The terrane concept and the Scandinavian Caledonides: a synthesis

DAVID ROBERTS

Roberts , D. 1988: The terrane concept and the Scandinavian Caledonides: a synthesis. Nor. geol . unders . Bull. 413. 93-99.

A revised terrane map is presented for the Scandinavian Caledcnldes. and an outline is given of the principal suspect and exot ic terranes and terrane-complexe s identified outboa rd from the Baltoscand ian miogeocline. The outermost part of the Baltoscandian continental margin is itself suspect , in the terrane sense. since the true palaeogeographical location s of rocks now represented in the Seve and serey-seuano Nappes, while inferred, are not known. The orogen -internal exotic terranes embrace the oceanic/eugeoclinal elements of the Caledonides, represented by the mag­ matosed imentary assemblages of the Koli Nappes, including ophiolite fragments and island arc products. Even more exot ic terranes occur in the highest parts of the tectonostratigraphy, inclu­ ding units which are thought possibly to derive from the Laurentian side of lapetus .

D. Roberts. Norges geologiske uruierseketse, Postboks 3006. Lade, N-7002 Trondbeim , Norway .

Introduction Project 233 has been to prepare a preliminary Earlier in this decade much of the research terrane map' at 1:5 M scale (Roberts et al. effort in the Caledonides of Scandinavia was 1986) for a larger, circum-Atlantic compilation. channelled through the highly successfu l IGCP This map, much simplified, is really one of Project 27 The Caledonide Orogen ' (Gee & palaeo-environments (marginal basins, vol­ Sturt 1985). An important aspect of the collabo­ canic arc comp lexes, overstep sequences , rative work in this project was that of map etc.), and not of terranes in the true sense. comp ilation, in particular the consensus rea­ Another terrane map, in somewhat simplified ched at establishing an overall tectonostrati­ form appeared in Stephens (1988), while simi­ graphy for the orogen (Gee et al. 1985, Rob­ lar broad-scale subdivisions of the orogen are erts & Gee 1985). Since then, many Caledon­ found in Hossack & Cooper (1985) and Barker ian workers have maintained the international & Gayer (1985). connection through the current IGCP Project The aim of this short contribution is to pre­ 233 "Terranes in the Circum-Atlantic Paleozoic sent a revised terrane map of the Scandina­ Orogens'; and the tectonostra tigraphic sub­ vian Caledonides (Plate 1) and to outline brief­ division of the Caledonides in Norway and ly the principal terranes and terrane-comp lexes Sweden into 4 major allochthons, each compri­ (Fig. 1) which can be identified. It is not sing an assemblage of nappe-complexes and the purpose, at this stage, to present detailed thrust-sheets, has indeed paved the way for descr iptions of each terrane ; these must await an assessment of the orogen in terms of geolo­ further Norweg ian-Swedish collaboration gical terranes . within Project 233. The map compilation and Since terranes are, by definition (see be­ terrane synthesis forms the basis of a presen­ low), character ised by an internal homogene ity tation given at an IGCP Project 233 sympos ium of geology and as their boundaries are of a in Nouakchott, Mauritania (Roberts 1987). tecton ic nature, any terrane map of the Scandi­ navian Caledonides will necessarily reflect the basic patterns of tectonostratigraphy. An ini­ The terrane concept: principles tial attempt at terrane division and map comp i­ and definitions lation, at 1:2'/, M scale, prepared towa rds the Recognition of the existence of geological 'ter­ end of IGCP Project 27 (D.R., manus. map ranes' in orogenic belts hinges on the initial 1983), identified some 15 terranes outboard identification of the relevant passive continen­ of the Baltoscandian miogeocline. As yet, the tal margins or miogeoclines. As the affinity only intra-Nordic collaboration within IGCP of these miogeocl inal sequences is known , 94 David Roberts GU- BULL. 413. 1988

TERRA NE M AP ( TERRA NE COMPLEXES )

' .. ' . ..

