The structure and depositional environments of Mesoproterozoic petroliferous carbonate complexes in the western Siberian craton

Abstract

On the basis of available sedimentological, isotope-geochemical, and geophysical data, we have refined the intrabasinal correlation and thestructure of Mesoproterozoic deposits of the Baikit anteclise. A pre-Vendian section was stripped within the Baikit anteclise, which can becorrelated with the section of the Mesoproterozoic Teya and Sukhoi Pit (pre-Pogoryui) Groups of the Yenisei Ridge. Most of the overlyingdeposits of the Tungusik Group were destroyed during the tectonic events in the Early Neoproterozoic (~860 Ma) and in pre-Vendian time.Using the results obtained, we have refined the variations in the sedimentation environments of Mesoproterozoic deposits in the Baikit antecliseand Yenisei Ridge and constructed paleogeographic schemes for particular time intervals in the modern frame of references. The predominanceof peritidal complexes and numerous signs of subaerial exposition indicate that the carbonate accumulation was periodically interrupted. Inthe periods (sometimes, long) when this process stopped, fine silicoclastic material transited from the shelf edge into a deep basin localizedsouthwest of the Baikit anteclise. The longest transition periods were in Early Yurubchen, Dolgokta, and Late Vingol’da time, though themain flow supplying silicoclastic material to the Yenisei Ridge passed south of the Baikit carbonate shelf. In the Mesoproterozoic, the basinwith predominantly carbonate sedimentation occupied a vast area in the western Siberian Platform, extending to the western margin of theAnabar Shield, where the Mesoproterozoic deposits were similar in structure and isotope-geochronological and isotope-geochemicalcharacteristics to the pre-Vendian deposits of the Baikit anteclise. Most part of the area with carbonate sedimentation in the Baikit anteclisewas remote from the shelf edge. The Mesoproterozoic shelf was much wider than its fragments in the recent structure on the western marginof the Siberian craton.