Caledonian and Baikalian tectonic structures on Varanger Peninsula, , , and coastal areas of Kola Peninsula, NW

DAVID ROBERT5

Roberts, D. 1996: Caledo nian and Baikalian tectoni c st ruct ures on Varanger Peninsula, Finnmark, Norway, and coas­ tal areas of Kola Peninsula, NW Russia. Nor. geol. unders. Bull. 431,59-65.

Based on data com piled from biostratigraphy, radiom etri c dating and palaeomagnetic studies,contractiona l defor­ mat ion and low-grade metamorphism in the Neoprot erozoic to earliest Palaeozoic successions of coastal areas of NE Norway and NW Russia have been constrained to two main stages. (1) Late Vendian to Early Camb rian Baikalian defo rmat ion, with mainly NW-5Etrendin g folds, affected Upper Riphean sequences on Rybachi and 5redni in Russia. These str uct ures can be followed into the eastern part of Varange r Peninsula. (2) Late 5ilurian to Early Devonian, Scandian deforma tion and metamorphism, with fold s and thrusts of mainly NE-5W trend, are recorded principally in western parts of Varanger, in the Caledon ian parautoc hthon and allochthon. Cross-folds and second cleavages in parts of NEVaranger may also be of Caledonian age. Within the succession of the Tanafjorden-Varangerfjorden Region of 5W Varanger Peninsula, palaeoc urrent data indicate that in the post-glacial Mid Vendia n to Early Cambrian period an uplifting land mass in th e northeast was the major source area for detritu s. This is in harmony with the notion of a rising Baikalian oroge nic and topographic hig h during thi s same period, in and beyond th e region now occupied by the Rybachi Penin sula. Combining all the evidence, th e Varanger Penin sula thu s appears to be in the somew hat unique situation of exposing vestiges of both Caledonia n and Baikalian structures and low-grade metamorphic fabrics. Mut ually interferi ng folds and cleavages occur in the eastern half of the Barents 5ea Region, not heast of the Trollfj orde n-Komagelva Fault Zone.

Oavid Roberts, Norges geolog iske undersekelse, p.a.Box 3006 i.ade, N-7002 Trondheim, Norway.

Introduction An important facto r in th e tectonothermal history of most geological terranes is the t iming of the principal In recent years, research within the Norweg ian-Russian phase of tectonic deformation. In the case of Varanger collaboration programme 'North Area' in Northeast Peninsula, it has been assumed almost wit hout question Finnmark, Norway, and the Kola Peninsula, NW Russia, that we are dealing exclusively with Caledonian deforma­ has led to several important advances in ou r knowledge tion, and by and large a st ruct ural architecture ascribed of the sedimentary successions occurr ing to the Late Silurian-Early Devon ian Scandian event. on th e Varanger, Rybachi and Sredni Peninsulas and Almost a century ago, howeve r, Rus sian and Finn ish geo­ Kildin Island (Fig.1) along the coastal fringes of the logists had considered that Varanger may well form a (several papers in Roberts & Nordgulen western extension of the so-called 'Timanian mountain 1995). Although investigations of Iit host ratigraphy and chain' stretching from the Timan s (Fig.2), along the nor­ sedim entary facies have formed the backbone of the thern coast of th e Kola Peninsula and immediate ly off­ Neoproterozoic project , research studies have included shore (Ramsay 1899, Tschernyschev 1901). Schatsky topics such as structu re, low-grade metamorphism, isoto­ (1935) later ascribed thi s Timanide deformation to the pic dating and palaeomagnetic investigations, some of Baikalian orogeny. wh ich are still in progress. Since that time, little attention has been directed