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OROGE - I TER AL TERRA ES - oceanic/ eug eoc li nal affil ia ion

OROGE - EXTER AL ELEME TS Outermost suspect terranes SERGE Baltoscandia n m iog eoc l inal sediments Platf or m s edim ents

BALTOSCA NDIAN CRYSTALLINE BASEME NT Allochthonousl parautochthonous Mainly autochthonous DR- 87

Fig. 1. Simplified map showing the principal terrane-complexes in the Scandinavian Caledonides. Within eash of the hree main terrane-complex zones there are several, separate, distinctive terr anes. More detailed subdivision is shown in Plate 1. NGU· BULL. 413. 1988 The terra ne conceptand the Scandinavian Caledonides 95

Le. they can be linked directly to, and derive nental margin. These constitute composite from, the nearby craton, then their palaeotec­ terranes and may carry a common sedimenta­ tonic setting is not really questioned. Out­ ry overstep sequence (Keppie 1985). Several board of these continental rise prisms, doma­ separate or composite terranes may form ins which constitute parts of what has general­ what has been termed a terrane-complex (Rob­ ly been termed the eugeocline may be viewed erts 1987). with varying degrees of suspicion or uncertain­ Constraints on the time of accretion of conti­ ty as to their original palaeogeographical set­ guous terranes may be recognised in a varie­ ting with respect to the cratonic margin. They ty of factors (Fig. 2): thus constitute suspect terranes. Orogen­ (a) Strata overstepping two or more adjacent parallel and transverse strike-slip displace­ terranes may carry fossils and thus pro­ ments of many hundreds of kilometres may vide a fairly reliable upper limit on terrane have been involved, prior to or coeval with accretion (Fig. 2a). post-metamorphic thrusting; and post-accre­ (b) The age of thrusting of one terrane upon tionary strike-slip and extensional fault move­ another (Fig. 2b) may be determined isoto­ ments have added to the complexity. pically or, less precisely, by the age of This, then, was the essence of the terrane the youngest fauna in either terrane. concept which evolved as an explanation for (c) Plutons or dyke swarms which straddle the complex Mesozoic and early Cenozoic or 'stitch' two or more terranes (Fig. 2c) accretionary history of the North American may be dated isotopically, thus providing Cordillera (Monger et al. 1972, Coney et al. an upper limit for terrane accretion. 1980). There, rock sequences in large-scale (d) Regional metamorphism which affects two domains, blocks or slices which are now juxta­ or more terranes or terrane-complexes posed may differ dramatically in terms of fau­ (Fig. 2d) may also be dated radiometrical­ nal age and provenance, palaeomagnetic re­ ly. This, coupled with other timing eviden­ cord or tectonothermal history, and bear evi­ ce within the terranes themselves, would dence of different ages of docking or accre­ help in dating accretion. tion. Application of the concept, involving sus­ pect and exotic terranes, spread to the Appala­ chian orogen (Keppie 1981, 1985, Williams & Hatcher 1982, Williams 1984), and helped lay the foundations for IGCP Project 233. The Baltoscandian margin and Terranes, as such, are defined primarily on their stratigraphy but also on a variety of featu­ terranes in the Scandinavian Cale­ res which render them distinctive from their donides neighbours. A modern definition is as follows Since terrane boundaries are generally faults (Keppie, in press): «aterrane is an area charac­ of one form or other, Caledonide tectonostra­ terised by an internal continuity of geology (inc­ tigraphy thus provides a ready scenario for luding stratigraphy, fauna, structure, meta­ attempts at terrane discrimination. In the map morphism, igneous petrology, metallogeny, compilation (Plate 1), a threefold grouping of geophysical properties and paleomagnetic re­ terranes has been made (see also Fig. 1). (1) cord) that is bounded by faults, melanges re­ Orogen-external suspect terranes. (2) Orogen­ presenting a trench complex, or cryptic suture internal exotic terranes. (3) Exotic terranes of zones across which neighbouring terranes (1) uncertain origin. may have a distinct geological record not ex­ Units of Baltoscandian miogeocline affilia­ plicable by facies changes (Le. exotic terra­ tion, in part with slices of Precambrian crystal­ nes), or (2) may have a similar geological re­ line basement, do not rank as terranes in the cord (i.e. proximal terranes) that may only be strict sense, and have been grouped together distinguished by the presence of the terrane as 'orogen-external elements'. Many of these boundary representing telescoped oceanic Baltoscandian elements, as well as the terra­ Iithosphere.» nes proper, carry geographical names (Plate Analysis of the accretionary histories of ter­ 1), some of which derive from their original ranes may show that two or more may have designation for nappes or nappe-complexes. amalgamated at some time before final accre­ These names, as used here, are strictly in­ tion on to the miogeoclinal prism of the conti- formal. 96 David Roberts NGU-8ULL.413,1988

