 8 wise‘ (Thomas Gray 1716–1761) – controversy in the basement blocks 9 of Scotland. Scottish Journal of Geology, 36, 97–101. 10 Bluck, B.J. (2001) Caledonian and related events in Scotland. 11 Transactions of the Royal Society of Edinburgh: Earth Sciences, 12 91, 375–404. 13 Bluck, B.J. (2002) The Midland Valley Terrane. In: Trewin, N.H. 14 (ed.) The Geology of Scotland. The Geological Society, London, 15 149–66. 16 Bluck, B.J. (2010) The Highland Boundary Fault and the Highland 17 Boundary Complex. Scottish Journal of Geology, 46, 113-124. 18 Bluck B.J. and Dempster T.J. (1991) Exotic metamorphic terranes in 19 the Caledonides: tectonic history of the Dalradian block, 20 Scotland. Geology, 19, 1133–6. 21 Bluck B.J., Dempster T.J., and Rogers G. (1997) Allochthonous 22 metamorphic blocks on the Hebridean passive margin, Scotland. 23 Journal of the Geological Society of London 154, 921–4. 24 Bluck, B.J., Gibbons, W. and Ingham, J.K. (1992). Terranes. 1–4 in 25 Atlas of palaeogeography and lithofacies. Cope, J.C.W., Ingham, 26 J.K., and Rawson, P.F. (editors). Geological Society of London 27 Memoir, No. 13. 28 Bluck B.J., Halliday A. N., Aftalion M., and Macintyre R.M. (1980) 29 Age and origin of the Ballantrae ophiolite and its significance to 30 the Caledonian orogeny and Ordovician time scale. Geology 8, 492– 31 95. 32 Bluck, B.J. and Ingham, J.K. (1997) The Highland Border 33 controversy: a discussion of ―New evidence that the Lower Cambrian 34 Leny Limestone at Callander, Perthshire belongs to the Dalradian 35 Supergroup, and a reassessment of the ‗exotic‘ status of the 36 Highland Border Complex‖. Geological Magazine, 134, 563–70. 37 Bluck B.J., Ingham J.K., Curry G.B., and Williams A. (1984) The 38 significance of a reliable age from some Highland Border rocks in 39 Central Scotland. Journal of the Geological Society of London 139, 40 451–4. 41 Boersma, J.R. (1969) Internal structures of some tidal megaripples 42 on a shoal in the Westerschelde estuary, the Netherlands. Geologie 43 on Mijnbouw, 48, 409–14. 44 Booth, J.E. (1984) Structural, stratigraphic and metamorphic 45 studies in the SE Dalradian Highlands. Unpublished PhD thesis. 46 University of Edinburgh. 47 Borradaile, G.J. (1970) The west limb of the Loch Awe syncline and 48 the associated cleavage fan. Geological Magazine, 107, 459–467. 49 Borradaile, G.J. (1972a) The structural and stratigraphic history 50 of the Dalradian rocks of the Northern Loch Awe syncline, 51 Argyllshire. Unpublished PhD thesis, University of Liverpool. 52 Borradaile, G.J. (1972b) Variably oriented co-planar primary folds. 53 Geological Magazine, 190, 89–98. 54 Borradaile, G. J. (1973) Dalradian structure and stratigraphy of 55 the northern Loch Awe district, Argyllshire. Transactions of the 56 Royal Society of Edinburgh, 69, 1–21. 57 Borradaile, G.J. (1974). Bulk finite strain estimates from the 58 deformation of Neptunian dykes. Tectonophysics, 22, 127–39. 59 Borradaile, G.J. (1977) The Dalradian rocks of the northern Loch 60 Awe district. Scottish Journal of Geology, 13, 155–64. 61 62 63 64 65 1 2 3 4 Borradaile, G.J. (1979). Pre-tectonic reconstruction of the Islay 5 anticline: implications for the depositional history of Dalradian 6 rocks in the SW Highlands. In The Caledonides of the British 7 Isles–reviewed. Harris, A L, Holland, C H, and Leake, B E 8 (editors). Special Publication of the Geological Society of 9 London, No. 8, pp. 229–38. 10 Borradaile, G.J. and Johnson, H.D. (1973) Finite strain estimates 11 from the Dalradian Dolomitic Formation, Islay, Argyll, Scotland. 12 Tectonophysics, 18, 249–59. 13 Boué, A. (1820) Essai Géologique sur l’Écosse. Ve Courcier, Paris. 14 Bouma, A. H. (1962). Sedimentology of some Flysch Deposits, a 15 Graphic Approach to Facies Interpretation. Elsevier Co. Amsterdam, 16 168 pp. 17 Bowden, A.J. (2007) Book review: MacCulloch‘s 1840 Geological Map 18 of Scotland. Scottish Journal of Geology, 43, 181–4. 19 Bowes, D.R. and Convery, H.J.E. (1966) The composition of some Ben 20 Ledi grits and its bearing on the origin of albite schists in the 21 south-west Highlands. Scottish Journal of Geology, 2, 67–75. 22 Bowes, D.R. and Wright, A.E. (1967) The explosion breccia pipes 23 near Kentallen, Scotland and their geological setting. 24 Transactions of the Royal Society of Edinburgh, 67, 109–43. 25 Bowes, D.R. and Wright, A.E. (1973) Early phases of Caledonian 26 deformation in the Dalradian of the Ballachulish district, 27 Argyll. Geological Journal, 8, 333–44. 28 Bowring, S., Myrow, P., Landing, E., Ramezani, J. and Grotzinger, 29 J. (2003) Geochronological constraints on Terminal Neoproterozoic 30 events and the rise of metazoans. Geophysical Research Abstracts 31 5, p13219. 32 Bradbury, H.J. (1978) Stratigraphic, structural, igneous and 33 metamorphic history of the Dalradian rocks of the Ben Vrackie-Ben 34 Vuirich district, Tayside, Scotland. Unpublished PhD thesis, 35 University of Liverpool. 36 Bradbury, H.J. (1979) Migmatization, deformation and porphyroblast 37 growth in the Dalradian of Tayside, Scotland. In The Caledonides 38 of the British Isles — Reviewed Harris, A.L., Holland, C.H. and 39 Leake, B.E. (eds). Geological Society, London, Special 40 Publications, 8, 351–6. 41 Bradbury, H.J. (1985) The Caledonian metamorphic core: an Alpine 42 model. Journal of the Geological Society of London, 142, 129–36. 43 Bradbury, H.J., and Harris, A.L. (1982) Low grade Dalradian 44 sediments carrying spaced cleavage; Polyphase deformation of 45 spaced cleavage. In Atlas of deformational and metamorphic rock 46 fabrics. Borradaile, G J, Bayly, M B, and Powell, C McA (editors). 47 Springer Verlag, Berlin, pp. 100–9. 48 Bradbury, H.J., Harris, A.L. and Smith, R.A. (1979). Geometry and 49 emplacement of nappes in the Central Scottish Highlands. In The 50 Caledonides of the British Isles - reviewed. (eds. Harris, A.L., 51 Holland, C.H. and Leake, B.E.), Special Publication of the 52 Geological Society of London, 8, 213–20. 53 Bradbury H.J., Smith R.A. and Harris A.L. (1976) ‗Older‘ granites 54 as time-markers in Dalradian evolution. Journal of the Geological 55 Society, London, 132, 677–84. 56 Brasier, M.D., Ingham, J.K. and Rushton, A.W.A. (1992) Cambrian. 57 13–18 in Atlas of Palaeogeography and Lithofacies. Cope, J.C.W., 58 Ingham, J.K. and Rawson, P. F. (editors). Memoirs of the 59 Geological Society, London, 13. 60 61 62 63 64 65 1 2 3 4 Brasier, M.D. and Mcilroy, D. (1998) Neonereites uniserialis from 5 c. 600 Ma year old rocks in western Scotland and the emergence of 6 animals. Journal of the Geological Society, London, 155, 5–12. 7 Brasier, M.D. and Shields, G. (2000) Neoproterozoic 8 chemostratigraphy and correlation of the Port Askaig glaciation, 9 Dalradian Supergroup of Scotland. Journal of the Geological 10 Society, London, 157, 909–14. 11 Brasier, M.D., McCarron, G., Tucker, R., Leather, J., Allen, P. and 12 Shields, G. (2000) New U-Pb zircon dates for the Neoproterozoic 13 Ghubrah glacaiation and for the top of the Huqf Supergroup, Oman. 14 Geology, 28, 175–8. 15 Briden, J.C., Turnell, H.B. and Watts, D.R. (1984) British 16 palaeomagnetism, Iapetus Ocean and the Great Glen Fault. Geology 17 12, 136–9. 18 Burgess J.G, Graham, C.M. and Harte, B. (1981). Kyanite and 19 chloritoid phyllites from the chlorite zone of the Scottish 20 Highlands. Journal of the Geological Society of London, 138, p. 21 634 (abstract). 22 Burt, C.E. (2002) Sedimentary environments and basin evolution of 23 the upper Dalradian: Tayvallich Subgroup and Southern Highland 24 Group. Unpublished PhD thesis, Kingston University. 25 Burton, C.J., Hocken, C., MacCallum, D. and Young, M.E. 1983. 26 Chitinozoa and the age of the Margie Limestone of the North Esk. 27 Proceedings of the Geological Society of Glasgow Vol. 124–125, 27– 28 32. 29 30 Cannat M. (1989) Late Caledonian northeastward ophiolite thrusting 31 in the Shetland Islands, U.K. Tectonophysics 169, 257–70. 32 Canning J.C., Henney P.J., Morrison M.A. and Gaskarth J.W. (1996) 33 Geochemistry of late Caledonian minettes from northern Britain: 34 implications for the Caledonian sub-continental lithospheric 35 mantle. Mineralogical Magazine 60, 221–36. 36 Canning, J.C., Henney, P.J., Morrison, M.A., Van Calsteren, P.W.C., 37 Gaskarth, J.W. and Swarbrick, A. (1998) The Great Glen Fault: a 38 major vertical lithospheric boundary. Journal of the Geological 39 Society, London, 155, 425–8. 40 Carty, J.P. (2001) Deformation, metamorphism, magmatism and fluid- 41 flow in the Portsoy Shear Zone, N.E. Scotland. Unpublished PhD 42 thesis, University of Derby. 43 Cawood, P.A., McCausland, P.J.A. and Dunning, G.R. (2001) Opening 44 Iapetus: constraints from the Laurentian margin in Newfoundland. 45 Geological Society of America Bulletin, 113, 443–53. 46 Cawood, P.A., Nemchin, A.A., Smith, M. and Loewy, S. (2003). Source 47 of the Dalradian Supergroup constrained by U-Pb dating of detrital 48 zircon and implications for the East Laurentian margin. Journal of 49 the Geological Society of London 160, 231–46. 50 Cawood, P.A., Nemchin, A.A., Strachan, R.A., Prave, A.R. and 51 Krabbendam, M. (2007) Sedimentary basin and detrital zircon record 52 along East Laurentia and Baltica during assembly and breakup of 53 Rodinia. Journal of the Geological Society, London, 164, 257–75. 54 Chew, D.M. (2001) Basement protrusion origin of serpentinite in the 55 Dalradian. Irish Journal of Earth Science, 19, 23-35. 56 Chew, D.M., Daly, J.S., Magna, T., Page, L.M., Kirkland, C.L., 57 Whitehouse, M.J. and Lam, R. (2010) Timing of ophiolite obduction 58 in the Grampian orogen. Geological Society of America Bulletin, 59 122, 1787-1799. 60 Chew, D.M., Fallon, N., Kennelly, C., Crowley, Q. and Pointon, 61 62 63 64 65 1 2 3 4 (2009) Basic volcanism contemporaneous with the Sturtian glacial 5 episode in NE Scotland. Earth and Environmental Science 6 Transactions of the Royal Society of Edinburgh, 100, 399-415 7 Chew, D.M., Graham, J.R. and Whitehouse, M.J. (2007) U-Pb zircon 8 geochronology of plagiogranites from the Lough Nafooey (= Midland 9 Valley) arc in western Ireland: constraints on the onset of the 10 Grampian orogeny. Journal of the Geological Society, London Vol. 11 164, 747–50. 12 Chinner, G.A. (1957) The metamorphic history of the Glen Clova 13 district, Angus. Unpublished PhD Thesis, University of Cambridge. 14 Chinner, G.A. (1960) Pelitic gneisses with varying ferrous/ferric 15 ratios from Glen Clova, Angus, Scotland. Journal of Petrology, 1, 16 178–217. 17 Chinner, G.A. (1961) The origin of sillimanite in Glen Clova, 18 Angus. Journal of Petrology Vol. 2, 312–23. 19 Chinner, G.A. (1966) The distribution of pressure and temperature 20 during Dalradian metamorphism. Quarterly Journal of the Geological 21 Society of London, 122, 159–86. 22 Chinner, G.A. (1978) Metamorphic zones and fault displacement in 23 the Scottish Highlands. Geological Magazine, Vol. 115, 37–45. 24 Chinner, G.A. and Heseltine, F.J. (1979) The Grampian 25 andalusite/kyanite isograd. Scottish Journal of Geology, Vol. 15, 26 117–127. 27 Coats, J.S., Pease, S.F. and Gallagher, M.J. (1984) Exploration of 28 the Scottish Dalradian. 21–34 in Prospecting in areas of glaciated 29 terrain. (London: Institution of Mining and Metallurgy.) 30 Coats, J.S., Smith, C.G., Gallagher, M.J., May, F., Fortey, N.J. 31 and Parker, M.E. (1978) Stratabound barium-zinc mineralisation in 32 Dalradian schist near Aberfeldy, Scotland: preliminary report. 33 Institute of Geological Sciences, Mineral Reconnaisance Programme 34 Report No. 26. 35 Coats, J.S., Smith, C.G., Fortey, N.J., Gallagher, M.J., May, F. 36 and McCourt, W.J. (1980) Stratabound barium-zinc mineralization in 37 Dalradian schist near Aberfeldy. Transactions of the Institution 38 of Mining and Metallurgy (Section B: Applied Earth Science), 89, 39 110–22. 40 Coats, J.S., Smith, C.G., Gallagher, M.J., May, F., McCourt, W.J., 41 Parker, M.E. and Fortey, N.J. (1981) Stratabound barium-zinc 42 mineralisation in Dalradian schist near Aberfeldy, Scotland: final 43 report. Institute of Geological Sciences, Mineral Reconnaissance 44 Programme Report No. 40. 45 Collerson, K.D., Jesseau, C.W. and Bridgewater, D. (1976). 46 Contrasting types of bladed olivine in ultramafic rocks from the 47 Archaean of Labrador. Canadian Journal of Earth Sciences, 13, 442– 48 50. 49 Collinson, J. (1994). Sedimentary deformational structures. pp. 95– 50 125 In Maltman, A. (ed.). The geological deformation of 51 sediments. Chapman and Hall. 52 Collinson, J.D. and Thompson, D.B. 1988. Sedimentary Structures. 53 George Allen and Unwin, London. 207 pp. 54 Condon, D.J. and Prave, A.R. (2000). Two from Donegal: 55 Neoproterozoic glacial episodes on the northeast margin of 56 Laurentia. Geology, 28, 951–4. 57 Cooper, M.R. and Johnston, T.P. (2004) Central Highlands (Grampian) 58 Terrane. 9–24, in: Mitchell, W.I. (editor), The Geology of 59 Northern Ireland–Our Natural Foundation (2nd edition). Geological 60 Survey of Northern Ireland, Belfast. 61 62 63 64 65 1 2 3 4 Coward, M.P. (1983) The thrust and shear zones of the Moine Thrust 5 Zone of NW Scotland. Journal of the Geological Society of London 6 140, 795–811. 7 Coward, M.P. (1990) The Precambrian, Caledonian and Variscan 8 framework to NW Europe. In Tectonic Events Responsible for 9 Britain’s Oil and Gas Reserves. Hardman, R.F.P. and Brooks, J. 10 (eds) Geological Society, London, Special Publications, 55, 1–34. 11 Craig G. Y., McIntyre D. B., and Waterston C. D. (1978) James 12 Hutton’s Theory of the Earth: the lost drawings. Scottish 13 Academic Press, Edinburgh. 14 Crane A., Goodman S., Krabbendam M., Leslie A. G., Paterson I. B., 15 Robertson S. And Rollin K. E. (2002) Geology of the Glen Shee 16 District. Memoir of the British Geological Survey. Sheet 56W with 17 parts of sheets 55E, 65W and 64E (Scotland). 18 Cummins, W.A. and Shackleton, R.M. (1955) The Ben Lui recumbent 19 syncline. Geological Magazine, 92, 353–62. 20 Cunningham Craig, E.H. (1904) Metamorphism in the Loch-Lomond 21 District. Quarterly Journal of the Geological Society, London, 60, 22 10–31. 23 Cunningham Craig, E.H. (2000) (written 1901). Explanation of Sheet 24 38 (Loch Lomond). Selected documents from the BGS Archives No 3. 25 British Geological Survey Technical Report No. WO/00/05. 26 Cunningham Craig, E.H., Wright, W.B. and Bailey, E.B. (1911) The 27 Geology of Colonsay and Oronsay with parts of Ross of Mull. Memoir 28 of the Geological Survey of Scotland, Sheet 35 (Scotland). 29 Curry, G.B., Bluck, B.J., Burton, C.J., Ingham, J.K., Siveter, D.J. 30 And Williams, A. (1984) Age, evolution and tectonic history of the 31 Highland Border Complex, Scotland. Transactions of the Royal 32 Society of Edinburgh: Earth Sciences, 75, 113–33. 33 Cutts, K.A., Hand, M., Kelsey, D.E. and Strachan, R.A. (2011) P–T 34 constraints and timing of Barrovian metamorphism in the Shetland 35 Islands, Scottish Caledonides: implications for the structural 36 setting of the Unst ophiolite. Journal of the Geological Society, 37 168, 1265-1284. 38 39 Dallmeyer, R.D., Strachan, R.A., Rogers, G., Watt, G.R. and Friend, 40 C.R.L. (2001) Dating deformation and cooling in the Caledonian 41 thrust nappes of north Sutherland, Scotland: insights from 42 40Ar/39Ar and Rb-Sr chronology. Journal of the Geological Society 43 of London 158, 501–12. 44 Daly, J.S., Muir, R.J. and Cliff, R.A. (1991) A precise U-Pb zircon 45 age for the Inishtrahull syenitic gneiss, County Donegal, Ireland. 46 Journal of the Geological Society, London, 148, 639–42. 47 Dalziel, I.W.D. (1994) Precambrian Scotland as a Laurentia–Gondwana 48 link: Origin and significance of cratonic promontories. Geology, 49 22, 589–92. 50 Dalziel, I.W.D. (1997) Neoproterozoic–Paleozoic geography and 51 tectonics; review, hypothesis, environmental speculation. 52 Geological Society of America Bulletin 109(1), 16–42. 53 Davidek, K., Landing, E., Bowring, S.A., Westrop, S.R., Rushton, 54 S.A., Fortey, R.A. And Adrain, J. (1998) New Uppermost Cambrian U- 55 Pb date from Avalonian Wales and age of the Cambrian-Ordovician 56 boundary. Geological Magazine, 135, 303–09. 57 Deer, W.A., Howie, R.A. and Zussman, J. (1992). An Introduction to 58 the Rock Forming Minerals, 2nd ed. Longman Scientific and 59 Technical, London. 60 61 62 63 64 65 1 2 3 4 Dempster, T.J. (1983) Studies of orogenic evolution in the Scottish 5 Dalradian. Unpublished PhD thesis, University of Edinburgh. 6 Dempster, T.J. (1985a) Uplift patterns and orogenic evolution in 7 the Scottish Dalradian. Journal of the Geological Society of 8 London, 142, 111–128. 9 Dempster, T.J. (1985b) Garnet zoning and metamorphism of the 10 Barrovian type. Contributions to Mineralogy and Petrology, 89, 30– 11 8. 12 Dempster T.J. and Bluck B.J. (1991) The age and tectonic 13 significance of the Bute amphibolite, Highland Border Complex, 14 Scotland. Geological Magazine 128, 77–80. 15 Dempster, T.J. and Harte, B. (1986) Polymetamorphism in the 16 Dalradian of the Central Scottish Highlands. Geological Magazine, 17 Vol. 123, 95–104. 18 Dempster, T.J., Hudson, N.F. and Rogers, G. (1995). Metamorphism 19 and cooling of the NE Dalradian. Journal of the Geological 20 Society, London, 152, 383–90. 21 Dempster, T.J., Rogers, G., Tanner, P.W.G., Bluck, B.J., Muir, 22 R.J., Redwood, S.D., Ireland, T.R. and Paterson, B.A. (2002) 23 Timing of deposition, orogenesis and glaciation within the 24 Dalradian rocks of Scotland: constraints from U-Pb zircon ages. 25 Journal of the Geological Society, London, 159, 83–94. 26 Dewey, H. and Flett, J.S. (1911) On some British pillow lavas and 27 the rocks associated with them. Geological Magazine, 8, 202–9, 28 240–8. 29 Dewey J. F. (1969) Evolution of the Appalchian/Caledonian orogen. 30 Nature, London 222, 124–9. 31 Dewey, J.F. (2005) Orogeny can be very short. Proceedings of the 32 National Academy of Sciences, USA Vol. 102, 15286–93. 33 Dewey, J.F. and Mange, M. (1999) Petrography of Ordovician and 34 Silurian sediments in the western Irish Caledonides: tracers of a 35 short-lived Ordovician continent–arc collision orogeny and the 36 evolution of the Laurentian Appalachian–Caledonian margin. In: 37 Continental Tectonics (edited by MacNiocaill, C. and Ryan, P. D.). 38 Geological Society, London, Special Publication, 164, 55–107. 39 Dewey, J.F. and Pankhurst, R.J. (1970) The evolution of the 40 Scottish Caledonides in relation to their radiometric age pattern. 41 Transactions of the Royal Society of Edinburgh, 68, 361–89. 42 Dewey, J.F. and Ryan, P.D. (1990) The Ordovician evolution of the 43 South Mayo Trough, Western Ireland. Tectonics, 9, 887–903. 44 Dewey J.F. and Shackleton R.M. (1984) A model for the evolution of 45 the Grampian tract in the early Caledonides and Appalachians. 46 Nature, London 312, 115–21. 47 Dewey, J.F. and Strachan, R.A. (2003) Changing Silurian–Devonian 48 relative plate motion in the Caledonides; sinistral transpression 49 to sinistral transtension. Journal of the Geological Society, 50 London, 160, 219–229. 51 Dickin, A.P. (1992). Evidence for an Early Proterozoic crustal 52 province in the North Atlantic region. Journal of the Geological 53 Society, London, 149, 483–6. 54 Dickin, A.P., and Bowes, D.R. (1991) Isotopic evidence for the 55 extent of the early Proterozoic basement of Scotland and northwest 56 Ireland. Geological Magazine, 128, 385–8. 57 Droop, G.T.R. (1987). A general equation for estimating Fe3+ 58 concentrations in ferromagnesian silicates or oxides from 59 microprobe analysis using stoichiometric criteria. Mineralogical 60 Magazine, 51, 431–55. 61 62 63 64 65 1 2 3 4 Droop G.T.R. and Charnley N. (1985) Comparative geobarometry of 5 pelitic hornfelses associated with the Newer Gabbros: a 6 preliminary study. Journal of the Geological Society of London 7 142, 53–62. 8 Droop, G.T.R., Clemens, J.D. and Dalrymple, D.J. (2003) Processes 9 and conditions during contact anatexis, melt escape and restite 10 formation: the Huntley Gabbro complex, NE Scotland. Journal of 11 Petrology Vol. 44, 995–1029. 12 Donovan, R.N. and Foster, R.J. (1972). Subaqueous shrinkage cracks 13 from the Caithness Flagstone Series (Middle Devonian) of north- 14 east Scotland. Journal of Sedimentary Petrology, 42, 309–17. 15 Downie, C. (1975) The Precambrian of the British Isles: 16 Palaeontology. In A Correlation of Precambrian Rocks in the 17 British Isles (eds. Harris, A.L., Shackleton, R.M., Watson, J.V., 18 Downie, C., Harland, W.B. and Moorbath, S.). Special Report of the 19 Geological Society of London, No. 6. Pp. 113–15 20 Downie, C. (1984) Acritarchs in British stratigraphy. Special 21 Report of the Geological Society of London, No. 17. 22 Downie, C., Lister, T.R., Harris, A.L. and Fettes, D.J. (1971) A 23 palynological investigation of the Dalradian rocks of 24 Scotland. Report of the Institute of Geological Sciences, No. 25 71/9. 26 Dymoke, P.L. (1989) Geochronological and petrological studies of 27 the thermal evolution of the Dalradian, South-west Scottish 28 Highlands. Unpublished PhD thesis, University of Edinburgh. 29 30 Eby G. N. (1992) Chemical subdivision of the A-type granitoids: 31 petrogenetic and tectonic implications. Geology, 20, 641–4. 32 Edwards, M.B. (1986) Glacial Environments. 416–436 in: Sedimentary 33 Environments and facies (Editor: H.G. Reading). Blackwell 34 Scientific 35 Publications. 36 Elles, G.L. (1926) The geological structure of Ben Lawers and Meall 37 Corranaich (Perthshire). Quarterly Journal of the Geological 38 Society of London, 82, 304–31. 39 Elles, G.L. (1931) Notes on the Portsoy coastal 40 district. Geological Magazine, 68, 24–34. 41 Elles, G.L. (1935) The Loch na Cille Boulder Bed and its place in 42 the Highland succession. Quarterly Journal of the Geological 43 Society of London, 91, 111–49. 44 Elles, G.L. and Tilley, C.E. (1930) Metamorphism in relation to 45 structure in the Scottish Highlands. Transactions of the Royal 46 Society of Edinburgh, 56, 621–46. 47 Ellis, D.J. and Green, D.H. (1979) An experimental study of the 48 effect of Ca upon garnet-clinopyroxene Fe-Mg exchange equilibria. 49 Contributions to Mineralogy and Petrology, 71, 13–22. 50 Ellis, N.V., Bowen, D.Q., Campbell, S., Knill, J.L., McKirdy, A.P., 51 Prosser, C.D., Vincent, M.A. and Wilson, R.C.L. (1996) An 52 Introduction to the Geological Conservation Review. Joint Nature 53 Conservation Committee, Peterborough. 54 Emery, M. (2005) Polyorogenic history of the Moine rocks of Glen 55 Urquhart, Inverness-shire. Unpublished PhD thesis, University of 56 Portsmouth. 57 Evans, J.A., Fitches, W.R. and Muir, R.J. (1998) Laurentian Clasts 58 in a Neoproterozic Tillite in Scotland. Journal of Geology, 106, 59 361–9. 60 61 62 63 64 65 1 2 3 4 Evans, J.A, and Soper, N.J. (1997) Discussion on metamorphism and 5 cooling of the NE Dalradian and U-Pb and Rb-Sr geochronology of 6 magmatism and metamorphism in the Dalradian of Connemara, western 7 Ireland. Journal of the Geological Society, London, 154, 357–60. 8 Evans, R.H.S. and Tanner, P.W.G. (1996). A late Vendian age for the 9 Kinlochlaggan Boulder Bed (Dalradian)? Journal of the Geological 10 Society, London, 153, 823–6. 11 Evans, R.H.S. and Tanner, P.W.G. (1997). Discussion on a late 12 Vendian age for the Kinlochlaggan Boulder Bed (Dalradian): reply. 13 Journal of the Geological Society, London, 154, 917–19. 14 Eyles, C.H. (1988) Glacially - and tidally - influenced shallow 15 marine sedimentation of the Late Precambrian Port Askaig 16 Formation, Scotland. Palaeogeography, Palaeoclimatology, 17 Palaeoecology, 68, 1–25. 18 Eyles, C.H. and Eyles, N. (1983) Glaciomarine model for upper 19 Precambrian diamictiles of the Port Askaig Formation, Scotland. 