Stratigraphy of Vendian terrigenous deposits in the northeast of the Nepa–Botuobiya Anteclise

Lebedev, M. V.; Моисеев, С. А.; Топешко, В А; Fomin, A. N.

doi:10.1016/j.rgg.2014.05.012

Cited by 4 publications

(1 citation statement)

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“…There are no matching structural patterns of the Riphean and Ediacaran complexes [12]. However, clastic rocks can also be found near the unconformity between the Ediacaran and Riphean, often being represented by sandstone and siltstone layers belonging to the Nepa, Tira, and Byuk horizons in the Nepa-Botuoba region and similar clastic formations occurring in the neighboring regions [16]. These sandy layers can contain petroleum reservoirs with good porosity and permeability (P&P) properties, but, in most cases, they have a high content of anhydrite and dolomite interstitial cement (reaching up to 15-20%) formed as a result of post-sedimentary alteration of the rocks [17].…”

Section: Geological Settingmentioning

confidence: 97%

Ancient Aeolian Reservoirs of the East Siberia Craton

Shaldybin,

Kvachko,

Rudmin

et al. 2023

Geosciences

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Fine-grained strata deposited on the Eastern Siberian craton are predominantly considered to mainly consist of Neoproterozoic sandstones. Clastic rocks near the unconformity border of the Ediacaran and the Riphean are represented by sandstone and siltstone layers with thicknesses of several tens of meters, belonging to the Nepa, Tira, and Byuk horizons in the Nepa–Botuoba region. These Neoproterozoic sandstones have features characteristic of aeolianites formed under the action of high wind velocity in the Ediacaran period. Sandstone samples near the Riphean–Ediacaran boundary were collected from five deep wells and characterized for granulometry and mineral composition using optical microscopy, XRD, SEM, and ICP-MS techniques. These sandstones have a high proportion of quartz (60–98%) with minor amounts of feldspars, carbonate, and sulfate cements. Thin sections of the sandy rocks feature bimodal distributions of the grains throughout many sections, with large well-rounded quartz grains being several orders of magnitude greater than the silt matrix grains. The monomineralic quartz rocks have an overgrowth of quartz grains. These rocks can be petroleum reservoirs with good porosity and permeability, but in most of the studied intervals, a high content of anhydrite and dolomite interstitial cement significantly reduces both. The porosity of the rocks is low, while the permeability is very low, which may be associated with a significant amount of clay and cement material. Aeolianites normally contain large amounts of bimodal quartz (due to its high stability and resistance to weathering) and possess the presence of heavy minerals.

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Section: Geological Settingmentioning

confidence: 97%

Ancient Aeolian Reservoirs of the East Siberia Craton

Shaldybin,

Kvachko,

Rudmin

et al. 2023

Geosciences

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C and Sr isotope chemostratigraphy of Vendian–Lower Cambrian carbonate sequences in the central Siberian Platform

Кочнев

Pokrovsky

Кузнецов

et al. 2018

Russian Geology and Geophysics

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We propose a detailed δ13C curve for the Vendian and Lower Cambrian (Tommotian) strata of the central Siberian Platform. Two positive carbon isotope excursions identified near the base of the Yuryakh Formation (up to 5.5‰) and in the lower Bilir Formation (up to 5‰) are assigned to the lowermost and middle Tommotian, respectively. This correlation is supported by paleontological data, specific 87Sr/86Sr values (0.70845–0.70856), and similar C isotope record in coeval Early Cambrian basins. The documented minor vertical oscillations (a few meters) of these isotope excursions relative to the formation boundaries in remote boreholes is presumably caused by the spatiotemporal migration of facies. A high-amplitude negative δ13C excursion (–8 to –11‰) in the upper Nepa Regional Stage putatively corresponds to the global Shuram–Wonoka negative carbon isotope excursion (Middle Ediacaran). Carbonates of the lower Nepa Regional Stage (Besyuryakh Formation) demonstrate positive δ13C values (up to 5‰) and minimum 87Sr/86Sr ratios of 0.70796–0.70832. The C and Sr isotope record of the Nepa Regional Stage provides its robust correlation with the Dal’nyaya Taiga and Zhuya Groups of the Patom Foredeep. Micropaleontological data herein reported and glacial diamictites documented at the base of the Vendian sedimentary cover both in the central Patom Foredeep and on its periphery suggest a full stratigraphic volume of the Ediacaran System in the most stratigraphically complete sections of the central Siberian Platform.

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Stratigraphic Structure of the Vendian Oil and Gas Complex of the Southern Oil and Gas Regions of the Lena–Tunguska Province of the Siberian Platform

Mel’nikov

2024

Russian Geology and Geophysics

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—The Vendian oil and gas complex (OGC) consists of the Vilyuchan, Nepa, and Tira stratigraphic horizons. The horizons are divided into correlation layers, stratigraphic charts are refined, cyclometric stratigraphic charts of oil and gas-bearing areas of the southern part of the Lena–Tunguska province are constructed. The lower boundary of the Vendian oil and gas complex and the base of the Vendian system are established in the Nuj zone of the Nepa–Botuoba and Irkutsk zones of the Angara–Lena oil and gas region (OGR) at the end of the pre-Vendian break in sedimentation. In the Angara–Lena OGR, the Typta Formation lies after a break both on different formations of the Baikalian system, and on the basement, and it is covered by sandstones of the Vendian Nepa horizon. The Typta Formation is assigned to the Vendian system, to the Vilyuchan horizon. In the Nepa–Botuoba OGR, a long pre-Vendian break divided the Talakan Formation into an upper Vendian and a lower Riphean parts. The name Talakan is left for the Vendian strata, the lower part is divided into three strata of the Baikalian system. The cyclometric stratigraphic scale is based on repetitions of cyclically constructed sections of horizons and their parts. Repetitions are considered as the result of oscillatory movements of the Earth, which take place at different intervals of time. The ranks of movements are planetary (40 Myr), long-period (20 Myr), and regional. In these ranks of time, nexacylites, horizons and regocyclites were formed. The horizons linked the regional and cyclometric stratigraphic scales. Breaks in the sedimentation of the Vendian OGC are divided by duration into short-term separating regocyclites, long-term separating horizons and two breaks – pre-Vendian and pre-Danilovo, the duration of which reaches 10–20 Myr.

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Stratigraphy of Vendian terrigenous deposits in the northeast of the Nepa–Botuobiya Anteclise

Cited by 4 publications

References 0 publications

Ancient Aeolian Reservoirs of the East Siberia Craton

Ancient Aeolian Reservoirs of the East Siberia Craton

C and Sr isotope chemostratigraphy of Vendian–Lower Cambrian carbonate sequences in the central Siberian Platform

Stratigraphic Structure of the Vendian Oil and Gas Complex of the Southern Oil and Gas Regions of the Lena–Tunguska Province of the Siberian Platform

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