Recent data on the paleogeography of the Early Carboniferous of the Minusinsk Depression

The paper deals with results of the sections correlation within the Lower Carboniferous deposits of the Bystryanskaya Suite of the Minusinsk Trough (Yuzhno-Minusinskaya, Sydo-Yerbinskaya, Severo-Minusinskaya and Nazarovskaya Depressions) by data of the field investigation and also from plant fossil remains collected by the author in 2012-2013, along with the data reported by other authors [2, 4, 5]. The occurrence and change in the thickness of carbonate rocks, structure of sections, composition and stratigraphic confinement of plant remains are analyzed. The Early Bystryanskian transgression was indicated to approach not only from the northern part of the trough from the side of the Kolyvan'-Tomsk region, as it was reported by Mogilyov [12], but also from the south-western part of the Yuzhno-Minusinskaya Depression, presumably from the southern side of the Kuznetsk Basin. This is indicated by reduced carbonate thickness up to its complete disappearance in the direction from the southeast of the Yuzhno-Minusinskaya Depression to its central and northern parts in the Lower Bystryanskian deposits. The greatest thickness of the bottom part of the suite is recorded in the southwest of the Yuzhno-Minusinskaya Depression and seems to be connected with the greatest subsidence of this territory in the Early Bystryan-skian time. The maximum subsidence in the Severo-Minusinskaya Depression was suffered by its north-western part; in the Nazarovskaya Depression it is its south-western part. In the Middle Bystryanskian Time, the connection of the Yuzhno-Minusinskaya Depression with the sea basin became disrupt due to the uplift of its south-western part. In the Nazarovskaya and Severo-Minusinskaya Depressions, on the contrary, the transgression intensifies. In the late Bystryanskian time, the territory of the Yuzhno-Minusinskaya depression represented predominantly an accumulation plain divided by a network of moderate inner uplifts. The northern part of the depression in its turn suffered the greatest subsidence. In this time territories of the Severo-Minusinskaya and Nazarovskaya Depressions were situated closer to the Kolyvan-Tomsk Sea and represented deltas sometimes changed by lagoons. The distribution of the fossil vegetation localities throughout the top of the Bystryanskaya Suite and their confinement to certain facies indicate that the Kolyvan-Tomsk Sea exerted influence on the vegetal complex composition in the Late Bystryanskian Time. In northern depressions occurring nearer to the sea, the vegetal complexes are dominated by Cyclostigma kiltorkense Haughton. In the Yuzhno-Minusinskaya Depression lying remote from the sea Pseudolepidodendropsis carneggianum (Heer) Schweitzer predominates.

Keywords

Authors

References