Fig. 2. Diagrammatic sketches showing features or criteria which help to provide upper limits on the time of accretion of juxtaposed terranes. (a) An 'overstep' sequence with basal unconformity blankets two disparate terranes which are separated by a major fault. The type of ornament or fold pattern used in this and subsequent sketches is me­ ant simply to portray the different geological histories in the contiguous terranes. (b) One terrane is thrust upon another. Such a situation could also possibly be taken to represent an original. vertical. strike-slip fault which has subsequently been reactivated and transposed into a flat lying thrust. (c) Two terranes have been juxtaposed along a fault surface, and then transected by a major pluton (or plutonic complex or dyke swarm). (d) Three terranes are shown with two different ages of amalgamation (one fault a is cut by the other). The entire complex ;s then affected by a regional metamorphic overprint. indicated by the dash-line ornament.

Orogen-external elements Elements in this orogen-external belt are those of Baltoscandian affinity, mostly packages of low- to medium-grade sedimentary rocks of platformal or miogeoclinal affiliation with incor­ porated tectonic slices or 'windows' of Protero­ zoic crystalline rocks derived and imbricated from the outer margin of the continent Balti­ ea. These units are essentially those compo­ sing the Parautochthon, Lower Allochthon and most of the Middle Allochthon of Caledonide tectonostratigraphic terminology, including the thick arkoslc sandstone nappes' of the rnlo­ geocline. Parts of this orogen-external belt carry isotopic evidence of early Caledonian (Finnmarkian) polyphase metamorphism, de­ formation and thrust dissection (e.g. sarv, Kaiak units); although most of the internal deformation, thrust imbrication and back-fol­ ding is of Mid Silurian to Early Devonlan (Scan­ dian) age. Structures ascribed to vertical shor­ tening - back-folds, associated flat-lying regio­ c nal cleavages and extensional faults - are even more common in the higher lying exotic terranes. Orogen-external suspect terranes Only the westernmost outboard parts of the Baltoscandian miogeocline, including the conti­ nent-ocean transition sequences (Andreasson & Gee 1986) - here termed the Seve terrane complex - can be viewed with any measure of suspicion as regard their true palaeogeo­ graphic derivation. Hence they qualify as sus­ pect terranes. Rocks of the Seve Nappes are considered to derive from somewhere along the «outer rifted margin of continent Baltica» (Stephens 1988)and locally show high-P meta­ morphic parageneses, including eclogitic facies rocks (Sm-Nd, 505 Ma - Merk et al. 1988) retrogressed and uplifted at around 490 Ma NGU-BULL.413.1988 The terrane concept and the Scandinavian Caledonides 97