20 Geology, 11, 692–6. 21 Eyles, N. and Clark, M. (1985) Gravity-induced soft-sediment 22 deformation in glaciomarine sequences of the upper Proterozoic 23 Port Askaig Formation, Scotland. Sedimentology, 32, 789–814. 24 25 Fairchild, I.J. (1977) Phengite spherules from the Dalradian 26 Bonnahaven Formation, Islay, Scotland: Glauconitized microfossils. 27 Geological Magazine, 114, 355–64. 28 Fairchild, I.F. (1980a) Sedimentation and origin of a Late 29 Precambrian ―dolomite‖ from Scotland. Journal of Sedimentary 30 Petrology, 50, 423–46. 31 Fairchild, I.J. (1980b) Stages in a Precambrian dolomitization, 32 Scotland: Cementing versus replacement textures. Sedimentology, 33 27, 631–50. 34 Fairchild, I.J. (1980c) The structure of NE Islay. Scottish Journal 35 of Geology, 16, 189–97. 36 Fairchild, I.J. (1985) Comment on ‗Glaciomarine model for Upper 37 Precambrian diamictiles of the Port Askaig Formation, Scotland‘. 38 Geology, 13, 89–90. 39 Fairchild, I.J. (1985) Petrography and carbonate chemistry of some 40 Dalradian dolomitic metasediments: preservation of diagenetic 41 textures. Journal of the Geological Society, London, 142, 167–85. 42 Fairchild, I.J. (1989) Dolomitic stromatolite-bearing units with 43 storm deposits from the Vendian of East Greenland and Scotland: a 44 case of facies equivalence. In Caledonian and related Geology of 45 Scandinavia (ed. Gayer, R. A.), pp. Graham and Trotman, London, 46 pp. 275–283. 47 Fairchild, I.J. (1991) Itinerary II: Topmost Islay Limestone (Appin 48 Group), Port Askaig and Bonahaven Formations (Argyll Group) Port 49 Askaig area, Islay. In The Late Precambrian geology of the 50 Scottish Highlands and Islands (ed. Lister, C.J.) Geologists‘ 51 Association Guide No. 44, pp. 33–41. 52 Fairchild, I.J. (1993) Balmy shores and icy wastes: the paradox of 53 carbonates associated with glacial deposits in Neoproterozoic 54 times. Sedimentology Review, 1, 1–16. 55 Ferry, J.M. and Spear, F.S. (1978) Experimental calibration of the 56 partitioning of Fe and Mg between biotite and garnet. 57 Contributions to Mineralogy and Petrology, 66, 113–17. 58 Fettes, D.J., (1968). Metamorphic structures of Dalradian rocks in 59 North East Scotland. Unpublished PhD thesis, University of 60 Edinburgh. 61 62 63 64 65 1 2 3 4 Fettes, D.J. (1970) The structural and metamorphic state of the 5 Dalradian rocks and their bearing on the age of emplacement of the 6 basic sheet. Scottish Journal of Geology, Vol. 6, 108–118. 7 Fettes, D.J. (1971) Relation of cleavage and metamorphism in the 8 Macduff Slates. Scottish Journal of Geology, 7, 248–53. 9 Fettes, D.J. (1979) A metamorphic map of the British and Irish 10 Caledonides. In: Harris, A.L., Holland, C.H. and Leake, B.E. (eds) 11 The Caledonides of the British Isles–Reviewed. Geological Society, 12 London, Special Publications, 8, 307–21. 13 Fettes, D.J. and Desmons, J. (editors) (2007) Metamorphic Rocks: a 14 Classification and Glossary of Terms. Recommendations of the 15 International Union of Geological Sciences Subcommission on the 16 Systematics of Metamorphic Rocks. Cambridge University Press, 17 Cambridge 18 Fettes, D.J., Graham, C.M., Harte, B., and Plant, 19 J.A. (1986a) Lineaments and basement domains; an alternative view 20 of Dalradian evolution. Journal of the Geological Society of 21 London, 143, 453–64. 22 Fettes, D.J., Graham, C.M., Sassi, F.P., and Scolari, A. (1976) The 23 lateral spacing of potassic white micas and facies series 24 variations across the Caledonides. Scottish Journal of Geology, 25 12, 227–36. 26 Fettes, D.J., Harris, A.L. and Hall, L.M. (1986b) The Caledonian 27 geology of the Scottish Highlands. In Synthesis of the 28 Caledonian rocks of Britain. Proceedings of the NATO Advanced 29 Study Institute. Fettes, D J, and Harris, A L (editors). Reidel 30 Dordrecht, pp. 303–34. 31 Fettes, D.J., Leslie A.G., Stephenson D., and Kimbell S.F. (1991) 32 Disruption of Dalradian stratigraphy along the Portsoy Lineament 33 from new geological and magnetic surveys. Scottish Journal of 34 Geology 27, 57–73. 35 Fettes, D.J., Long, C.B., Bevins, R.E., Max, M.D., Oliver, G.J.H., 36 Primmer, T.J., Thomas, L.J. and Yardley, B.W.D., 1985. Grade and 37 time of metamorphism in the Caledonide Orogen of Britain and 38 Ireland. . 5 In, Harris, A.L.(ed), The Nature and Timing of 39 Orogenic Activity in the Caledonian Rocks of the British Isles. 40 Memoir of the Geological Society, London, 9. 41 Fettes, D.J., Macdonald, R., Fitton, J.G., Stephenson, D. and 42 Cooper, M.R. (2011) Geochemical evolution of Dalradian 43 metavolcanic rocks: implications for the break-up of the Rodinia 44 supercontinent. Journal of the Geological Society, 168, 1133-1146. 45 Fisk, S. (1986) An oxygen isotope study of siliceous rocks 46 associated with stratabound mineralisation in Scotland and 47 Ireland. Unpublished PhD thesis, University of Strathclyde. 48 Fitches, W. R. And Maltman, A. J. (1984) Tectonic development and 49 stratigraphy of the western margin of the Caledonides: Islay and 50 Colonsay, Scotland. Transactions of the Royal Society of 51 Edinburgh, 75, 365–82. 52 Fitches, W.R., Muir, R.J., Maltman, A.J. and Bentley, M.R. (1990) 53 Is the Colonsay–west Islay block of SW Scotland an allochthonous 54 terrane? Evidence from Dalradian tillite clasts. Journal of the 55 Geological Society, London, 147, 417–20. 56 Fitches, W.R., Pearce, J.A., Evans, J.A. and Muir, R.J. (1996) 57 Provenance of the late Proterozoic Dalradian tillite clasts, Inner 58 Hebrides, Scotland. In Precambrian Crustal Evolution in the North 59 Atlantic Region (ed. Brewer, T. S.), pp. 367–77. 60 61 62 63 64 65 1 2 3 4 Flinn, D., (1953) Regional metamorphism and migmatisation in 5 Delting, Shetland. Unpublished PhD thesis, University of London, 6 Imperial College. 7 Flinn, D. (1954) On the time relations between regional 8 metamorphism amd permeation in Delting, Shetland. Quarterly 9 Journal of the Geological Society of London, 110, 177–99. 10 Flinn, D. (1961) Continuation of the Great Glen Fault beyond the 11 Moray Firth. Nature, London, 191, 589–91. 12 Flinn, D. (1967) The metamorphic rocks of the southern part of the 13 Mainland of Shetland. Geological Journal, 5, 251–90. 14 Flinn, D. (1985) The Caledonides of Shetland. In Gee, D. G. and 15 Sturt, B. A. (editors) The Caledonide Orogen–Scandinavia and 16 Related Areas. John Wiley and Sons, Chichester. 1161–72. 17 Flinn, D. (1995) Formation of gneisses of migmatite and diatexite 18 appearance in Yell, Shetland by solid-state grain growth 19 recrystallisation. Geological Journal, 30, 415–22. 20 Flinn, D. (1999) The Shetland Ophiolite. 31–33, 36–58 In Stephenson 21 et al. (editors) Caledonian Igneous Rocks of Great Britain. 22 Geological Conservation Review Series, No. 17. Joint Nature 23 Conservation Committee, Peterborough, UK. 24 Flinn, D. (2001) The basic rocks of the Shetland Ophiolite Complex 25 and their bearing on its genesis. Scottish Journal of Geology, 37, 26 79–96. 27 Flinn, D. (2007) The Dalradian rocks of Shetland and their 28 implications for the plate tectonics of the northern Iapetus. 29 Scottish Journal of Geology, Vol. 43, 125–42. 30 Flinn, D. in press. Geology of Unst and Fetlar in Shetland. Memoir 31 of the British Geological Survey, Sheet 131 (Scotland). 32 Flinn, D. and Moffat, D. T. 1985. A peridotitic komatiite from the 33 Dalradian of Shetland. Geological Journal, 20, 287–292. 34 Flinn, D. and Moffat, D.T. (1986) A reply to R. W. Nesbitt and L. 35 A. Hartmann. Geological Journal, 21, 207–9. 36 Flinn, D. and Pringle, I.R. (1976). Age of migmatisation in the 37 Dalradian of Shetland. Nature, London, 259, 299–300. 38 Flinn, D., Frank, P.L., Brook, M. and Pringle, I.R. (1979) 39 Basement–cover relations in Shetland. In The Caledonides of the 40 British Isles–reviewed. Harris, A.L., Holland, C.H. and Leake, 41 B.E. (eds), Geological Society of London Special Publication No. 42 8, 109–15. 43 Flinn, D., May, F., Roberts, J.L. and Treagus, J.E. (1972). A 44 revision of the stratigraphic succession of the East Mainland of 45 Shetland. Scottish Journal of Geology, 8, 335–343. 46 Flinn, D., Miller, J.A. and Roddam, D. (1991) The age of the 47 Norwick hornblendic schists of Unst and Fetlar and the obduction 48 of the Shetland ophiolite. Scottish Journal of Geology 27, 11–19. 49 Flinn, D. and Oglethorpe, R.J.D. (2005). A history of the Shetland 50 Ophiolite Complex. Scottish Journal of Geology, 41, 141–8. 51 Fortey, N.J., Coats, J.S., Gallagher, M.J., Greenwood, P.G. and 52 Smith, C.G. (1993) Dalradian stratabound baryte and base metals 53 near Braemar, NE Scotland. Transactions of the Institution of 54 Mining and Metallurgy (Section B: Applied Earth Science), Vol. 55 102, B55–64. 56 Fortey, N.J. and Smith, C.G. (1986). Stratabound mineralisation in 57 Dalradian rocks near Tyndrum, Perthshire. Scottish Journal of 58 Geology, 22, 377–93. 59 France, D.S. (1971) Structure and metamorphism of Moine and 60 Dalradian rocks in the Grampians of Scotland near Beinn Dorain 61 62 63 64 65 1 2 3 4 between Tyndrum and Moor of Rannoch. Unpublished PhD thesis, 5 University of Liverpool. 6 Francis, E.H. (1982). Magma and sediment–1: Emplacement mechanisms 7 of late Carboniferous tholeiitic sills in Northern Britain. 8 Journal of the Geological Society, London, 139, 1–20. 9 Friedrich, A.M, Hodges, K.V., Bowring, S.A. and Martin, M.W. (1999) 10 Geochronological constraints on the magmatic, metamorphic and 11 thermal evolution of the Connemara Caledonides, western Ireland. 12 Journal of the Geological Society, London, 156, 1217–30. 13 Friend, C.R.L., Kinny, P.D., Rogers, G., Strachan, R.A. and 14 Patterson, B.A. (1997) U-Pb zircon geochronological evidence for 15 Neoproterozoic events in the Glenfinnan Group (Moine Supergroup): 16 the formation of the Ardgour granite gneiss, north-west Scotland. 17 Contributions to Mineralogy and Petrology 128, 101–13. 18 Friend, C.R.L., Strachan, R.A., Kinny, P.D. and Watt, G.R. (2003) 19 Provenance of the Moine Supergroup of NW Scotland; evidence from 20 geochronology of detrital and inherited zircons from 21 (meta)sedimentary rocks, granites and migmatites. Journal of the 22 Geological Society, London 160, 247–57. 23 24 Gallagher, M.J., Smith, C.G., Coats, J.S., Greenwood, P.G., 25 Chacksfield, B.C., Fortey, N.J. and Nancarrow, P.H.A. (1989) 26 Stratabound barium and base-metal mineralisation in Middle 27 Dalradian metasediments near Braemar, Scotland. British Geological 28 Survey, Mineral Reconnaisance Programme Report, No. 104. 29 Ganguly, J. (1979) Garnet and clinopyroxene solid solutions, and 30 geothermometry based on Fe-Mg distribution coefficient. Geochemica 31 and Cosmochemica Acta 43, 1021–9. 32 Garson, M.S, and Plant, J. (1973) Alpine Type Ultramafic Rocks and 33 Episodic Mountain Building in the Scottish Highlands. Nature 34 Physical Science, 242, 34–8. 35 Geikie, A. (1865) The scenery of Scotland viewed in connection with 36 its physical geology (with a geological map by Sir Roderick I. 37 Murchison and Archibald Geikie). Macmillan, London and Cambridge. 38 Geikie, A. (1897) Annual report of the Geological Survey of the 39 United Kingdom and of the Museum of Practical Geology for the year 40 ending December 31, 1896. In Appendix E from the 44th Report of 41 the Department of Science and Art. (London: Her Majesty‘s 42 Stationery Office.) 43 Gibbons, W. And Harris, A.L. (1994) A Revised Correlation of 44 Precambrian rocks in the British Isles. Special Reports, 45 Geological Society, London, 22. 46 Gillen, C. (1987) Huntly, Elgin and Lossiemouth. 149–160 in 47 Excursion Guide to the Geology of the Aberdeen area. (editors 48 N.H.Trewin, B.C. Kneller, and C. Gillen,). (Edinburgh: Scottish 49 Academic press for Geological Society of Aberdeen). 50 Gillespie, M.R. and Styles, M.T. (1999). BGS rock classification 51 scheme, Volume 1: Classification of igneous rocks, 2nd edition. 52 British Geological Survey Research Report, RR/99/6 53 Glover, B.W. (1989). The sedimentology and basin evolution of the 54 Grampian Group. Unpublished PhD Thesis. University of Keele. 55 Glover, B.W. (1993). The sedimentology of the Neoproterozoic 56 Grampian Group and the significance of the Fort William Slide 57 between Spean Bridge and Rubha Cuilcheanna, Inverness-shire. 58 Scottish Journal of Geology, 29, 29–43. 59 60 61 62 63 64 65 1 2 3 4 Glover, B.W. (1998). Sedimentology and lateral extent of the 5 Glenshirra succession, Monadhliath Mountains, Scotland. British 6 Geological Survey Technical Report, WA/98/23. 7 Glover B.W., Key, R.M., May, F., Clark, G.C., Phillips, E.R. and 8 Chacksfield, B.C. (1995). A Neoproterozoic multi-phase rift 9 sequence: the Grampian and Appin groups of the southwestern 10 Monadhliath Mountains of Scotland. Journal of the Geological 11 Society of London, 152, 391–406. 12 Glover B.W. and McKie, T. (1996). A sequence stratigraphical 13 approach to the understanding of basin history in orogenic 14 Neoproterozoic successions: an example from the central Highlands 15 of Scotland. In: Sequence stratigraphy in British Geology (eds. 16 Hesselbo, S.P. and Parkinson, D.N. ). Geological Society of 17 London, Special Publication, 103, 257–69. 18 Glover, B.W. and Winchester, J.A. (1989) The Grampian Group: a 19 major Late Proterozoic clastic sequence in the central Highlands 20 of Scotland. Journal of the Geological Society, London, 146, 85– 21 97. 22 Goodman, S (1991) The Pannanich Hill Complex and the origin of the 23 Crinan Subgroup migmatites in the North-eastern and Central 24 Highlands. Scottish Journal of Geology, 27, 147–56. 25 Goodman, S. (1994) The Portsoy-Duchray Hill Lineament; a review of 26 the evidence. Geological Magazine 131, 407–15. 27 Goodman, S., Crane, A., Krabbendam, M. and Leslie, A.G. (1997) 28 Correlation of lithostratigraphic sequences in a structurally 29 complex area: Gleann Fearnach to Glen Shee, Scotland. Transactions 30 of the Royal Society of Edinburgh, 87, 503–13. 31 Goodman, S, and Lappin, M.A. (1996) The thermal aureole of the 32 Lochnagar Complex: mineral reactions and implications from thermal 33 modelling. Scottish Journal of Geology, 27, 159–72. 34 Goodman, S., Leslie, A.G., Ashcroft, W.A. and Crane, A. (1990) The 35 geology of the central part of Sheet 65E (Ballater); contribution 36 to the memoir. British Geological Survey Technical Report No. 37 WA/90/59. 38 Goodman, S. and Winchester, J.A. (1993) Geochemical variations 39 within metavolcanic rocks of the Dalradian Farragon Beds and 40 adjacent formations. Scottish Journal of Geology, 29, 131–41. 41 Gorokhov, M., Siedlecka, A., Roberts, D., Melnikov, N.N. and 42 Turchenko, T.L. (2001) Rb–Sr dating of diagenetic illite in 43 Neoproterozoic shales, Varanger Peninsula, northern Norway. 44 Geological Magazine, 138, 541–62. 45 Gould, D. (1997) The geology of the country around Inverurie and 46 Alford. Memoir of the British Geological Survey, Sheets 76E and 47 76W (Scotland). 48 Gould, D. (2001) Geology of the Aboyne district. Memoir of the 49 British Geological Survey, Sheet 66W (Scotland). 50 Gower, P.J. (1973) The Middle–Upper Dalradian Boundary with special 51 reference to the Loch Tay Limestone. Unpublished PhD thesis, 52 University of Liverpool. 53 Gower, P.J. (1977) The Dalradian rocks of the west coast of the 54 Tayvallich peninsula. Scottish Journal of Geology, 13, 125–33. 55 Gradstein, F.M., Ogg, J.G., and Smith, A.G., Agterberg, F.P., 56 Bleeker, W., Cooper, R.A., Davydov, V., Gibbard, P., Hinnov, L.A., 57 House, M.R., Lourens, L., Luterbacher, H.P., McArthur, J., 58 Melchin, M.J., Robb, L.J., Shergold, J., Villeneuve, M., Wardlaw, 59 B.R., Ali, J., Brinkhuis, H., Hilgen, F.J., Hooker, J., Howarth, 60 R.J., Knoll, A.H., Laskar, J., Monechi, S., Plumb, K.A., Powell, 61 62 63 64 65 1 2 3 4 J., Raffi, I., Röhl, U., Sadler, P., Sanfilippo, A., Schmitz, B., 5 Shackleton, N.J., Shields, G.A., Strauss, H., Van Dam, J., van 6 Kolfschoten, T., Veizer, J., and Wilson, D. (2004) A Geologic Time 7 Scale 2004. Cambridge University Press, 589 pp. 8 Graham, C.M. (1976) Petrochemistry and tectonic significance of 9 Dalradian metabasaltic rocks of the SW Scottish Highlands. Journal 10 of the Geological Society, London, 132, 61–84. 11 Graham, C.M. (1983). High-pressure greenschist to epidote- 12 amphibolite facies metamorphism of the Dalradian rocks of the SW 13 Scottish Highlands. Geological Society Newsletter, 12, No. 4, 19. 14 Graham, C.M. (1986) The role of the Cruachan Lineament during 15 Dalradian evolution. Scottish Journal of Geology, 22, 257–70. 16 Graham, C.M. and Borradaile, G.J. (1984). The petrology and 17 structure of Dalradian metabasic dykes of Jura: implications for 18 Dalradian evolution. Scottish Journal of Geology, 20, 257–70. Same 19 page range as previous ref? 20 Graham, C.M. and Bradbury, H.J. (1981) Cambrian and late 21 Precambrian basaltic igneous activity in the Scottish Dalradian: a 22 review. Geological Magazine, 118, 27–37. 23 Graham, C.M., Greig, K.M., Sheppard, S.M.F. and Turi, B. (1983) 24 Genesis and mobility of the H2O-CO2 fluid phase during regional 25 greenschist and epidote amphibolite facies metamorphism: a 26 petrological and stable isotope study in the Scottish Dalradian. 27 Journal of the Geological Society, London, 140, 577–599. 28 Graham, C.M. and Harte, B. (1985) Conditions of Dalradian 29 metamorphism. Journal of the Geological Society, London, 142, 1–3. 30 Grant Wilson, J.S. (1882) Explanation of Sheet 97. Northern 31 Aberdeenshire, Eastern Banffshire. Memoir of the Geological 32 Survey, Scotland. 33 Grant Wilson, J.S. (1886) Explanation of Sheet 87, North-east 34 Aberdeenshire and detached portions of Banffshire. Memoir of the 35 Geological Survey, Scotland. 36 Grant Wilson, J.S., and Hinxman, L.W. (1890) Geology of central 37 Aberdeenshire. Memoir of the Geological Survey of Scotland, Sheet 38 76 (Scotland). 39 Green, J.F.N. (1924) The structure of the Bowmore–Portaskaig 40 District of Islay. Quarterly Journal of the Geological Society, 41 London, 80, 72 –105. 42 Green, J.F.N. (1931) The South-west Highland Sequence. Quarterly 43 Journal of the Geological Society of London 87, 513–550. 44 Gregory, J.W. (1910) Work for Glasgow geologists–the problems of 45 the South-western Highlands. Transactions of the Geological 46 Society of Glasgow 14, 1–29. 47 Gregory, J.W. (1916) Pre-Cambrian of Scotland. Handbuch der 48 Regionaler Geologie, III, Part I, 34–42. 49 Gregory, J.W. (1928) The geology of Loch Lomond. Transactions of 50 the Geological Society of Glasgow 18, 301–23. 51 Gregory, J.W. (1929) The Pre-Cambrian or Pre-Palaeozoic of 52 Scotland. 28–42 in Evans, J. W. and Stubblefield, C. J. (editors) 53 Handbook of the geology of Great Britain. Murby. 54 Gregory, J.W. (1930) The sequence in Islay and Jura. Transactions 55 of the Geological Society of Glasgow Vol. 18, 420–441. 56 Gregory, J.W. (1931) Dalradian Geology: The Dalradian Rocks of 57 Scotland and their Equivalents in other Countries. Methuen, 58 London. 59 60 61 62 63 64 65 1 2 3 4 Greig, K.M., (1987) Metamorphosed carbonates and fluid behaviour in 5 the Dalradian of S.W. Argyll, Scotland. Unpublished PhD thesis, 6 University of Edinburgh 7 Grieve, A. (1996) Ruskin and Millais at Glenfinlas. The Burlington 8 Magazine, 138, 228–234. 9 Gunn, A.G., Styles, M.T., Stephenson, D., Shaw, M.H. and Rollin, 10 K. (1990) Platinum-group elements in ultramafic rocks of the 11 Upper Deveron Valley, near Huntly, Aberdeenshire. Mineral 12 Reconnaissance Programme Report, British Geological Survey, No. 13 115. 14 Gunn, W., Clough, C.T. and Hill, J.B. (1897) The Geology of Cowal, 15 including the part of Argyllshire between the Clyde and Loch Fyne. 16 Memoirs of the Geological Survey of Scotland, Sheets 29, 37 and 17 38. 18 19 Hackman, B.D. and Knill, J.L. (1962) Calcareous algae from the 20 Dalradian of Islay. Palaeontology, 5, 268–71. 21 Hall, A.J. (1993) Stratiform mineralisation in the Dalradian of 22 Scotland. In Mineralisation in the British Isles. Pattrick, 23 R.A.D., and Polya, D.A. (editors). Chapman and Hall, London, pp. 24 38–101. 25 Hall, J., Brewer, J.A., Matthews, D.H. and Warner, M. (1984) 26 Crustal structure across the Caledonides from the WINCH seismic 27 reflection profile: Influences on the evolution of the Midland 28 Valley of Scotland. Transactions of the Royal Society of 29 Edinburgh: Earth Sciences, 75, 97–109. 30 Halliday, A.N., Graham, C.M., Aftalion, M. and Dymoke, P. (1989) 31 The depositional age of the Dalradian Supergroup: U-Pb and Sm-Nd 32 isotopic studies of the Tayvallich Volcanics, Scotland. Journal of 33 the Geological Society, London, 146, 3–6. 34 Hambrey, M.J. (1983) Correlation of the Late Proterozoic tillites 35 in the North Atlantic region and Europe. Geological Magazine, 120, 36 209–32. 37 Hambrey, M.J. and Harland, W.B. (editors). (1981) Earth’s pre- 38 Pleistocene glacial record. Cambridge University Press, Cambridge. 39 Hambrey, M.J. and Harland, W.B. (1985) The Late Proterozoic glacial 40 era. Palaeogeography, Palaeoclimatology and Palaeoecology, 51, 41 255–72. 42 Hambrey, M.J. and Waddams, P. (1981) Glaciogenic boulder-bearing 43 deposits in the Upper Dalradian Macduff Slates, northeastern 44 Scotland. In Earth’s pre-Pleistocene glacial record. Hambrey, 45 M.J. and Harland, W.B. (editors). Cambridge University Press, 46 Cambridge, pp. 571–5. 47 Harkness, R. (1861) On the rocks of the portions of the Highlands 48 of Scotland south of the Caledonian Canal; and on their 49 equivalents in the north of Ireland. Quarterly Journal of the 50 Geological Society of London 17, 256–71. 51 Harris, A.L. (1960) Dalradian geology of an area between Pitlochry 52 and Blair Atholl. Unpublished PhD thesis, University of Wales, 53 Aberystwyth. 54 Harris, A.L. (1962) Dalradian geology of the Highland Border, near 55 Callander. Bulletin of the Geological Survey of Great Britain, 19, 56 1–15. 57 Harris, A.L. (1963). Structural investigations in the Dalradian 58 rocks between Pitlochry and Blair Atholl. Transactions of the 59 Edinburgh Geological Society, 19, 256–278. 60 61 62 63 64 65 1 2 3 4 Harris, A.L. (1969) The relationships of the Leny Limestone to the 5 Dalradian. Scottish Journal of Geology, 5, 187–90. 6 Harris, A.L. (1972) The Dalradian rocks at Dunkeld, Perthshire. 7 Bulletin of the Geological Survey of Great Britain, 38, 1–10. 8 Harris, A.L. (1995) Nature and timing of orogenesis in the Scottish 9 Highlands and the role of the Great Glen Fault. In Current 10 perspectives in the Appalachian–Caledonian Orogen, Hibbard, J., 11 van Stall, C.R. and Cawood, P.A. (editors) Geological Association 12 of Canada, Special Paper 41, 65–79. 13 Harris, A.L., Baldwin, C.T., Bradbury, H.J., Johnson, H.D. and 14 Smith, R.A. (1978) Ensialic basin sedimentation: the Dalradian 15 Supergroup. In Crustal evolution in northwestern Britain, Bowes, D 16 R, and Leake, B E (editors)Special Issue of the Geological Journal 17 No. 10 . Seel House Press, Liverpool, pp. 115–38 18 Harris, A.L., and Bradbury, H.J. (1977) Discussion of ‗The 19 evolution and transport of the Tay Nappe‗. Scottish Journal of 20 Geology, 13, 81–3. 21 Harris, A.L., Bradbury, H.J. and McGonigal, N.H. (1976) The 22 evolution and transport of the Tay Nappe. Scottish Journal of 23 Geology, 12, 103–13. 24 Harris, A.L. And Fettes, D.J. (1972) Stratigraphy and structure of 25 Upper Dalradian rocks at the Highland Border. Scottish Journal of 26 Geology, 8, 253–64. 27 Harris, A.L., Fettes, D.J. And Soper, N.J. (1998a) Age of the 28 Grampian event: a Discussion of ―New evidence that the Lower 29 Cambrian Leny Limestone at Callander, Perthshire, belongs to the 30 Dalradian Supergroup, and a re-assessment of the ―exotic‖ status 31 of the Highland Border Complex―. Geological Magazine, 135, 575. 