From October 10 to 18, the National Natural Science Foundation of China’s major research program "Tethys Geodynamic System" carried out a seven-day geological investigation in the Nepal Himalaya, in collaboration with the team led by Academician Bishal N. Upreti of Tribhuvan University, Nepal. The expedition was headed by Academician WU Fuyuan of IGGCAS, and brought together 25 experts from Peking University, the Chinese Academy of Geological Sciences, and other institutions. This represents the largest overseas cooperative scientific expedition organized by the program in recent years.

The investigation targeted two internationally significant scientific questions: (1) the timing and mechanisms of the initial India-Asia continental collision and (2) the evolutionary history and processes of Himalayan uplift. The Nepal Himalaya preserves an exceptionally complete geological record spanning the onset of the India-Asia collision through subsequent orogenesis, making it a key region for resolving these fundamental geodynamic issues.

The research team traversed the Himalayan orogenic belt from south to north. Along the transect, they examined several major tectonic boundaries—such as the Main Frontal Thrust and the Main Boundary Thrust—as well as the geological units they delimit, including the Siwalik foreland basin deposits and the Lesser Himalayan sequences. These investigations aimed to elucidate the tectonic architecture and underlying dynamic processes shaping the region.

The field expedition addressed three major research teams: (1) the provenance and geodynamic significance of Gangdese-derived material within the Eocene Tansen Group on the southern flank of the Himalaya; (2) the metamorphic and structural characteristics, evolution and origin of the inverted metamorphic zone across the Main Central Thrust; and (3) the genetic relationship between the High Himalayan Crystalline Sequence and the South Tibetan Detachment System in the context of Himalayan uplift.

During the field campaign, Chinese and Nepalese scientists conducted extensive on-site discussions and systematically collected rock samples. The next stage of the project will involve detailed laboratory analyses to address key questions identified during the fieldwork, thereby advancing scientific understanding and enabling further breakthroughs in Tethyan geodynamics.

Academician WU Fuyuan explaining the discovery process and geological significance of the South Tibetan Detachment System

Academician Bishal N. Upreti discussing the rock assemblages of the Lesser Himalaya