Paragenetic analysis of the recent fault network in Central Altai

Geomorphological survey revealed a network of the recently active faults that control the formation of main features of the modern relief in the central part of the Altai Mountains. A paragenetic analysis of the identified latest faults has been performed. The result of the paragenetic analysis with reconstruction of three stress fields turned out to satisfy the formal reliability criteria. In general, the results of the paragenetic analysis confirm the preliminary conclusion about the formation of the fault network of the Central Altai in three dynamic settings made after the implementation of the first stage. They made it possible to construct schemes of faults active in each of the three reconstructed stress fields. Judging by the results of the analysis, the rock massif of the central part of the Altai Mountains is at the third stage of destruction, when individual faults are connected into a complete fault network with a characteristic structural pattern, and the earth’s crust is broken into a system of blocks contacting along faults. The block subdivision of the Central Altai is formed by a system of faults forming an ensemble of a right-lateral strike-slip dislocation. As the scale of the studies increases, the number of identified faults increases as well. On the regional neotectonics maps of 1:1,000,000 scale only major ridges and depressions are expressed in the relief as boundaries of large blocks. A network of faults outlining blocks within the ridges and depressions is identified on neotectonic maps of 1:50,000 scale. In the central part of the Altai Mountains, the fault network follows the lower-level hierarchical structural patterns and orographic structure of the Greater Altai, e. g., northwestern right-lateral strike-slip faults, sublatitudinal reverse faults, and extension zones with a predominant submeridional extension. Paragenetic analysis resulted in a reliable reconstruction of the kinematic characteristics of the most recent faults of the Central Altai based on their position in the structural ensemble. The obtained schemes and settings of the recent faults can serve as a foundation for further discussion about the nature and mechanisms of crustal destruction in the region using seismological, GPS-geodetic and other materials.

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