32 Harris, A.L., Haselock, P.J., Kennedy, M.J., Mendum, J.R., Long, 33 J.A., Winchester, J.A. and Tanner, P.W.G. (1994). The Dalradian 34 Supergroup in Scotland, Shetland, and Ireland, In A Revised 35 Correlation of the Precambrian Rocks of the British Isles (eds. W. 36 Gibbons and A.L. Harris), Geological Society, London, Special 37 Report No. 22, 33–53. 38 Harris, A.L., Parson, L.M., Highton, A.J. and Smith, D.I. 1981. 39 New/Old Moine relationships between Fort Augustus and Inverness 40 (Abstract). Journal of Structural Geology, 3, 187–88. 41 Harris, A.L. and Pitcher, W.S. (1975) The Dalradian Supergroup. In 42 A Correlation of Precambrian Rocks in the British Isles. (eds. 43 Harris, A. L., Shackleton, R. M., Watson, J.V., Downie, C., 44 Harland, W. B. and Moorbath, S.), Special Reports of the 45 Geological Society, London, 6, pp. 52–75. 46 Harte, B. (1966) Stratigraphy, structure and metamorphism in the 47 south-eastern Grampian Highlands of Scotland. Unpublished PhD 48 thesis, University of Cambridge. 49 Harte, B., (1975) Determination of a pelite petrogenetic grid for 50 the eastern Scottish Dalradian. Yearbook of the Carnegie 51 Institute, Washington, 74, 438–446. 52 Harte, B. (1979) The Tarfside succession and the structure and 53 stratigraphy of the eastern Scottish Dalradian rocks. In Special 54 Publications, Geological Society, London, 8 (eds. Harris, A. L., 55 Holland, C. H. and Leake, B. E.), pp. 221–28. 56 Harte, B. (1987) Glen Esk Dalradian, Barrovian metamorphic zones. 57 In Excursion Guide to the Geology of the Aberdeen area. (editors 58 N.H.Trewin, B.C. Kneller, and C. Gillen,). Scottish Academic press 59 for Geological Society of Aberdeen, Edinburgh, p 193–210. 60 61 62 63 64 65 1 2 3 4 Harte, B. (1988) Lower Palaeozoic metamorphism in the Moine– 5 Dalradian belt of the British Isles. In The Caledonian— 6 Appalachian Orogen. Harris, A L, and Fettes, D J (editors). 7 Special Publication of the Geological Society of London, No. 38, 8 pp. 123–34. 9 Harte, B., Booth, J.E., Dempster, T.J., Fettes, D.J., Mendum, J.R. 10 and Watts, D. (1984) Aspects of the post-depositional evolution of 11 Dalradian and Highland Border Complex rocks in the Southern 12 Highlands of Scotland. Transactions of the Royal Society of 13 Edinburgh, 75, 151–63. 14 Harte, B., Booth, J.E. and Fettes, D.J., (1987) Stonehaven to 15 Findon: Dalradian Structure and Metamorphism. In Excursion Guide 16 to the Geology of the Aberdeen Area (eds Trewin, N. H., Kneller, 17 B. C. and Gillen, C.). Scottish Academic Press for Geological 18 Society of Aberdeen, Edinburgh, pp. 211–26 19 Harte, B. and Dempster, T.J. (1987) Regional metamorphic zones: 20 tectonic controls. Philosophical Transactions of the Royal Society 21 of London Vol. 321, 105–27. 22 Harte, B, and Hudson, N.F.C. (1979) Pelite facies series and the 23 temperatures and pressures of Dalradian metamorphism in E 24 Scotland. in The Caledonides of the British Isles–Reviewed. (eds. 25 A.L. Harris, C.H. Holland, and B.E. Leake,) Geological Society of 26 London Special Publication, 8, pp 323–37. 27 Harte, B, and Johnson, M.R.W. (1969) Metamorphic history of 28 Dalradian rocks in Glens Clova, Esk and Lethnot, Angus, Scotland. 29 Scottish Journal of Geology, 5, 54–80. 30 Haselock, P.J. (1982) The geology of the Corrieyairack Pass area, 31 Inverness-shire. Unpublished PhD thesis, University of Keele. 32 Haselock, P.J. (1984) The systematic geochemical variation between 33 two tectonically separate successions in the southern 34 Monadhliaths, Inverness-shire. Scottish Journal of Geology. 20, 35 191–205. 36 Haselock, P.J. and Gibbons, W. (1990). The Central Highland 37 controversy: a traverse through the Precambrian metasediments of 38 the Central Highlands of Scotland. Episodes 13, 113–15. 39 Haselock, P.J. and Leslie, A.G. (1992). Polyphase deformation in 40 Grampian Group rocks of the Monadhliath defined by a group 41 magnetic survey. Scottish Journal of Geology 28, 81–7. 42 Haselock, P.J., Winchester, J.A. and Whittles, K.H. (1982). The 43 stratigraphy and structure of the southern Monadhliath Mountains 44 between Loch Killin and upper Glen Roy. Scottish Journal of 45 Geology, 18, 275–90. 46 Heddle, M.F. (1878) Chapters on the mineralogy of Scotland. Chapter 47 fourth - augite, hornblende and serpentinous change. Transactions 48 of the Royal Society of Edinburgh 28, 453–555. 49 Heddle M. F. (1901) The mineralogy of Scotland. D. Douglas, 50 Edinburgh. 51 Henderson, S.M.K. (1938) The Dalradian Succession of the Southern 52 Highlands. Report of the meeting of the British Association for 53 the Advancement of Science, Cambridge, 1938, 424. 54 Henderson, W.G. and Robertson, A.H.F. (1982). The Highland Border 55 rocks and their relation to marginal basin development in the 56 Scottish Caledonides. Journal of the Geological Society of London, 57 139, 433–50. 58 Henderson, W.G., Tanner, P.W.G. and Strachan, R.A. (2009) The 59 Highland Border Ophiolite of Scotland: observations from the 60 61 62 63 64 65 1 2 3 4 Highland Workshop field excursion of April 2008. Scottish Journal 5 of Geology, 45, 13–18. 6 Hibbert, S. (1822) A Description of the Shetland Islands: 7 comprising an account of their geology, scenary, antiquities and 8 superstitions. Constable and Co., Edinburgh. 9 Hickman, A.H. (1975) The stratigraphy of late Precambrian 10 metasediments between Glen Roy and Lismore. Scottish Journal of 11 Geology, 11, 117–42. 12 Hickman, A H. (1978) Recumbent folds between Glen Roy and Lismore. 13 Scottish Journal of Geology, 14, 191–212. 14 Hickman, A.H. and Roberts, J.L. (1977). Discussion of the North 15 Ballachulish Dalradian. Journal of the Geological Society of 16 London, 133, Part 3, 277–79. 17 Hickman, A.H. and Wright, A.E. (1983) Geochemistry and 18 chemostratigraphical correlation of slates, marbles and quartzites 19 of the Appin Group, Argyll, Scotland. Transactions of the Royal 20 Society of Edinburgh: Earth Sciences, 73, 251–78. 21 Highton, A.J. (1986). Caledonian and pre-Caledonian events in the 22 Moine south of the Great Glen Fault, Unpublished PhD thesis, 23 University of Liverpool. 24 Highton, A.J. (1992). The tectonostratigraphical significance of 25 pre-750 Ma metagabbros within the northern Central Highlands, 26 Inverness-shire. Scottish Journal of Geology 28, 71–6. 27 Highton, A.J. (1999). Solid Geology of the Aviemore District. 28 Memoir of the British Geological Survey, Sheet 74E (Scotland). 29 Highton, A.J., Hyslop, E.K. and Noble, S.R. (1999).U-Pb zircon 30 geochronology of migmatization in the northern Central Highlands: 31 evidence for pre-Caledonian (Neoproterozoic) tectonmetamorphism in 32 the Grampian Block, Scotland. Journal of the Geological Society, 33 London, 156, 1195–204. 34 Hill, J.B. (1899) On the progressive metamorphism of some Dalradian 35 sediments in the region of Loch Awe. Quarterly Journal of the 36 Geological Society, London, 40, 470–93. 37 Hill, J.B. (1905) The geology of mid-Argyll. Memoirs of the 38 Geological Survey, Scotland. Explanation of Sheet 37. 39 Hill, J. and Buist, D. (1994) A Geological Field Guide to the 40 Island of Bute, Scotland. (editor Greensmith, J. T.) Geologists’ 41 Association Guide, No. 51, 95 pp. Warwick Press. 42 Hinxman, L.W. (1896). Explanation of Sheet 75. West Aberdeenshire, 43 Banffshire, parts of Elgin and Inverness. Memoir of the Geological 44 Survey, Scotland. 45 Hinxman, L. W. and Anderson, E. M. (1915). The geology of Mid- 46 Strathspey and Strathdearn, including the country between 47 Kingussie and Grantown, Scotland. Memoir of the Geological Survey, 48 Scotland, Sheet 74 (Scotland). 49 Hinxman, L. W., Carruthers, R. G. and Macgregor, M. (1923). The 50 geology of Corrour and the Moor of Rannoch. Memoir of the 51 Geological Survey, Scotland, Sheet 54 (Scotland). 52 Hinxman, L.W. and Grant Wilson, J.S. (1902) The geology of Lower 53 Strathspey. Memoir of the Geological Survey, Scotland, Sheet 85 54 (Scotland). 55 Hoffmann, P.F., Condon, D.J., Bowring, S.A. and Crowley, J.L. 56 (2004) U-Pb zircon date from the Neoproterozoic Ghaub Formation, 57 Namibia: Constraints on Marinoan glaciation. Geology, 32, 817–20. 58 Holdsworth, R.E., Woodcock, N. and Strachan, R. (2000) Geological 59 Framework of Britain and Ireland. In Geological History of Britain 60 61 62 63 64 65 1 2 3 4 and Ireland (edited by Woodcock, N. and Strachan, R.) Blackwell 5 Science, Oxford. 6 Holland, C.H. and Sanders, I.S. (editors) 2009. The Geology of 7 Ireland (2nd edition). Dunedin Academic Press, Edinburgh. 576 pp. 8 Howarth, R.J. and Leake, B.E. (2002) The Life of Frank Coles 9 Phillips (1902–1982) and the Structural Geology of the Moine 10 Petrofabric Controversy. Memoir of the Geological Society, London, 11 23, 95pp. 12 Hudson, N.F.C. (1976) Mineral facies in pelitic rocks, with 13 particular reference to the Buchan type metamorphism of north- 14 eastern Scotland. Unpublished PhD thesis, University of Edinburgh. 15 Hudson, N.F.C. (1980) Regional metamorphism of some Dalradian 16 pelites in the Buchan area, NE Scotland. Contributions to 17 Mineralogy and Petrology, 73, 39–51. 18 Hudson, N.F.C. (1985) Conditions of Dalradian metamorphism in the 19 Buchan area. Journal of the Geological Society of London, 142, 20 63–76. 21 Hutchison, A.R. and Oliver, G.J.H. (1998) Garnet provenance 22 studies, juxtaposition of Laurentian marginal terranes and timing 23 of the Grampian Orogeny in Scotland. Journal of the Geological 24 Society, London, 155, 541–50. 25 Hutton D.H.W. (1987) Strike slip terranes and a model for the 26 evolution of the British and Irish Caledonides. Geological 27 Magazine 124, 405–425. 28 Hutton, D.H.W. and Alsop, G.I. (2004) Evidence for a major 29 Neoproterozoic orogenic unconformity within the Dalradian 30 Supergroup of NW Ireland. Journal of the Geological Society, 31 London, 161, 629–40. 32 Hutton, D.H.W. and Alsop, G.I. (2005) Discussion on evidence for a 33 major Neoproterozoic orogenic unconformity within the Dalradian 34 Supergroup of NW Ireland. Journal of the Geological Society, 35 London, 162, 221–4. 36 Hutton J. (1788) Theory of the Earth; or an Investigation of the 37 Laws observable in the Composition, Dissolution, and Restoration 38 of the Land upon the Globe. Transactions of the Royal Society of 39 Edinburgh 1, 209–304. 40 Hyslop, E. K. (1992). Strain-induced metamorphism and pegmatite 41 development in the Moine rocks of Scotland. Unpublished PhD 42 thesis, University of Hull. 43 Hyslop, E.K. and Piasecki, M.A.J. (1999). Mineralogy, geochemistry 44 and the development of ductile shear zones in the Grampian Slide 45 Zone of the Scottish Central Highlands. Journal of the Geological 46 Society, London, 156, 577–90. 47 Hyslop, E.K. and Pickett, E.A. (1999) Stratigraphy and magmatism in 48 the uppermost Dalradian of the SW Scottish Highlands: A field 49 excursion to Tayvallich, Loch Avich and Tarbert (Loch Fyne). BGS 50 Technical Report WA/99/73. 51 52 Indares, A. and Dunning, G.R. (1997) Coronitic metagabbro and 53 eclogite from the Grenville Province of western Quebec; 54 interpretation of U-Pb geochronology and metamorphism. Canadian 55 Journal of Earth Sciences 34, 891–901. 56 57 Jacques J.M. and Reavy R.J. (1994) Caledonian plutonism and major 58 lineaments in the SW Scottish Highlands. Journal of the Geological 59 Society, London, 151, 955–69. 60 61 62 63 64 65 1 2 3 4 Jamieson, T.F. (1861) On the structure of the south-west Highlands 5 of Scotland. Quarterly Journal of the Geological Society of 6 London, 17, 133–45. 7 Jehu, T.J. and Campbell, R. (1917) The Highland Border rocks of the 8 Aberfoyle District. Transactions of the Royal Society of 9 Edinburgh, 52, 175–212. 10 Johnson, M.R.W. (1962) Relations of movement and metamorphism in 11 the Dalradians of Banffshire. Transactions of the Edinburgh 12 Geological Society, 19, 29–64. 13 Johnson, M.R.W. (1963) Some time relations of movement and 14 metamorphism in the Scottish Highlands. Geologie en Mijnbouw, 42, 15 121–42. 16 Johnson, M.R.W. (1965) Dalradian. In The Geology of Scotland (1st 17 edition). Craig, G. Y. (ed.) Oliver and Boyd, Edinburgh. 117–60. 18 Johnson, M.R.W. (1983) Dalradian. In Geology of Scotland (2nd 19 edition), Craig, G. Y. (ed.), Scottish Academic Press, Edinburgh, 20 pp. 77–104. 21 Johnson, M.R.W. (1991) Dalradian. In Geology of Scotland (3rd 22 edition). Craig, G. Y. (ed.) The Geological Society, London, pp. 23 125–60. 24 Johnson, M.R.W. and Harris, A.L. (1967) Dalradian–?Arenig relations 25 in part of the Highland Border, Scotland, and their significance 26 in the chronology of the Caledonian orogeny. Scottish Journal of 27 Geology, 3, 1–16. 28 Johnson, M.R.W. and Stewart, F.H. (1960) On Dalradian structures 29 in north-east Scotland. Transactions of the Edinburgh Geological 30 Society, 18, 94–103. 31 Johnson T.E. (1999) Partial melting in Dalradian pelitic migmatites 32 from the Fraserburgh–Inzie Head area of Buchan, northeast 33 Scotland. Unpublished PhD thesis, University of Derby. 34 Johnson T.E., Hudson N.F.C. and Droop G.T.R. (2001a) Partial 35 melting in the Inzie Head gneisses: the role of water and a 36 petrogenetic grid in KFMASH applicable to anatectic pelitic 37 migmatites. Journal of Metamorphic Geology, 19, 99–118. 38 Johnson T.E., Hudson N.F.C. and Droop, G.T.R (2001b) Melt 39 segregation structures within the Inzie Head gneisses of the 40 northeastern Dalradian. Scottish Journal of Geology, 37, 59–72. 41 Johnson T.E., Hudson N.F.C. and Droop G.T.R. (2003) Evidence for a 42 genetic granite–migmatite link in the Dalradian of NE Scotland. 43 Journal of the Geological Society, London, 160, 447– 57. 44 Johnstone, G.S. (1966) British regional geology: the Grampian 45 Highlands (3rd edition). HMSO, Edinburgh for Geological Survey and 46 Museum. 47 Johnstone, G.S. (1975) The Moine Succession. In A Correlation of 48 Precambrian Rocks in the British Isles (eds. Harris, A. L., 49 Shackleton, R. M., Watson, J.V., Downie, C., Harland, W. B. and 50 Moorbath, S.) Geological Society, London, Special Report, 6, 30– 51 42. 52 Johnstone, G.S. and Smith, D.I. (1965) Geological observations 53 concerning the Breadalbane Hydroelectric Project, 54 Perthshire. Bulletin of the Geological Survey of Great Britain, 55 22, 1–52. 56 Johnstone, G.S. and Wright, J.E. (1957) The Geology of the tunnels 57 of the Loch Sloy hydroelectric scheme. Bulletin of the Geological 58 Survey of Great Britain, 12, 1–17. 59 60 61 62 63 64 65 1 2 3 4 Jones, K.A. (1959) The tectonic and metamorphic history of the Ben 5 More–Am Binnein area, Western Perthshire. Unpublished PhD thesis, 6 University of Wales, Swansea. 7 8 Kearns, S. (1989) Metamorphism of calc-silicate and related rocks 9 from the Dalradian of N.E. Scotland. Unpublished PhD thesis, 10 Derbyshire College of Higher Education. 11 Kennedy, M.J. (1975) The Fleur de Lys Supergroup: stratigraphic 12 comparison of Moine and Dalradian equivalents in Newfoundland with 13 the British Caledonides. Journal of the Geological Society, 14 London, 131, 305–10. 15 Kennedy W.Q. (1946) The Great Glen Fault. Quarterly Journal of the 16 Geological Society of London, 102, 41–76. 17 Kennedy, W.Q. (1948) On the significance of thermal structure in 18 the Scottish Highlands. Geological Magazine, 85, 229–34. 19 Kessler, L.G. and Gollop, I.G. (1988) Inner shelf/shoreface– 20 intertidal transition, Upper Precambrian, Port Askaig Tillite, 21 Isle of Islay, Argyll, Scotland. In Tide Influenced Sedimentology, 22 Environments and Facies (eds. de Boer, P. L., van Gelder, A. and 23 Nio, S. D.), Reidal, Dohdrecht, pp. 341–58. 24 Key, R.M., Clark, G.C., May, F., Phillips, E.R., Chacksfield, B.C. 25 and Peacock, J.D. (1997). Geology of the Glen Roy district. Memoir 26 of the British Geological Survey, Sheet 63W (Scotland). 27 Kilburn, C., Pitcher, W.S. and Shackleton, R.M. (1965) The 28 stratigraphy and origin of the Portaskaig Boulder Bed series 29 (Dalradian). Geological Journal, 4, 343–60. 30 Kinny, P.D., Friend, C.R.L., Strachan, R.A., Watt, G.R. and Burns, 31 I.M. (1999) U-Pb geochronology of regional migmatites in East 32 Sutherland, Scotland; evidence for crustal melting during the 33 Caledonian Orogeny. Journal of the Geological Society, London, 34 156, 1143–52. 35 Kinny, P.D., Strachan, R.A., Friend, C.R.L., Kocks, H., Rogers, G. 36 and Paterson, B.A. (2003a) U-Pb geochronology of deformed 37 metagranites in central Sutherland, Scotland; evidence for 38 widespread late Silurian metamorphism and ductile deformation of 39 the Moine Supergroup during the Caledonian orogeny. Journal of the 40 Geological Society of London, 160, 259–69. 41 Kinny, P.D., Strachan, R.A., Kocks, H. and Friend, C.R.L. (2003b) 42 U-Pb geochronology of late Neoproterozoic augen granites in the 43 Moine Supergroup, NW Scotland: dating of rift-related, felsic 44 magmatism during supercontinent break-up? Journal of the 45 Geological Society of London, 160, 925–34. 46 Klein, G.D.V. (1970) Tidal origin of a Precambrian quartzite – the 47 Lower Fine-grained Quartzite (Middle Dalradian) of Islay, 48 Scotland. Journal of Sedimentary Petrology, 40, 973–85. 49 Klein, G.D.V. (1971) Tidal origin of a Precambrian quartzite – the 50 Lower Fine-grained Quartzite (Middle Dalradian) of Islay, 51 Scotland: Reply. Journal of Sedimentary Petrology, 41, 886–9. 52 Kneller, B.C. (1985) Dalradian basin evolution and 53 metamorphism. Journal of the Geological Society of London, 142, 4 54 (abstract). 55 Kneller, B.C. (1987) A geological history of NE Scotland. 1–50. 56 In Excursion guide to the geology of the Aberdeen area. Trewin, 57 H.N., Kneller, B.C. and Gillen, C. (editors). Scottish Academic 58 Press for Geological Society of Aberdeen, Edinburgh. 59 Kneller, B.C. (1988) The geology of part of Buchan. Unpublished 60 PhD thesis, University of Aberdeen. 61 62 63 64 65 1 2 3 4 Kneller, B.C. and Aftalion M. (1987) The isotopic and structural 5 age of the Aberdeen Granite. Journal of the Geological Society of 6 London 144, 717–21. 7 Kneller, B.C. and Leslie, A.G. (1984) Amphibolite facies 8 metamorphism in shear zones in the Buchan area of NE Scotland. 9 Journal of Metamorphic Geology 2, 83–94. 10 Knill, J.L. (1959) Palaeocurrents and sedimentary facies of the 11 Dalradian metasediments of the Craignish–Kilmelfort district. 12 Proceedings of the Geologists’ Association, 70, 273–84. 13 Knill, J.L. (1960) The tectonc pattern in the Dalradian of the 14 Craignish–Kilmelfort District, Argyllshire. Quarterly Journal of 15 the Geological Society of London, 115, 339–64. 16 Knill, J.L. (1963) A sedimentary history of the Dalradian Series. 17 In The British Caledonides. (eds Johnson, M.R.W. and Stewart, 18 F.H.). Oliver and Boyd, Edinburgh, pp. 99–121. 19 Krabbendam, M. and Leslie, A.G. (1996) Folds with vergence opposite 20 to the sense of shear. Journal of Structural Geology, 18, 777–81. 21 Krabbendam, M., Leslie, A.G., Crane, A. and Goodman, S. (1997) 22 Generation of the Tay Nappe, Scotland, by large-scale SE-directed 23 shearing. Journal of the Geological Society, London, 154, 15–24. 24 Krabbendam, M., Prave, A.R. and Cheer, D.A. (2008) A fluvial origin 25 for the Neoproterozoic Morar Group, NW Scotland; implications for 26 Torridon–Morar Group correlation and the Grenville Orogen foreland 27 basin. Journal of the Geological Society, London, 165, 379–94. 28 Kruhl, J. and Voll, G. (1975) Large scale pre-metamorphic and pre- 29 cleavage inversion at Loch Leven, Scottish Highlands. Neues 30 Jahrbuch für Mineralogie, 2, 71–8. 31 Kynaston, H. and Hill J.B. (1908) The Geology of the country near 32 Oban and Dalmally. Memoir of the Geological Survey, Sheet 45 33 (Scotland). 34 35 Lambert, R.St. J. (1975) Discussion of Moine–Dalradian 36 relationships in the River Leven. Journal of the Geological 37 Society of London, 131, 327–8. 38 Lambert, R.St.J., Holland, J.G. and Winchester, J.A. (1982) A 39 geochemical comparison of the Dalradian Leven Schists and the 40 Grampian Division Monadhliath Schists of Scotland. Journal of the 41 Geological Society of London, 139, 71–84. 42 Lambert, R.St.J. and McKerrow, W.S. (1976) The Grampian Orogeny. 43 Scottish Journal of Geology, 12, 271–92. 44 Lambert, R.St.J, Winchester, J.A. and Holland, 45 J.G. (1981) Comparative geochemistry of pelites from the Moinian 46 and Appin Group (Dalradian) of Scotland. Geological Magazine, 47 118, 477–90. 48 Lawson, J. D. and Weedon, D. S. (editors) (1992) Geological 49 Excursions around Glasgow and Girvan. Geological Society of 50 Glasgow, Glasgow. 51 Leake, B.E. (1982) Volcanism in the Dalradian. In Igneous rocks 52 of the British Isles. Sutherland, D. S. (editor). John Wiley and 53 Sons, Chichester, pp. 45–50. 54 Leake, B.E. and Tanner, P.W.G. (1994) The Geology of the Dalradian 55 and Associated Rocks of Connemara, Western Ireland: a report to 56 accompany the 1:63360 geological map and cross sections. Royal 57 Irish Academy, Dublin. 58 Lee, G.W. and Bailey, E.B. (1925) The pre-Tertiary geology of Mull, 59 Loch Aline and Oban. Memoir of the Geological Survey of Great 60 Britain, Sheet 44 (Scotland). 61 62 63 64 65 1 2 3 4 Leggo, P.J., Tanner, P.W.G. and Leake, B.E. (1969) Isochron study 5 of Donegal Granite and certain Dalradian rocks of Britain. In 6 North Atlantic-geology and Continental Drift, a symposium (ed. M. 7 Kay), Memoir of the American Association of Petroleum Geologists, 8 12, pp. 354–62. 9 Le Maitre, R.W (editor) (2002). Igneous Rocks: a Classification and 10 Glossary of Terms; Recommendations of the International Union of 11 Geological Sciences Subcommission on the Systematics of Igneous 12 Rocks. Cambridge University Press, Cambridge, 236 pp. 13 Leslie, A.G., Chacksfield, B.C., Smith, M. and Smith, R.A. (1999). 14 The Geophysical signature of a major shear zone in the Central 15 Highlands of Scotland. British Geological Survey Technical Report 16 No. WA/99/32R. 17 Leslie, A.G., Krabbendam, M. and Smith, R.A. (2006) The Gaick Fold 18 Complex: large-scale recumbent folds and their implications for 19 Caledonian structural architecture in the Central Grampian 20 Highlands. Scottish Journal of Geology, 42, 149–60. 21 Leslie, A.G., Smith, M. and Soper, N.J. (2008) Laurentian margin 22 evolution and the Caledonian orogeny–a template for Scotland and 23 East Greenland. In The Greenland Caledonides: Evolution of the 24 Northeast Margin of Laurentia. Higgins, A.K., Gilotti, J.A. and 25 Smith, M.P. (editors), Geological Society of America Memoir, 202, 26 307–43. 27 Lindsay, N.G. (1988) Contrasts in Caledonian tectonics of the 28 Northern and Central Highlands. Unpublished PhD thesis, University 29 of Liverpool. 30 Lindsay, N.G., Haselock, P.J. and Harris, A.L. (1989). The extent 31 of Grampian orogenic activity in the Scottish Highlands. Journal 32 of the Geological Society of London, 146, 733–5. 33 Litherland, M. (1970) The stratigraphy and structure of the 34 Dalradian rocks around Loch Creran, Argyll. Unpublished PhD 35 thesis, University of Liverpool. 36 Litherland, M. (1975) Organic remains and traces from the Dalradian 37 of Benderloch, Argyll. Scottish Journal of Geology, 11, 47–50. 38 Litherland, M. (1980) The stratigraphy of the Dalradian rocks 39 around Loch Creran, Argyll. Scottish Journal of Geology, 16, 105– 40 23. 41 Litherland, M. (1982) The structure of the Loch Creran Dalradian 42 and a new model for the SW Highlands. Scottish Journal of Geology, 43 18, 205–25. 44 Loudon, T.V. (1963) The sedimentation and structure in the Macduff 45 District of North Banffshire and Aberdeenshire. Unpublished PhD 46 thesis, University of Edinburgh. 47 Lowe, D. R. 1976. Subaqueous liquified and fluidised sediment flows 48 and their deposits. Sedimentology, 23, pp. 285-308. 