Activity stages and tectonic division in the Kuznetsk Basin,Southern Siberia

The fault system reflected in the topography and structure of Cenozoic cover sediments in the Kuznetsk Basin is mostly recent. The positions of recent faults match those of Paleozoic and Mesozoic disjunctive dislocations only at the Kuznetsk Alatau and the Salair Range boundaries. These marginal features are associated with the greatest amplitudes of vertical movements in recent time: 80–100 m; less frequently, up to 250 m in the north and within 600 m in the south. The recent disjunctive dislocations are generally fractured zones from 300 to 2000 m in width, which were occupied by watercourses during the formation of the erosion valley system. Except for marginal recent tectonic bodies, vertical movements along the majority of recent faults do not exceed 5–10 m, reaching 30–70 m at the boundaries of recent tectonic regions and subregions. There is no reliable evidence of notable horizontal movements. For particular bodies, it is conjectured to be within 300–700 m by analogy with other regions of the Altai–Sayan folded area.The recent fault pattern can be interpreted as a result of crushing by submeridional compression with a slight right slip. The types of recent tectonic activity are different in different areas of the depression. The smallest uplift is recorded in the north of the basin, where the elevations of the Late Cretaceous peneplain are within 300 m, being within 230–250 m in the near-Salair subregion. This points to an insignificant downwarping in this area. Vertical movements along recent faults within the region are small, and the most intense movements are at its boundary. The central region is slightly elevated with reference to the northern one, and the elevation of its planation surface is within 300–380 m. It is characterized by differentiated movements along block boundaries with amplitudes reaching 60–70 m. The maximum activity occurred in the southern region. The elevations of its Late Cretaceous peneplain vary from 400 to 600 m. This region is characterized by notable vertical movements along block boundaries in the form of straight tectonic scarps and valleys. The northern and central regions constitute the present-day Kuznetsk intermontane depression, whereas the southern region belongs to the periphery of the mountainous framing of the Kuznetsk Depression.