Neotectonic Stress State of the Chuya–Kurai Depression and Adjacent Structures (Southeastern Altai Mountains)

IF 0.3 Q4 GEOCHEMISTRY & GEOPHYSICS Seismic Instruments Pub Date : 2023-03-21 DOI:10.3103/S0747923922080096

A. V. Marinin, L. A. Sim, E. A. Manuilova, I. V. Bondar, N. A. Gordeev

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Abstract

A set of tectonophysical methods has been applied to reconstruct the neotectonic stresses of the southeastern Altai Mountains within the Chuya–Kurai depression and its framing structures. It is suggested that at the neotectonic stage, the tectonic structures of the Altai Mountains underwent a transformation of geodynamic conditions—a situation of sublatitudinal horizontal compression with predominant reverse-fault and transpressional movements along faults that existed up to the Neogene was replaced by horizontal shear conditions with a NNE and NE subhorizontal compression axis and WNW and NW extension axis. With such a stress field, the dominant NW-trending faults in this territory are mainly characterized by dextral strike-slip displacements, and NE-trending faults, by sinistral. Submeridionally trending faults that formed at the neotectonic stage show clear signs of extensional structures. A feature of the faults of the Chuya–Kurai depression according to these studies is a fairly small number of megafractures (indicators of shear displacements) in shear zones. This indicates dominant reverse-fault and transpressional movements over large disjunctive structures in the region in the Paleozoic and Mesozoic versus neotectonic shear movements. The results of the research are of practical importance in studying the regional seismicity.

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阿尔泰山东南部Chuya-Kurai坳陷及其邻近构造的新构造应力状态

应用构造物理方法重建了阿尔泰山脉东南部楚亚-库莱坳陷及其框架构造的新构造应力。在新构造阶段，阿尔泰山脉的构造构造经历了地球动力学条件的转变，由原来存在于新近纪的以逆断层和逆断层运动为主的亚垂直水平挤压状态，转变为以北北东向和北北东向亚水平挤压轴和西北西向和北西向伸展轴为主的水平剪切状态。在这样的应力场下，本区北西向断裂以左旋走滑为主，北东向断裂以左旋走滑为主。新构造期形成的潜向断裂具有明显的伸展构造特征。根据这些研究，Chuya-Kurai坳陷断层的一个特征是在剪切带中有相当少量的巨型裂缝(剪切位移的标志)。这表明该地区古生代和中生代主要是逆断层和跨挤压运动，而不是新构造剪切运动。研究结果对研究区域地震活动性具有实际意义。

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来源期刊

Seismic Instruments GEOCHEMISTRY & GEOPHYSICS-

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期刊介绍： Seismic Instruments is a journal devoted to the description of geophysical instruments used in seismic research. In addition to covering the actual instruments for registering seismic waves, substantial room is devoted to solving instrumental-methodological problems of geophysical monitoring, applying various methods that are used to search for earthquake precursors, to studying earthquake nucleation processes and to monitoring natural and technogenous processes. The description of the construction, working elements, and technical characteristics of the instruments, as well as some results of implementation of the instruments and interpretation of the results are given. Attention is paid to seismic monitoring data and earthquake catalog quality Analysis.