49 Lyubetskaya, T. and Ague, J.J., 2010. Modeling metamorphism in 50 collisional orogens intruded by magmas: fluid flow and 51 implications for Barrovian and Buchan metamorphism, Scotland. 52 American Journal of Science, 310, 459-491. 53 54 McAteer, C.A., Daly, J.S., Flowerdew, M.J., Connelly, J.N., Housh, 55 T.B. and Whitehouse, M.J. (2010) Detrital zircon, detrital 56 titanite and igneous clast U-Pb geochronology and basement-cover 57 relationships of the Colonsay Group, SW Scotland: Laurentian 58 provenance and correlation with the Neoproterozoic Dalradian 59 Supergroup. Precambrian Research, 181, 21-42. 60 61 62 63 64 65 1 2 3 4 McCallien, W.J. (1925) Notes on the Geology of the Tarbet district 5 of Loch Fyne. Transactions of the Geological Society of Glasgow, 6 17, 233–63. 7 McCallien, W.J. (1926) The structure of South Knapdale (Argyll). 8 Transactions of the Geological Society of Glasgow, 17, 377–94. 9 McCallien, W.J. (1929) The metamorphic rocks of 10 Kintyre. Transactions of the Royal Society of Edinburgh, 56, 409– 11 36. 12 Mccallien, W.J. (1938) The Geology of Bute. Transactions of the 13 Buteshire Natural History Society, 12, 84–112. 14 McCay, G.A., Prave, A.R., Alsop, G.I. and Fallick, A.E. (2006) 15 Glacial trinity: Neoproterozoic Earth history within the British– 16 Irish Caledonides. Geology, 34, 909–12. 17 McClay, K.R. (1987) The Mapping of Geological Structures. 18 Geological Society of London Handbook, Open University Press, 19 Milton Keynes, 161 pp. 20 McClay K.R., Norton M.G., Cony P. and Davis G.H. (1986) Collapse of 21 the Caledonian Orogen and the Old Red Sandstone. Nature, London 22 323, 147–9. 23 MacCulloch, J. (1814) Remarks on several parts of Scotland which 24 exhibit quartz rock, and on the nature and connexions of this rock 25 in general. Transactions of the Geological Society, 2, 450–87. 26 MacCulloch, J. (1819) A description of the western islands of 27 Scotland including the Isle of Man: comprising an account of their 28 geological structure; with remarks on their agriculture, scenary 29 and antiquities. 3 volumes. Constable, London. 30 MacDonald, J.G. and Herriot, A. (1983) Macgregor’s excursion guide 31 to the geology of Arran. (3rd edition). Geological Society of 32 Glasgow and University of Glasgow, Glasgow. 33 Macdonald, R. and Fettes, D.J. (2007) The tectonomagmatic evolution 34 of Scotland. Transactions of the Royal Society of Edinburgh: Earth 35 Sciences, 97, 213–95. 36 Macdonald, R., Fettes, D.J., Stephenson, D. and Graham, C.M. (2005) 37 Basic and ultrabasic volcanic rocks from the Argyll Group 38 (Dalradian) of NE Scotland. Scottish Journal of Geology, 41, 159– 39 74. 40 MacGregor, A.G. (1948) British regional geology: the Grampian 41 Highlands (2nd edition), HMSO for Geological Survey and Museum, 42 Edinburgh. 43 MacGregor, A.R. (1996) Edzell and Glen Esk. 93–108 in Fife and 44 Angus Geology, an excursion guide (3rd edition) by A.R. MacGregor, 45 Pentland Press, Durham. 46 MacGregor, S.M.A. and Roberts, J.L. (1963) Dalradian pillow lavas, 47 Ardwell Bridge, Banffshire. Geological Magazine, 100, 17–23. 48 McIntyre, D.B. (1950) Lineation, boudinage and recumbent folding in 49 the Struan Flags (Moine), near Dalnacardoch, Perthshire. 50 Geological Magazine, 87, 205–25. 51 McIntyre, D.B. (1951) The tectonics of the area between Grantown 52 and Tomintoul (mid-Strathspey). Quarterly Journal of the 53 Geological Society of London, 107, 1–22. 54 McKenzie, D.P. and Bickle, M.J. (1988). The volume and composition 55 of melt generated by the extension of the lithosphere. Journal of 56 Petrology, 29, 625–79. 57 McKie, T. (1990) Tidal and storm-influenced sedimentation from a 58 Cambrian transgressive passive margin sequence. Journal of the 59 Geological Society, London, 147, 785–94. 60 61 62 63 64 65 1 2 3 4 Mackie, W. (1908) Evidence of contemporaneous volcanic action in 5 the Banffshire schists. Transactions of the Edinburgh Geological 6 Society, 9, 93–101. 7 McLellan, E.L. (1983) Barrovian migmatites and the thermal history 8 of the south-eastern Grampians. Unpublished PhD thesis, University 9 of Cambridge. 10 McLellan, E.L., 1985. Metamorphic reactions in the kyanite and 11 sillimanite zones of the Barrovian type area, Journal of 12 Petrology, 26, 789-818. 13 Macnair, P. (1896) The altered clastic rocks of the Southern 14 Highlands: their structure and succession. Geological Magazine, 15 Decade 4, 3, 167–174, 211–217. 16 Macnair, P. (1906) On the development of the great axial lines of 17 folding in the Highland schists. Proceedings of the Royal 18 Philosophical Society of Glasgow Vol. 37, 129–xxx. 19 Macnair, P. (1908) The Geology and Scenery of the Grampians and the 20 Valley of Strathmore, James MacLehose and Sons, Glasgow, 2 21 volumes, 256 pp. 22 Marcantonio, F., Dickin, A.P., McNutt, R.H. and Heaman, L.M. 23 (1988). A 1880-million year old Proterozoic gneiss terrane in 24 Islay with implications for crustal evolution of Britain. Nature, 25 335, 62–64. 26 Mather, J.D. (1968) A geochemical, mineralogical and petrological 27 study of rocks of lower greenschist facies from the Dalradian of 28 Scotland. Unpublished PhD thesis, University of Liverpool. 29 May, F. (1970) Movement, metamorphism and migmatization in the 30 Scalloway region of Shetland. Bulletin of the Geological Survey of 31 Great Britain, 31, 205–26. 32 May, F. and Highton, A.J. (1997) Geology of the Invermoriston 33 district. Memoir of the British Geological Survey. Sheet 73W 34 (Scotland). 35 Melezhik, V.A., Gorokhov, I.M., Kuznetsov, A.B. and Fallick, A.E. 36 (2001). Chemostratigraphy of Neoproterozoic carbonates: 37 implications for ‗blind dating‘. Terra Nova, 13, 1–11. 38 Mendum, J.R. 1987. Dalradian of the Collieston coast section. 161– 39 172 in Excursion guide to the geology of the Aberdeen 40 area. Trewin, N H, Kneller, B C, and Gillen, C (editors). 41 (Edinburgh: Scottish Academic Press for Geological Society of 42 Aberdeen.) 43 Mendum, J.R., Barber, A.J., Butler, R.W.H., Flinn, D., Goodenough, 44 K.M., Krabbendam, M., Park, R.G. and Stewart, A.D. (2009) 45 Lewisian, Torridonian and Moine rocks of Scotland, Geological 46 Conservation Review Series, No. 34, Joint Nature Conservation 47 Committee, Peterborough, 722 pp. 48 Mendum, J.R. and Fettes, D.J. (1985) The Tay nappe and associated 49 folding in the Ben Ledi–Loch Lomond area. Scottish Journal of 50 Geology, 21, 41–56. 51 Mendum, J.R. and Noble, S.R. (2010) Mid-Devonian sinistral 52 transpression on the Great Glen Fault: the rise of the Rosemarkie 53 Inlier and the Acadian Event in Scotland. In Continental tectonics 54 and mountain building: the legacy of Peach and Horne. (eds R.D. 55 Law, R.W.H. Butler, R.E. Holdsworth, M. Krabbendam and R.A. 56 Strachan), Geological Society, London, Special Publication, No. 57 335, pp. 161-187. 58 Mendum, J.R. and Thomas, C.W. (1997) Discussion on the generation 59 of the Tay Nappe, Scotland, by large-scale SE-directed shearing. 60 Journal of the Geological Society, London, 154, 581–3. 61 62 63 64 65 1 2 3 4 Miall, A. D. 1985. Architectural-element analysis: a new method of 5 facies analysis applied to fluvial deposits. Earth Science 6 Reviews, 22, pp. 261-308. 7 Miall, A. D. 1992. Alluvial Deposits. In: Walker, R. G. & James, N. 8 P. (eds), Facies models – response to sea level changes. 9 Geoscience Canada, pp. 119-1992. 10 Millar, I.L. (1999) Neoproterozoic extensional basic magmatism 11 associated with the West Highland granite gneiss in the Moine 12 Supergroup of NW Scotland. Journal of the Geological Society, 13 London 156, 1153–62. 14 Moffat, D.T. (1987) The serpentinized ultramafites of the Shetland 15 Caledonides. Unpublished PhD thesis, University of Liverpool. 16 Moig, N.A.W. (1986) A structural study of the Dalradian rocks of 17 the Banff coastal transect, NE Scotland. Unpublished PhD thesis, 18 University of Dundee. 19 Moles, N.R. (1985a) Geology, geochemistry and petrology of the Foss 20 stratiform baryte–base metal deposit and adjacent Dalradian 21 metasediments, near Aberfeldy. Unpublished PhD thesis, University 22 of Edinburgh. 23 Moles, N.R. (1985b) Metamorphic conditions and uplift history in 24 central Perthshire: evidence from mineral equilibria in the Foss 25 celsian-barite-sulphide deposit, Aberfeldy. Journal of the 26 Geological Society of London, 142, 39–52. 27 Möller, C. (1998) Decompressed eclogites in the Sveconorwegian 28 (Grenvillian) Orogen of SW Sweden; petrology and tectonic 29 implications. Journal of Metamorphic Geology, 16, 641–56. 30 Molyneux, S.G. 1998. An upper Dalradian microfossil reassessed. 31 Journal of the Geological Society, London, 155, 740–743. 32 Morgan, W.C. (1966) The metamorphic history of the Dalradian rocks 33 between Tomintoul and Loch Builg, Banfshire. Unpublished Ph D 34 thesis, University of Aberdeen. 35 Morris, G.A. and Hutton, D.H.W. (1993) Evidence for sinistral shear 36 associated with the emplacement of the early Devonian Etive dyke 37 swarm. Scottish Journal of Geology, 29, 69–72. 38 Mould, D.D.C.P. (1946) The geology of the Foyers ‗granite‘ and the 39 surrounding country. Geological Magazine, 83, 249–65. 40 Muir, R.J. (1990) The Precambrian basement and related rocks of the 41 southern Inner Hebrides, Scotland. Unpublished PhD thesis, 42 University of Wales, Aberystwyth. 43 Muir, R.J., Fitches, W.R. and Maltman, A.J. (1989) An Early 44 Proterozoic link between Greenland and Scandinavia in the Inner 45 Hebrides of Scotland. Terra Abstract, 1, 5. 46 Muir, R.J., Fitches, W.R. and Maltman, A.J. (1992). Rhinns Complex: 47 a missing link in the Proterozoic basement of the North Atlantic 48 region. Geology, 20, 1043–6. 49 Muir, R.J., Fitches, W.R. and Maltman, A.J. (1994a). The Rhinns 50 Complex: Proterozoic basement on Islay and Colonsay, Inner 51 Hebrides, Scotland, and on Inishtrahull, NW Ireland. Transactions 52 of the Royal Society of Edinburgh: Earth Sciences, 85, 77–90. 53 Muir, R.J., Fitches, W.R., Maltman, A.J. and Bentley, M.R. (1994b) 54 Precambrian rocks of the southern Inner Hebrides–Malin Sea region: 55 Colonsay, west Islay, Inishtrahull and Iona. In: Gibbons, W. and 56 Harris, A.L. (eds) A revised correlation of Precambrian rocks in 57 the British Isles. Geological Society, London, Special Report 22, 58 54–58. 59 60 61 62 63 64 65 1 2 3 4 Muir, R.J., Fitches, W.R. and Maltman, A.J. (1995). The Colonsay 5 Group and basement–cover relationship on the Rhinns of Islay, 6 Inner Hebrides. Scottish Journal of Geology, 31, 125–30. 7 Munro, M. (1986) Geology of the country around Aberdeen. Memoir of 8 the British Geological Survey, Sheet 77 (Scotland). 9 Munro, M. and Gallagher, J W. (1984) Disruption of the ‗Younger 10 Basic‘ masses in the Huntly–Portsoy area, Grampian 11 Region. Scottish Journal of Geology, 20, 361–82. 12 Murchison, R.I. (1851) On the Silurian rocks of the south of 13 Scotland. Quarterly Journal of the Geological Society of London, 14 7, 139–78. 15 Murchison, R.I. (1859) Siluria: the History of the Oldest Known 16 Rocks Containing Organic Remains, With a Brief Sketch of the 17 Distribution of Gold Over the Earth. 3rd edition. John Murray, 18 London. 19 Murchison, R.I. and Geikie, A. (1861) On the altered rocks of the 20 Western Islands of Scotland and the North-Western and Central 21 Highlands. Quarterly Journal of the Geological Society of London 22 17, 171– ??. 23 Mutti, E. and Normark, W.R. (1987) Comparing examples of modern and 24 ancient turbidite systems: problems and concepts. In Marine 25 Clastic Sedimentology (eds. Legget, J.K and Zuffa, G.G.), Graham 26 and Trotman, pp.1–38. 27 Mykura, W. (1976) British Regional Geology: Orkney and Shetland. 28 HMSO, Edinburgh for the Institute of Geological Sciences. 29 30 Nell, P.A.R. (1984) The geology of lower Glen Lyon. Unpublished PhD 31 thesis, University of Manchester. 32 Nell, P.A.R. (1986) Discussion on the Caledonian metamorphic core: 33 an Alpine model. Journal of the Geological Society of London, 34 143, 723–8. 35 Nesbitt, R.W. and Hartmann, L.A. (1986) Comments on ‗A peridotitic 36 komatiite from the Dalradian of Shetland‘ by D. Flinn and D.T. 37 Moffat. Geological Journal, 21, 201–5. 38 Nicol, J. (1844) Guide to the geology of Scotland: Containing an 39 Account of the Character, Distribution and More Interesting 40 Appearances of its Rocks and Minerals. Oliver and Boyd, Edinburgh. 41 Nicol, J. (1852) On the geology of the southern portion of the 42 peninsula of Cantyre, Argyllshire. Quarterly Journal of the 43 Geological Society of London, 8, 406–25. 44 Nicol J. (1863) On the geological structure of the Southern 45 Grampians. Quarterly Journal of the Geological Society of London 46 19, 180–209. 47 Noble, S.R., Hyslop, E.K. and Highton, A.J. (1996). High-precision 48 U-Pb monazite geochronology of the c. 806 Ma Grampian Shear Zone 49 and the implications for evolution of the Central Highlands of 50 Scotland. Journal of the Geological Society, London, 153, 511–14. 51 52 Okonkwo, C.T. (1985). The geology and geochemistry of the 53 metasedimentary rocks of the Loch Laggan–Upper Strathspey area, 54 Inverness-shire. Unpublished PhD thesis, University of Keele. 55 Okonkwo, C.T. (1988). The stratigraphy and structure of the 56 metasedimentary rocks of the Loch Laggan–Upper Strathspey area, 57 Inverness-shire. Scottish Journal of Geology, 24, 21–34. 58 Oldroyd, D.R. and Hamilton, B.M. (2002) Themes in the early history 59 of Scottish geology. In: Trewin N. H. (ed.) The Geology of 60 Scotland. The Geological Society, London, pp. 27–43. 61 62 63 64 65 1 2 3 4 Oliver, G.J.H. (2001) Reconstruction of the Grampian episode in 5 Scotland: its place in the Caledonian Orogeny. Tectonophysics, 6 332, 23–49. 7 Oliver, G.J.H. (2002) Chronology and terrane assembly, new and old 8 controversies. In The Geology of Scotland (edited by Trewin, N. 9 H.) The Geological Society, London, 201–11. 10 Oliver, G.J.H., Chen, F., Buchwald, R. and Hegner, E. (2000) Fast 11 tectonometamorphism and exhumation in the type area of the 12 Barrovian and Buchan zones. Geology, 28, 459–62. 13 Oliver, G.J.H., Simon, A.W., Wan, Y., 2008. Geochronology and 14 geodynamics of Scottish granitoids from the late Neoproterozoic 15 break-up of Rodinia to Palaeozoic collision. Journal of the 16 Geological Society, London, 165, 661-674. 17 18 Pankhurst, R.J. (1970) The geochronology of the basic igneous 19 complexes. Scottish Journal of Geology, 6, 83–107. 20 Pankhurst, R.J. and Pidgeon, R.T. (1976) Inherted isotope systems 21 and the source region prehistory of the early Caledonian granites 22 in the Dalradian Series of Scotland. Earth and Planetary Science 23 Letters, 31, 58–66. 24 Pantin, H.M. (1952) Part 1: The petrology and structure of the Ben 25 Vrackie epidiorite. Part 2: Some new observations on Dalradian 26 stratigraphy and tectonics. Unpublished PhD thesis, University of 27 Cambridge. 28 Pantin H.M. (1961) The stratigraphy and structure of the Blair 29 Atholl–Ben a‘ Gloe area, Perthshire, Scotland. Transactions of the 30 Royal Society of New Zealand, 88, 597–622. 31 Park, R.G. (1992) Plate kinematic history of Baltica during the 32 Middle to Late Proterozoic: a model. Geology 20, 725–8. 33 Park, R.G. (1994) Early Proterozoic tectonic overview of the 34 northern British Isles and neighbouring terrains in Laurentia and 35 Baltica. Precambrian Research, 68, 65–79. 36 Parson, L M. (1982) The Precambrian and Caledonian geology of the 37 ground near Fort Augustus, Inverness-shire. Unpublished PhD 38 thesis, University of Liverpool. 39 Paterson, I.B., Hall, I.H.S. and Stephenson, D. (1990) Geology of 40 the Greenock district. Memoir of the British Geological Survey, 41 Sheet 30W and part of Sheet 29E (Scotland). 42 Pattrick, R.A. and Treagus, J.E. (1996) Economic geology of the 43 Schiehallion district, central highlands of Scotland. British 44 Geological Survey Technical Report No. WA/96/89. 45 Peach, B.N. (1904) Summary of Progress of the Geological Survey of 46 the United Kingdom for 1903, 69. 47 Peach, B.N. and Horne, J. (1930) Chapters on the Geology of 48 Scotland, Oxford University Press, London. 49 Peach, B.N., Kynaston, B.A. and Muff, H.B. (1909) The geology of 50 the seaboard of mid Argyll including the islands of Luing, Scarba, 51 the Garvellachs, and the Lesser Isles, together with the northern 52 part of Jura and a small portion of Mull. Memoirs of the 53 Geological Survey of Scotland, Sheet 36. 54 Peach, B.N., Wilson, J.G.S., Hill, J.B., Bailey, E.B. and Grabham, 55 G.W. (1911) The Geology of Knapdale, Jura and North Kintyre. 56 Memoirs of the Geological Survey of Scotland, Sheet 28. 57 Peach, B.N. and Horne, J. (1930) Chapters on the Geology of 58 Scotland, Oxford University Press, Oxford. 59 60 61 62 63 64 65 1 2 3 4 Peacock, J.D., Berridge, N.G., Harris, A.L. and May, F. (1968) The 5 geology of the Elgin district. Memoir of the Geological Survey of 6 Scotland, Sheet 95 (Scotland). 7 Phillips, E.R. (1996) The mineralogy and petrology of the igneous 8 and metamorphic rocks exposed in the Macduff district (Sheet 96E), 9 Northeast Scotland. British Geological Survey, Mineralogy and 10 Petrology Technical Report, WG/96/26. 11 Phillips, E.R. and Auton, C.A. (1997) Ductile fault rocks and 12 metamorphic zonation in the Dalradian of the Highland Border SW of 13 Stonehaven, Kincardineshire. Scottish Journal of Geology, 33, 83– 14 93. 15 Phillips, E.R., Clark, G.C. and Smith, D.I. (1993) Mineralogy, 16 petrology, and microfabric analysis of the Eilrig Shear Zone, Fort 17 Augustus, Scotland. Scottish Journal of Geology, 29, 143–58. 18 Phillips, E.R., Hyslop, E.K., Highton, A.J and Smith, M. (1999). 19 The timing and P-T conditions of regional metamorphism in the 20 Central Highlands. Journal of the Geological Society, London, 156, 21 1183–93. 22 Phillips, F.C. (1930) Some mineralogical and chemical changes 23 induced by progressive metamorphism in the Green Bed group of the 24 Scottish Dalradian. Journal of the Mineralogical Society, 22, 240– 25 256. 26 Phillips, F.C. (1954) The Use of Stereographic Projection in 27 Structural Geology, Arnold, London. 28 Phillips, W.E.A., Stillman, C.J. and Murphy, T. (1976) A Caledonian 29 plate tectonic model. Journal of the Geological Society of London, 30 132, 579–609. 31 Piasecki M.A.J. (1975) Tectonic and metamorphic history of the 32 Upper Findhorn, Inverness-shire, Scotland. Scottish Journal of 33 Geology, 11, 87–115. 34 Piasecki, M.A.J. (1980). New light on the Moine rocks of the 35 Central Highlands of Scotland. Journal of the Geological Society 36 of London, 137, 41–59. 37 Piasecki, M.A.J. and van Breemen, O. (1979a) A Morarian age for 38 the ―younger Moines‖ of central and western Scotland. Nature, 39 London, 278, 734–6. 40 Piasecki, M.A.J. and van Breemen, O. (1979b). The ‗Central Highland 41 Granulites‘: cover-basement tectonics in the Moine. In The 42 Caledonides of the British Isles - reviewed. (editors. Harris, 43 A.L., Holland, C.H. and Leake, B.E.), The Geological Society of 44 London, Special Publications, 8, 139–44. 45 Piasecki, M.A.J. and van Breemen, O. (1983) Field and isotopic 46 evidence for a c. 750 Ma tectonothermal event in Moine rocks in 47 the Central Highland region of the Scottish Caledonides. 48 Transactions of the Royal Society of Edinburgh: Earth Sciences, 49 73, 119–34. 50 Piasecki, M.A.J., van Breemen, O. and Wright, A.E. (1981) Late 51 Precambrian geology of Scotland, England and Wales. In Geology of 52 the North Atlantic Borderlands, Kerr, J.W. and Fergusson, A.J. 53 (eds). Memoir of the Canadian Society of Petroleum Geologists, 7, 54 57–94. 55 Piasecki, M.A.J. and Temperley, S. (1988a). The Central Highland 56 Division. In: Winchester, J.A. (ed) Later Proterozoic stratigraphy 57 of the Northern Atlantic regions. Blackie, Glasgow and London, 46– 58 53. 59 Piasecki, M.A.J. and Temperley, S. (1988b). The northern sector of 60 the central Highlands. 51-68 in An excursion guide to the Moine 61 62 63 64 65 1 2 3 4 geology of the Scottish Highlands. Allison, I, May, F, and 5 Strachan, R A (editors). (Edinburgh: Scottish Academic Press for 6 Edinburgh Geological Society and Geological Society of Glasgow.) 7 Pickering K.T., Bassett M.G., and Siveter D.J. (1988) Late 8 Ordovician–early Silurian destruction of the Iapetus Ocean: 9 Newfoundland, British Isles and Scandinavia: A discusion. 10 Transactions of the Royal Society of Edinburgh: Earth Sciences, 11 79, 361–82. 12 Pickett, E.A. (1997) An introduction to the Green Beds of the 13 Southern Highland Group: previous research and an account of 14 preliminary work carried out in 1997. British Geological Survey 15 Technical Report WA/97/92. 16 Pickett, E.A., Hyslop, E.K. and Petterson, M.G. (2006) The Green 17 Beds of the SW Highlands: deposition and origin of a basic 18 igneous-rich sedimentary sequence in the Dalradian Supergroup of 19 Scotland. Scottish Journal of Geology, 42, 43–57. 20 Pidgeon R.T. and Compston W. (1992) A Shrimp ion microprobe study 21 of inherited and magmatic zircon from Scottish Caledonian 22 granites. Transactions of the Royal Society, Edinburgh: Earth 23 Sciences, 83, 473–83. 24 Pitcher, W.S. and Berger, A.R. (1972) The Geology of Donegal: a 25 study of granite emplacement and unroofing. Wiley-Interscience, 26 New York, 435 pp. 27 Plant, J.A., Stone, P. and Mendum, J.R. (1999) Regional 28 geochemistry, terrane analysis and metallogeny in the British 29 Caledonides. In Continental Tectonics. MacNiocaill, C and Ryan, 30 P.D. (editors), Geological Society, London, Special Publication No 31 164, 109–26. 32 Plant, J.A., Watson, J.V. and Green, P.M. (1984) Moine–Dalradian 33 relationships and their palaeotectonic significance. Proceedings 34 of the Royal Society, 395a, 185–202. 35 Powell, R. and Evans, J.A. (1983). A new geobarometer for the 36 assemblage biotite-muscovite-chlorite-quartz. Journal of 37 Metamorphic Geology, 1, 331–6. 38 Power, M.R. and Pirrie, D. (2000) Platinum-group mineralization 39 within ultramafic rocks at Corrycharmaig, Perthshire: implications 40 for the origin of the complex. Scottish Journal of Geology, 36, 41 143–50. 42 Prave, A.R. (1999) The Neoproterozoic Dalradian Supergroup of 43 Scotland: an alternative hypothesis. Geological Magazine, 136, 44 609–17. 45 Prave, A.R., Fallick, A.E., Thomas, C.W. and Graham, C.M. (2009a) A 46 composite C-isotope profile for the Neoproterozoic Dalradian 47 Supergroup of Scotland and Ireland. Journal of the Geological 48 Society, 166, 845-857. 49 Prave, A.R., Strachan, R.A. and Fallick, A.E. (2009b) Global C 50 cycle perturbations recorded in marbles: a record of 51 Neoproterozoic Earth history within the Dalradian succession of 52 the Shetland Islands, Scotland. Journal of the Geological Society, 53 166, 129-135. 54 Pringle, I.R. (1972) Rb-Sr age determinations on shales 55 associated with the Varanger Ice Age. Geological Magazine, 109, 56 465–72. 57 Pringle, J. (1940) The discovery of Cambrian trilobites in the 58 Highland Border rocks near Callander, Perthshire (Scotland). 59 British Association for the Advancement of Science: Annual Report 60 for 1939–40, 1, 252. 61 62 63 64 65 1 2 3 4 Pumpelly, R., Wolff, J.E. and Dale, T.N. (1894) Geology of the 5 Green Mountains. United States Geological Survey Memoir, 23, 1– 6 157. 7 8 Rainbird, R.H., Hamilton, M.A. and Young, G.M. (2001) Detrital 9 zircon geochronology and provenance of the Torridonian, NW 10 Scotland. Journal of the Geological Society, London, 158, 15–27. 11 Ramsay, D.M. (1959) Structure and metamorphism of Glen Lyon. 12 Unpublished PhD thesis, University of Glasgow. 