Located in the southeastern Tibetan Plateau, the Jiali fault zone (JLF) is an important strike-slip fault system, which delineates the southern boundary of the south-eastward extrusion of the Tibetan Plateau. The JLF features long-recurrent seismicity and plays an important role in balancing the local stress field. However, previous geophysical studies have mostly focused on regional studies in the northwestern segment and the southeastern end of the JLF. Few geophysical studies have been conducted on the JLF segment in the Eastern Himalayan Syntaxis region. To better understand the deep structures of the JLF and to provide geophysical constraints for the regional seismicity, we propose a crustal-scale resistivity model derived from magnetotelluric profile data across the three branches (Xixingla, Puqu, and Parlung faults) of the southeastern segment of JLF. The three-dimensional electrical structure shows that the JLF is generally characterized by a series of northeast dipping features. Unlike Parlung and Puqu branches, which are currently relatively inactive, the Xixingla fault is imaged to dip steeply in the shallow part of the crust and gradually turninto a gentle dip angle in the deeper section, before ultimately converging with a low-resistivity layer in the mid-to-lower crust. As the recent seismicity shows a combination of thrusting and strike-slip mechanisms, the primary strike-slip tectonic background for the regional seismicity may be modified by the northeastward compression from the subducting Indian Plate. Combined with other geological and geophysical evidence, we suggest that the reverse thrust and strike-slip displacement of faults may jointly contribute to the combined dynamic mechanism for seismicity in this area, due to the intrusion of the Namcha Barwa metamorphic complex beneath the Lhasa terrane.

中文翻译：

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加里东南断裂带深部电气构造特征及区域地震活动


嘉里断裂带 （JLF） 位于青藏高原东南部，是重要的走滑断裂系统，划定了青藏高原东南向外延的南部边界。JLF 具有长期反复的地震活动，在平衡局部应力场方面发挥着重要作用。然而，以前的地球物理研究主要集中在 JLF 西北段和东南端的区域研究。对东喜马拉雅 Syntaxis 地区的 JLF 段进行的地球物理研究很少。为了更好地了解 JLF 的深层结构并为区域地震活动提供地球物理约束，我们提出了一个地壳尺度电阻率模型，该模型源自 JLF 东南段三个分支（Xixingla、Puqu 和 Parlung 断层）的大地磁剖面数据。三维电学结构表明，JLF 通常以一系列东北倾角特征为特征。与目前相对不活跃的 Parlung 和 Puqu 分支不同，Xixingla 断层在地壳的较浅部分被成像为陡峭的倾斜，并在较深的部分逐渐转变为平缓的倾斜角，然后最终与中下地壳中的低电阻率层汇合。由于最近的地震活动显示了逆冲和走滑机制的组合，区域地震活动的主要走滑构造背景可能会被俯冲印度板块的东北压缩所改变。 结合其他地质和地球物理证据，我们认为，由于 Namcha Barwa 变质杂岩在拉萨地表下的侵入，断层的反向逆冲和走滑位移可能共同促进了该地区地震活动的综合动力机制。