Fig.1. Location map showing the Varanger, Rybachi and Sredni Peninsulas and Kildi n Island, NE Norway-NW Russia. The pericra­ tonic (TVR, Sredni,Kildin) and basinal (BSR, Ryba chi) doma ins are indicated by different dotted orn aments. TVR - Tanafjorden­ Varangerfjorden Region; BSR - Barents Sea Region; TKFZ - Trollfjo rden-Kom age/va Fault Zone; SRFZ - Sredni-Rybachi Fault Zone; GNC - Gaissa Nappe Comp lex; TN ­ Tanahorn Nappe. The area wi tho ut orna­ ment is underlain by Archaean to Early Proterozoic crystalline rocks. 60 David Raberts NGU-BULL 431 . 1996

60·E

P e c hora

»>: \--­ 68·"., \ ------\\ \

o 100 200 km ~--_--'!WrF I I

Fig. 2. Location map showing the Timans, Kola Penin sula and the no rth ern Urals. The boxed area is that shown in more detail in Figs. 1and 3. The shaded are­ as in Tim an and th e Urals indicate th e areas ofmain outcrop of Neoproterazaic rocks. Principal fau lts in the Timans: WTF - West Timan Fault; UF - Central Tima n Fault; ETF- East Timan Fault. The NW-SE trend ing belt delimited by the WTF and CTFcorresponds to the pericrat onic domain ofVaranger, Sredni and Kildin. Likewise, the basinal do main (equivalent to Rybachi and the 8SR of Varanger) is that between the CTFand the ETF. VP - Varanger Peninsula ; RP ­ Rybachi Peninsula; KP - Kanin Peninsula. The structural subdivision of Tim an is mo di fied from map versions present ed by Getsen (1987), Olovyanishnikov (1995) andSiedlecka & Roberts (1995).

towards these early ideas, although they were mentioned ness. This pericratonic realm (Siedlecka & Roberts 1995) by Siedlecka & Siedlecki (1967) and discussed by also characterises t he fluvial, delta ic and coastal marine Siedlecka (1975) in her comprehensive review of Russian successions on Sredni Peninsula and Kildin Island, south­ and other early literature of the Finnmark-Timan region. west of the SRFZ, alth ough in this case there are no glaci­ At that time the issue could not be resolved. Specific stu­ al depo sits present and the microfau nal evidence favours dies w ithin part of the 'North Area' programme, how ever, on ly Late Ri phean deposition (Samuelsson 1995 and in have helped to refine our constraints on the time of the press). In Northea st Varanger Peninsula (the Barents Sea main tectonothermal event. Comparison with structural Region - BSR) and on Rybachi, submar ine turbidite sys­ t rends prevailing on Varanger Peninsula has thus allowed tems c.3-4 km thick represent a distinctive basinal reasoned conclusions to be made concerning the likely domain, termed th e Rybachi-Vara nger Basin by regional distribution of Ba ikalian and Caledonian structu­ Drinkwater et al.(1996). Microfaunas here also denote a res. The purpose of this short cont ribut ion is to present Late Riphean age. Thus, Vendian and younger deposits relevant data whi ch suggest that Baikalian st ructures are apparent ly lacking on both the Sredni and the almost certainly occur in the eastern parts of Varanger Rybach i Peninsulas. Peninsula. Geological framework Structure and metamorphism

Details of the formal lit hostr atigraphies of the Neopro­ Tectonic stru ctures and metamorphic features of the sue­ terozoic successions of the Varanger, Rybachi and Sredni cession s on Varanger Peninsula have been described in a Peninsulas and Kildin Island (Fig.1) can be fo und in number of publications , to which the reader is referred Siedlecka & Roberts (1992) and Siedlecka et al. (1995a, b). for details (e.g. Roberts 1972, Bevins et al. 1986, Rice et al. On Varanger, the polyphase NW-SE-trending Trollfjor­ 1989, Siedlecka & Roberts 1992, Karpuz et al. 1993). In the den-Komagelva Fault Zone (TKFZ) effectively divides the case of th e Rybachi and Sredni Peninsulas, the most rele­ peninsu la int o two regions, and can be followed south­ vant contributions on these part icular topi cs are those by eastwards on to the Rybachi and Sredni Peninsulas, whe ­ Negrutsa (1971), Roberts (1995) and Rice & Roberts re it has been termed the Sredni-Rybachi Fault Zone (SRFZ) (1995). (Roberts 1995)(Fig.1). The struc tural deformation and metamo rph ism of the ­ The southw estern Varanger Peninsula (t he Tana­ se various successions changes app reciably in crossing fjorden-Varangerfjorden Region - TVR) exposes an Upper the majo r NW-SE fault zone (TKFZ and SRFZ). Successions Riphean to Cambrian record up to 3.5 km thick, including in most of th e pericratonic doma in of SW Varanger (TVR), t he Early Vendian Varangerian glacial deposits. The Sredni and Kildin in general display only low er diagene­ Upper Riphean succession alone is some 2.3 km in thi ck- sis-grade compactional fab rics. Folds, where present at NGU-BULL431 , 1996 David Roberts 61