13 Ramsay, D.M. and Sturt, B.A. (1979) The status of the Banff 14 Nappe. In The Caledonides of the British Isles—reviewed. Harris, 15 A L, Holland, C H and Leake, B E (editors). Special Publication of 16 the Geological Society of London, No. 8. 145–151 17 Ramsay, J.G. (1958) Moine–Lewisian relations at Glenelg, Inverness- 18 shire. Quarterly Journal of the Geological Society of London 113, 19 487–523. 20 Rast, N. (1956) Tectonics of Central Perthshire. Unpublished PhD 21 thesis, University of Glasgow. 22 Rast, N. (1958) Metamorphic history of the Schiehallion complex, 23 Perthshire. Transactions of the Royal Society of Edinburgh, 64, 24 413–31. 25 Rast, N. (1963). Structure and metamorphism of the Dalradian rocks 26 of Scotland. In The British Caledonides. (editors. Johnson, M.R.W. 27 and Stewart, F.H.). Oliver and Boyd, Edinburgh, 123–42. 28 Rast, N. and Litherland, M. (1970) The correlation of the 29 Ballachulish and Perthshire (Islay) successions. Geological 30 Magazine, 107, 259–72. 31 Read, H.H. (1919) The two magmas of Strathbogie and Lower 32 Banffshire. Geological Magazine 56, 364–71. 33 Read, H.H. (1923) The geology of the country around Banff, Huntly, 34 and Turriff, Lower Banffshire and north-west Aberdeenshire. Memoir 35 of the Geological Survey, Scotland. Sheets 86 and 96 (Scotland). 36 Read, H.H. (1927) The igneous and metamorphic history of Cromar, 37 Deeside. Transactions of the Royal Society of Edinburgh, 55, 317– 38 53. 39 Read, H.H. (1928) The Highland Schists of middle Deeside and east 40 Glen Muick. Transactions of the Royal Society of Edinburgh, 55, 41 755–72. 42 Read, H.H. (1933). On quartz-kyanite rocks in Unst, Shetland 43 Islands, and their bearing on metamorphic differentiation. 44 Mineralogical Magazine, 23, 317–28. 45 Read, H.H. (1934) The metamorphic geology of Unst in the Shetland 46 Islands. Quarterly Journal of the Geological Society of London 90, 47 637–88. 48 Read, H.H. (1935) British Regional Geology: the Grampian Highlands 49 (1st edition). HMSO for Geological Survey and Museum, Edinburgh. 50 Read, H.H. (1936) The stratigraphical order of the Dalradian rocks 51 of the Banffshire coast. Geological Magazine, 73, 468–75. 52 Read, H.H. (1937) Metamorphic correlation in the polymetamorphic 53 rocks of the Valla Field Block, Unst, Shetland Islands. 54 Transactions of the Royal Society of Edinburgh, 59, 195–221. 55 Read, H.H. (1952) Metamorphism and migmatisation in the Ythan 56 Valley, Aberdeenshire. Transactions of the Edinburgh Geological 57 Society, 15, 265–79. 58 Read, H.H. (1955) The Banff nappe: an interpretation of the 59 structure of the Dalradian rocks of north-east Scotland. 60 Proceedings of the Geologists’ Association, 66, 1–29. 61 62 63 64 65 1 2 3 4 Read, H.H. (1960) North-east Scotland: the Dalradian. Geologists‘ 5 Association Guide, 31. Benham and Co., Colchester. 6 Read, H.H. and Farquhar, O.C. (1956) The Buchan Anticline of the 7 Banff Nappe of Dalradian rocks in north-east Scotland. Quarterly 8 Journal of the Geological Society of London, 112, 131–56. 9 Richardson, S.W. and Powell, R. (1976) Thermal causes of the 10 Dalradian metamorphism in the Central Highlands of 11 Scotland. Scottish Journal of Geology, 12, 237–68. 12 Ritchie, J.D. and Hitchen, K. (1993) Discussion on the location and 13 history of the Walls Boundary fault and Moine thrust north and 14 south of Shetland. Journal of the Geological Society, London, 150, 15 1003–8. 16 Roberts, J.L. (1959) Fold Structures in the Dalradian Rocks of 17 Knapdale, Argyllshire. Geological Magazine, 94, 221–9. 18 Roberts, J.L. (1963) The Dalradian of the southwest highlands of 19 Scotland. Unpublished PhD thesis, University of Liverpool. 20 Roberts, J.L. (1966a) Sedimentary affiliations and stratigraphic 21 correlation of the Dalradian rocks in the South-west Highlands of 22 Scotland. Scottish Journal of Geology, 2, 200–23. 23 Roberts, J.L. (1966b) The formation of similar folds by 24 inhomogeneous plastic strain, with reference to the fourth phase 25 of deformation affecting the Dalradian rocks in the southwest 26 Highlands of Scotland. Journal of Geology, 74, 831–55. 27 Roberts, J.L. (1974) The structure of the Dalradian rocks in the SW 28 Highlands of Scotland. Journal of the Geological Society of 29 London, 130, 93–124. 30 Roberts, J.L. (1976) The structure of the Dalradian rocks in the 31 north Ballachulish district of Scotland. Journal of the Geological 32 Society of London, 132, 139–54. 33 Roberts, J.L. (1977a) The evolution and transport of the Tay Nappe: 34 Discussion. Scottish Journal of Geology, 13, 79–80. 35 Roberts, J.L. (1977b) The Dalradian rocks of Rosneath and South- 36 east Cowal. Scottish Journal of Geology, 13, 101–11. 37 Roberts, J.L. (1977c) The Dalradian rocks of Knapdale and North 38 Kintyre. Scottish Journal of Geology, 13, 113–124. 39 Roberts, J.L. and Sanderson, D.J. (1974) Oblique fold axes in the 40 Dalradian rocks of the Southwest Highlands. Scottish Journal of 41 Geology, 9, 281–96. 42 Roberts, J.L. and Treagus, J.E. (1964) A reinterpretation of the 43 Ben Lui Fold. Geological Magazine, 101, 512–16. 44 Roberts, J.L, and Treagus, J.E. (1975) The structure of the Moine 45 and Dalradian rocks in the Dalmally district of Argyllshire, 46 Scotland. Geological Journal, 10, 59–74. 47 Roberts, J.L, and Treagus, J.E. (1977a) The Dalradian rocks of the 48 South-west Highlands–Introduction. Scottish Journal of Geology, 49 Vol. 13, 87–99. 50 Roberts, J.L. and Treagus, J.E. (1977b) The Dalradian rocks of the 51 Loch Leven area. Scottish Journal of Geology, 13, 165–184. 52 Roberts, J.L. and Treagus, J.E. (1977c) Polyphase generation of 53 nappe structures in the Dalradian rocks of the Southwest Highlands 54 of Scotland. Scottish Journal of Geology. 13, 237–254. 55 Roberts, J.L, and Treagus, J.E. (1979) Stratigraphical and 56 structural correlation between the Dalradian rocks of the SW and 57 Central Highlands of Scotland. 199–204 in The Caledonides of the 58 British Isles–reviewed. Harris, A.L., Holland, C.H., and Leake, 59 B.E.(editors). Special Publication of the Geological Society of 60 London. 8. 61 62 63 64 65 1 2 3 4 Roberts, J.L, and Treagus, J E. (1980) The structural 5 interpretation of the Loch Leven area. Scottish Journal of 6 Geology, 16, 73–5. 7 Robertson, S. (1991) Older granites in the south-eastern Scottish 8 Highlands. Scottish Journal of Geology, 27, 21–6. 9 Robertson, S. (1994) Timing of Barrovian metamorphism and ‗Older 10 Granite‘ emplacement in relation to Dalradian deformation. Journal 11 of the Geological Society of London, 151, 5–8. 12 Robertson, S. (1999) BGS Rock Classification Scheme Volume 2: 13 Classification of metamorphic rocks. British Geological Survey 14 Research Report, RR 99–02. 15 Robertson, S. and Smith, M. (1999) The significance of the Geal 16 charn–Ossian Steep Belt in basin development in the Central 17 Scottish Highlands. Journal of the Geological Society, London, 18 156, 1175–82. 19 Rock, N.M.S. (1985) A compilation of analytical data for 20 metamorphic limestones from the Scottish Highlands and Islands, 21 with lists of BGS registered samples, and comments on the 22 reproducibility and accuracy of limestone analyses by different 23 analytical techniques. Mineralogical and Petrological Report 24 British Geological Survey, No. 85/5. 25 Rock, N.M.S. (1986) Chemistry of the Dalradian (Vendian–Cambrian) 26 metalimestones, British Isles. Chemical Geology, 56, 289–311. 27 Rock, N.M.S., Macdonald, R. and Bower, J. (1986) The comparative 28 geochemistry of some Highland pelites (Anomalous local limestone– 29 pelite successions within the Moine outcrop; II). Scottish Journal 30 of Geology, 22, 107–26. 31 Rogers, G., Dempster, T.J., Bluck, B.J. and Tanner, P.W.G. (1989) A 32 high precision U-Pb age for the Ben Vuirich Granite: implications 33 for the evolution of the Scottish Dalradian Supergroup. Journal of 34 the Geological Society, London, 146, 789–98. 35 Rogers, G., Hyslop, E.K., Strachan, R.A., Paterson, B.A. and 36 Holdsworth, R.A. (1998) The structural setting and U-Pb 37 geochronology of the Knoydartian pegmatites of W Inverness-shire: 38 evidence for Neoproterozoic tectonothermal events in the Moine of 39 NW Scotland. Journal of the Geological Society, London, 155, 685– 40 96. 41 Rogers, G., Kinny, P.D., Strachan, R.A., Friend, C.R.L. and 42 Patterson, B.A. (2001) U-Pb geochronology of the Fort Augustus 43 granite gneiss, constraints on the timing of Neoproterozoic and 44 Paleozoic tectonothermal events in the NW Highlands of Scotland. 45 Journal of the Geological Society, London, 158, 7–14. 46 Rogers, G. and Pankhurst, R.J. (1993) Unravelling dates through the 47 ages: geochronology of the Scottish metamorphic complexes. Journal 48 of the Geological Society, London, 150, 447–64. 49 Rollin, K.E. (1994) Geophysical correlation of Precambrian rocks in 50 northern Britain. In A Revised Correlation of Precambrian Rocks in 51 the British Isles. Gibbons, W. and Harris, A.L. (eds.) Geological 52 Society, London, Special Report, 22, 65–74. 53 Rooney, A.D., Chew, D.M. and Selby, D. (2011) Re – Os geochronology 54 of the Neoproterozoic – Cambrian Dalradian Supergroup of Scotland 55 and Ireland: implications for Neoproterozoic stratigraphy, 56 glaciations and Re – Os systematics. Precambrian Research, 57 Rose, P.T.S. (1989) The emplacement of the Tay Nappe Scotland. 58 Unpublished PhD thesis, University of Liverpool. 59 Rose, P.T.S. and Harris, A.L. (2000) Evidence for the lower 60 Palaeozoic age of the Tay Nappe; the timing and nature of Grampian 61 62 63 64 65 1 2 3 4 events in the Scottish Highland sector of the Laurentian margin. 5 Journal of the Geological Society, London, 157, 789–98. 6 Rushton, A.W.A., Owen, A.W., Owens, R.M. and Prigmore, J.K. (1999) 7 British Cambrian and Ordovician stratigraphy, Geological 8 Conservation Review Series No. 18, Joint Nature Conservation 9 Committee, Peterborough. 10 Russell, M.J., Hall, A.J., Willan, R.C.R., Allison, I., Anderton, 11 R., and Bowes, G. (1984) On the origin of the Aberfeldy 12 celsian+barite+base metals deposits, Scotland. In Prospecting in 13 areas of glaciated terrain, 1984. Institution of Mining and 14 Metallurgy, London, pp. 159–170. 15 Ryan, P.D. and Soper, N.J. (2001) Modelling anatexis in intra- 16 cratonic basins: an example from the Neoproterozoic rocks of the 17 Scottish Highlands. Geological Magazine, 138, 577–588. 18 Ryan, P.D., Soper, N.J., Snyder, D.B., England, R.W. and Hutton, 19 D.H.W. (1995) The Antrim – Galway Line: a resolution of the 20 Highland Border Fault enigma of the Caledonides of Britain and 21 Ireland. Geological Magazine, 132, 171–184. 22 23 Saha, D. (1989) The Caledonian Loch Skerrols Thrust, SW Scotland: 24 Microstructure and Strain. Journal of Structural Geology, 11, 553– 25 568. 26 Schermerhorn, L.J.G. (1974) Late Precambrian mixtites: glacial 27 and/or non-glacial? American Journal of Science, 274, 673–824. 28 Schermerhorn, L.J.G. (1975) Tectonic framework of Late Precambrian 29 supposed glacials. In Ice Ages: Ancient and Modern (eds. Wright, 30 A.E. and Moseley, F.), proceedings of the Inter-University 31 Geological Congress (University of Birmingham) (1974), Geological 32 Journal special issue No. 6, 242–247. 33 Scott, R.A. (1987) Lithostratigraphy, structure and mineralization 34 of the Argyll Group Dalradian near Tyndrum, Scotland. Unpublished 35 PhD thesis, University of Manchester. 36 Scott, R.A., Pattrick, R.A.D., and Polya, D.A. (1991) Origin of 37 sulphur in metamorphosed stratabound mineralization from the 38 Argyll Group Dalradian of Scotland. Transactions of the Royal 39 Society of Edinburgh: Earth Sciences, Vol. 82, 91–98. 40 Scott, R.A., Polya, D.A., and Pattrick, R.A.D. (1988) Proximal Cu + 41 Zn exhalites in the Argyll Group Dalradian, Creag Bhocan, 42 Perthshire. Scottish Journal of Geology, Vol. 24, 97–112. 43 Seranne, M. (1992) Devonian extensional tectonics versus 44 Carboniferous inversion in the northern Orcadian basin. Journal of 45 the Geological Society, London, 149, 27–37. 46 Shackleton, R. M. 1958. Downward-facing structures of the Highland 47 Border. Quarterly Journal of the Geological Society, London, 113, 48 361–392. 49 Shackleton, R.M. (1979) The British Caledonides: comments and 50 summary. 299–304 in The Caledonides of the British Isles— 51 reviewed. Harris, A L, Holland, C H, and Leake, B E (editors). 52 Special Publication of the Geological Society of London, No. 8. 53 Shearman, D.J. and Smith, A.J. (1985) Ikaite, the parent mineral of 54 jarrowite-type pseudomorphs. Proceedings of the Geologists’ 55 Association, 96, 305–314. 56 Sibson, R.H. (1977) Fault rocks and fault mechanisms. Journal of 57 the Geological Society, London, Vol 133, 191–213. 58 Simpson, A. and Wedden, D. (1974) Downward-facing structures in the 59 Dalradian Leny Grits on Bute. Scottish Journal of Geology, 10, 60 257–267. 61 62 63 64 65 1 2 3 4 Skelton, A.D.L. (1993) Petrological, geochemical and field studies 5 of fluid infiltration during regional metamorphism of the 6 Dalradian of the SW Scottish Highlands. Unpublished PhD thesis, 7 University of Edinburgh. 8 Skelton, A.D.L., Bickle, M.J. and Graham, C.M. (1997) Fluid-flux 9 and reaction rate from advective-diffusive carbonation of mafic 10 sill margins in the Dalradian, southwest Scottish Highlands. Earth 11 and Planetary Science Letters, 146, 527–539 12 Skelton, A.D.L., Graham, C.M. and Bickle, M.J. (1995) Lithological 13 and structural constraints on regional 3-D fluid flow patterns 14 during greenschist facies metamorphism of the Dalradian of the SW 15 Highlands. Journal of Petrology, 36, 563–586. 16 Skevington, D. (1971) Palaeontological evidence bearing on the age 17 of the Dalradian deformation and metamorphism in Ireland and 18 Scotland. Scottish Journal of Geology, Vol. 7, 285–288. 19 Smallwood, J.R. (2007) Maskelyne‘s 1774 Schiehallion experiment 20 revisited. Scottish Journal of Geology, Vol. 43, 15–31. 21 Smith, A.J. and Rast, N. (1958) Sedimentary dykes in the Dalradian 22 of Scotland. Geological Magazine 95, 234 –240. 23 Smith, C.G., Gallagher, M.J., Coats, J.S. and Parker, M.E. (1984) 24 Detection and general characteristics of stratabound 25 mineralization in the Dalradian of Scotland. Transactions of the 26 Institution of Mining and Metallurgy (Section B: Applied Earth 27 Science), Vol. 93, B125–133. 28 Smith, C.G., Gallagher, M.J., Grout, A., Coats, J.S., Vickers, 29 B.P., Peachey, D., Pease, S.F., Parker, M.E. and Fortey, N.J. 30 (1988) Stratabound base-metal materialisation in Dalradian rocks 31 near Tyndrum, Scotland. Mineral Reconnaissance Programme Report, 32 British Geological Survey, No. 93. 33 Smith, C.G., Goodman, S. and Robertson, S. (2002) Geology of the 34 Ballater district. Memoir of the British Geological Survey, Sheet 35 65E (Scotland). 36 Smith, M., Robertson, S. and Rollin, K.E. (1999) Rift basin 37 architecture and stratigraphical implications for basement-cover 38 relationships in the Neoproterozoic Grampian Group of the Scottish 39 Caledonides. Journal of the Geological Society, London, 156, 1163– 40 1173. 41 Smith, R.A. (1980) The Geology of the Dalradian rocks around Blair 42 Atholl, Central Perthshire, Scotland. Unpublished PhD thesis, 43 University of Liverpool. 44 Smith, R.A. and Harris, A,L. (1976) The Ballachulish rocks of the 45 Blair Atholl District. Scottish Journal of Geology, Vol. 12, 153– 46 157. 47 Smith, T.E. (1968) Tectonics in Upper Strathspey, Inverness-shire. 48 Scottish Journal of Geology, 4, 68–84. 49 Snyder, D.B. and Flack, C.A. (1990) A Caledonian age for reflectors 50 within the mantle lithosphere north and west of Scotland. 51 Tectonics, 9, 903–922. 52 Soper N.J. (1994) Was Scotland a Vendian RRR junction? Journal of 53 the Geological Society, London, 151, 579–582. 54 Soper N.J. (1994) Neoproterozoic sedimentation on the northeast 55 margin of Laurentia and the opening of Iapetus. Geological 56 Magazine, 131, 291–299. 57 Soper, N.J. and Anderton, R. (1984) Did the Dalradian slides 58 originate as extensional faults? Nature, London, Vol. 307, 357– 59 360. 60 61 62 63 64 65 1 2 3 4 Soper, N.J. and England, R.W. (1995) Vendian and Riphean rifting in 5 NW Scotland. Journal of the Geological Society, London 152, 11–14. 6 Soper, N.J. and Evans, J.A., 1997. Discussion on metamorphism and 7 cooling of the NE Dalradian. Journal of the Geological Society, 8 London. 154, 357-360. 9 Soper N.J. and Hutton D.H.W. (1984) Late Caledonian sinistral 10 displacements in Britain: Implications for a three-plate collision 11 model. Tectonics 3, 781–794. 12 Soper, N.J., Ryan, P.D. and Dewey, J.F. (1999) Age of the Grampian 13 Orogeny in Scotland and Ireland. Journal of the Geological 14 Society, London 156, 1231–1236. 15 Soper N.J., Strachan R.A., Holdsworth R.E., Gayer R.A. and 16 O‘Greiling, R.O. (1992) Sinistral transpression and the Silurian 17 closure of Iapetus. Journal of the Geological Society, London 149, 18 871–880. 19 Spear, F.S. (1993) Metamorphic phase equilibria and pressure- 20 temperature-time paths. Mineralogical Society of America. 21 Spencer, A.M. (1971) Late Precambrian glaciation in Scotland. 22 Memoir of the Geological Society of London, No. 6. 23 Spencer, A.M. (1981) The late Precambrian Port Askaig Tillite in 24 Scotland. In Earth‘s pre-Pleistocene glacial record (eds. Hambrey, 25 M. J. and Harland, W. B.), pp. 632–636. Cambridge University 26 Press, Cambridge. 27 Spencer, A.M. (1985) Mechanisms and environments of deposition of 28 Late Precambrian geosynclinal tillites: Scotland and East 29 Greenland. Palaeogeography, Palaeoclimatology and Palaeoecology, 30 51, 143–157. 31 Spencer, A.M. and Pitcher, W.S. (1968) Occurrence of the Port 32 Askaig Tillite in north-east Scotland. Proceedings of the 33 Geological Society of London, No. 1650, 195–198. 34 Spencer, A.M. and Spencer, M. (1972) The Late Precambrian/Lower 35 Cambrian Bonnahaven Dolomite of Islay and its stromatolites. 36 Scottish Journal of Geology, 8, 269–282. 37 Spray J.G. and Dunning G.R. (1991) A U/Pb age for the Shetland 38 Islands oceanic fragment, Scottish Caledonides: evidence from 39 anatectic plagiogranites in ―layer 3‖ shear zones. Geological 40 Magazine 128, 667–671. 41 Stephenson, D. (1993) Amphiboles from Dalradian metasedimentary 42 rocks of NE Scotland: environmental inferences and distinction 43 from meta-igneous amphibolites. Mineralogy and Petrology, Vol. 44 49, 45–62. 45 Stephenson, D., Bevins, R.E., Millward, D., Highton, A.J., Parsons, 46 I., Stone, P. and Wadsworth, W.J. (1999) Caledonian Igneous rocks 47 of Great Britain. Geological Conservation Review Series No.17. 48 Joint Nature Conservation Committee, Peterborough. 648pp. 49 Stephenson, D. and Gould, D. (1995) British regional geology: the 50 Grampian Highlands (4th edition). HMSO for the British Geological 51 Survey, London. 52 Stewart, A.D. (1960) On the sedimentary and metamorphic history of 53 the Torridonian, and the later igneous intrusions of Colonsay and 54 Oronsay. Unpublished PhD thesis, University of Liverpool. 55 Stewart, A.D. (1962) On the Torridonian sediments of Colonsay and 56 their relationship to the main outcrop in north-west Scotland. 57 Liverpool and Manchester Geological Journal 3, 121–156. 58 Stewart, A.D. (1969) Torridonian rocks of Scotland reviewed. In 59 Kay, M. (ed.) North Atlantic-Geology and Continental Drift, a 60 61 62 63 64 65 1 2 3 4 symposium. Memoir of the American Association of Petroleum 5 Geologists 12, 595–608. 6 Stewart, A.D. (1975) ‗Torridonian‘ rocks of western Scotland. In: A 7 correlation of Precambrian rocks in the British Isles (eds. 8 Harris, A. L., Shackleton, R. M., Watson, J.V., Downie, C., 9 Harland, W. B. and Moorbath, S.) Geological Society, London, 10 Special Report, 6, 43–51. 11 Stewart, A.D. and Hackman, B.D. (1973) Precambrian sediments of 12 Islay. Scottish Journal of Geology, 9, 185–201. 13 Stewart, M., Strachan, R.A. and Holdsworth, R.E. (1999) Structure 14 and early kinematic history of the Great Glen fault zone, 15 Scotland. Tectonics 18, 326–342. 16 Stewart, M., Strachan, R.A., Martin, M.W. and Holdsworth, R.E. 17 (2001) Constraints on early sinistral displacements along the 18 Great Glen Fault Zone, Scotland; structural setting, U-Pb 19 geochronology and emplacement of the syn-tectonic Clunes Tonalite. 20 Journal of the Geological Society, London 158, 821–830. 21 Stoker, M.S., Howe, J.A. and Stoker, S.J. (1999) Late Vendian- 22 ?Cambrian glacially influenced deep-water sedimentation, Macduff 23 Slate Formation (Dalradian), NE Scotland. Journal of the 24 Geological Society, London, 156, 55–61. 25 Stone, M. (1957) The Aberfoyle Anticline, Callander, Perthshire. 26 Geological Magazine, 94, 265–276. 27 Stone, P., Plant, J.A., Mendum, J.R. and Green, P.M. (1999) A 28 regional geochemical assessment of some terrane relationships in 29 the British Caledonides. Scottish Journal of Geology, 35, 145–156. 30 Strachan, R.A. (2000) The Grampian Orogeny: Mid-Ordovician arc– 31 continent collision along the Laurentian margin of Iapetus. In: 32 Woodcock, N.H. and Strachan, R.A. (eds) Geological History of 33 Britain and Ireland. Blackwell Science Ltd, 88–106. 34 Strachan, R.A., Harris, A.L., Fettes D.J. and Smith, M. (2002) The 35 Northern Highland and Grampian terranes. In: Trewin N. H. (ed.) 36 The Geology of Scotland. (4th edition) The Geological Society, 37 London, pp. 81–148. 38 Strachan, R.A. and Holdsworth, R.E. (2000) Proterozoic 39 sedimentation, orogenesis and magmatism on the Laurentian Craton 40 (2700–750 Ma). In: Geological history of Great Britain and Ireland 41 (edited by Woodcock, N. and Strachan, R. A.) Blackwell Science. 42 Oxford, 52–72. 43 Stringer, P.J. (1957) Polyphase deformation in the Upper Dalradian 44 rocks of the Southern Highlands of Scotland. Unpublished PhD 45 thesis, University of Liverpool. 46 Stupavsky, M., Symons, D.T.A. and Gravenor, C.P. (1982) Evidence 47 for metamorphic remagnetisation of the upper Precambrian tillite 48 in the Dalradian Supergroup of Scotland. Transactions of the Royal 49 Society of Edinburgh, 73, 59–65. 50 Sturt, B.A. (1959) Studies in the metamorphic rocks of the Loch 51 Tummel district, Perthshire. Unpublished PhD thesis, University of 52 Wales, Aberystwyth. 53 Sturt, B.A. (1961) The geological structure of the area south of 54 Loch Tummel. Quarterly Journal of the Geological Society of 55 London, Vol. 117, 131–156. 56 Sturt, B.A. and Harris, A.L. (1961) The metamorphic history of 57 the Loch Tummel area. Liverpool and Manchester Geological 58 Journal, Vol. 2, 689–711. 59 Sturt, B.A., Ramsay, D.M., Pringle, I.R. and Teggin, 60 D.E. (1977) Precambrian gneisses in the Dalradian sequence of NE 61 62 63 64 65 1 2 3 4 Scotland. Journal of the Geological Society of London, Vol. 134, 5 41–44. 6 Sutton, J. and Watson, J.V. (1954) Ice-borne boulders in the 7 Macduff Group of the Dalradian of Banffshire. Geological 8 Magazine, Vol. 91, 391–398. 9 Sutton, J. and Watson, J.V. (1955) The deposition of the Upper 10 Dalradian rocks of the Banffshire coast. Proceedings of the 11 Geologists’ Association, Vol. 66, 101–133. 12 Sutton, J. and Watson, J.V. (1956) The Boyndie syncline of the 13 Dalradian of the Banffshire coast. Quarterly Journal of the 14 Geological Society of London, Vol. 112, 103–130. 15 16 Tanner, P. W. G. 1992. Rosneath Peninsula and Loch Long. In 17 Geological excursions around Glasgow and Girvan (eds. Lawson, J. 18 D. and Weedon, D. S.), pp. 159–185. Geological Society of Glasgow. 19 Tanner, P. W. G. 1995. New evidence that the Lower Cambrian Leny 20 Limestone at Callander, Perthshire, belongs to the Dalradian 21 Supergroup, and a reassessment of the ‗exotic‘ status of the 22 Highland Border Complex. Geological Magazine, 132, 473–483. 