Upper Devonian and Lower Carboniferous (Tournaisian) sequence stratigraphy of the Yuzhno-Minusinskaya depression

The zoning of the Upper Devonian and Lower Carboniferous sections of the Yuzhno-Minusinskaya depression has been performed with the use of the sequence stratigraphy method. The Upper Devonian section of the Yuzhno-Minusinskaya Depression is subdivided into two sequences. The basement of the first sequence is the lowstand system tract (LST) corresponding to the volume of the Oidanovskaya suite and characterizing the regression maximum. The tract is composed of terrigenous red deposits. They are replaced by the Kokhaiskaya suite representing the highstand system tract (HST). Its composition differs from that of the underlying tract by the presence of terrigenous-carbonate and carbonate rocks in the section. The volume of the second sequence coincides with the red Tubinskaya suite being LST and formed in the result of the depression territory uplift followed by regression. The lithological characteristic of the suite is similar to that of the Oidanovskaya suite. The Lower Carboniferous (Tournaisian) section of the Yuzhno-Minusinskaya depression is subdivided into three sequences. The first sequence persists as a single tract (HST) in the result of the pre-Carboniferous hiatus and includes the lower and middle parts of the Bystryanskaya suite. These parts are composed of the terrigenous-carbonate unconformable rocks on the washed out surface of the Upper Devonian deposits. The second sequence includes the upper part of the Bystryanskaya suite, the Altaiskaya and Ka-myshtinskaya suites. To its bottom, the tract (LST) is confined, including the top of the Bystryanskaya suite and the lower part of the Altaiskaya suite which are composed of predominating terrigenous deposits. The lower Altaiskian deposits correspond to the maximum regression. Meanwhile, the upper Altaiskian deposits are characterized by the sediment transgressive type (TT) composed mainly of fine-grained sandstones, siltstones, claystones and silicified limestones. The third sequence corresponds to the interval from the Samokhvalskaya to Solomenskaya suites. The basement of this sequence is the terrigenous Samokhvalskaya suite (LST) composed of medium- and coarse-grained sandstones, siltstones and more rarely claystones. It is replaced by the thick Krivinskaya suite composed by the monotonous alternation of fine-grained sandstones, tuffaceous sandstones, siltstones, claystones and rare limestone interbeds. As opposed to the Samokhvalskaya suite, deposits of the Krivinskaya suite are predominantly more fine-grained and characterized by the enhanced carbonate content. On this basis, the deposits of this suite are assigned to the beginning of a new transgression (TT). Its maximum falls on the Solomenskaya suite (HST), the structure of which is very similar to that of the Ka-myshtinskaya suite.

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