Opening of the Arctic Ocean has been the subject of much debate, and the placement of terranes in Early Mesozoic remains a crucial part of this important discussion. Several continental terranes complicate the paleogeographic reconstruction. One such terrane is Crockerland, which has been inferred to explain sediment distribution in the Arctic throughout the Mesozoic. However, the Triassic successions throughout the Arctic basins bear many similarities, and a common sedimentary source could offer a simpler explanation with fewer implications for the basin configuration in the Arctic. The study's goal is to test the hypothesis of long-distance sediment transport from a common source to all Arctic basins in the Triassic, and to demonstrate how estimates of sediment routing distances can improve pre-breakup plate tectonic reconstructions. Results confirm that (1) the Arctic basins were closely connected prior to breakup in the Mesozoic, (2) based on regional facies distribution, sediment budgets, sediment modelling and detrital zircon age spectra, the Crockerland terrane is unlikely to have existed, (3) the reconstructed Arctic sediment routing system can help to constrain plate tectonic models, (4) and statistical estimate of sediment transport is a novel and potentially important tool for improving plate tectonic and paleogeographic reconstructions.
Abstract Triassic strata in the Greater Barents Sea Basin are important records of geodynamic activity in the surrounding catchments and sediment transport in the Arctic basins. This study is the first attempt to investigate the evolution of these source areas through time. Our analysis of sediment budgets from subsurface data in the Greater Barents Sea Basin and application of the BQART approach to estimate catchment properties shows that (1) during the Lower Triassic, sediment supply was at its peak in the basin and comparable to that of the biggest modern-day river systems, which are supplied by tectonically active orogens; (2) the Middle Triassic sediment load was significantly lower but still comparable to that of the top 10 largest modern rivers; (3) during the Upper Triassic, sediment load increased again in the Carnian; and (4) there is a large mismatch (70%) between the modeled and estimated sediment load of the Carnian. These results are consistent with the Triassic Greater Barents Sea Basin succession being deposited under the influence of the largest volcanic event ever at the Permian-Triassic boundary (Siberian Traps) and concurrent with the climatic changes of the Carnian Pluvial Event and the final stages of the Northern Ural orogeny. They also provide a better understanding of geodynamic impacts on sedimentary systems and improve our knowledge of continental-scale sediment transport. Finally, the study demonstrates bypass of sediment from the Ural Mountains and West Siberia into the adjacent Arctic Sverdrup, Chukotka, and Alaska Basins in Late Carnian and Late Norian time.
Opening of the Arctic Ocean has been the subject of much debate, and the placement of terranes in the Early Mesozoic remains a crucial part of this important discussion. Several continental terranes complicate the palaeogeographical reconstruction. One such terrane is Crockerland, which has been inferred to explain sediment distribution in the Arctic throughout the Mesozoic. However, Triassic successions throughout the Arctic basins bear many similarities, and a common sedimentary source could offer a simpler explanation with fewer complications for the past configuration of the Arctic. The study's goal is to test the hypothesis of long-distance sediment transport from a common source in present-day Russia to all Arctic basins in the Triassic, and to demonstrate how estimates of sediment routing distances can improve pre-break-up plate-tectonic reconstructions. Results confirm that (1) the Arctic basins were closely connected prior to break-up in the Mesozoic, (2) based on regional facies distribution, sediment budgets, sediment modelling and detrital zircon age spectra, the Crockerland terrane is unlikely to have existed as a major sediment supplying area, (3) the reconstructed Arctic sediment routing system can help to constrain plate-tectonic models, and (4) statistical estimation of sediment transport is a novel and potentially important tool for improving plate-tectonic and palaeogeographical reconstructions. Supplementary material : A database for provenance study, detrital zircon age spectra and the sedimentary length calculations method are available at https://doi.org/10.6084/m9.figshare.c.6086468
Identification of the source rock potential and distribution area is the most important stage of the basin analysis and oil, and gas reserves assessment. Based on analysis of the large geochemical and geological data base of the Petroleum geology department of the Lomonosov Moscow State University and integration of different-scale information (pyrolysis results and regional palaeogeographic maps), generation potential, distribution area and maturity of the main source rock intervals of the Barents-Kara Sea shelf are reconstructed. These source rocks wide distribute on the Barents-Kara Sea shelf and are characterized by lateral variability of generation potential and type of organic matter depending on paleogeography. During regional transgressions in Late Devonian, Early Permian, Middle Triassic and Late Jurassic, deposited source rocks with marine organic matter and excellent generation potential. However in the regression periods, during the short-term transgressions, formed Lower Carboniferous, Upper Permian, Induan, Olenekian and Late Triassic source rocks with mixed and terrestrial organic matter and good potential. Upper Devonian shales contain up to 20.6% (average – 3%) of marine organic matter, have an excellent potential and is predicted on the Eastern-Barents megabasin. Upper Devonian source rocks are in the oil window on the steps, platforms and monoclines, while are overmature in the basins. Lower Permian shale-carbonate source rock is enriched with marine organic matter (up to 4%, average – 1.4%) and has a good end excellent potential. Lower Permian source rocks distribute over the entire Barents shelf and also in the North-Kara basin (Akhmatov Fm). These rocks enter the gas window in the Barents Sea shelf, the oil window on the highs and platforms and are immature in the North-Kara basin. Middle Triassic shales contain up to 11.2% of organic matter, there is a significant lateral variability of the features: an excellent generation potential and marine organic matter on the western Barents Sea and poor potential and terrestrial organic matter in the eastern Barents Sea. Middle Triassic source rocks are in the oil window; in the depocenters it generates gas. Upper Jurassic black shales are enriched with marine and mixed organic matter (up to 27,9%, average – 7.3%) and have an excellent potential. On the most Barents-Kara Sea shelf, Upper Jurassic source rock are immature, but are in the oil window in the South-Kara basin and in the deepest parts of the Barents Sea shelf.
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