Structure and seismostratigraphy of the East Siberian sea shelf along the Indigirka Bay - Jannetta Island seismic profile (original) (raw)
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Journal of Geodynamics
The Eastern Siberian Arctic Shelf (ESAS) represents a geologically complex realm with a history related to the final stages of the Pangaea supercontinent formation during the Mesozoic and its subsequent disintegration during Late Cretaceous and Cenozoic times. It is a key region to constrain the origin of the deep-water basins and intervening ridges of the Amerasia Basin. We present results of gravity modelling of published OBS refraction data and seismic reflection profiles acquired between 1989 and 2012 in the ESAS and adjacent Arctic Ocean along five composite geotransects using Getech satellite altimeter derived gravity data. Our main goal was to examine published crustal models and to present new models for the ESAS that are constrained by both seismic data and 2D gravity forward modelling. We consider several topics important for understanding of the Arctic geology: (i) hyperextension within the Laptev Rift System and possible extent of the exhumed mantle, (ii) relationship between the New Siberian Shelf and the Lomonosov Ridge, (iii) nature of the collapsed late Mesozoic fold belt in the southern part of the East Siberian Sea, (iv) character of transition between the De Long Massif and the deep-water Podvodnikov Basin, (v) lateral extent of the hyperextended North Chukchi Basin and nature of its basement, and (6) relationship between the Mendeleev Ridge and Chukchi Plateau crustal domains. Our results do not confirm the previously inferred extent of continental crust beneath the oceanic realm. The latter is dominated by either exhumed mantle regions and/or HALIP igneous crust. We discuss the existence of a dismembered continental Bennett-Barrovia block currently represented by three smaller fragments, or massifs. This block when restored to its possible single state, can play a crucial role in reconstructing the pre-Canada Basin Arctic.
Structure and geology of the continental shelf of the Laptev Sea, Eastern Russian Arctic
Tectonophysics, 1998
The Laptev Sea is of great significance for studying the processes of the initial breakup of continents. It is the southern termination of the Gakkel spreading ridge and thus the location of structural features resulting from a continental margin=spreading ridge intersection. The present-day understanding of the Laptev Shelf geology is based on the Russian multichannel seismic reflection data and extrapolation of the terrestrial geology. Geologic and plate-kinematic data are used to constrain the interpretation of the seismic reflection data. The Laptev Rift System consists of several deep subsided rifts and high standing blocks of the basement. From west to east these are: the West Laptev and South Laptev rift basins, Ust' Lena Rift, East Laptev and Stolbovoi horsts, Bel'kov-Svyatoi Nos and Anisin rifts. The central and eastern parts of the shelf have the greatest contrasts in the gravity field ranging from 60 mGal over the rifts to 50 mGal over the horsts. The rifts contain up to five seismic stratigraphic units bounded by clear regional reflectors and underlain by folded heterogeneous basement. They are suggested to be Late Cretaceous to Holocene in age and reflect different stages of spreading ridge=continental margin interaction. The estimated total thickness of the rift-related sediments varies between 4 and 8-10 km while the sedimentary cover on the uplifts is significantly reduced and generally does not exceed 1-2 km. An eastward decrease of the total thickness of the sedimentary sections from about 10 km in the South Laptev Basin to 4-5 km in the Bel'kov-Svyatoi Nos Rift and the simplicity of the entire rift structure may indicate a rejuvenation of the rifts in the same direction. The entire rift system is covered by the uppermost seismic unit, which probably reflects a deceleration of the rifting during the last reorganization of the North American=Eurasian plate interaction since about 2 Ma.
The Mesozoic–Cenozoic tectonic evolution of the New Siberian Islands, NE Russia
Geological Magazine, 2014
On the New Siberian Islands the rocks of the east Russian Arctic shelf are exposed and allow an assessment of the structural evolution of the region. Tectonic fabrics provide evidence of three palaeo-shortening directions (NE–SW, WNW–ESE and NNW–SSE to NNE–SSW) and one set of palaeo-extension directions revealed a NE–SW to NNE–SSW direction. The contractional deformation is most likely the expression of the Cretaceous formation of the South Anyui fold–thrust belt. The NE–SW shortening is the most prominent tectonic phase in the study area. The WNW–ESE and NNW–SSE to NNE–SSW-oriented palaeo-shortening directions are also most likely related to fold belt formation; the latter might also have resulted from a bend in the suture zone. The younger Cenozoic NE–SW to NNE–SSW extensional direction is interpreted as a consequence of rifting in the Laptev Sea.
Geotectonics, 2013
The tectonic evolution of the Arctic Region in the Mesozoic and Cenozoic is considered with allowance for the Paleozoic stage of evolution of the ancient Arctida continent. A new geodynamic model of the evolution of the Arctic is based on the idea of the development of upper mantle convection beneath the continent caused by subduction of the Pacific lithosphere under the Eurasian and North American lithos pheric plates. The structure of the Amerasia and Eurasia basins of the Arctic is shown to have formed progres sively due to destruction of the ancient Arctida continent, a retained fragment of which comprises the struc tural units of the central segment of the Arctic Ocean, including the Lomonosov Ridge, the Alpha-Men deleev Rise, and the Podvodnikov and Makarov basins. The proposed model is considered to be a scientific substantiation of the updated Russian territorial claim to the UN Commission on the determination of the Limits of the Continental Shelf in the Arctic Region.