(Dallmeyer & Gee 1986), Le. during the Early of importance in deciphering likely source areas Ordovician. of sedimentation for some of these truly exo­ Rocks of the serey-seuanc terrane, inclu­ tic terranes (Bruton 1986, Bruton & Harper ding the synorogenic Seiland Igneous Provin­ 1988). ce, have acquired a gradually more suspect The Sm01a terrane is of interest, not just for character in recent years, even though one its North American fauna but also because it can follow a common lithostratigraphy into the carries evidence for a Mid Ordovician tectono­ subjacent Kaiak unit. The plutonic rocks may thermal event, broadly equivalent to the Tacon­ possibly derive from a tectonically active rifting lan of the Appalachians (Hall & Roberts 1988); milieu (Andreasson 1987, Krill & Zwaan 1987) and in this terrane the Scandian overprint is or a local transtensional situation within a trans­ hardly detectable. The Sm01a terrane also pressive regime (Roberts, in press) along the contains a considerable volume of Ordovlcian, deforming outermost margin of Baltica, with cafe-alkaline magmatic rocks, which distin­ involvement of a microcontinental plate (Gayer guishes it from adjacent terranes. et al. 1987). This was part of the early Caledo­ As mentioned earlier, the terrane-linking nian (Finnmarkian sensu lato) accretionary overstep sequences are an important element wedge (Dallmeyer & Gee 1986), such that the in terrane-accretion analysis. Two principal most outboard (western most) terranes may overstep assemblages are known in Scandina­ show evidence of the oldest (?Cambrian) tecto­ via, one of which is represented by the Ordovl­ nothermal events. These terranes were subse­ cian sediments and volcanites noted above. quently aeereted to the margin of Baltiea du­ Where faunas are present they are mainly of ring the Scandian thrusting event. North American affinity in the Early Ordovician and mainly Baltoscandian in Late Ordovician time. Overstep thus occurred in diverse loca­ tions within lapetus, with final terrane accreti­ Orogen-internal exotic terranes on on to the Baltoscandian margin dating to Units within this category are far-travelled the Scandian orogeny. The second major over­ nappes and thrust-sheets of the Upper AIIoch­ step sequence is represented by the Late Silu­ tnon, exotic terranes derived from the oceanic/ rlan to Mid Devonian Old Red Sandstone (ORS) eugeoclinal realm of lapetus (cf. Barker & molasse deposits of western and central Nor­ Gayer 1985, Hossack & Cooper 1985, Step­ way. These sediments blanket a variety of hens & Gee 1985, Stephens 1988). Rock as­ Scandian-assembled terranes (Sturt & Roberts semblages in these exotic terranes include a 1987) ranging from exotic ophiolite assem­ wide variety of magmatosedimentary complex­ blages to Baltoscandian rocks of the Western es. including fragmented ophlolltes, primitive Gneiss Region. The ORS rocks are folded, and mature island arc/forearc associations, metamorphosed at low grade. and locally affec­ rifted arc sequences and marginal basin sue­ ted by Late Devonian thrusting. cessions. In terms of Caledonide tectonostra­ tigraphy these 'oceanic' units are representa­ tive of the Koli Nappes. Nine separate terra­ Exotic terranes of uncertain origin nes are distinguished in Plate 1; some of the- The highest and most outboard tectonic units. se are composite terranes. I in the Uppermost Allochthon, are representa­ Ophiolites have been separated into two age tive of terranes of uncertain origin. The Bar­ groups based on field and structural criteria ents-Varanger terrane is included in this cate­ (Fumes et al. 1985): (a) An early category, gory, even though it is really less exotic or which participated in Early to Middle Ordovi­ suspect than the other units. cian obduction and orogenesis. These were Except for the Barents-Varanger terrane, uplifted, partially eroded. and overlain by Late these particular terranes or terrane-complexes Arenig or younger sediments or volcanites are heterogeneous units of supracrustal, gneis­ (Brekke et al. 1984, Sturt 1984). (b) A later sic crystalline and younger Caledonian grani­ grouping of Mid to Late Ordovician marginal toid rocks which have been considered to basin ophiolites (Roberts et al. 1984). Isotopic derive. in part, from the Laurentian side of dating studies are confirming this temporal lapetus (Roberts et al. 1985. Stephens & Gee subdivision (Dunning & Pedersen 1988). Fau­ 1985). Fragments of microcontinents may also nal affiliation and suggested provinciality are have been involved. Some terranes, e.g. Helge- 98 DavidRoberts NGU - BULL. 413,1988 land