Downloaded from http://mem.lyellcollection.org/ by guest on October 1, 2021 The Neoproterozoic Timanide Orogen of eastern Baltica: introduction D. G. GEE 1 & V. PEASE 2 1Uppsala University, Department of Geosciences, Villaviigen 16, 752 36, UppsaIa, Sweden 2Department of Geology and Geochemistry, Stockholm University, SE-106 91, Sweden This volume was conceived during EUROPROBE' s investigations complex crustal evolution. Deep drilling (up to c. 5 km) of the into the dynamic evolution of the Palaeozoic Uralide Orogen and Pechora Basin provided convincing evidence (Belyakova & relationships northwards into the Eurasian high Arctic. During Stepanenko 1991) that a broad belt of calc-alkaline igneous these European Science Foundation studies, the preservation of rocks flanked terrigenous slope-to-basin deposits of the Timan Neoproterozoic deformation over large regions of northern Range. Late Neoproterozoic granites carry Grenville-age zircon Europe became increasingly apparent. This mainly Vendian tec- xenocrysts and complexes of this age were shown to exist tonic event is referred to as the Timanian Orogeny and became further towards the hinterland within the Palaeozoic allochthons the focus of many recent and on-going investigations. Much pro- of the Subarctic Urals. Late Neoproterozoic ophiolites, albeit frag- gress has been made in understanding Timanian Orogeny and a mented, were described from the Polar Urals (Dushin 1997). Thus, Memoir synthesizing our current knowledge is not only timely, despite powerful resistance (e.g. Ivanov & Rusin 2000), an but also relevant to Neoproterozoic global tectonic alternative hypothesis has emerged that favours the existence reconstructions. of a Timanian accretionary orogen, on the eroded roots of The type area for the Timanide Orogen is located in the Timan which were deposited the early to mid-Palaeozoic rifted and Range of northwestern Russia, which separates the East European passive margin successions which flanked the Uralian ocean. Craton from the Pechora Basin and Polar Urals. The orogen Continent-ocean collision played an important role in the extends over a distance of at least 3000 km, from the southern orogenic process and some authors (e.g. Sengor et al. 1993) Ural Mountains of Kazakhstan to the Varanger Peninsula of north- have speculated on the possible continuity between the 'Timanian' ernmost Norway, flanking the eastern margin of the older craton and Uralian oceans; however, the question remains unresolved. (Fig. 1). From the Timan Range, it reaches northeastwards below The studies of the Timanides included in this Memoir are struc- the thick Phanerozoic successions of the Pechora Basin and tured to provide a comprehensive overview of the orogen. The first Barents Shelf (O'Leary et al. 2004), and reappears in the Polar three contributions treat the pre-Timanian rifted margin of the East Ural Mountains and northwards through Pai Khoi to Novaya European Craton. Roberts et al. describe the Neoproterozoic Zemlya. Timanian orogeny thus influenced a vast region of north- passive margin sedimentary successions of the Kanin Peninsula, western Russia. The Phanerozoic cover, Arctic shelf areas and, and northern and central parts of the Timan Range. Maslov further east, Uralian deformation, obscure the importance of this provides comprehensive descriptions of the Mesoproterozoic and orogenic event for the geodynamic evolution of Europe. Neoproterozoic (Riphean-Vendian) stratigraphy preserved The Timanide Orogen has been referred to by various other within the Uralian foreland and western flank of the Ural Moun- names, most frequently as the 'Baikalides'. The term 'Baikalian tains, making regional correlations to the Timan-Pechora area. Orogeny', with a type area along the southern margin of the Grazhdankin follows with an overview of the late Neoprotero- Siberian Craton, was introduced by Edelstein (1923) and promoted zoic differential subsidence patterns of the East European Craton by Shatsky (1963), and suggested a tectonic event that started in in the Mezin Basin SW of the Timan Range, significantly relating the Late Precambrian and finished in the Early Palaeozoic. this to development of a Timanian foreland basin in the late Vendian. Other authors prefer to restrict 'Baikalian' events to those that The magmatic, metamorphic and structural evolution of the took place in the Neoproterozoic time interval of 850-650 Ma Timanide Orogen is described regionally, divided into the (e.g. Khomentovsky 2002). The term 'Baikalian' has also been Timan Range, the Pechora Basin, and Ural Mountains. Roberts used to designate a late Precambrian stratigraphic system in & Olovyanishnikov present the structural and tectonic develop- Siberia, corresponding to the Cryogenian of the