东向追踪龙木错-双湖缝合带延伸轨迹

The Tibetan Plateau is composed of a series of complex geologic terranes sutured along EW structural boundaries. Eastward trace of Longmuco-Shuanghu suture zone in Central Qiangtang, North Tibet is still in dispute. In general, it stretches eastward on surface along Tanggula Mountain, and then connects with Changdu-Lancangjiang Suture zone in East Tibet. Conversely, its surface locus could be traced along Tumen-Gela fault and finally be truncated by BNS at Suoxian. The proposal will deploy 25broadband seismic stations in the area and will employ integrated seismic method ( Fast Marching Method Tomography, Receiver functions, Common-Converted Point stacking, Reverse Time Migration, Surface Tomography and Double-Difference Tomography ) to capture deep structure and to identify surface locus to be traced eastward, further to recognize tectonic assembles of Tibet. Meanwhile, tectonic affinity of Amdo metamorphic complex (also named Amdo basement rocks) will be distinguished to helpfully notify what happened in closure of Bangong-Nujiang Ocean in Late Jurassic.

青藏高原是由多期次的地体拼合而成。其中之一的龙木错－双湖缝合带东向延伸的地表形迹在安多－唐古拉山－莫云-索县－安多区域产生了激烈争论。普遍认为其沿着唐古拉山向东与昌都－澜沧江缝合带相连，相反观点则认为其经土门格拉断裂终止于班公湖－怒江缝合带。这直接影响到了高原内部一级地体单元的划分。为此，本项目将在该争议区域内布置25台宽频带地震观测仪，连续观测18个月，收集记录着深部结构的天然地震事件波形数据，通过多种地震学方法反演区域下的深部结构特征来甄别追踪龙木错－双湖缝合带的东向延伸轨迹，厘清青藏高原一级构造单元组成，并进而从深部结构特征上识别安多变质核杂岩（或基底）的构造归属，有助于班公湖怒江缝合带演化机制认识统一。

青藏高原是由多期次的地体拼合而成。其中之一的龙木错－双湖缝合带东向延伸的地表形迹在安多－唐古拉山－莫云-索县－安多区域产生了激烈争论。普遍认为其沿着唐古拉山向东与昌都－澜沧江缝合带相连，相反观点则认为其经土门格拉断裂终止于班公湖－怒江缝合带。这直接影响到了高原内部一级地体单元的划分。.本项目将在该争议区域内布置42台宽频带地震观测仪，收集记录着深部结构的天然地震事件波形数据，通过接收函数分析（H-k叠加、一维速度反演）和噪音层析成像联合反演技术初步获取了龙木措-双湖缝合带东向延伸位置，即南羌塘地体具有完整的深部结构特征，其向北俯冲的前缘位于雁石坪南约10km，由此确认了龙木措-双湖-雁石坪南10km-昌都-澜沧江相连。此外，安多增生杂岩具有稳定的独立的高速异常的地壳结构特征，表明安多变质核杂岩是一个微陆块。