and Beiarn, are especially heterogeneous down more precisely the ages of terrane and contain slices of assumed Early Ordovi­ amalgamation and subsequent accretion; and clan ophiolite complexes with their overstep­ more fieldwork and laboratory time should be ping Ordo-Silurian sedimentary sequences, reserved for the search for fossils, including tightly imbricated with Precambrian crystalli­ microfauna, especially in critical areas. nes. The Barents-Varanger terrane of north­ Another important feature is that of strike­ east Finnmark, North Norway, is a strike-slip slip displacement, so prominent in interpreting allochthon consisting of Late Proterozoic to the accretionary histories of e.g. the British Vendian sediments unrelated both sedimento­ Isles, Ireland and Newfoundland, but such logically and geochemically to the parautoch­ originally near-vertical structural discontinuities thonous sediments of the Baltoscandian mar­ may now be totally masked or transposed by gin. Although originally linked to an unknown simple shear into the ubiquitous flat-lying palaeogeographical location along a dissected thrusts. The map picture is further complicated cratonic margin (Kj0de et al. 1975), these sedi­ by extensional faults which post-date the stack­ ments may possibly have formed along the ing of the nappes and terranes. This compo­ northern margin of a microcontinental block nent of vertical shortening/lateral extension is which drifted away from Baltica (Gayer et al. essentially of Late Silurian age, but also exten­ 1987, Rice et al. in press). ded into the Devonian period during deposition of the ORS sediments. A roughly NW-SE hori­ Summary zontal shortening regime, far less intense than The concept of geological terranes, which during the Scandian orogeny, was subsequent­ originated in the Cordilleras of western North ly reimposed during latest Devonian time (Sturt America, has been applied with some initial & Roberts 1987). success to the Scandinavian Caledonides. Terranes or terrane-complexes can be group­ ed according to their fundamental geological Acknowledgements characteristics and to their present relation­ The author is grateful to David Bruton, Rodney Gayer and ship to the rocks of the Baltoscandian miogeoc­ Brian Sturt for helpful comments and discussion on as­ pects of the manuscript and main map. line. Moving towards the hinterland of the mountain belt, orogen-external suspect terra­ Norwegian contribution no. 4 to IGCP project 233 - "Terra­ nes of the outermost, rifted, Baltoscandian nes in the circum-Atlantic Peteeozoic orogens'. margin give way to even more suspect and exotic oceanic elements which include ophioli­ tes and magmatic arc products. Further out, and higher in the tectonostratigraphy, terranes consist of heterogeneous units of both Lauren­ tian-continental and oceanic affiliation. Overstep sequences occur in two main peri­ ods, following terrane amalgamation: (1) in the Ordovician, represented by thick volcanosedi­ References Andreasson, P.G. 1987: Early evolution of the Late Protero­ mentary successions; and (2) during the latest zoic Baltoscandian margin: inferences from rift mag­ Silurian to Mid Devonian, characterised by the matism. (Extended abstract). Geol. Foren. Stockh. Forn. Old Red Sandstone molasse. 109, 336-340. At this stage, little work has yet been carri­ Andreasson, P.G. & Gee. D.G. 1986: Reconstruction of the Baltoscandian continent-ocean transition zone and sub­ ed out on terrane analysis in Scandinavia. The sequent accretion along the eastern lapetus margin. map compilation shows the basic terrane sub­ (Abstract). IGCP Project 233 Symposium. oviedo, Spa­ divisions, but these are informal designations in. 67. guided in part by personal prejudices. What Barker. A.J. & Gayer. RA 1985: Caledonian-Appalachian tectonic analysis and evolution of related oceans. In is required is active joint Norwegian-Swedish Gayer. R.A. (ed.) The tectonic evolution of the Caledoni­ collaboration within IGCP project 233, with the an-Appalachian orogen. Friedr. Vieweg & Sohn, Braun­ aim of producing a truly cooperative cartogra­ schweig. 126-165. phic compilation. More detailed mapping and Brekke, H.• Furnes. H.• Nordas, J. & Hertogen. J. 1984: Lower Palaeozoic plate margin volcanism on aemic, structural studies are needed in order to differ­ SW Norway, and its bearing on the tectonic environ­ entiate more clearly between the individual ments of the Norwegian Caledonides. Jour. Geol. Soc. terranes. Isotopic data are required to help tie London 141. 1015-1032. NGU - BULL. 413, 1988 Theterraneconcept and theScandinavianCaledonides 99

