The Tethyan Himalayan tectonic belt, which is located at the forefront of the Indo-Eurasian continental collision, has various extensional detachment structures, including gneiss domes, the South Tibetan detachment system (STDS), and north-south−trending rifts (NSTRs). Gneiss domes are tectonic features of the Tethyan Himalayan belt. Previous studies have revealed significant differences in the formation mechanisms and mineral enrichment patterns of North Himalayan gneiss domes, suggesting that their formation was affected by multiple tectonic processes, such as magmatic activity and extensional detachment. However, the mechanisms responsible for these differences and the relationship between shallow and deep structures remain poorly understood. In this study, we used short-period seismic array data from the eastern and western segments of the Tethyan Himalayan belt for analysis. We applied ambient noise tomography and incorporated constraints from deep seismic reflection data to conduct upper crustal imaging of the gneiss domes across the eastern and western regions. Our findings indicate the following: (1) distinct seismic velocity patterns reveal low-velocity channels beneath the Cuonadong (CND) and Malashan (MLS) domes, contrasting with the high-velocity anomalies under the Yalaxiangbo (YLXB) dome, suggesting fundamental differences in their formation mechanisms; (2) the NSTRs and STDS both contributed to dome formation, but the former had a greater effect on the CND and MLS domes, whereas the latter played a dominant role in the evolution of the YLXB dome; and (3) the formation of these domes was followed by magmatic differentiation and crystallization, which concurrently controlled rare metal mineralization. Spatial imaging of the deep structures of leucogranites provides critical insights into how the unique upper crustal architecture of different domes influences rare metal enrichment patterns.
Wang et al. (Tue,) studied this question.