Fold belts and sedimentary basins of the Eurasian Arctic

arktos, Jul 2016

The vast Eurasian Arctic epicontinental shelf and adjoining mainland has a very complex structure and tectonic history as a result of a series of continent–continent collisions, accretion of terranes and crustal extension phases during Neoproterozoic and Phanerozoic times. Significant parts of major Eurasian fold belts extend far north into the Arctic below thick infill of post-orogenic sedimentary basins, where their architecture remains highly disputed. Large Eurasian Arctic sedimentary basins formed as a result of orogenic collapse, back-arc extension, or intracontinental extension associated with the breakup of the Laurussia, Laurasia, Pangea and Eurasia supercontinents. There are over 40 sedimentary basins of variable age and genesis which are thought to bear significant undiscovered hydrocarbon resources in the region. This article reviews the current state-of-knowledge of Eurasian Arctic tectonics and highlights questions that remain to be addressed. The overall focus is on the Russian sector of the Arctic being less known to a broad geoscience community.

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Fold belts and sedimentary basins of the Eurasian Arctic

Arktos Fold belts and sedimentary basins of the Eurasian Arctic Sergey S. Drachev 0 1 0 ArcGeoLink Ltd. , 48 Tupwood Gardens, Caterham, Surrey CR3 6EW , UK 1 & Sergey S. Drachev The vast Eurasian Arctic epicontinental shelf and adjoining mainland has a very complex structure and tectonic history as a result of a series of continent-continent collisions, accretion of terranes and crustal extension phases during Neoproterozoic and Phanerozoic times. Significant parts of major Eurasian fold belts extend far north into the Arctic below thick infill of post-orogenic sedimentary basins, where their architecture remains highly disputed. Large Eurasian Arctic sedimentary basins formed as a result of orogenic collapse, back-arc extension, or intracontinental extension associated with the breakup of the Laurussia, Laurasia, Pangea and Eurasia supercontinents. There are over 40 sedimentary basins of variable age and genesis which are thought to bear significant undiscovered hydrocarbon resources in the region. This article reviews the current state-of-knowledge of Eurasian Arctic tectonics and highlights questions that remain to be addressed. The overall focus is on the Russian sector of the Arctic being less known to a broad geoscience community. basin; Rift Introduction Arctic is a unique region of our planet in many respects including its geology. In a relatively confined area north of the Arctic Circle there is a great variety of tectonic crustal domains and overlying sedimentary accumulations ranging from the pre-Neoproterozoic North America, Baltica and Siberia cratons, to Cretaceous and Cenozoic Amerasia and Eurasia oceanic basins. In between, there is a series of Neoproterozoic and Phanerozoic fold belts extending into the Arctic shelves and forming the tectonic basement of large offshore sedimentary basins. The latter are considered the last hydrocarbon frontier and estimated to hold as much as 90 billion barrels of undiscovered recoverable oil and 1670 trillion cubic feet of recoverable natural gas [ 39 ] of hydrocarbon resources. The present-day Arctic has formed due to the northerly directed drift of continents, which resulted in creation of the Pangea Supercontinent in Permian time, and following disintegration of this supercontinent during Mesozoic and Cenozoic time [ 85, 145 ]. This geological history is recorded in the rocks of the Arctic fold belts and sedimentary basins. Geological data from Arctic continental margins are also a significant source of information about processes that formed the deep water basins and ridges of the High Arctic, especially true for the Amerasia Basin where datasets remain scarce. The Eurasian Arctic is dominated by fold belts that extend offshore under thick sedimentary accumulations and consequently are poorly understood. There have been several overviews published relatively recently attempting to summarize the geology of parts of the Arctic [ 26, 49, 52, 115, 120 ]. This paper focusses on the Russian Arctic, where new data allows for an improved understanding of the tectonics of a vast offshore region. Fold belts The Arctic fold belts are all products of major postPalaeoproterozoic orogenic events, i.e., Neoproterozoic, early Palaeozoic (Caledonian), late Palaeozoic (analogues of Hercynian orogeny in Central Europe), and late Mesozoic and Cenozoic orogenies. Most of these fold belts are located in the Eurasian sector. For the purpose of this overview, Mesoproterozoic fold belts are not differentiated from the older rocks of the cratons and, therefore, are not characterized below. Neoproterozoic Timanian fold belt (TFB) The TFB surrounds the Baltica Craton to the NE and E (present-day coordinates). It is locally exposed in the Timan Range, on Kanin, Rybachii and Varanger peninsulas (Figs. 1, 2), while a major part of it is buried under thick sediments of the Timan-Pechora Platform (basin) where Precambrian rocks are documented by petroleum exploration wells at 0.5–4.5 km depth. The eastern flank of the TFB is reworked by Late Palaeozoic Uralian deformation (see Uralian Fold Belt below). Detailed information about geology and history of Timanides is summarized by Gee and Pease [ 42 ], Kuznetsov et al. [ 80–83 ], Pease et al. [119], Andreichev [ 3 ]. The TFB consists of two first-order tectonic elements (from west to east): the Timan and Bol’shezemel’sk domains separated by the Pripecho-Ilych-Chikshinsk Suture. The latter is inferred to mark the NE limit of the Baltican crustal domain [ 65 ]. The Timan domain represents a proximal to Baltica Cryogenian passive continental margin dominated by weakly to moderately metamorphosed and deformed shelfal siliciclastic rocks. It is separated from the Baltica Craton by the West Timanian Thrust. The eastern flank of the domain (Izym Block in the Russian literature) is dominated by distal deep-water slate rocks [ 3 ]. The Bol’shezemel’sk domain is mostly composed of metamorphosed and intensely deformed (...truncated)


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Sergey S. Drachev. Fold belts and sedimentary basins of the Eurasian Arctic, arktos, 2016, pp. 21, Volume 2, Issue 1, DOI: 10.1007/s41063-015-0014-8