Whether the central metamorphic belt of the Qiangtang terrane in the Qinghai-Tibet Plateau should be attributed to a suture zone, is still heavily debated, due to inadequate deep structure constraints. Using the data collected from 16 stations in the northern part of the Hi-Climb profile and 16 broadband seismic stations recently arranged in the northern part of Gaize County, this study developed a broadband seismic profile running through the in-situ Central Qiangtang Metamorphic Belt (CQMB) roughly along 84.5°E. Significantly characteristics of the crust and mantle structure beneath the profile were obtained through P-wave receiver function analyses: (i) The south Qiangtang terrane has a complex Moho structure at depth 56–82 km, while the north Qiangtang terrane has a nearly horizontal Moho at depth approximately 62 km. Moreover, the northward-inclining Moho is noticeably dislocated with a maximum offset of approximately 18 km under the CQMB. (ii) The crustal low-velocity zones on both sides of the CQMB are transversely discontinuous and are also distinct from each other. (iii) A northward-subducting interface occurs beneath the in-situ CQMB (34.0°N–34.5° N). Based on the geological outcrops and their petrological analysis, the structural characteristics beneath the CQMB are interpreted as the traces of the Longmucuo-Shuanghu suture zone, which was formed by the northward subduction-collision of the south Qiangtang terrane left after the closure of the Paleo-Tethys Ocean at the end of the Triassic.

中文翻译：

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藏西中部羌塘变质带原位作为典型缝合带：P波接收函数分析的壳幔构造足迹证据

由于深部构造约束不足，青藏高原羌塘地体中央变质带是否属于缝合带仍存在争议。利用Hi-Climb剖面北部16个台站和改则县北部近期布设的16个宽带地震台站资料，建立了原位穿过羌塘中部变质带的宽带地震剖面（ CQMB）大约沿 84.5°E。通过纵波接收函数分析，得到了剖面下方地壳、地幔结构的显着特征：(i)南羌塘地体在深度56~82 km处具有复杂的莫霍面结构，北羌塘地体在深度56~82 km处具有近水平的莫霍面结构。深度约62公里。此外，北倾莫霍面在 CQMB 下方明显错位，最大偏移量约为 18 km。 (ii) CQMB 两侧的地壳低速区横向不连续且彼此明显。 (iii) 向北俯冲界面出现在原位 CQMB (34.0°N–34.5°N) 下方。根据地质露头和岩石学分析，将中山盆地下方的构造特征解释为龙木措-双湖缝合带的痕迹，该缝合带是古地体闭合后留下的南羌塘地体向北俯冲碰撞形成的。 -三叠纪末期的特提斯洋。