IUGS Inter- ment of the Timanide Orogen in the Timan region. Larionov national Stratigraphic Chart (2000). To avoid ambiguity, we advo- et al. present U-Pb ages on an alkaline igneous suite in northern cate the use of the term 'Timanian' Orogeny to describe the late Timan which provides constraints on the beginning of Timanian Neoproterozoic tectonic events documented along the eastern Orogeny. Using Neoproterozoic high-grade metamorphic rocks margin of the East European Craton, best exemplified in the from the Kanin Peninsula, Lorenz et al. document PIT conditions Timan-Pechora region, and restrict the use of the term Baikalian associated with Timanian orogenesis. to tectonic events associated with Siberia. In the Pechora Basin region, drillcore samples of pre-Palaeozoic For much of the last century, the dominating hypothesis for the basement provide the foundations for our understanding of the evolution of northwestern Europe has explained Timanian pre-Palaeozoic events. Belyakova & Stepanenko's paper (1991) tectono-thermal activity in terms of rift basin (aulacogen) inver- documenting the different structural and metamorphic zones sion. Thick Neoproterozoic and partly Mesoproterozoic sedimen- within the basement to the Pechora Basin, is particularly important. tary successions were described and interpreted to separate blocks New geochemical evidence from Dovzhikova et al. (2004) suggests of older Precambrian crust that previously had been a part of the that the Precambrian mafic complexes in the Pechora zone represent Archaean and Palaeoproterozoic core of Europe. Thus, Stille Neoproterozoic oceanic crust, probably accreted during Timanian (1958) inferred that the Timanides were a result of deformation orogenesis. Pease et al. provide geochemical evidence for the between the Fennoscandian Craton and an outboard continent, calc-alkaline affinity of Vendian granitoid rocks which are inter- which he called Barentsia. Subsequent geophysical studies, preted to indicate late-orogenic westward subduction beneath north- particularly potential field, but also seismic, suggested a more eastern Baltica at about 560 Ma. From: GEE, D. G. & PEASE, V. (eds) 2004. The Neoproterozoic Timanide Orogen of Eastern Baltica. Geological Society, London, Memoirs, 30, 1-3. 0435-4052/04/$15 © The Geological Society of London 2004. Downloaded from http://mem.lyellcollection.org/ by guest on October 1, 2021 2 D.G. GEE& V. PEASE 30°E /40°E 50°E I KARA SEA RENTS SEA Vaigach erma Kolguev ~ KstTin Nar'yan-Mar.r - .......~._. / : LEGEND Cenozoic Cretaceous l I Jurassic f ~ t Triassic ~ Permian Carboniferous Devonian Caledonides Uralian Accreted Terranes Baltica Margin Early Palaeozoic Timanides Volgograd Palaeoproterozoic -Archaean Fig. 1. Geological map of the eastern margin of Baltica, showing the extent of the Timanides from the southern Urals to Novaya Zemlya and the Varanger Peninsula (VP). Downloaded from http://mem.lyellcollection.org/ by guest on October 1, 2021 THE NEOPROTEROZOIC TIMANIDE OROGEN OF EASTERN BALTICA: INTRODUCTION 3 ute significantly to a clearer understanding of its role in the tec- Cambrian tonic evolution of Baltica. 545 - 545 540 Several different geological timescales are in routine use within Late Late Neoproterozoic III the scientific community at present. Though the use of the IUGS 7endian .620 International Stratigraphic Chart (2000) has been encouraged, Early 650 • " 650 m ,650 650 the older International Stratigraphic Chart of Plumb (1991), as Middle Cryogenian well as the Russian timescale (Keller & Chumakov 1983) in which Riphean and Vendian are used to subdivide parts of the Pre- 2 850 q 85o Early Tonian cambrian, have also been used. For the convenience of the reader, 1000 "~ipheon lOOO 1000 we provide a cross-reference for these three timescales (Fig. 2). Stenian Additionally, the International Commission of Stratigraphy has 1200 recently revised the Precambrian timescale (Gradstein et al. Mesoproterozoic 1350 Ectasian 2004), but it has not yet received wide usage. Regarding nomen- =>. 1400 clature and especially the translation of Russian stratigraphic 2, Calymmian terms, a few more years are needed to achieve consensus on 1600 1600 1650 these matters. Paleoproterozoic and Archaen Plumb {1991) Keller & Chumakov [1983) lUGS [2000] References Fig. 2. Comparison of Mesa- and Neoproterozoic timescales used in this volume. BELYAKOVA, g. T. & STEPANENKO, V. Ya. 1991. Magmatism and geo- dynamics of the Baikalide Basement of the Pechora Syneclise. Doklady Akademii nauk SSSR (geologiya), 106-117 [in Russian]. Within the Ural Mountains, the evidence for Timanian orogeny DOVZHIKOVA,E., PEASE, V. & REMIZOV, D. 2004. Neoproterozoic island is fragmentary and the contributions are geographically restricted arc magmatism