23 Tanner, P. W. G. 1996. Significance of the early fabric in the 24 contact metamorphic aureole of the 590 Ma Ben Vuirich Granite, 25 Perthshire, Scotland. Geological Magazine, 133, 683–695. 26 Tanner, P. W. G. 1997. The Highland Border controversy: Reply to a 27 Discussion of ‗New evidence that the Lower Cambrian Leny Limestone 28 at Callander, Perthshire, belongs to the Dalradian Supergroup, and 29 a reassessment of the ‗exotic‘ status of the Highland Border 30 Complex‘. Geological Magazine, 134, 565–570. 31 Tanner, P. W. G. 1998a. Interstratal dewatering origin for 32 polygonal patterns of sand-filled cracks: a case study from Late 33 Proterozoic metasediments of Islay, Scotland. Sedimentology, 45, 34 71–89. 35 Tanner, P W G. 1998b. Age of the Grampian event: Reply to a 36 Discussion of ‗New evidence that the Lower Cambrian Leny Limestone 37 at Callander, Perthshire belongs to the Dalradian Supergroup, and 38 a reassessment of the ‗exotic‘ status of the Highland Border 39 Complex‗. Geological Magazine, Vol. 135, 575–579. 40 Tanner, P. W. G. 2005. Discussion on evidence for a major 41 Neoproterozoic orogenic unconformity within the Dalradian 42 Supergroup of NW Ireland. Journal of the Geological Society, 43 London, 162, 221–224. 44 Tanner, P.W.G. 2007. The role of the Highland Border Ophiolite in 45 the ~ 470 Ma Grampian Event, Scotland. Geological Magazine Vol. 46 144, 597–602. 47 Tanner, P.W.G. 2008. Tectonic significance of the Highland Boundary 48 Fault. Journal of the Geological Society, London Vol. 165, 915– 49 921. 50 Tanner, P.W.G. and Bluck, B.J. (2011) Discussion of 'The Highland 51 Boundary Fault and the Highland Boundary Complex' by B.J. Bluck 52 Scottish Journal of Geology 46, 113-124. Scottish Journal of 53 Geolgy, 47, 89-93. 54 Tanner, P. W. G. and BLUCK, B. J. 1999. Current controversies in 55 the Caledonides. Journal of the Geological Society, London, 156, 56 1137–1141. 57 Tanner, P. W. G. and Evans, J. A. 2003. Late Precambrian U-Pb 58 titanite age for peak regional metamorphism and deformation 59 (Knoydartian Orogeny) in the western Moine, Scotland. Journal of 60 the Geological Society, London 160, 555–564. 61 62 63 64 65 1 2 3 4 Tanner, P. W. G. and Leslie, A. G. 1994. A pre-D2 age for the 590 5 Ma Ben Vuirich Granite in the Dalradian of Scotland. Journal of 6 the Geological Society, London, 151, 209–212. 7 Tanner P. W. G., Leslie A. G. and Gillespie M.R. 2006. Structural 8 setting and petrogenesis of a rift-related intrusion: the Ben 9 Vuirich Granite of the Grampian Highlands, Scotland. Scottish 10 Journal of Geology, Vol. 42, 113–136. 11 Tanner, P. W. G. and Pringle, M. 1999. Testing for a terrane 12 boundary within Neoproterozoic (Dalradian) to Cambrian siliceous 13 turbidites at Callander, Perthshire, Scotland. Journal of the 14 Geological Society, London, 156, 1205–1216. 15 Tanner, P.W.G. and Sutherland, S. 2007. The Highland Border 16 Complex, Scotland: a paradox resolved. Journal of the Geological 17 Society, London, 164, 111–116. 18 Tannner, P.W.G. and Thomas, P.R. (2010) Major nappe-like D2 folds 19 in the Dalradian rocks of the Beinn Udlaidh area, Central 20 Highlands, Scotland. Earth and Environmental Science Transactions 21 of the Royal Society of Edinburgh. 100, 371-389. 22 Temperley, S. (1990). The Late Proterozoic to Early Palaeozoic 23 geology of the Glen Banchor area in the Monadhliath Mountains of 24 Scotland, with particular reference to deformation in Knoydartian 25 shear zones and the Caledonian Central Highland steep belt. 26 Unpublished PhD thesis, University of Hull. 27 Thomas, C W. 1989. Application of geochemistry to the 28 stratigraphic correlation of Appin and Argyll Group carbonate 29 rocks from the Dalradian of northeast Scotland. Journal of the 30 Geological Society of London, Vol. 146, 631–647. 31 Thomas, C. W. 1993. Sources of Rare Earth elements in Appin Group 32 limestones, Dalradian, north-east Scotland. Mineralogy and 33 Petrology Vol. 49, 27–44 . 34 Thomas, C.W. (1995). The geochemistry of metacarbonate rocks from 35 the Monadhliath Project area. British Geological Survey Technical 36 Report. WA/95/40/R. 37 Thomas, C. W. (1999). The isotope Geochemistry and Petrology of 38 Dalradian Metacarbonate Rocks, Unpublished PhD thesis, University 39 of Edinburgh. 40 Thomas, C.W. and Aitchison (1998). Application of logratios to the 41 statistical analysis of the geochemistry of metamorphosed 42 limestones from the Northeast and Central Highlands of Scotland: 43 the case for Appin Group correlations. British Geological Survey 44 Technical Report, WA/98/03. 45 Thomas, C W, Aitken, A M, Pickett, E P, Mendum, J R, Hyslop, E K, 46 and Petterson, M.P. in press. Geology of the Aberfoyle District. 47 Sheet Description for the British Geological Survey, 1:50 000 48 Series Sheet 38E (Scotland). 49 Thomas, C. W., Graham, C. M., Ellam, R.M. and Fallick, A. E. 50 (2004). 87Sr/86Sr chemostratigraphy of Neoproterozoic Dalradian 51 limestones of Scotland: constraints on depositional ages and 52 timescales. Journal of the Geological Society, London 161, 223– 53 243. 54 Thomas, C.W., Smith, M. and Robertson, S. (1997). The geochemistry 55 of Dalradian metacarbonate rocks from the Schiehallion District 56 and Blargie, Laggan: implications for stratigraphical correlations 57 in the Geal Charn–Ossian Steep Belt. British Geological Survey 58 Technical Report, WA/97/81. 59 60 61 62 63 64 65 1 2 3 4 Thomas, P R. 1965. The structure and metamorphism of the Moinian 5 rocks in Glen Garry, Glen Tilt, and adjacent areas of Scotland. 6 Unpublished PhD thesis, University of Liverpool. 7 Thomas, P R. 1979. New evidence for a Central Highland Root Zone. 8 205–211 in The Caledonides of the British Isles –Reviewed. Harris, 9 A L, Holland, C H, and Leake, B E (editors). Special Publication 10 of the Geological Society, No. 8. 11 Thomas, P R. 1980. The stratigraphy and structure of the Moine 12 rocks north of the Schiehallion Complex, Scotland. Journal of the 13 Geological Society of London, Vol. 137, 469–482. 14 Thomas, P R. 1988. A9 road section—Blair Atholl to 15 Newtonmore. 39–50 in An excursion guide to the Moine geology of 16 the Scottish Highlands. Allison, I, May, F, and Strachan, R A 17 (editors). (Edinburgh: Scottish Academic Press for Edinburgh 18 Geological Society and Geological Society of Glasgow.) 19 Thomas, P R, and Treagus, J E. 1968. The stratigraphy and structure 20 of the Glen Orchy area, Argyllshire, Scotland. Scottish Journal of 21 Geology, Vol. 4, 121–134. 22 Thomson, J. 1877. On the geology of the Island of Islay. 23 Transactions of the Geological Society of Glasgow, 5, 200–222. 24 Tilley, C.E. (1925) A preliminary survey of metamorphic zones in 25 the southern Highlands of Scotland. Quarterly Journal of the 26 Geological Society of London, Vol. 81, 100–110. 27 Tollo R. P., Aleinikoff J. N., Bartholomew M. J. and Rankin D. W. 28 2004. Neoproterozoic A-type granitoids of the central and southern 29 Appalachians: intraplate magmatism associated with episodic 30 rifting of the Rodinian supercontinent. Precambrian Research, 128, 31 3–38. 32 Torsvik, T. H., Smethurst, M. A., Meert, J. G., Van der Voo, R., 33 McKerrow, W. S., Brasier, M. D., Sturt, B. A. and Walderhaug, H. 34 J. 1996. Continental break-up and collision in the Neoproterozoic 35 and Palaeozoic–a tale of Baltica and Laurentia. Earth Science 36 Reviews 40, 229–258. 37 Treagus, J. E. 1964a. The structural and metamorphic history of an 38 area of Moine and Dalradian rocks south of Loch Rannoch, 39 Perthshire. Unpublished PhD thesis, University of Liverpool. 40 Treagus, J E. 1964b. Notes on the structure of the Ben Lawers 41 Synform. Geological Magazine, Vol. 101, 260–270. 42 Treagus, J.E. (1969). The Kinlochlaggan Boulder Bed. Proceedings of 43 the Geological Society of London, 1654, 55–60. 44 Treagus, J E. 1974. A structural cross-section of the Moine and 45 Dalradian rocks of the Kinlochleven area, Scotland. Journal of the 46 Geological Society of London, Vol. 130, 525–544. 47 Treagus, J.E. (1981). The Lower Dalradian Kinlochlaggan Boulder 48 Bed, Central Scotland. In: Earth’s pre-Pleistocene glacial record. 49 (editors. Hambrey, J.M. and Harland, W.B.), Cambridge University 50 Press, 637–639. 51 Treagus, J E. 1987. The structural evolution of the Dalradian of 52 the Central Highlands of Scotland. Transactions of the Royal 53 Society of Edinburgh: Earth Sciences, Vol. 78, 1–15. 54 Treagus, J E. 1991. Fault displacements in the Dalradian of the 55 Central Highlands. Scottish Journal of Geology, Vol. 27, 135–145. 56 Treagus, J. E. (editor). 1992. Caledonian Structures in Britain 57 South of the Midland Valley, Geological Conservation Review Series 58 No. 3. London: Chapman and Hall. 59 60 61 62 63 64 65 1 2 3 4 Treagus, J.E. (1997) Discussion on a late Vendian age for the 5 Kinlochlaggan Boulder bed (Dalradian). Journal of the Geological 6 Society, London, 154, 917–919. 7 Treagus, J E. 1999. A structural reinterpretation of the Tummel 8 Belt and a transpressional model of evolution of the Tay Nappe in 9 the Central Highlands of Scotland. Geological Magazine, Vol. 136, 10 Pt 6, 643–660. 11 Treagus, J. E. 2000. The Solid Geology of the Schiehallion 12 District. Memoir of the British Geological Survey. Sheet 55W 13 (Scotland). 14 Treagus, J.E. 2009. The Dalradian of Scotland. Geologists’ 15 Association Guide No. 67. 202pp. 16 Treagus, J E, and King, G. 1978. A complete Lower Dalradian 17 succession in the Schiehallion district, central Perthshire. 18 Scottish Journal of Geology, Vol. 14, 157–166. 19 Treagus, J E, Pattrick, R A D, and Curtis, S F. 1999. Movement and 20 mineralization in the Tyndrum fault zone, Scotland and its 21 regional significance. Journal of the Geological Society, London, 22 Vol. 156, 591–604. 23 Treagus, J E. and Roberts, J L. 1981. The Boyndie Syncline, a D1 24 structure in the Dalradian of Scotland. Geological Journal, Vol. 25 16, 125–135. 26 Treagus, J E, Talbot, C J, and Stringer, P. 1972. Downward-facing 27 structures in the Birnam Slates, Dunkeld, Perthshire. Geological 28 Journal, Vol. 8, 125–128. 29 Treagus, J E, and Treagus, S H. 1971. The structures of the 30 Ardsheal peninsula, their age and regional significance. 31 Geological Journal, Vol. 7, 335–346. 32 Treagus, J E, and Treagus, S H. 1981. Folds and the strain 33 ellipsoid; a general model. Journal of Structural Geology, Vol. 3, 34 Pt 1, 1–17. 35 Trewin, N. H. (editor) 2002. The Geology of Scotland. (4th edition) 36 The Geological Society, London. 576 pp. 37 Trewin, N.H., Kneller, B.C. and Gillen, C. (1987) Excursion Guide 38 to the Geology of the Aberdeen area. (Edinburgh: Scottish Academic 39 Press, for Geological Society of Aberdeen). 40 Trewin, N.H. and Rollin, K. 2002. In: Trewin, N.H. (ed.) The 41 geology of Scotland.(4th edition) The Geological Society, London, 42 1–25. 43 Trewin, N.H. and Thirlwall, M.F. 2002. Old Red Sandstone. In: 44 Trewin N. H. (ed.) The Geology of Scotland. (4th edition) The 45 Geological Society, London, pp. 213–249. 46 Tyrrell, G.W. 1921. Some points in petrographic nomenclature. 47 Geological Magazine Vol. 58, 494–502. 48 49 Underhill, J.R. 1993. Discussion on the location and history of the 50 Walls Boundary fault and Moine thrust north and south of Shetland. 51 Journal of the Geological Society, London, 150, 1003–1008. 52 Upton, P.S., 1983. A stratigraphic, structural and metamorphic 53 study of the lower and middle Dalradian, between Braemar and the 54 Spittal of Glenshee, N.E. Scotland. Unpublished PhD thesis, 55 University of Manchester. 56 Upton, P S. 1986. A structural cross-section of the Moine and 57 Dalradian rocks of the Braemar area. Report of the British 58 Geological Survey, Vol. 17, No. 1, 9–19. 59 60 61 62 63 64 65 1 2 3 4 Van Breemen, O., Aftalion, M. and Johnson, M. R. 1979. Age of the 5 Loch Borrolan complex, Assynt and late movements along the Moine 6 Thrust Zone. Journal of the Geological Society of London 16, 489– 7 495. 8 Van de Kamp, P.C. 1968. Origins of para-amphibolites. Unpublished 9 PhD thesis, University of Bristol. 10 Van de Kamp, P C. 1970. The Green Beds of the Scottish Dalradian 11 Series: geochemistry, origin and metamorphism of mafic 12 sediments. Journal of Geology, Vol. 78, 281–303. 13 Van Staal, C. R., Dewey, J. F., McKerrow, W. S. and MacNiocaill, C. 14 1998. The Cambrian–Silurian tectonic evolution of the northern 15 Appalachians and British Caledonides: history of a complex, 16 southwest Pacific-type segment of Iapetus. In: Lyell: the Present 17 is in the Past (edited by Blundell, D. J. and Scott, A. C.). 18 Geological Society, London, Special Publication, 143, 199–242. 19 Vance, D., Strachan, R. A. and Jones, K. A. 1998. Extensional 20 versus compressional settings for metamorphism: Garnet chronometry 21 and pressure–temperature–time histories in the Moine Supergroup, 22 northwest Scotland. Geology 26, 927–930. 23 Viete, D.R., Forster, M.A. and Lister, G.S. (2011) The nature and 24 origin of the Barrovian metamorphism, Scotland: 40Ar/39Ar apparent 25 age patterns and the duration of metamorphism in the biotite zone. 26 Journal of the Geological Society, London, 168, 133-146. 27 Viete, D.R., Hermann, J., Lister, G.S. and Stenhouse, I.R. (2011) 28 The nature and origin of the Barrovian metamorphism, Scotland: 29 diffusion length scales in garnet and inferred thermal time 30 scales. Journal of the Geological Society, London, 168, 115-132. 31 Viete, D.R., Richards, S.W., Lister, G.S., Oliver, G.J.H. and 32 Banks, G.J. (2010) Lithospheric-scale extension during Grampian 33 orogenesis in Scotland. in Law, R.D., Butler, R.W.H., Holdsworth, 34 R.E., Krabbendam, M. and Strachan, R.A. (editors) Continental 35 Tectonics and Mountain Building: the Legacy of Peach and Horne. 36 Geological Society, London, Special Publications, 335, 121-160. 37 Viljoen, M. J and Viljoen, R. P. 1969. Evidence for the existence 38 of a mobile extrusive peridotite magma from the Komati Formation 39 of the Onverwacht Group. Geological Society of South Africa, 40 Special Publication No. 2, 87–112. 41 Vogt, T. 1930. On the chronological order of deposition in the 42 Highlands. Geological Magazine, 67, 68–76. 43 Voll, G. 1960. New work on Petrofabrics. Liverpool and Manchester 44 Geological Journal, 2, 503–567. 45 Voll, G. 1964. Deckenbau und fazies im Schottischen Dalradian. 46 Geologische Rundschau, Vol. 53, 590–612. 47 Vorhies, S.H. and Ague, J.J. (2011) Pressure – temperature 48 evolution and thermal regimes in the Barrovian zones, Scotland. 49 Journal of the Geological Society, London, 168, 1147-1166. 50 51 Wain, A. (1999). The petrography and metamorphic evolution of 52 metabasic rocks from the Lower Dalradian of the Central Highlands 53 area. British Geological Survey Technical Report No. WA/99/13. 54 Watkins, K.P. 1982. The structure and metamorphism of the 55 Balquhidder–Crianlarich region of the Scottish Dalradian. 56 Unpublished PhD thesis, University of Cambridge. 57 Watkins, K P. 1983. Petrogenesis of Dalradian albite porphyroblast 58 schists. Journal of the Geological Society of London, Vol. 140, 59 601–618. 60 61 62 63 64 65 1 2 3 4 Watkins, K P. 1984. The structure of the Balquhidder–Crianlarich 5 region of the Scottish Dalradian and its relation to the Barrovian 6 garnet isograd surface. Scottish Journal of Geology, Vol. 20, 53– 7 64. 8 Watkins, K.P. 1985. Geothermometry and geobarometry of inverted 9 metamorphic zones in the W. Central Scottish Dalradian. Journal of 10 the Geological Society of London, 142, 157–165. 11 Watson, J. V. 1984. The ending of the Caledonian Orogeny in 12 Scotland. Journal of the Geological Society of London 141, 193– 13 214. 14 Weiss, L E, and McIntyre, D B. 1957. Structural geometry of 15 Dalradian rocks at Loch Leven, Scottish Highlands. Journal of 16 Geology, Vol. 65, 575–602. 17 Wells, P. R. A. and Richardson, S. W. 1979. Thermal evolution of 18 metamorphic rocks in the Central Highlands of Scotland. In Harris, 19 A. L., Holland, C. H. and Leake, B. E. (editors), The Caledonides 20 of the British Isles–reviewed. Geological Society of London 21 Special Publication No. 8, published by Scottish Academic Press, 22 Edinburgh, 339–344. 23 Whalen J. B., Currie J. L. and Chappell B. W. 1987. A-type 24 granites: geochemical characteristics, discrimination and 25 petrogenesis. Contributions to Mineralogy and Petrology, 95, 407– 26 419. 27 Whitten, E H T. 1959. A study of two directions of folding; the 28 structural geology of the Monadhliath and mid-Strathspey. Journal 29 of Geology, Vol. 67, 14–47. 30 Whittles, K.H. 1981. The geology and geochemistry of the area west 31 of Loch Killin, Inverness-shire. Unpublished PhD thesis, 32 University of Keele. 33 Wilkinson, S. B. 1907. The geology of Islay. Memoirs of the 34 Geological Survey of Scotland, Sheets 19 and 27, and parts of 20. 35 Willan, R. C. R., and Coleman, M L. 1983. Sulphur isotope study of 36 the Aberfeldy barite, zinc, lead deposit and minor sulfide 37 mineralization in the Dalradian metamorphic terrain, Scotland. 38 Economic Geology, Vol. 78, 1619–1656. 39 Williamson, D. H., 1953. Petrology of chloritoid and staurolite 40 rocks north of Stonehaven, Kincardineshire. Geological Magazine, 41 90, 353–361. 42 Williamson, W O. 1935. The composite gneiss and contaminated 43 granodiorite of Glen Shee, Perthshire. Quarterly Journal of the 44 Geological Society of London, Vol. 91, 382–422. 45 Wilson, J.R. and Leake, B.E. 1972. The petrochemistry of the 46 epidiorites of the Tayvallich Peninsula, North Knapdale, 47 Argyllshire. Scottish Journal of Geology 8, 215–252. 48 Winchester, J.A. 1974. The zonal pattern of regional metamorphism 49 in the Scottish Caledonides. Journal of the Geological Society of 50 London, 130, 509–24. 51 Winchester, J.A. and Glover, B.W. (1988). The Grampian Group, 52 Scotland. In: Later Proterozoic stratigraphy of the Northern 53 Atlantic region. (editor Winchester, J.A.). Blackie, Glasgow and 54 London, 146–161. 55 Winchester, J.A. and Glover, B.W. (1991). Grampian Group: Pitlochry– 56 Loch Laggan–Glen Spean. In: The Late Precambrian Geology of the 57 Scottish Highlands and Islands. (editors Hambrey, M.J., Fairchild, 58 I.J., Glover, B.W., Stewart, A.D., Treagus, J.E. and Winchester, 59 J.A.). Geologists‘ Association Guide No. 44, 66–85. 60 61 62 63 64 65 1 2 3 4 Wiseman, J D H. 1934. The central and south-west Highland 5 epidiorites: a study in progressive metamorphism. Quarterly 6 Journal of the Geological Society of London, Vol. 90, 354–417. 7 Wood, D.S. 1964. Some structures in the Dalradian pillow lavas of 8 the Tayvallich Peninsula, Argyll. Geological Magazine, 101, 481 9 Woodcock, N. and Strachan, R. 2000. Geological History of Britain 10 and Ireland. Blackwell Science, Oxford. 11 Wright, A.E. 1976. Alternating subduction direction and the 12 evolution of the Atlantic Caledonides Nature, London 264, 156. 13 Wright, A. E. 1988. 15. The Appin Group. In Later Proterozoic 14 Stratigraphy of the Northern Atlantic Regions (editor Winchester, 15 J. A.), pp. 177–199. Blackie. 16 17 Yardley B. W. D. (1989) An introduction to metamorphic petrology. 18 Longman, Harlow. 19 Yardley, B.W.D. and Valley, J.W. 1997. The petrologic case for a 20 dry lower crust. Journal of Geophysical Research, 106 B6, 12173– 21 12185. 22 23 Zeh, A. and Millar, I. L. 2001. Metamorphic evolution of garnet- 24 epidote-biotite gneiss from the Moine Supergroup, Scotland, and 25 geotectonic implications. Journal of Petrology 42, 529–554. 26 Zenk, M. and Schulz, B. 2004. Zoned Ca-amphiboles and related P-T 27 evolution in metabasites from the classical Barrovian metamorphic 28 zones in Scotland. Mineralogical Magazine, 68, 769-786. 29 30 31 Figure 1 Map of the Northern Grampian Highlands showing 32 distribution of subgroups (after Smith et al., 1999). Circled 33 letters on the map refer to stratigraphical columns in Figure 3. 34 GCR Sites: 1 An Suidhe, Kincraig 2 The Slochd, 3 Lochan Uaine, 35 4 Blargie Craig, 5 River E, 6 Garva Bridge, 7 Rubha na Magach, 36 8 Kinloch Laggan Road A86, 9 Allt Mhainisteir, 10 Aonach Beag 37 and Geal-charn, 11 Ben Alder. 38 Abbreviations: BS Boundary Slide, ESZ Eilrig Shear-zone, ELF 39 Ericht–Laidon Fault, FSSZ Flichity–Slochd Shear-zone, GB Glen 40 Banchor, GOSB Geal-charn–Ossian Steep Belt, IMF Inverpattack– 41 Markie Fault, KC Kincraig, LSZ Lochindorb Shear-zone, SF 42 Sronlairig Fault. 43 44 Figure 2 Rift basins and their bounding lineaments in the 45 Northern Grampian Highlands (after Smith et al., 1999). Based on a 46 simplified geological map after restoration and removal of major 47 faults and intrusions. Solid linework shows the outline of the 48 main subgroups (see Figure 1). 49 Abbreviations: MPH Meall Ptarmigan High, SOL Strath Ossian 50 Lineament. 51 52 Figure 3 Stratigraphical correlations in the Northern Grampian 53 Highlands (after Smith et al., 1999) for the areas shown by circled 54 letters in Figure 1. Thicknesses are relative but not to scale. 55 Blank areas in columns indicate stratigraphical breaks. 56 Abbreviations: AB Aonach Beag Semipelite Fm, ACH Achneim Striped 57 Psammite Fm, AD Ardair Semipelite Fm, AP Appin Group, undivided, 58 BAS Ben Alder succession, BSZ Blargie Shear-zone, CC Coire Cheap 59 Semipelite Fm, CM Creag Meagaidh Psammite Fm, CNL Coire nan Laogh 60 61 62 63 64 65 1 2 3 4 Semipelite Fm, CS Clachaig Semipelite Fm, DRS Drumochter 5 succession, DS Dava Subgroup, EF Eilde Flag Formation, EL Elrick 6 Formation, ESZ Eilrig Shear-zone, FSSZ Flichity–Slochd Shear- 7 zone, GB Glen Buck Psammite Fm, GBS Glen Banchor Subgroup, GS 8 Glenshirra Subgroup (undivided), IL Inverlair Psammite Fm, K 9 Kincraig Formation, KLQ Kinlochlaggan Quartzite Fm, LL Loch 10 Laggan Psammite Fm, LSZ Lochindorb Shear-zone, LTQ Loch Treig 11 Schist and Quartzite Fm, NB Nethybridge Fm, PT Pitmain Semipelite 12 Fm, PY Pityoulish Semipelite Fm, RS Ruthven Semipelite Fm, STS 13 Strathtummel succession, TB Tarff Banded Semipelite Fm, TP 14 Tormore Psammite Fm. 15 16 Figure 4 Opposed verging fold-pairs separated by a vertical 17 high-strain zone in psammites of the Glen Spean Subgroup in the 18 Geal-charn–Ossian Steep Belt. North-east of Loch a'Bhealaich 19 Leamhain, Ardverikie Forest (NN 5060 7960, 5 km north-east of the 20 Aonach Beag and Geal-charn GCR site). S. Robertson provides a 21 scale. (Photo: BGS No. P 508351, reproduced with the permission of 22 the Director, British Geological Survey, © NERC.) 23 24 Figure 5 Map of the area around the An Suidhe, Kincraig GCR site 25 (after BGS 1:10 000 Sheet NH80NW, 1998) 26 27 Figure 6 Generalized vertical section of strata at the An 28 Suidhe, Kincraig GCR site. 29 30 Figure 7 Interbanded metacarbonate rock and phyllitic calcareous 31 semipelite overlain by semipelite of the Kincraig Formation, Leault 32 Limestone Quarry (NH 8210 0638), An Suidhe, Kincraig GCR site. 33 Hammer shaft is 35 cm long. (Photo: BGS No. P220941, reproduced with 34 the permission of the Director, British Geological Survey, © NERC.) 35 36 Figure 8 Map of the area around The Slochd GCR site(after BGS 37 1:10 000 sheets NH82NW and NH82SW, 1998). 38 39 Figure 9 Migmatized gneissose psammite with leucosomes and 40 incipient melt segregations, Slochd Psammite Formation, south-east of 41 the road and rail summit at The Slochd at NH 8370 2516. Hammer head 42 is 16.5 cm long. (Photo: BGS No. D 5586, reproduced with the 43 permission of the Director, British Geological Survey, © NERC.) 44 45 Figure 10 46 (a) The A9 roadcut at The Slochd (NH 8366 2548). (Photo: BGS No. D 47 5582, reproduced with the permission of the Director, British 48 Geological Survey, © NERC.) 49 (b) Sketch of the geology seen in the A9 roadcut at The Slochd 50 (after Piasecki and Temperley, 1988b). 51