Kild in Island __ Rybachi Peninsula /' ~--­ /' / /' /' /'

Fig. 3. Simplified map of the varanqer­ Rybachi-Sredni-Kildin tract showing the RUSSIA principal structural trends, mostly the axial surface traces offolds but partly the strike of N- to NE-dipping strata in Kildin, Sredni and FINLAND SO Km southernmo st Varang er.

all, are gentle upright structures, trend broadly E-W to holds mo re significance than might at first meet the eye. NW-SE and lack any pervasive axial surface cleavage; and Since the situation on the Varanger Peninsula is evidently their precise age is uncertain. Towards the west in the unclear, except, as mentioned, in the far west where TVR on Varanger Peninsula, however, one is passing into Caledonian structures prevail, it is more appropriate to the Caledonian parautochthon and ultimately into the consider first the relevant data from the Russian areas. As Lower Allochthon (Gaissa Nappe Complex - Fig.1 ), where well as structural (fold axial) trend, biostratigraphic and folds become quite common, trend c.NE-SW (Fig.3), face isotopic constraints are clearly important, but interesting southeast, and carry a penetrative axial-planar cleavage. information can also be gained from palaeocurrent data In contrast, in the basinal domain on Rybachi, northe­ and from field and laboratory studies on mafic dykes. ast of the SRFZ, the turbiditic rocks show abundant NW­ SE trending and SW-facing, open to tight folds (Fig.3) and an associated, penetrative, tightly spaced or slaty cleava­ Rybachi, Sredni and Kildin ge. Illite crystallinity data (illite 002 peak) record a lower anchizone grade of metamorphism in the northeast, but Biostratigraphic evidence from these three areas shows only upper diagenesis grade moving closer to the SRFZ that the success ions are wholly Upper Riphean (Rice et aI.1995). The age of this tectonothermal cycle on (Samuelsson 1995). Earlier, the stratigraphically highest Rybachi has not yet been determined with any precision; unit on Sredni Peninsula, the Volokovaya Group however, several Russian workers have assumed that it (Siedlecka et al. 1995a), had been assigned a Vendian age equates with the Baikalian of Timan. More information is by Russian workers, but this is now rejected on the basis provided below. of recent microfossil studies (Samuelsson 1995 and in Some 60 km to the northwest, in the easternmost part press).This also accords better with the fact that there are of the Barents Sea Region of Varanger Peninsula, much no Varangerian tillites on Sredni. the same NW-SE (to N-S) fold-and-c1eavage trend is The diagenetic compactional fabric present in the peli­ encountered (Fig.3), although cross-folds cause local tes on Sredni and Kildin has been dated using the Rb-Sr structural complexities (Roberts 1972, Herrevold 1993). method on illite subfractions (Gorokhov et aI.1995). Early This low-grade metamorphic phase has not yet been authigenic illite subfractions from two separate formati­ dated. Moving towards the northwest within the BSR, the ons from the Sredni Peninsula yielded an age of 610-620 fold -axial trend gradaually sw ings through N-S to NE-SW Ma. Close to the SRFZ, on Sredni, a widely spaced NW-SE and ultimately ENE-WSW (Fig.3), with ubiquitous SE­ trending cleavage is quite well developed. From one par­ facing tight folds , local thrusts and the Tanahorn Nappe ticular formation in this subarea, within the fault zone, (Fig.1) signifying their association with the Caledonian Gorokhov et al.(1995) separated a second, even finer, illite orogenic cycle. subfraction and obta ined a Rb-Sr maximum age for thi s of 570 Ma. This was considered to relate to an influx of non-marine, subsurface water arising from an episode of Timing of deformation and fault movement along the SRFZ. metamorphism On Rybachi, the common NW-SE trending, open to tight, SW-facing folds are believed to represent a stage of basin inversion (Roberts 1995) - termed epikinegenesis In considering the currently known constraints on the (Raznitsyn 1972) in Rus sian literature - the folds and clea­ age, or ages of th e folding and very low-grade metamor­ vage gradually dying out towards, and just across, the phism outlined above, the map of principal structural SRFZ. Accepting that the 570 Ma maximum age noted trends (Fig.3) provides a useful backcloth; and one which 62 Dovid Roberts NGU-BULL 431. 1996