Tectonic implications of the lithospheric structure across the Barents and Kara shelves
Geological Society, London, Special Publications, 2017
This paper considers the lithospheric structure and evolution of the wider Barents–Kara Sea region based on the compilation and integration of geophysical and geological data. Regional transects are constructed at both crustal and lithospheric scales based on the available data and a regional three-dimensional model. The transects, which extend onshore and into the deep oceanic basins, are used to link deep and shallow structures and processes, as well as to link offshore and onshore areas. The study area has been affected by numerous orogenic events in the Precambrian–Cambrian (Timanian), Silurian–Devonian (Caledonian), latest Devonian–earliest Carboniferous (Ellesmerian–Svalbardian), Carboniferous–Permian (Uralian), Late Triassic (Taimyr, Pai Khoi and Novaya Zemlya) and Palaeogene (Spitsbergen–Eurekan). It has also been affected by at least three episodes of regional-scale magmatism, the so-called large igneous provinces: the Siberian Traps (Permian–Triassic transition), the High ...
Structure of the Laptev Sea Shelf–Eurasian Basin Transition Zone (Arctic Ocean)
Geotectonics, 2018
Based on obtained data, the paper considers the structure of the sedimentary cover and basement in the continent-ocean transition zone. We analyze the structure of modern tectonic activity zones in the Laptev Sea and structurally similar zones in the Novosibirsk Trough and the De Long Massif. Three sedimentary Anisin-Laptev, Amundsen, and West Laptev basins separated by basement uplifts are distinguished in sedimentary cover. The Anisin-Laptev Basin is separated from the West Laptev Basin by the North Laptev Horst and from the Amundsen Basin by an uplift stretching from the Lomonosov Ridge and covered by the Neogene-Quaternary deposits. The modern tectonic activity zone, marked by a rift valley and earthquakes, stretches across the continental slope from the Gakkel Ridge above a sedimentary rock sequence possessing many-kilometers thickness. The zone reached its present-day position in the Pliocene. Near the shelf boundary, the zone bifurcates, with one branch departing into the West Laptev Basin, and the other branch departing into grabens that developed to the west of New Siberian Islands forming the Laptev microplate.
Tectonic of the Laptev Sea Region in North-Eastern Siberia
2000
Summary: Seismic reconnaissance lines were surveyed on the wide, virtually unexplored shelf of the Laptev Sea between the New Siberian Islands and the Taimyr Peninsula. The most pro minent ritt basin is the Ust' Lena rift with a minimum width of 300 km E-W at latitude 75 "N. It is bounded to the Laptev horst in the east by a westerly dipping major listric fault, the MV Lazarev fault. The 100 to 150 km wide Laptev horst is subdivided into three parts by minor rift basins. Another rift graben, the Anisin basin, is separated from the Kotel'nyi horst by a deep fault, the IB Kapitan Dranitsin fault. The onset of the rift is inferred to have been in the Late Cretaceous and the main extension took place from the Paleocene to the Oligocene.
The South Anyui suture zone consists of late Paleozoic-Jurassic ultramafic rocks and Jurassic-Cretaceous pre-, syn-, and postcollisional sedimentary rocks. It represents the closure of a Mesozoic ocean basin that separated two microcontinents in northeastern Russia, the Kolyma-Omolon block and the Chukotka block. In order to understand the geologic history and improve our understanding of Mesozoic paleogeography of the Arctic region, we obtained U-Pb ages on pre-and postcollisional igneous rocks and detrital zircons from sandstone in the suture zone. We identified four groups of sedimentary rocks: (1) Triassic sandstone deposited on the southern margin of Chukotka;
Tectonophysics, 2013
We present a digital model SibCrust of the crustal structure of the Siberian craton (SC) and the West Siberian basin (WSB), based on all seismic profiles published since 1960 and sampled with a nominal interval of 50 km. Data quality is assessed and quantitatively assigned to each profile based on acquisition and interpretation method and completeness of crustal model. The database represents major improvement in coverage and resolution and includes depth to Moho, thickness and average P-wave velocity of five crustal layers (sediments, and upper, middle, lower, and lowermost crust) and Pn velocity. Maps and cross sections demonstrate strong crustal heterogeneity, which correlates weakly with tectono-thermal age and strongly with tectonic setting. Sedimentary thickness varies from 0–3 km in stable craton to 10–20 km in extended regions. Typical Moho depths are 44–48 km in Archean crust and up-to 54 km around the Anabar shield, 40–42 km in Proterozoic orogens, 35–38 km in extended cratonic crust, and 38–42 km in the West Siberian basin. Average crustal Vp velocity is similar for the SC and the WSB and shows a bimodal distributionwith peaks at ca. 5.4 km/s in deep sedimentary basins and ~6.2–6.6 km/s in parts of the WSB and SC. Exceptionally high basement Vp velocities (6.8–7.0 km/s) at the northern border between the SC and the WSB indicate the presence of magmatic intrusions and are proposed to mark the source zone of the Siberian LIP. The cratonic crust generally consists of three layers and high-velocity lowermost crust (Vp ~ 7.4 km/s) is observed only locally. Pn velocities are generally ~8.2 km/s in the SC and WSB and abnormally high (8.6–8.9 km/s) around kimberlite fields. We discuss the origin of crustal heterogeneity and link it to regional crustal evolution.