Яндекс.Метрика

J.K. Sovetov,A.E.Kulikova,M.N.Medvedev

: Geological Society of America Special Papers
: Geological Society of America Special Papers

We discuss the Late Neoproterozoic and Vendian and Cambrian evolution of sedimentary basins and regional deposition events in the southwestern and southern margins of the Siberian craton from the Igarka region in the lower reaches of the Yenisei to the Patom Upland northeast of Lake Baikal. The deposition history between ca. 750 and 543 Ma was reconstructed using correlation of Late Neoproterozoic sediments with regard to diamictite deposited during global Sturtian and Varangerian glacials, rifting and collisional events, and eustatic sea level fluctuations. The accretionary and collisional events of 880-750 Ma were followed by the breakup of the supercontinent that included Siberia and the inception of failed rifts in the territory of the Yenisei Ridge, the Sayan and Baikal regions, and the Patom Upland. The main rifting stage was associated with the formation of the passive continental margin and high-energy tidal deposition on widespread broad shelves. The earliest Vendian (Ediacaran) was marked by the onset of another accretionary stage when marine deposition was disturbed by regional-scale continental glaciation (the Varangerian glacial epoch) and deep exaration of Late Riphean shelves. Vendian climate and tectonic events are reflected in the evolution of a peripheral foreland basin on the craton margin that went through several stages: (1) Early-Late Vendian subduction, glaciation, and then terrigenous carbonate shelf deposition (ca. 600 Ma). Subduction was accompanied by transgression of the fringing seas onto the craton and centrifugal transport of clastics. (2) Late Vendian collision and accretion, growth of bordering orogens, and continental molasse deposition (ca. 550 Ma). The collisional processes interrupted the marine deposition of the previous stage, closed the remnant marginal basins, and produced a peripheral orogen of a great extent. Deposition was on broad alluvial plains, and clastics were transported centripetally. (3) Late Vendian-Early Cambrian rifting and subsidence of a hangingwall clastic basin (ca. 543 Ma). Plate reorganization caused extension and related rifting and doming on the craton. The hangingwall basin on the slopes of domes received clastics from new sources on the uplifted basement blocks on the craton periphery. The dispersal of the collision-accretionary collage (the Vendian Pannotia continent) was completed in the Early-Middle Cambrian by the formation of carbonate platforms and an evaporite basin
индекс в базе ИАЦ: 041959