ИСТИНА

Triassic strata in the Greater Barents Sea Basin (GBSB) are critical to understanding the evolution of surrounding hinterlands, including the Urals, Siberia, and Fennoscandia as well as adjoining Arctic basins in the Lower Mesozoic. Previous studies on the Triassic succession in the GBSB have provided information about which source contributed sediments at different stages in the basin history. However, none have focused on the evolution of the source areas throughout time. Here, we use state-of-the-art basin-wide correlation of stratigraphic units in the GBSB and adjacent Timan-Pechora and Kara basins to: i) calculate sediment load for each time-unit and use this information to understand Triassic sediment supply; ii) link changes in sediment supply and catchment parameters to tectonic events in the source area; and iii) investigate whether the Triassic sediment source in GBSB also acted as a source for other sedimentary basins in the Arctic. Our results, which use seismic data and BQART equation using Monte-Carlo simulations, show that sediment loads were extremely high during the Lower Triassic. This sediment supply matched the biggest modern river systems with sources in the most tectonically active orogens (Himalayas and Andes). Middle Triassic sediment load was significantly lower but still comparable to the top ten biggest modern rivers, as and ancient counterparts (Paleogene Wilcox Formation, Gulf of Mexico). Another peak in sediment supply occurred in the Late Triassic, coinciding with a westward depocenter shift. The Upper Triassic contains four time-units, three of which show a considerable mismatch between observed and modelled sediment load. This mismatch in the sedimentary budget, together with sediment transport direction, is evidence for sediment transport through and beyond GBSB and into other Arctic basins. These results have important implications: The western Urals have traditionally been regarded as the sediment source for the Triassic deposits in the GBSB, but the sediment volumes are too large to have been supplied only from this catchment. Our results strongly suggest that West Siberia and possibly the Central Asian Orogenic Belt also supplied sediment to the GBSB. Furthermore, the large amounts of sediment supplied to the GBSB during the lower Triassic requires tectonic reactivation of the Urals orogeny, likely caused by onset of the greatest volcanic event during the Phanerozoic, the Siberian Traps Large Igneous Province. The low sediment loads during the middle Triassic indicates sediment storage in proximal basins that lay E and SE of the GBSB, and the renewed high sediment loads and subsequent bypass in the late Triassic suggests an early onset of the final Northern Ural orogeny, possibly combined with climate changes related to the Carnian Pluvial Event. During the late Carnian and Norian, these events led to sediment spilling to the Sverdrup Basin and the tectonically offset Chukotka Basin.