Tectonic attribute of the Lincang terrane in the eastern Tethyan domain

Abstract

Closure of the Proto–Tethys Ocean and opening of the Paleo–Tethys Ocean played crucial role in the global plate tectonic reconfiguration in the early to late Paleozoic transition. How the Proto– and Paleo–Tethys transition occurred in the eastern Tethyan domain has been a topic of hot debates in the last decades. Compilation of published and our new data on detrital zircon U–Pb dating and whole–rock geochemical analysis from the Lincang and contiguous blocks in the eastern Tibetan Plateau provide constraints on the paleogeographic positions and tectonic affinities of these blocks during the Proto– to Paleo–Tethys Ocean evolution in the Paleozoic. The results show that the Lincang terrane, as a magmatic arc terrane, was geographically proximal to the Baoshan block in the northern margin of the Australian and Indian plates of the Gondwana during the early Paleozoic. The block, however, drifted as part of the passive margin of the South China–Indochina block in the Paleo–Tethys Ocean and received sedimentary inputs from the latter. Through MDS analysis of detrital zircon data, the Yunxian-Menghai Proto–Tethys ocean to Changning-Menglian Paleo–Tethys ocean, in which the Baoshan and Lincang blocks were evolved. The Changning-Menglian Paleo-Tethys Ocean opened as a post-collisional rift basin. Closure of the Proto–Tethys Ocean was followed by opening of the Paleo–Tethys Ocean that separated the Lincang terrane from the Greater Gondwana. This study reveals that changes in mantle convection regime during the plate interactions and evolution of ocean basins are the primary driving forces behind the subduction of oceanic plates, and rifting and drifting of continental blocks. The study underscores the intricate dynamics of plate tectonics and the significance of geochronological and geochemical investigations in deciphering the complex history of continental blocks and plate interactions.