above truly relates to fault mot ion, then this presumably c.NE-SW-trend ing dykes are comparatively unaltered and reflect s th e inversion and widespread SW-directed com­ post-date the early, NNW-SSE-trending spaced cleavage. pressional defo rmation represented by t he struct ures on As yet, the only isotopic dating available on these dykes is RybachL Alternatively, the 'maximum-s70' age may indi­ t hat of K-Ar data w hich have provided ages of c.350 Ma cate the end stage of th e inversion, such th at th e peak (Beckinsale et al. 1975). Combining the biostratigraph ic metamorphic age, reflected in the pervasive cleavage on and pub lished K-Ar data, we therefore have a meaning­ Rybachi, could be somewhere between 610 (Sredni dia­ less time interval of at least 300 million years (latest genesis) and 570 Ma. Riphean to earliest Carboniferous) in which to place the In contrast, the minimum age for the main deform ati­ tectonometa morphic transformation of the host rocks to on on Rybachi Peninsula is poo rly constrained. In north­ these dykes. western areasof th e peninsula, a few dolerite dykes up to Despite t he lack of precise radiometric dat ing, signifi­ 6.5 m in th ickness cut th rough the NW-SE-trendin g folds cant clues asto the likely age of these NNW-SSE-trending, and cleavage at high angles; i.e., they trend c.NE-SW. An syn-c1eavage folds can be sought in a consideration of 4°Ar_39Ar laser microprobe study gave no definitive the structural trend (Fig.3) and the character of the cleav­ emp lacement age, suggesting only that the dykes are age, aided by an examinat ion of satellite images (Karpuz older than 450-400 mode l ages (Roberts & Onstott 1995), et al. 1993) and comparative field stud ies both on while palaeomagnetic data favoured a Late Vendian to Rybachi and in th is part ofthe BSR on Varanger Peninsula. Cambrian age (Torsvik et al. 1995). The fold ing and meta­ To th e present author, the structures and fabrics encoun­ mo rphism of the Rybachi succession, which preceded the tered in th e Varde district are very much reminiscent of dyke intrusion, would therefore seem to fall within the those seen on the Rybachi Peninsula, th e inference being time inte rval Late Vendian to Early Cambrian, with the th at again we are conceivably dealing with stru ctures of Vendian period taken to extend from 650 to 545 Ma. Baikalian age (Roberts 1993, 1995). If anyt hing, the cleav­ Turning briefly to the situ ation in Timan, whi ch has age in the eastern BSR is slig ht ly more doma inal in cha­ similar pericraton ic and basinal palaeoenvironmental racter t han that on Rybachi, but t his is partly because of zones as in the Rybachi-Sredni-Varanger region (Fig.2), Iithological differences and the fact that t he Ba ikalian radiometric dat ing there, mostly by th e K-Ar meth od, has deformation and metamorphism was probab ly dying out indicated t hat the Late Riphean succession wasdeform ed laterally, northwestwards. and metamorphosed in two stages;(1) a main 