Bruton, D.L. 1986: Palaeontological aspects of terrane analy­ Monger, J'w.H., Souther, J.G. & Gabrielsen, H. 1972: Evolu­ sis. (Abstract). IGCP Project 233 Symposium, Ovtedo, tion of the Canadian Cordillera: a plate-tectonic model. Spain, 13. Am. J. Sci. 272, 577-602. Bruton, D.L. & Harper, DAT. 1988: Arenig-L1andovery stra­ M0rk, M.B.E., Kullerud, K. & Stabel, A. 1988: Sm-Nd dating tigraphy and faunas across the Scandinavian Caledoni­ of Seve eclogites, Norbotten, Sweden - evedence of des. In Harris, A.L. & Fettes, D.J. (eds.) The Caledoni­ Early Caledonian (505 Ma) high-pressure metamorp­ an-Appalachian Orogen. Geol. Soc. Spec. Publ. No. 38, hism. (Abstract). 18th. Nor. Geol. vtntermeao, Keben­ 247-268. havn, 1988, 289-290. Coney, P.J., Jones, D.L. & Monger, J'w.H. 1980: Cordille­ Roberts, D. 1987: Terranes on the Caledonides of Scandina­ ran suspect terranes. Nature, 288, 329-333. via: origins and accretionary history. (Extended ab­ Dallmeyer, RD. & Gee, D.G. 1986: 40Ar/39Ar mineral data stract). Project 233 Symposium, Nauakchott, Maurita­ from retrogressed exlogites within the Baltoscandian nia, 171-175. miogeocline: implications for a polyphase Caledonian Roberts, D. 1988: Reinterpretation of Finnmarkian deformati­ oroqenic evolution. Bull. Geoil. Soc. Am,er. 97, 26-34. on on western S0r0Y, northern Norway: some com­ Dunning, G.R. & Pedersen, RB. 1988: UlPb ages of ophioli­ ments. Nor. Geol. Tidsskr. 68 (in press). tes and arc-related plutons of the Norwegian Caledoni­ Roberts, D. & Gee, D.G. 1985: An introduction on the struc­ des: implications for the development of lapetus. Contr. ture of the Scandinavian Caledonides. In Gee, D.G. & Mineral. Petrol. 98, 13-23. Sturt, BA (eds.) The Caledonide Orogen - Scandinavia Furnes, H., Ryan, P.D., Grenne, T., Roberts, D., Sturt, BA and related areas. John Wiley & Sons, Chichester, 55-68. & Prestvik, T. 1985: Geological and geochemical classi­ Roberts, D., Grenne, T. & Ryan, P.D. 1984: Ordovician fication of the ophiolite fragments in the Scandinavian marginal basin development in the Central Norwegian Caledonides. In Gee, D.G. & Sturt, BA (eds.) The Caledonides. In Kokelaar, B.P. & Howells, M.F. (eds.) Caledonian Orogen - Scandinavia and related areas. Marginal basin geology. Geol. Soc. London Spec. Publ. John Wiley & Sons, Chichester, 657-670. 16, 233-244. Gayer, RA, Rice, A.H.N., Roberts, D., Townsend, C. & Roberts, D., Sturt, BA & Furnes, H. 1985: Volcanite assem­ Welbon, A. 1987: Restoration of the Caledonian Balto­ blages and environments in the Scandinavian Caledoni­ scandian margin from balanced cross-sections: the pro­ des and the sequential development history of the blem of excess continental crust. Trans. Royal Soc. mountain belt. In Gee, D.G. & Sturt, BA (eds.) The Edinb.: Earth Sci. 78, 197-217. Caledonide orogen - Scandinavian and related areas. Gee, D.G. & Sturt, BA (eds.) 1985: The Caledonian Orogen John Wiley & Sons, Chichester, 919-930. - Scandinavia and related areas. John Wiley & Sons, Roberts, D., Stephens, M.B., Gee, D.G. & Andresen, A. Chichester, 1266 pp. 1986: Scandinavian Caledonides, preliminary terrane Gee, D.G., Kumpulainen, R, Roberts, D., Stephens, M.B., map, 1:5 M: manuscript map, IGCP Project 233. Thon, A. & Zachrisson, E. 1985: Scandinavian Caledoni­ Rice, A.H.N., Gayer, RA., Robinson, D. & Bevins, RE. des, Tectonostratigraphic map, 1:2 M scale. 