Seminar

Despite a bunch of studies have been carried out on the Wuyi-Yunkai orogen in South China, the tectonic evolution of this early Paleozoic remains ambiguous. One school of thought interprets this orogen as intra-continental due to the absence of early Paleozoic ophiolites, deep-sea sedimentary rocks, and arc magmatism, and the planar rather than linear distribution of the Silurian granitoids. Another view interprets this orogen as resulting from the continental collision of West Cathaysia with an unknown terrane. Early Paleozoic granitoids are widespread (~ 22,000 km²) in the Wuyi-Yunkai orogen, thought to be a response to the early Paleozoic orogeny. Thus, clarifying the origin of these granites is of great significance to shed light on the nature of this orogen. In this contribution, this research study focus on some Tonalite-Trondhjemite-Granodiorite (TTG) suite, mafic microgranular enclave (MME)-bearing granite and gneissic granites in the orogen. Based on the temporal and spatial distribution characteristics of this early Paleozoic magmatic rocks, a new tectonic model “syn-convergent extension and asthenosphere upwelling during the intracontinental orogeny” is proposed. The syn-convergent extension zones, which including a series of NW-trending transverse faults and the NE-trending reactivated pre-existing suture and rift zone (i.e., Shaoxing-Jiangshan- Pingxiang-Chenzhou fault) within the WYO, are in favour of asthenosphere upwelling leading to intensive crust-mantle interaction.

Additional information: Miss Yuexin Xie, u3005563@connect.hku.hk