Sergei Frolov

Tectonic evolution of the Siberian Platform during the Vendian and Phanerozoic

This paper presents characteristics of the structural regions surrounding the Siberian Platform and discusses the Vendian-present time evolution of the Siberian Paleocontinent with the Siberian Craton making up its nucleus. It shows that the paleocontinent underwent significant intraplate compressional deformations with vertical movements and formation of inversion structural features within broad areas. Such epochs of deformation took place at the Riphean-Vendian time boundary, during the Late Paleozoic, Late Triassic, Early Cretaceous, and during the Late Cenozoic. The principal rifting events took place during the Middle-Late Devonian. The paper presents paleotectonic reconstructions of East Siberia at several key time intervals.

Sills and gas generation in the Siberian Traps

On its way to the surface, the Siberian Traps magma created a complex sub-volcanic plumbing system. This resulted in a large-scale sill emplacement within the Tunguska Basin and subsequent release of sediment-derived volatiles during contact metamorphism. The distribution of sills and the released sediment-stored gas volume is, however, poorly constrained. In this paper, results from a study of nearly 300 deep boreholes intersecting sills are presented. The results show that sills with thicknesses above 100 m are abundant throughout the upper part of the sedimentary succession. A high proportion of the sills was emplaced within the Cambrian evaporites with average thicknesses in the 115–130 m range and a maximum thickness of 428 m. Thermal modelling of the cooling of the sills shows that the contact metamorphic aureoles are capable of generating 52–80 tonnes of CO2 m−2 with contributions from both marine and terrestrial carbon. When up-scaling these borehole results, an area of 12–19 000 km2 is required to generate 1000 Gt CO2. This represents only 0.7–1.2% of the total area in the Tunguska Basin affected by sills, emphasizing the importance of metamorphic gas generation in the Siberian Traps. These results strengthen the hypothesis of a sub-volcanic trigger and driver for the environmental perturbations during the End-Permian crisis. This article is part of a discussion meeting issue ‘Hyperthermals: rapid and extreme global warming in our geological past’.

Late Vendian-Early Cambrian formations of the north-west Siberian Craton

The composition and structure of principal key-sections for the Tira (Late Vendian) and Danilovo (Late Vendian-Early Cambrian) Horizons were characterized on the basis of deep-drilling data and studies of natural outcrops along the peripheries of the Kureika syneclise. The typical sedimentary formations/associations were recognized, their vertical and lateral successions were distinguished, and their deposition environments were interpreted. A distribution pattern scheme of thicknesses and depositional environments of Upper Vendian-Lower Cambrian deposits was compiled at the 1: 1000000 scale. The reservoir characteristics of the formations are discussed and forecasted for poorly studied areas of the northwestern Siberian platform.

Neoproterozoic and Lower Cambrian Rock Complexes in Central Areas of the Siberian Craton: Their Structure and Petroleum Prospects

The paper summarizes data on the geology, lithology, and geochemistry of petroliferous Riphean, Vendian, and Lower Cambrian rocks in the central parts of the Siberian Craton. The petrological-geological properties of these sediments have been assessed based on results of paleogeographic analysis of these rocks, discrimination of oil reservoirs and oil-source successions, determination of secondary alterations of the rocks, and sources of oil generation and regional migration of hydrocarbons into various traps in zones of possible oiland-gas accumulation.

Geology and petroleum potential of the upper proterozoic basins of northern siberian craton

In spite of insufficient geological and geophysical knowledge of upper Proterozoic formations in the north of Siberian platform there were several large sedimentary paleobasins. Part of them (for example, Anabar-Kureika and Udza basins) were intracratonic, another part of basins (for example, Turukhansk) were formed on the ancient continental margin. The data analysis of seismic surveys allows to suppose that these basins were the part of similar basins of central platform areas. There are several Riphean source rocks at the different stratigraphic levels. Meanwhile the Lower-Middle source rocks have realized of their hydrocarbon potential in quite a number of cases at the end of Riphean. These hydrocarbon accumulations most probably were destroyed during Baikalian tectonic processes. Maximum of Upper Riphean source rocks hydrocarbon generation was in Palaeozoic. It is the rocks which contribute to formation of oil-and-gas accumulation well preserved up to the present moment. The most intensive Vendian sedimentation occurred in the central part of Kureika syneclise area. Discovery hydrocarbon potential first of all refers to sides of syneclise near the slopes of Anabar and Baikit anteclises. We assume that Lower Vendian deltaic and coastal marine sandy bodies are present within these areas

Riphean Petroleum Systems of The Western Part of Siberian Platform

After discoveries of large oil-and-gas fields within Yuribchen-Tokhoma Zone the Riphean deposits are considered as a promising object for an exploration. The rocks are quite widespread and probably have been deposited within several anisochronous basins. During pre-Vendian these deposits have undergone irregular erosion and deformations, which have occurred at western periphery of the platform to larger extent. This period has effaced a significant volume of Riphean sediments and has complicated their distribution as well as during this time a majority of already formed hydrocarbon accumulations have been obliterated. Source rocks are known at various levels within each basin. According to basin oil-and-gas formation modeling, the Upper Riphean source rocks had to make the biggest contribution to formation of recently present fields. Their maximum hydrocarbon generation shall be attributed to Early - Middle Paleozoic. Riphean reservoirs are placed in weathering crust of carbonates and have been formed under favourable combination of tectonic and lithological factors.