52 Figure 11 Map of the Lochan Uaine area, Strath Errick (after BGS 53 1:10 000 Sheet NH62SW). 54

55 Figure 12 Convolute lamination and cross-lamination in the 56 Gairbeinn Pebbly Psammite Formation, east flank of Beinn Mheadhoin 57 (NH 607 217), near the Lochan Uaine GCR site. Lens cap is 7 cm in 58 diameter. (Photo: BGS No. P 518573, reproduced with the permission 59 of the Director, British Geological Survey, NERC.) 60 © 61 62 63 64 65 1 2 3 4 5 Figure 13 6 (a) Map of the area around the Blargie Craig GCR site, 7 incorporating part of the Laggan Inlier after BGS 1:10 000 sheets 8 NN59NE NN59SE, NN69NW and NN69SW (1997). 9 (b) Generalized cross-section across the Laggan Inlier showing 10 general distribution of lithologies and structure, drawn 4 km 11 north-east of Blargie Craig, from BGS 1:50 000 Sheet 63E 12 (Dalwhinnie, 2002). 13 14 Figure 14 Glacially smoothed exposure in the Blargie Craig GCR 15 site, showing contact between the Aonach Beag Semipelite Formation 16 of the Appin Group (left) and the Creag Liath Psammite of the Glen 17 Banchor Subgroup (right). The hammer shaft (35 cm long) lies along 18 the inferred unconformity. Locality 250 m north-west of Coul Farm 19 at NN 5870 9425. (Photo: BGS No. P 611930, reproduced with the 20 permission of the Director, British Geological Survey, © NERC.) 21 22 Figure 15 Map of the River E section. 23 24 Figure 16 25 (a) Inversely graded, matrix-supported pebbly psammite overlain by 26 a psammite displaying a variety of cross-lamination and some 27 dewatering structures. Beds young upwards in the photo. River E 28 (NH 5463 1363). Open compass is 17.5 cm long. 29 (b) Pebbly lag at the base of trough cross-laminated psammite. 30 Beds young upwards in the photo. River E (NH 5458 1375). Tape 31 measure is 10 cm in diameter. 32 (c) Well-preserved sand volcano in heterolithic pink and grey 33 psammite showing ripple lamination. Beds young upwards in the 34 photo. River E (NH 5445 1410). Pencil is 14 cm long. 35 (Photos: C.J. Banks.) 36 37 Figure 17 Sedimentary log for the section in the River E at NH 38 5460 1367, illustrating facies stacking pattern in pebbly psammite- 39 dominated parts of the succession. Gms matrix-supported pebbly 40 psammite (debris flow), Gt trough cross-laminated pebbly psammite 41 (stream-flow reworking or longitudinal bars), Sp planar laminated 42 psammite (sandy bar form), St trough cross-laminated psammite 43 (sandy bar form), Cl slumped layer, E erosive base. 44 45 Figure 18 Map of the area around the Geal Charn–Ossian Steep Belt 46 after Robertson and Smith (1999), with GCR sites superimposed. B 47 Blargie Craig, Ch Coire Cheap, G Garva Bridge, Ki Kinloch Laggan, 48 Mh Allt Mhainisteir, RM Rubha na Magach. 49 50 Figure 19 Map of the Glenshirra Dome and the area of the Garva 51 Bridge GCR site. The overall geological setting is given in Figure 52 18. 53 54 Figure 20 55 (a) Heterolithic association, Garva Bridge Psammite Formation, 56 Allt Coire Iain Oig. Cleaning and muddying upwards cycles. The 57 clean sand component of each cycle is invariably ripple cross- 58 laminated. The more-muddy parts of each cycle contain thin planar 59 beds of psammite (originally clean sand) or small gutter casts 60 filled with heterolithic sand and mud. 61 62 63 64 65 1 2 3 4 (b) Numerous elongate quartz pebbles within micaceous psammite in 5 the Gairbeinn Pebbly Psammite Member of the Garva Bridge Psammite 6 Formation, Gairbeinn. The parting present in the psammite above 7 this pebbly bed is tectonic rather than original bedding. 8 (Photos: B.W. Glover.) 9 10 Figure 21 Schematic cross-section through the Glenshirra Subgroup 11 illustrating the proposed lateral facies changes and the possible 12 basin configuration. After Glover (1998). 13 14 Figure 22 Map showing the location of the Rubha na Magach 15 localities and the general geology of the area to the north-west of 16 Loch Laggan. The overall geological setting is given in Figure 18. 17 18 Figure 23 Measured sedimentary logs for: 19 (a) Rubha na Magach (NN 4618 8492). 20 (b) lochside exposures at NN 4653 8516. Note the crude thinning 21 and fining-upward cycles from thick-bedded psammite, micaceous 22 psammite and semipelite up into thinner bedded micaceous psammite 23 and semipelite, shown to illustrate the lithofacies present. Log 24 (a) is c. 50 m higher in the stratigraphy than log (b). 25 26 Figure 24 27 (a) Complex ripple-drift cross-lamination in a thick bed of 28 micaceous psammite at Rubha na Magach (NN 4618 8492). Open compass 29 is 17.5 cm long. (Photo: C.J. Banks.) 30 (b) Loading and convolute lamination on a thick micaceous psammite 31 grading into semipelite. Also shows a calcsilicate pod below the 32 notebook. Lochside exposure at NN 4653 8516. Notebook is 20 cm 33 long. (Photo: C.J. Banks.) 34 (c) Bouma units Ta to Te in a thick psammite to semipelite bed on 35 the Rubha na Magach promontory at NN 4618 8492. A basal massive 36 psammite (Ta) passes into a lower plane bed (Tb), a cross-laminated 37 horizon (Tc), an upper plane bed (Td) and is finally capped by 38 semipelite (Te). Pen is 15 cm long. (Photo: J.A. Winchester.) 39 40 Figure 25 Map of the area around the Kinloch Laggan Road A86 GCR 41 site. After Robertson and Smith (1999). The wider geological 42 setting is shown on Figure 18. KLS, Kinlochlaggan Syncline. 43 44 Figure 26 Typical lithofacies of the Kinlochlaggan Boulder Bed with 45 40 x 16 cm granite boulder in centre of view (NN 548 897). Hammer 46 head is 16.5 cm long. (Photo: BGS No. P 221180, reproduced with 47 the permission of the Director, British Geological Survey, © NERC.) 48 49 Figure 27 Lithostratigraphy of the area within and west of the 50 Geal-charnOssian Steep Belt in the vicinity of the Kinloch Laggan 51 Road, Allt Mhainisteir and Aonach Beag and Geal-charn GCR sites. 52 After Robertson and Smith (1999). 53 54 Figure 28 Map of the Allt Mhainisteir and Allt Liath nam Badan 55 sections, south of Loch Laggan. The overall geological setting is 56 shown in Figure 18. 57 58 Figure 29 Intense isoclinal folding in the Creag Meagaidh 59 Psammite Formation adjacent to the Allt Mhainisteir Slide, NN 5343 60 61 62 63 64 65 1 2 3 4 8535. Hammer head is 16.5 cm long. (Photo: BGS No. P 221176, 5 reproduced with the permission of the Director, British Geological 6 Survey, © NERC.) 7 8 Figure 30 Map of the area around the Allt Mhainisteir, Rubha na 9 Magach and Aonach Beag and Geal-charn GCR sites. After Robertson 10 and Smith (1999). The line of cross-section in Figure 31 is shown 11 as A–A’. AG Aonach Beag and Geal-charn GCR site, KLS Kinlochlaggan 12 Syncline, Mh Allt Mhainisteir GCR site, RM Rubha na Magach GCR 13 site. 14 15 Figure 31 Schematic cross-section across the Geal-charnOssian 16 Steep Belt along the line A–A' indicated on Figure 30. ABS Aonach 17 Beag Slide, CC Coire Cheap, CS Coire Sgoir, SGF Sron Garbh Fold- 18 complex, SS Sgoir slides. After Robertson and Smith (1999). 19 Ornaments as on Figure 30. 20 21 Figure 32 Annotated view south-south-west from below Diollaid 22 a'Chairn (NN 4920 7540) to Coire Sgòir, Loch an Sgòir and Sgòr 23 Iutharn in the Aonach Beag and Geal-charn GCR site, showing 24 structures on the south-east edge of the Geal-charn–Ossian Steep 25 Belt. The smaller folds are diagrammatic. Migmatization increases 26 north-westwards in the steep belt. gPs gneissose psammite, gSp 27 gneissose semipelite, Pe pelite, Ps psammite, Sp semipelite, 28 LEA Lancet Edge Antiform (plunges steeply into the hillside). 29 (Photo: BGS No. P 001217, reproduced with the permission of the 30 31 Director, British Geological Survey, © NERC.) 32 33 Figure 33 Looking south-west from the Allt a'Chaoil-reidhe by 34 Culra Bothy (NN 5230 7600) to Ben Alder, Sgor Iutharn and Geal- 35 charn. The prominent gap between Ben Alder and Sgor Iutharn is the 36 Bealach Dubh; the Ben Alder GCR site lies to the left of the 37 bealach and the Aonach Beag and Geal-charn GCR site is to the 38 right. (Photo: BGS No. P 001218, reproduced with the permission of 39 the Director, British Geological Survey, © NERC.) 40 41 Figure 34 Map of the area around the Aonach Beag and Geal-charn 42 and Ben Alder GCR sites (after Thomas, 1979). ABA Aonach Beag 43 Anticline (F1), ABS Alder Bay Synform (F2), ACA Aisre Cham 44 Anticline (F1), BAA Ben Alder Antiform (F2), BAAn Ben Alder 45 Anticline (F1), BAS Ben Alder Synform (F2), BDS Bealach Dubh 46 Synform (F3), CCA Coire Cheap Anticline (F1), CIA Coire na h’ 47 Iolaire Antiform (F3), CLS Coire Labhair Syncline (F1), CNLA Coire 48 na Lethchois Antiform (F3), CNLS Coire na Lethchois Synform (F3), 49 CSA Coire Sgoir Anticline (F1), GCF Garbh Coire Fault, GCS Geal 50 Charn Syncline (F1), KLS Kinlochlaggan Syncline (F1), LEA Lancet 51 Edge Antiform (F3), SMA Sgairneach Mhor Antiform (F2). 52 53 Figure 35 Secondary upright folding superimposed on earlier tight 54 to isoclinal folds in Grampian Group psammites. Structural 55 architecture is typical of that developed within the ‘Ben Alder 56 folds’ (sensu Thomas, 1979). South-east side of Bealach Dubh, NN 57 5014 7120. Hammer shaft is 35 cm long. (Photo: C.J. Banks, BGS 58 No. P605207.) 59 60 61 62 63 64 65 1 2 3 4 Figure 36 Schematic cross-section, approximately true-scale, 5 across the Aonach Beag and Geal-charn and Ben Alder GCR sites 6 (after Thomas, 1979). 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Figure 5.1