'Baikalian' Cross-folds of ENE-WSW to NE-SW, or even E-W trend tectonothermal event dat ing to th e period c.600-575 Ma are common in th is area, as reflected in the dome-and­ (Malkov 1992, recalculated ages); (2) a less prom inent sta­ basin map pattern (Roberts 1972, Siedlecki 1980, Rice et ge of deforma tion in the period c.505-470 Ma. The age al. 1989, Aamodt et al. 1996). As such transverse stru ctu­ constraints so far available from Rybachi and Sredni thus res are absent on Rybachi (Roberts 1995), it is reasonable support the long -standing noti on that the prin cipal to argue that the cross-folds in th e eastern BS R are Baikalian deformation also affect ed the se part icular coas­ Caledonian folds whi ch have developed as a result of tal Kola, Neoproterozoic successions. open, SS E-directed macro-buckling of pre-existing Baikalian struct ures. As well as these mutu ally interfering folds of disparate age, two cleavages are also present Varanger Peninsula locally (Roberts 1995), but no systematic work has yet been done to assess th e regio nal exten t of these cleava­ Barents Sea Region: varde district ges. In such a scenario one would expect the NW-SE, assumed 'Baikalian' cleavage to die out gradually west­ As noted earlier, this easternmost part of the BSR is cha­ wards; and th e NE-SW 'Caledonian' cleavage to appear racterised by a princ ipal cleavage and fold axial trend and intensify in the same direct ion. which is roug hly NNW-SSE, t houg h wit h local variati ons There has been only one attempt to date a cleavage due t o c.ENE-W SW cr o ss-folding (Ro b ert s 19 72, He rrev ol d directly, that of Tay lo r & Pic kering (19 8 1).Th ese authors et al., in prep.). It was initially assumed by Roberts (1972) produced an imprec ise Rb-Sr wh ole-rock date of 520 ± 47 th at all foldi ng in this area developed during Late Silurian, Ma from cleaved pelites in the Kongsfjord Format ion near Caledonian (Scandian) orogenesis. An explanation for t he (Fig.3). Although no details were given, the anomalous, c.NW-SE structural trend and facing reversal cleavage near the sampling sites is known to strike c.NE­ was sought in the likely bufferin g effect of a basement SW. The significance and interpretation of th is dat e has 'ridge' concealed beneath the sea area south east of been questioned by Rice et al. (1989) who argued that Varanger Peninsula. Rice et al.(1989) interpreted t he th e first Ca ledon ian deformation in this particular area same, WSW-facing stru ctu res as tip folds associated wi th was of Sca ndian age. a late-stage, backthrust sense of movement along an inferred sole thrust beneat h the BSR, thu s appealing to a late Scandian phaseof deformation. Eastern part of the Tanafjorden-Varangerfjorden Mafic dykes are rare in this particular part of the BS R Region and have, as yet, offered meagre constraints on the mini­ mum age for the cleavage and fold development. The Tecton ic deformation in th is part icular part of the TVR NGU-BULL 431 , 1996 Oavid Roberts 63

