Active Faults of Northern Central Mongolia, Their Correlation with Neotectonics and Deep Structure of the Region

IF 1 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Geotectonics Pub Date : 2024-08-23 DOI:10.1134/s0016852124700109

V. G. Trifonov, S. A. Sokolov, A. N. Ovsyuchenko, S. Yu. Sokolov, Ts. Batsaikhan, S. Demberel, Yu. V. Butanaev, N. G. Koshevoy

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Abstract

The active tectonics of northern Central Mongolia is studied between two largest W–E-trending left lateral fault zones: the Khangai Fault and the Tunka–Mondy. These strike-slip zones are part of a single ensemble of active faults in the Mongol–Baikal region, formed under conditions of maximum northeastern compression and maximum northwestern extension. Their ENE-trending Erzin–Agardag and Tsetserleg faults with a dominant sinistral component extend between these zones. A series of the N-trending graben basins (Busiyngol, Darkhat, and Khubsugul) are located between the eastern end of the Erzin–Agardag strike-slip fault and the western part of the Tunka–Mondy strike-slip zone. The basins form a sinistral deformation zone, which is kinematically similar with the strike-slip faults, which follow the latter. In contrast to the largest boundary strike-slip faults, this structural paragenesis formed under conditions of N–S-trending relative compression and N–S-trending extension. A change in the orientation of the axes of the principal normal stress may be caused by the rotation of the block between the boundary faults. The area of graben-shaped basins is located above the top of a vast volume of low-velocity mantle, which we have identified as the Khangai plume. The lithospheric mantle above this rise is reduced; the remaining part of the lithosphere is heated and softened. The large active strike-slip faults are located above areas of subsidence of the low-velocity top of the mantle. Our trenching of the active faults showed that strong earthquakes repeated in the area of graben-shaped basins more often than in the large strike-slip zones, but they were characterized by lower magnitudes.

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蒙古中北部的活动断层及其与新构造运动和该地区深部结构的相关性

摘要对蒙古中北部两个最大的 W-E 走向左侧断层带：康盖断层和通卡-蒙地断层之间的活动构造进行了研究。这些走向滑动带是蒙古-贝加尔湖地区活动断层群的一部分，是在最大东北压缩和最大西北伸展条件下形成的。其ENE走向的Erzin-Agardag断层和Tsetserleg断层在这些断层带之间延伸，具有主要的正弦成分。一系列 N 向地堑盆地（Busiyngol、Darkhat 和 Khubsugul）位于 Erzin-Agardag 走向滑动断层的东端和 Tunka-Mondy 走向滑动带的西部之间。这些盆地形成了一个正弦变形带，在运动学上与沿后者的走向滑动断层相似。与最大边界走向滑动断层不同的是，这种结构副成因是在 N-S 向相对压缩和 N-S 向延伸的条件下形成的。边界断层之间的岩块旋转可能导致主法向应力轴线方向的改变。地堑状盆地区域位于一个巨大的低速地幔体顶部的上方，我们将其确定为康盖羽流。该隆起上方的岩石圈地幔被压缩；岩石圈的剩余部分被加热并软化。大型活动走向滑动断层位于低速地幔顶部下沉区域的上方。我们对活动断层的挖掘表明，在地堑形盆地区域重复发生强震的频率高于大型走向滑动带，但其特点是震级较低。

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来源期刊

Geotectonics 地学-地球化学与地球物理

CiteScore

1.90

自引率

9.10%

发文量

审稿时长

3 months

期刊介绍： Geotectonics publishes articles on general and regional tectonics, structural geology, geodynamics, and experimental tectonics and considers the relation of tectonics to the deep structure of the earth, magmatism, metamorphism, and mineral resources.