On the nature of transversal zonation in the Ural fold belt

Research subject. The transverse (sub-latitudinal) structures of the sub-meridional Ural fold belt. Aim . To clarify the nature and age of the transverse structures and their metallogenic significance. Methods and materials . The analysis of geological, tectonic, and structural data on the sub-latitudinal structures throughout the Urals was performed. Results . The current knowledge of the transverse structures of the Urals has been reviewed and generalized. In the West Mugodzhar volcanic zone and the Irgiz synclinorium of the Mugodzhars, geological complexes corresponding to the deeper levels of the Magnitogorsk megasynclinoorium were brought to the Earth’s surface. Such exposure could only have resulted from a vertical uplift of approximately 5–8 km followed by erosion of Paleozoic rocks in the Mugodzhars. In the western sector of the Urals, the structural pattern differs markedly from that in the eastern sector. Here, beginning in the south – where the influence of the Caspian Depression is already pronounced – a gradual northward uplift is observed. This is accompanied by the progressive exposure, at the present-day erosion level, of increasingly ancient complexes, transitioning from sedimentary rocks in the south to metamorphic rocks in the northern part of the Southern Urals. The amplitude of uplift in these metamorphic complexes reaches at least 12 km. Thus, the vertical movements that caused the observed sublatitudinal zonation of the Urals in the south occurred in different directions in its western and eastern sectors. Conclusions . The observed lateral zonation of the Urals is primarily controlled by variations in the present-day depth of erosion across different regions. These variations, in turn, reflect differences in the rates and magnitudes of post-Paleozoic uplift, most notably during the Middle and Late Triassic. Consequently, lateral zonation is only indirectly related to the formation of pre-Mesozoic mineral resources in the region. Nevertheless, understanding the depth of erosion in different parts of the Urals is essential for metallogenic assessments. For younger mineral resources, such as hydrocarbons (oil and gas) and placer deposits, sub-latitudinal zonation plays a decisive role.