was clearly less intense than in the BSR directly northeast in the TVR are highly relevant. These authors, and also of the TKFZ. That the TKFZalso represents a metamorphic Edwards (1984), have pointed to an important change in break is seen in the fact that the rocks in this area have sediment dispersal patterns which occurred shortly after yielded illite crystallinity values indicative only of diage­ the end of the Varangerian glacial epoch. During this nesis grade (Bevins et al. 1986). There is also no trace of period, Le. broadly Mid Vendian to Early Cambrian, pala­ any regionally penetrative, steeply dipping cleavage in eocurrent data indicate that the major source area for this southeastern part of the Tanafjorden-Varangerfjor­ Vestertana Group sedimentation lay somewhere to the den Region. present-day northeast. Banks et al.(1971 ) suggested that A maximum age both for the diagenetic compactional this uplifted northeasterly situated «land mass» was pro­ fabr ic and for the oldest folds is set by the fact that the bably located somewhere to the northeast of the youngest formation here, the Stappogiedde, is of assu­ Trollfjorden-Komagelva Fault Zone, or a related parallel med Late Vendian age. Work is in progress (Rb-Sr on illite fault. subfractions) in an attempt to date the diagenesis. Here, Although not mentioned in name, the land mass refer­ it can be noted that from the southwestern TVG, red to by Banks et al. (1971) as supplying the major volu­ Dallmeyer & Reuter (1989) have recorded what they des­ me of detritus to the Vestertana Group was almost cer­ cribe as a «diagenetically related disturbance at c.635 tainly the rising topographic high which resulted from Ma». the Baikalian basinal inversion, tectonic deformation and In general, the stratigraph ic succession in the eastern metamorphism of the Upper Riphean succession, parts of TVR dips at a few degrees to the north with large-scale, wh ich are now exposed on the Rybachi Peninsula. gentle, upright folding on c.E-W axes appearing within 10 Vendian deposits are absent on Rybachi and Sredni, and km of the TKFZ (Fig.3). The axial trend of these folds is on Kildin Island, and it is mo re likely than not that they thus oblique to the main fault zone. In their trend and en were never deposited in these part icular 'eastern' areas echelon pattern these folds are comparable to post-cle­ during this period of inversion and diastrophism. avage folds occurring close to the SRFZ on Sredni Peninsula (Roberts 1995), which are indicators of dextral Western VarangerPeninsula; BSR and TVR strike-slip movement. Mesoscopic shear zones trending ENE-WSW and ESE-WNW, with a generally right-lateral The structural deformation and metamorphism of the shear sense, have also been recorded in the eastern TVR northwestern halves of both the Barents Sea Region and (Herrevold et al., in prep .). Closer to the TKFZ, small-scale the Tanafjorden-Varangerfjorden Region have been NW-SE-trending, SW-facing folds and minor thrusts indi­ documented in many papers (full bibliography in cate a phase of SW-directed compression (Karpuz et al. Siedlecka & Roberts 1992). In this present contribution, it 1993) or possibly transpression. Although the relations­ will suffice to note that the widespread folding and thrus­ hip of these SW-facing structures to the E-Wfolds is unk­ ting - SE-facing in the western TVR and SSE-facing in the nown, as is the actual age of the folds, it is reasonable to western BSR - and related metamorphism were acqui­ assume that the former are older and quite likely red as a result of Caledonian orogenesis. In the parau­ Baikalian. tochthon of the western TVR, the youngest formation The precise age of uncommon, c.N-S trending mafic affected by this deformation is of Early Cambrian age, dykes occurring in two places along the southeastern whereas on the nearby Digermul Peninsula Oust west of coast of the TVR remains unknown. K-Ar data have yiel­ southwestern Varanger Peninsula) the deformed succes­ ded a figure of c.350 Ma (Beckinsale et al. 1975) while sion, part of the Gaissa Nappe Complex, extends up into 4°Ar_39Ar pyro xene data are inconclusive (Roberts et al. the Tremadoc. 1995). One of these dykes has yielded palaeomagnetic Constraints on the precise timing ofthis pervasive fold­ data suggesting that its age may be Late Vendian to Early and-thrust event, however, remain poor. Radiometric Cambrian (Torsvik et al. 1995). For the t ime being, at least, data from the Gaissa Nappe Complex are not definitive, we therefore have no reliable upper constraint in this an age of c.440 Ma (K-Ar) having been suggested by area for the timing of diagenesis or fold deformation. Dallmeyer et al. (1989) as a maximum for slaty cleavage The importance of hiatuses and angular unconformiti­ development. Earlier, a Rb-Sr whole-rock isochron age of es in providing records of distant orogenic events is well c.504 Ma had been obta ined on cleaved pelites from the known, and thei r potential significance in this Finnmark­ western TVR (Sturt et aI.1975), but the reliability of this Kola region has been noted by Schatsky (1960) and date has been contested (Dallmeyer & Reuter 1989). Siedlecka (1975). Accepting that the rocks on Rybachi Bylund (1994) has reported palaeomagnetic data from Peninsula and in the Vardo district of the Ba rents Sea two sites in the western most TVR, also in the Gaissa Region have been affected by a Late Vendian-Early Nappe, which provide evidence of an Early Ordovician Cambrian Baikalian tectonothermal event associated remagnetisation event in those rocks. Clearly, we are in with b a s in invers ion and uplift , then the n orthwestern dire need o f reliable, precise d ating from these areas. For 'tail end' of the Baikalian may conceivably be reflected in the present, the general consensus is that the principal breaks in the Iith ostratigraphy of the TVR. In this regard, tectonometamorphic event is Scandian, in the time inter­ the sedimentological invest igations of Banks et al.(1971 ) val Late Silurian to Early Devonian . 64 David Roberts NGU-BULL431,1996

