Early Cretaceous paleogeography of the proto North Atlantic margin of the Barents Sea
The Early Cretaceous represents the time when the North Atlantic and Arctic basins changed their configuration leading to their current morphology. From and almost continuous basin, the arctic region broke up during formation of the Canada basin and initial rift between Greenland and the western margin of the Barents Sea. Extensional tectonics dominated the southwestern part of the Barents Sea, with the development of deep basins and highs whereas the northern margin was dominated by compressional tectonics and uplift. To the east, Novaya Zemlya also was uplifting during most of the Early Cretaceous. The cause for the uplift is still not fully understood, but it was related to a rift phase in the North Atlantic and to the rift and drift phase (i.e. breakup and seafloor spreading) associated with the opening of the Canada and Amerasia basins. As part of the LoCRA consortium (locra.ux.uis.no), which focus is to improve the understanding of the stratigraphy, presence of clastic wedges, paleogeography of the Barents Sea region and ultimately the Arctic during the Early Cretacoeus, a sequence stratigraphic framework based on outcrop, well and seismic data using revised biostratigraphy has allowed the definition of seven third order genetic sequences (Fig. 1). Six detailed paleogeographic maps are presented from Berriasian to Cenomanian, including the implications for the development of the North Atlantic. During the lowest most sequences (sequence 0 to 2; Berriasian to early Albian), the main source of sedimentation came from the N and NW, sourced from a land to the north and Greenland. Uplift dominated the northern margin of the Barents Sea, and subaerial exposure resulted in major incision. Transitional conditions dominated most of the western margin of the Barents Sea, evidenced by high angle, low relief prograding clinoforms south- and southeastwards. Oher sources of sedimentation were the Timan Pechora and the Novaya Zemlya regions, filling the eastern Barents Sea deep basin. Along the western margin of the Barents Sea, major rifting initiated, forming deep N-S Cretaceous basins, marking major crustal thinning between northern Greenland and the Barents Sea. During the upper most sequences (sequence 3 to 6; middle Albian to Cenomanian), The Barents Sea was characterized by retreat of the transitional environments in the west and NW and advancement of shallow marine to continental environments in the east and northeast. An Arctic Seaway was established between northern Greenland and the Barents Sea. In the western margin of the Barents Sea, subsidence predominated along the main N-S basins, interrupted by periods of inversion, which may have induced development of local deposition of mass transport complexes. In addition, salt tectonics became quite active in these basins. By the end of the Lower Cretaceous, the area was dominated by transgression with mostly shelf sedimentation. During the Late Cretaceous and Cenozoic, major inversion resulted in exposure of structural highs, and exposure of Lower Cretaceous rocks produced local sources of sedimentation for the deep basins prior to opening to major extension westward and opening of the North Atlantic.
AAPG Datapages/Search and Discovery Article #90325 © 2018 AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin, Lisbon, Portugal, May 2-3, 2018