地球与行星物理论评（中英文）2025，Vol.56Issue(6)：699-709,11.DOI:10.19975/j.dqyxx.2025-030
墨脱断裂带背崩乡段深部电性结构研究
The deep electrical structure of Motuo fault zone in Beibeng area
摘要
Abstract
To elucidate the contact relationship between Indian and Eurasian plates along the Yarlung-Zangbo suture zone(IYS)and associated geodynamic processes,we acquired a high-resolution magnetotelluric(MT)pro-file extending 20 km across the Motuo fault zone near Beibeng Township,Motuo County,eastern Xizang.This NW-SE oriented transect employed 30 MT stations with approximately 300-m spacing,covering frequency bands of 10000-0.0001 Hz to resolve crustal structure down to 30 km depth.Key findings from the electrical resistivity model reveal:(1)At shallow crustal levels(<5 km depth),the Motuo fault system exhibits a negative flower struc-ture characterized by downward-converging conductive shear zones,diagnostic of dominant strike-slip deforma-tion.(2)Preservation of Indian slab subduction traces beneath the Lhasa Block along the IYS,with possible deve-lopment of a pop-up structure in the Indian upper crust near the eastern Himalayan syntaxis.(3)The resistive Lhasa Terrane upper crust is～20 km thick-33％thinner than the 30-km average in southern Xizang.This disparity im-plies either:(ⅰ)incomplete syn-collisional crustal shortening due to strain partitioning into strike-slip faults,or(ⅱ)absence of crustal growth episodes that thickened the Lhasa Terrane.(4)A mid-crustal conductor at 15-30 km depth aligns with the suture zone.Its upward-flaring geometry indicates southward migration of melts from the Lhasa lower crust,which is facilitated by transpressional uplift along the IYS.These results demonstrate that the Motuo fault system operates as a crustal-scale transfer zone,where strike-slip kinematics preserve early collisional features while enabling melt migration through reactivated suture structures.The integrated model provides new constraints on strain accommodation mechanisms during continental indentation.关键词
雅鲁藏布江缝合带/墨脱断裂带/大地电磁测深/内部结构Key words
Yarlung-Zangbo suture zone/Motuo fault zone/magnetotelluric/structural framework分类
天文与地球科学引用本文复制引用
王刚,张翔,常小鹏,葛欣旺,野柳帅,方慧,裴发根,肖都,张小博,张耀阳,彭炎,白大为,乔汉青..墨脱断裂带背崩乡段深部电性结构研究[J].地球与行星物理论评（中英文）,2025,56(6):699-709,11.基金项目
中国地质调查局地质调查资助项目(DD20250102801,DD20240101902) （DD20250102801,DD20240101902）
华北—东北大地电磁子网一期(2024ZD1000203-06) （2024ZD1000203-06）
国家自然科学基金资助项目(41804075)Supported by the China Geological Survey(Grant Nos.DD20250102801,DD20240101902),China Magnetotelluric Array(Grant No.2024ZD1000203-06)and the National Natural Science Foundation of China(Grant No.41804075) （41804075）