Conclusions References

Aamodt, L., Alam, A., Clausen, J.A., Gaabrielsen, R.H., Gjeelsvik,T., Based partly on constraints provided by biostratigraphic, Haaland, HJ., Haugan, M., Kahn, M.5., l.othe, A., Rahman, B. & radiometric and palaeomagnetic investigations, the 5ygnabere, T.O. 1996: Double folding of Eocamb rian siliciclastic timing of deformation and very low-grade metamor­ sediments in the Varanger Peninsula, north ernmos t Norw ay. phism of the Neoproterozoic to earliest Palaeozoic sue­ (Abstract). 22nd. Nordic Geolog ical Winter Meeting, Abo, Finland, Janua ry 1996, Abstract vol ume. cessions on the Varanger, Rybachi and Sredni Peninsulas Banks, N.L., Edwards, M.B., Geddes, W.P., Hobda y, D.A. & Reading, H.G. can be deduced. A significant element which also has a 1971: Late Precambrian and Cambro-Ordovician sedimen tation in bearing on the topic is that of fold axial trend and the East Finnmark. Nor. geol. unders. 269, 197-236. character of the associated, pervasive, axial planar cleava­ Beckinsale, R.D, Reading, H.G& Rex, D.e. 1975: Potassium-argon ages for basic dykes from East Finnmark: stratigraphical and struct ural ge. Pala eocurrent data are also shown to provide crucial im plications . Scott. Jour. Geol. 12, 51-55. information bearing on the question of timing of oroge­ Bevins, R.E., Robinson, D., Gayer, RA & Allma n, 5. 1986: Low-grade nesis. metamor phism and its relationship to thrust tectonics in the A principal conclusion is that the Varanger Peninsula is Caledo nides of Finnmark, North Norway. Nor. geol. unders . Buff. 404, 33-44. in the somewhat unique situation of exposing the vesti­ Dallmeyer, R.D. & Reuter, A. 1989: "'Ar-"Ar whole-rock dat ing and the ges of both Caledonian and Baikalian tectonic structures age of cleavage in the Finnm ark autoch thon, northeasternmost and low-grade metamorphic fabrics. In the Rybachi­ Scandi navian Caledon ides. Lithos 22,213-21 7. Sredni-Kildin area in Russia, the tectonothermal event Dallmeyer, RD., Reuter, A., C1auer, N. & Leiwig, N. 1989: Chronology of tectonot hermal activ ity within the Gaissa and Laksefjord Nappe marking the basinal inversion or epi kinegenic stage Complexes, Finnmark, Nort h Norway: evidence from K-Ar and ,oAr­ appears to fall in the period Late Vendian to Early 19Ar ages. In Gayer, RA (ed.) The Caledonian geology ofScandinavia, Cambrian, correspond ing to th e Baikalian orogeny of ear­ Graham & Trotma n, London , 9-26. Drinkwater, NJ., Pickering, K.T. & Siedlecka, A. 1996: Deep-water, fault­ lier Russian workers. The prominent, Baikalian, NW-SE controlled sedimen tation , Arctic Norway and Russia: response to fold -and-c1 eavage t rend seen on Rybachi Peninsula can Late Proterozoic rifling and the open ing of the lapetus Ocean.Jour. be traced without difficulty into the Varde district of the Geol. Soc. 