1988: Strike-slip restoration of Barents Sea Caledoni­ Hall, L.M. & Roberts, D. 1988: Timing of Ordovician deforma­ des 'terrane' to the Caledonides of Finnmark, North tion in the Caledonian-Appalachian orogen. In Harrls, Norway. Tectonics (in press). A.L. & Fettes, D.J. (eds.) The Caledonian-Appalachian Stephens, M.B. 1988: The Scandinavian Caledonides: a Orogen. Geol. Soc. Spec. Publ. No. 38, 291-309. complexity of collisions, Geol. Today, Jan. - Feb. 1988, Hossack, J.R & Copper, MA 1985: Collision tectonics in 120-26. the Scandinavian Caledonides: In Coward, M.P. & Ri­ Stephens, M.B. & Gee, D.G. 1985: A tectonic model for the es, A.C. (eds.) Collision tectonics. Geol. Soc. Spec. evolution of the eugeoclinal terranes in the central Publ. No., 19, 287-304. Scandinavian Caledonldes. In Gee, D.G. & Sturt, BA Keppie, J.D. 1981: The Appalachian collage. (Abstrackt). (eds.) The Caledonide orogen - Scandinavian and rela­ Terra Cognita, 1. 54. ted areas. John Wiley & Sons, Chichester, 953-970. Keppie, J.D. 1985: The Appalacian collage. In Gee, D.G. & Sturt, BA 1984: The accretion of ophiolitic terrains in the Sturt, BA (eds.] The Caledonian Orogen - Scandinavi­ Scandinavian Caledonides. Geo/. Mijinb. 63, 201-212. an and related areas. John Wiley & Sons, Chichester, Sturt, BA & Roberts, D, 1987: Terrane linkage in the final 1217-1226. stages of the Caledonian orogeny in Scandinavia. (Exten­ Keppie, J.D. 1989: Northern Appalachian terranes and their ded abstract). EGCP Project 233 Symposium, Nouak­ accretionary history. Geol. Soc. Amer. Spec. Paper 230 ctiott, Mauritania, 193-196. (in press). Williams, H. 1984: Miogeoclines and suspect terranes of Kj0de, J., Storetvedt, K.M. Roberts, D. & Gidskehaug, A. the Caledonian-Appalachian Orogen: tectonic patterns 1978: Palaeomagnetic evidence for large-scale dextral in the North Atlantic region, Can. J. Earth Sci, 21m movement along the Trollfjord-Komagelv Fault, Finn­ 887-901. mark, North Norway. Phys. Earth Planet.lnt. 16.132-144. Williams, H. & Hatcher , RD, Jr. 1982: Suspect terranes Krill, A.G. & Zwaan, K.B. 1987: Reinterpretation of Finn­ and accretionary history of the Appalachian orogen. markian deformation on western S0r0Y, northern Nor­ Geology 10, 530-536. way. Nor. Geol. Tidsskr. 67, 15-24. NGU Bulletin 413 - Roberts - PI. 1

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OTHER UNITS

bfEU;\~WU:/:J SEDlMENTS OF JURASSIC - CRET ACEOUS AGE (AND0Y)

SKAGERRAK OLD RED SANDSTONE CLASTICS, LATE SILURIAN TO MIDDLE DEVONIAN AGE MAGMA TIC AND SEDIMENTARY ROCKS, MIDDLE CARBONIFEROUS TO PERMIAN AGE (OSLO RIFT)

Scale 1:3 million o Kilometres 300 I I DAVID RDBERTS 1987

Plate 1. Map of Caledonian terranes and terrane-complexes in Scandinavia.