25 30

Rothes Fault 85 N Inverness

LSZ

t L l u a F

n e l G

t 2 a 3 e A r G I

5 Aviemore

SF H K B 1

ESZ KC G 80

4 GB C 6 F

8 BS D E 7 9

Old Red Sandstone

IMF Supergroup GOSB10 granitic plutons 11 (Caledonian) J Appin and Argyll groups Glen Spean lt au Subgroup F y a Corrieyairack Grampian T

h Subgroup Group c o ELF L Glenshirra BS Subgroup Badenoch Group (Dava and Glen Banchor subgroups) fault 0 kilometres 20 shear-zone 2 GCR site in Chapter 5 Figure 5.2

N

Inverness Rothes Lineament

? basin or

lt allochthonous u a block Cromdale F n le Basin G t a re G

F o y e r s –

Corrieyairack C Basin a i r n g o r m L i n e a m e n t MPH

SOL Strath Tummel Basin

h ig H r o h c n a B n e e l id G l S y r a d n u o 0 kilometres 20 B Figure 5.3

D L Loch Laggan J to Grantown Appin Group Geal-charn–Ossian Ben Alder to Knockando Steep Belt to Glen Spean Glen Garry AP Subgroup C CC AP SubgroupCorrieyairack Glen Roy E F psammite GroupGrampian KLQ Kinlochlaggan Glen TP LTQ Banchor CC ST semipelite AB (south) I K EF KLQ AP Aviemore ? Findhorn psammite AB H IL IL G B Kingussie semipelite Glen to NB NB Loch Killen Banchor Kincraig DRS CS CM CM Glenshirra

(north) Badenoch TB CM Group TB CM Subgroup A AD AD BAS AD PT PY Dava and Glen Strathnairn ?? ? Banchor subgroups base not seen Shear-zone LL LL LL LL LL LL

ACH

RS Sronlairig Fault CNL CNL CNL K EL Fault Ericht-Laidon

Grampian Group Appin Group ESZ

GS Fault Inverpattack–Markie Great Glen Fault Glen Great GB base not seen GS GS

GBS base not seen LSZ GBS DS FSSZ BSZ GBS DS GBS GBS GBS FSSZ DS Badenoch Group Badenoch Figure 25.581 282 8 N An Suidhe π 16 π 8 18 π 20 π 15 π

L Q π 42 66 22 20 28 Kincraig track 30 House 22 12 23 44 mylonitic π 15 10 Bedden 12 Cottage 806 15 urn lt B au 42 25 22 Le Q L Leault A9 Kincraig track 20 Q 54 20 16 20 32 B9152 L

Q 38 25 10

47 22 8 0metres 200 05 Loch Laggan Formation lime kiln Psammite psammite inclined bedding, Badenoch Group Group Grampian dip in degrees psammite and semipelite inclined foliation,

dip in degrees Formation L semipelite, calcsilicate rock Kincraig horizontal foliation with metacarbonate rock (L) Q and quartzite (Q) fault zone of ductile shear, some amphibolite with pegmatitic granite veins axial plane trace of psammite and semipelite major anticline Glen Banchor Subgroup axial plane trace of quartzite major syncline direction of younging striped semipelite indicated by graded bedding and psammite π late veins of granite and semipelite and calcsilicate rock pegmatitic granite Figure 5.6 younging

well-bedded psammite and micaceous psammite with partings of semipelite and rare calcsilicate pods. Arranged in fining upward turbiditic cycles Loch Laggan 6-10 cm thick Psammite Formation

Grampian Group

flaggy interlayered psammite, quartz psammite and semipelite, ‘rhythmites’, beds 1-3 cm thick

podiform metacarbonate rock in phyllitic calcsilicate rock and quartzite schistose and phyllitic calcsilicate rock Kincraig with quartzite, semipelite and rare Formation lenses of metacarbonate

banded garnet amphibolite

? unconformity? P interlayered gneissose psammite and quartz psammite with schistose and phyllonitic semipelite, sheared with foliated pegmatitic granite veins (P)

Blargie quartzite massively bedded migmatitic quartzite and siliceous psammite, flaggy towards top with biotite psammite Glen Banchor Subgroup

interlayered schistose semipelite, quartz psammite and quartzite with bands of calcsilicate rock and feldspar porphyroclasts

20 metres

0 A9 2Figure83 5.8 284 285 N railway 48

48 Carn nam roadcut, 50 Bain-tighearna Fig 5.10 F 23 80 85 F 16 60 825 P Torr Mor 48 P

A 30 l 78 lt 62 S l A o l c lt h R d u ig M he an -t sa h 64 bhail u i r

38 68 80 42 π

824 P 40 A9

inclined foliation, dip in degrees 60 72 vertical foliation

fault axial plane trace of major reclined fold (F2) toward closure axial plane trace of major Bracklettermore antiform (F3) 54 823 zone of shearing at contact π 68 site of dated sample

banded micaceous psammite stratigraphical affinity and semipelite (non-gneissose) unknown

Slochd Psammite Formation Dava Subgroup

Creag Bhuidhe Semipelite Formation, with quartzites

Beinn Bhreac Psammite Formation

metagabbro P microdiorite F felsite 0kilometres 1 π pegmatitic granite Figure 5.10b

non-gneissose striped unit (stratigraphical affinities uncertain)

NW A P A C C A drain P C P A C A C A A P P

non-gneissose striped unit (stratigraphical affinities uncertain) Slochd Psammite Formation

0 metres 15 SE

drain Q

P Q Q P P P P P

C P C

?Grampian Group flaggy psammite C calcsilicate rock A amphibolite and hornblende-biotite schist

P Dava Subgroup direction of younging late pegmatitic vein quartzofeldspathic and psammitic gneisses Q late migmatization late quartz vein semipelitic gneiss localities where basement-cover fault or shatter zone contacts have been described Figure 5.11 Ruthven GroupGrampian semipelite, migmatitic Semipelite Formation (Corrieyairack Subgroup) psammite, pebbly Gairbeinn Pebbly Psammite Formation banded quartzite and semipelite (Glenshirra Subgroup) F felsite intrusion, Caledonian F

axial plane trace of major anticline F

axial plane trace of major syncline 67 57 inclined bedding, dip in degrees inclined bedding known to be overturned, dip in degrees Garbhal Mór 73 84 inclined foliation, dip in degrees 72 vertical foliation F direction of younging f, cross bedding zone of high strain

magnetic boundary 82 fault 823

45 66 80

Lochan 84 Uaine

55

F

67

822 80 43

70

h

d

i

82 t l i f 43 a 75

C

t l l

f A 71 Beinn Mheadhoin

F N 45 F 0 metres 500 26 F 62 44 261 262 Figure 5.13a

7 260 97 80 80 82 e id 85 Sl g ea B 2 ch 59 na Ao 82

80 or uinn M Tars Allt 7 70 96 0 metres 500 Mashie Fault

N 78 86 80 80 g Bea inn Allt Tar su 85 76 68 78 Blargie CraigCraig Gargask Craig 2 80 795 7 40 95

8080 G 80 64 G 81 e lid S 80 ag Be h 78 86 ac BlargieBlairgie on A 1 60 85 86 86

7 70 84 94 Coull Farm

61 Spey Dam Dalchully River Spey House Figure 5.13b

NW SE

Section 1 AONACH [5946 0069] [6471 9421] BEAG Marg na Stac metres SLIDE Craige Buidhe metres 2000 2000

1500 1500

1000 1000

500 500

OD granite OD

-500 -500 Markie Fault -1200 -1200 Figure 5.13 key

semipelite, calcsilicate rock and micaceous psammite Coire Cheap Formation (Ballachulish and/or metalimestone Blair Atholl subgroups Appin Group massive quartzite, white with pebbly layers Aonach Beag Semipelite Formation (Lochaber Subgroup) schistose semipelite and Dalradian Supergroup micaceous psammite Creag Meagaidh psammite and micaceous psammite Psammite Formation Grampian Group banded semipelite and Ardair Semipelite Formation micaceous psammite (Corrieyairack Subgroup) psammite and micaceous psammite with calcsilicate rock lenses Loch Laggan Psammite Formation unconformity gneissose feldspathic psammite and semipelite Creag Liath Blargie Quartzite Member, Psammite Formation quartzite migmatitic Glen Banchor Subgroup Badenoch Group banded semipelite and psammite, An Stac Semipelite Formation migmatitic semipelite in part psammite, variably gneissose Creag an Loin Psammite Formation

semipelite and psammite, Markie Gneisses (stratigraphical position uncertain) interbanded, gneissose locally

amphibolite sheets and lenses inclined foliation, dip in degrees G granite vein vertical foliation

fault, with sense of movement where shown direction of younging indicated by graded bedding

slide 1 unsheared contact high-strain zones and shearing characteristic of the Grampian Shear-zone 2 dated sheared pegmatitic vein

axial plane trace of major anticline

axial plane trace of major syncline Figure 5.15

N Dumnaglass Lodge

estate track Loch Ness Foyers Loch Mhor

s r e 40 40 y o F

20 r e

v i

R 32

80 Whitebridge River E GCR Site cross-bedded pebbly R . psammite with abundant F River E e c 75 scattered clasts h l in 0 kilometres 5 75 N 55 cross-bedded units of Key to inset map 80 pebbly psammite Corrieyairack Subgroup 20-30 cm thick. Common dewatering structures R Glenshirra Subgroup iv e r

14 E granitic pluton 80 80 72

thick slumped units 80 45 inversely graded pebbly psammite sheets overlain by trough cross- laminated psammite.

Key to map symbols 68 excellent exposures of pebbly psammite with direction of younging well-preserved trough cross-lamination inclined bedding, dip in degrees 55 42 inclined bedding known to be overturned, dip in degrees

axial plane trace of major antiform 42 56

inferred fault finely laminated 58 pebbly 0 metres 500 psammite metres Figure 5.17 1 3 4 5 7 8 9 2 6

pelite semipelite micaceous psammite psammite Sp St granule psammite C1 Gms Gms pebbly psammite Gms Gms E C1 Gms Gt Gt Gms Gms Gt Gms E E E E E E E Figure 5.18 250 260

ie 7 k 00 r a

M n le G

G B

River Spey t l

u

a

F

h

t

a

i

L Ki g 7

a 90

e

r

C

n ga ag L ch lt o u Mh L a RM F ie Dalwhinnie k t r l Ericht-Laidon Fault a u M a F

k t c a h t c t i a r p E A9 r e h v c 7 n 80 I o L N

0 kilometres 5 Aonach Beag Ch

granitic intrusions

Appin Group, undivided Leven Schist Formation and Appin Group Sron Garbh Formation Glen Spean Subgroup Inverlair Psammite Formation

Clachaig Semipelite and Psammite Formation Corrieyairack Subgroup The Fara Formation

Creag Meagaidh Psammite Formation Grampian Group Ardair Semipelite Formation

Loch Laggan Psammite Formation

Coire nan Laogh Semipelite Formation

Glenshirra Subgroup undivided

Glen Banchor Subgroup Badenoch Group

psammite and semipelite (stratigraphical position uncertain) fault Figure 5.19

799 Gairbeinn Allt Crom Complex

2 ?

2 Creag Mhor a h n A m ll a t h G i A G l b l ’ e l a t

t C Corrieyairack ll o i A r e

I Pluton a i n O i ? g 3 Garva Bridge 795 3 River Spey

N

792 0 kilometres 2

246 250 254

2 axial plane trace of major F2 antiform Loch Laggan Psammite Formation Corrieyairack Coire nan Laogh Semipelite Formation Subgroup 2 axial plane trace of major F2 synform Gairbeinn Pebbly Psammite Member Psammite Formation

Garva BridgeGarva 3 axial plane trace of major F3 antiform

semipelite and micaceous psammite Glenshirra direction of F2 fold vergeance psammite Subgroup direction of younging

fault granitic intrusions Figure 5.21

NW SE 15km

200m

? Coire nan Laogh Semipelite Formation Psammite Formation

Gairbeinn Pebbly Psammite Member BridgeGarva (fluvial dominated) fluvial sands (psammite association) shallow marine storm-dominated sands and muds (heterolithic association) quartz pebbles Figure 5.22

N 246 424 Am Meall 247 f o excellent exposure 7 22 e 86 c of pegmatitic veins ra m t r 40 e fo and felsic dykes at ti 400 n in road-cut 7 im 92 x A n ro a 36 p g Coire Dubh p g 350 a a L 916

50 n 7 300 A86 a 91 g g a 52 L h 785 32 c 700 o 60 L 790 Rubha na Magach 45 excellent sedimentary structures on loch shore 0 kilometres 1 Meall Damh Tullochroam 464 789

CREAG MEAGAIDH NATIONAL e or NATURE RESERVE nm ewto to N 788 Ardverikie Puist Coire Ardair 1070 787

n A86 a Markie2 Fault nn g 51 ui Am Meall rs g ha 424 T a g 2 ea L 50 r 993 C h Rubha na Magach c 2 785 o 49 L Inset 248 Creag Meagaidh 784 247 Psammite Formation Corrieyairack Subgroup Ardair Semipelite Moy Lodge Formation 246 ge Loch Laggan ean Brid 7 Sp Psammite Formation 83 to N 245 Coire nan Laogh Semipelite Formation 244 inclined bedding, dip in degrees 782 243 fault 0 kilometres 2 localities mentioned in text 242 quartzite psammite micaceous Psammite semipelite pelite calcsilicate pods rip-up clasts

b) metres 0 5

quartzite psammite convolute lamination planar lamination micaceous Psammite cross lamination semipelite

pelite

a) Figure 5.23 Figure Figure 5.25

granitic intrusions A s l l

t

C KLS o

i Appin Group undivided r e

n I a r z - boulder bed i u n B O e i i g k Glen Spean Subgroup r a

M Inverlair Psammite 95 Formation Garva s Blargie Craig GroupGrampian Bridge Corrieyairack Subgroup er Spey Creag Meagaidh Riv Psammite Formation KLS s Ardair Semipelite Formation Loch Laggan Psammite Formation A86 Coire nan Laogh Semipelite Formation

s Glenshirra Subgroup

t l u undivided a F Badenoch Group

e i k s r a M Glen Banchor Subgroup KLS z 90

fault Kinloch s t l u Laggan a F s an g k N slide ag c k L a c t a h t t c a t o a L s p P axial plane trace of

r

e r v e major syncline v n i I R

kilometres KLS 0 3

s s 55 60 Figure252 5.28 253 254 255 N 787

e 58 d li S ir te is 7 in 86 ha M llt A

88

t l u a

F

k c a t 62 t a

p r e

v n 7 I 85

k c

a

t t t

72 t a an a d P a B r e v m i a R n th ia L lt e l d A li S g ir a te e is 76 B in h a c h a n M o lt A l A 252 253 254 255 784 Coire Cheap Formation, Ballachulish/Blair Atholl subgroups including metalimestone Group Grampian Group Appin Sron Garbh Semipelite 0 kilometres 1 Formation Kinlochlaggan Quartzite Lochaber Subgroup Formation inclined foliation, Aonach Beag dip in degrees Semipelite Formation direction of younging Inverlair Psammite Glen Spean Subgroup Formation as seen from graded bedding Creag Meagaidh Psammite Formation tectonic slide Ardair Semipelite Corrieyairack Subgroup Formation Loch Laggan Psammite Formation psammite and semipelite Glen Banchor Subgroup psammite

psammite and semipelite (stratigraphical position uncertain) Figure 5.30

KLS

Markie Fault n A86 a g g RM a 7 L 85 h a c b Mh o r L a E

a n

n a h c o L

k c a t t a

P

r e v i KLS R

e A d i l S 7 80 g a e B h c a n o A Loch Pattack t l

u a

F

k c a t t a p r e e d v li n I S N ir ò g AG S Coire na 7 75 Coichille t 1 h A ic Aonach Beag Geal-chàrn r E 0kilometres 2 h c o L 245 250 255

granitic intrusions Appin Group Grampian Group Grampian Group Appin fault Appin Group, undivided slide Leven Schist Formation and axial plane trace of Sron Garbh Semipelite Formation major syncline Glen Spean Subgroup Inverlair Psammite Formation Clachaig Semipelite and Psammite Formation Corrieyairack Subgroup The Fara Psammite Formation Creag Meagaidh Psammite Formation Ardair Semipelite Formation Loch Laggan Psammite Formation Glen Banchor Subgroup Badenoch Group

psammite and semipelite (stratigraphical position uncertain) Figure 5.27 Ballachulish/ Blair AthollBlair Subgroup Appin Group Appin

Coire Cheap Formation Subgroup Sron Garbh Semipelite Fm Lochaber Kinlochlaggan Boulder Bed Kinlochlaggan Quartzite Fm Aonach Beag Semipelite Fm Glen Spean Glen Subgroup Inverlair Psammite Formation

Clachaig Semipelite and Psammite Formation Creag Meagaidh Psammite Formation Ardair Semipelite Formation Grampian Group Grampian Corrieyairack Subgroup

Loch Laggan Psammite Formation

Coire nan Laogh Semipelite Formation Glen Shirra Shirra Glen Subgroup Garva Bridge Psammite Formation Badenoch Group

Glen Banchor Subgroup Figure 5.31

NW SE A Kinlochlaggan Syncline A 1 Beinn a’ Chlachair SGF Markie Inverpattack ABS CS SS Fault Fault

??? 2

kilometres 0 0 2 Figure 5.34

1 2 2 2 1 2 46 e 47 48 49 ach Beag Sli d 1 on Axial plane traces of major folds A Loch Coire 1 1 1 1 es Cheap 1st generation anticlines and synclines d li 1 s 2 2 p 2nd generation antiforms and synforms ea 1 h 7 ABA KLS C Loch an 3 3 75 1 1 3rd generation antiforms and synforms 1 Sgòir 1 3 slide ( on hanging wall) Aonach GCS 3 Beag 1 3 fault 1114m 1 ACA 1 CSA LEA 1 3

7 1 1 CLS 74 1 0 kilometre 1 BDS1 2

3 1 CCA 1 3 LA 2 1 3 2 CN CNLS

1 7 3 2 73 Sgoir Slide 2

3 BAA 1 3 2 2

1 BAS

3 2 7 Ben Alder Loch a’ 72 1148m CLS 1 Bealach Bheithe

2 GCF 1

BAA 1 1 1 1 771

1 1 CLS? 3 Geal-charn – Ossian 3 Steep Belt Succession CLS? 3 Blair Atholl and CIA 1 Ballachulish subgroups 2 1 CLS? SMA 7 Kinlochlaggan Quartzite 70 Lochaber 2 1 Subgroup 1 undivided 1 2 t h 1 c Grampian Group i 2 r ABS E 2 769 Ben Alder Succession of Thomas (1979) h 1 c schistose pelite Loch Ericht Faulto N L

schistose semipelite and psammite Grampian Group ABS

2 schistose psammite 250 251 252 Figure 5.36

NW Aonach Beag Lancet Edge Ben Alder SE 1114m 1014m 1148m 0 kilometres 2 Coire Sgóir Coire Labhair Coire Cheap Bealach Dubh Garbh Coire Loch Ericht

Loch Garbh Coire Ericht Fault Fault Aonach Beag slides Cheap slides Sgóir Slide

Geal-charn – Ossian Steep Belt refolded nappes of Ben Alder

anticlines Aonach Coire Aisre Coire Ben Beag Cheap Cham Sgóir Alder F1 synclines Geal Coire Kinlochlaggan Charn Labhair Ben Alder Antiform Sgairneach Alder F2 Mhor Bay Ben Alder Synform Antiform Synform Lancet Bealach Coire na Coire na h’Iolaire F3 Edge Dubh Lethchois Antiform Antiform Synform open folds

Grampian GroupGrampian fault psammite Blair Atholl and Ballachulish subgroups slide psammite and semipelite Kinlochlaggan Quartzite Lochaber undivided Subgroup F2 axial plane trace pelite F3 axial plane trace Figure 5.4 colour Click here to download high resolution image Figure 5.7 colour Click here to download high resolution image Figure 5.9 colour Click here to download high resolution image Figure 5.10a colour Click here to download high resolution image Figure 5.12 colour Click here to download high resolution image Figure 5.14 colour Click here to download high resolution image Figure 5.16a colour Click here to download high resolution image Figure 5.16b colour Click here to download high resolution image Figure 5.16c colour Click here to download high resolution image Figure 5.20a colour Click here to download high resolution image Figure 5.20b Click here to download high resolution image Figure 5.24a colour Click here to download high resolution image Figure 5.24b colour Click here to download high resolution image Figure 5.24c colour Click here to download high resolution image Figure 5.26 colour Click here to download high resolution image Figure 5.29 colour Click here to download high resolution image Figure 5.32 colour Click here to download high resolution image Figure 5.33 colour Click here to download high resolution image Figure 5.35 colour Click here to download high resolution image Figure 5.4 B&W Click here to download high resolution image Figure 5.7 B&W Click here to download high resolution image Figure 5.9 B&W Click here to download high resolution image Figure 5.10a B&W Click here to download high resolution image Figure 5.12 B&W Click here to download high resolution image Figure 5.14 B&W Click here to download high resolution image Figure 5.16a B&W Click here to download high resolution image Figure 5.16b B&W Click here to download high resolution image Figure 5.16c B&W Click here to download high resolution image Figure 5.20a B&W Click here to download high resolution image Figure 5.24a B&W Click here to download high resolution image Figure 5.24b B&W Click here to download high resolution image Figure 5.26 B&W Click here to download high resolution image Figure 5.29 B&W Click here to download high resolution image Figure 5.33 B&W Click here to download high resolution image Figure 5.35 B&W Click here to download high resolution image Figure 5.24c B&W Click here to download high resolution image Figure 5.32 B&W Click here to download high resolution image