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Specia l Publ. 7, 330. the Caledonian parautochthon and Lower Allochthon in Herrevold , T. 1993: Strukeurgeologisk analyse av den aust leqaste delen av Trofffjorden-Komagelvaforkastninga, Varanger. Unpubl. Cand. the west where Scandian defo rmat ion and metamor­ Scient. thesis, Univ. of Bergen. phism is dominant. In the eastern TVR, where the strati­ Karpuz, M.R., Roberts, D., Olesen, 0 ., Gabrielsen, R.H. & Herrevold , T. graphy extends up into the Late Vendian, a reliable upper 1993: Applica tion of multiple data sets to structural stu dies on (mi nimum) constraint for the deformation is so far lac­ Varanger Peninsula, . Int. Jour. Remote Sensing 14, 979-1003. king, but unconformities may instead be providing reflec­ Malkov, BA 1992: Timan Baikalides: myth or reality? Ukhta branch. USSR tions of distant Baikalian movements. Sedimentological Min eralogical Society, Syktyvkar, 21-29. (in Russian) Negrut sa, V.Z. work in this part of southern Va ra nge r Pe ninsula ha s 1971: Stratigraphy of hyperborean deposits in the Sredni and Rybachi Peninsula and in Kildin Island. VSEGEI 175, 153-1 86 .(in show n that in t he post-glacial Mid Vend ian to Early Russian). Cambrian period th e majo r source for th e detr itu s accu­ Olovy anishnikov, V.G. 1995: Guide for stu dy of stra tot ypi c section of mulatin g in the Vestertana Group was a land mass situa­ Vym skaya Series of Upper Precambrian of Timan . (Unpubl. field ted somewhere to the northeast. This is in good accor­ guide). Inst. of Geology, Russian Acad . Sci., Syktyvkar, Komi Republic, Russia 20 pp . dance with the concept of a rising Baikalian orogenic welt Ramsay, W. 1899: Neue Beitraqe zur Geologi e der Halbinsel Kola. Fennia and topographic high in and beyond the region of pre­ 15.4. 1-15. sent-day Rybachi Peninsula. Raznitsyn, V.A. 1972: Caledon ian and Variscan cycles in stabili zation of struc tures in northeast of European USSR.Int. Geol. Rev. 15,8,883­ 890. Acknowledgements Rice, A.H.N., Gayer. RA, Robinson, D. & Bevin s, R.E. 1989: Strik e-slip restora tion of the Barents Sea Caledonides terrane, Finnmark, The author is grateful to Roy Gabrielsen, 5tephen Lippa rd and Brian North Norway. Tectonics 8,247-264. 5turt for thei r helpful reviews of th e manuscript; to Anna 5iedlecka for Rice, A.H.N. & Roberts, D. 1995: Very low- grade metamor phism of Upper com ments at a later stage; and to Valery Moralev and Vsevolod Proterozoic sedimen tary rocks of the Rybachi and Sredni Olovyanishnikov for discussions on aspects of the geo logy ofTiman. Peninsulas and Kildin Island, NW Kola region, Russia. Nor. geol. unders. Special Publ. 7, 259-270. Roberts, D. 1972: Tecton ic deformation in the Barent s Sea Region of Varanger Peninsula, Finnmark. Nor. geol. unders. 282, 1-39. Roberts, D. 1993: Aspects of the structural geolog y of Rybachi and Sredni Peninsulas, and some compa risons wi th Varanger Peninsula. (Abstract). tst. Inte rnational Barents Symposium , NGU-BULL431, 1996 David Roberts 65

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Manuscript received April-May 7996; fina l manuscript ready July 7996.