Abstract Since the Mesozoic, the Lhasa-Gangdese block has undergone several stages of tectonism-magmatism caused by the closure of the New-Tethys Ocean and the collision between the Indian and Eurasian plates, which led to the lithospheric shortening and crustal uplift. Through the careful processing and analysis of the magnetotelluric data on the eastern margin of the Lhasa-Gangdese block near 92°E, a reliable 3D electrical model was obtained to examine the relationship between the lithospheric electrical structure and geodynamics. Some conductive and resistive layers were obtained, which may be formed in some tectonic processes. The thermal model of the lithospheric uppermost mantle (75–100 km) were calculated using the Arrhenius equation and the Hashin-Shtrikman (HS) boundary condition. Combined with the terrestrial heat flow point and curie isothermal in the study area, the temperature distribution at the 30–100 km depths was calculated. The melt fractions of the mid-lower crust calculated by the classical Archie's law, pressure calculated by density and temperature at different depths can be obtained in a meantime. The resistor beneath the Tethys-Himalaya terrane represented the subduction of the Indian plate with a deep angle. The subduction of the Indian crust may not exceed the Indus-Yarlung Zangbo suture, while the Indian lithospheric mantle may not reach the Luobadui-Milashan fault. Additionally, our electrical and thermal structure indicated that the Indian lithospheric mantle probably detached from the Indian crust. Our study further discussed the underplating of the mantle-derived materials and the southern extrusion along the Main Himalaya Trust, and offered a subsidiary evidence for the possible “south-eastward crustal flow” in a local area. Finally, the relationship between the electrical structure and the deep metallogenic mechanism was briefly established.

中文翻译：

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基于三维电模型的拉萨-冈底斯带东缘深部热态及其对构造动力学的约束

摘要 中生代以来，拉萨-冈底斯地块经历了新特提斯洋闭合、印度板块与欧亚板块碰撞等几个阶段的构造作用-岩浆作用，导致岩石圈缩短和地壳隆升。通过对92°E附近拉萨-冈底斯地块东缘大地电磁数据的精心处理和分析，获得了可靠的3维电模型，用于考察岩石圈电结构与地球动力学的关系。获得了一些导电层和电阻层，它们可能在一些构造过程中形成。岩石圈最上地幔（75-100 公里）的热模型是使用 Arrhenius 方程和 Hashin-Shtrikman (HS) 边界条件计算的。结合研究区陆地热流点和居里等温线，计算了30~100 km深度的温度分布。可以同时得到经典阿尔奇定律计算的中下地壳熔体分数、不同深度密度和温度计算的压力。特提斯-喜马拉雅地体下方的电阻器代表了印度板块以大角度俯冲。印度地壳的俯冲可能不会超过印度河-雅鲁藏布江缝合带，而印度岩石圈地幔可能不会到达罗巴堆-米拉山断裂带。此外，我们的电和热结构表明印度岩石圈地幔可能与印度地壳分离。我们的研究进一步讨论了地幔衍生材料的底镀和喜马拉雅主信托的南部挤压，并为局部地区可能的“东南向地壳流动”提供了辅助证据。最后，简要建立了电性结构与深部成矿机制的关系。