Professor GAO Jun and his team present geochemical and geochronological data of a leucogranite dike which runs across the HP–LT metamorphic belt in the Chinese South Tianshan Orogen and thus constrain the upper age limit for HP–LT metamorphism and subsequent collision between the Tarim and Yili blocks in order to understand the geotectonic framework and the Phanerozoic continental growth of the Altaids.

The petrological and geochemical data suggest that the SP leucogranite dike intruded during the exhumation of overthickened crust in the post-collisional setting between the Yili (–Central Tianshan) and Tarim blocks. The dataset presented here in conjunction with previously published data corroborate that the HP–LT metamorphism must have occurred earlier than the Permian in the Tianshan Orogen. Therefore, the collision between the Yili (–Central Tianshan) and Tarim blocks and the final amalgamation of the Southwestern Altaids must have been terminated in Late Paleozoic and not in Triassic times as previously suggested.

Gao. et al. The collision between the Yili and Tarim blocks of the Southwestern Altaids: Geochemical and age constraints of a leucogranite dike crosscutting the HP–LT metamorphic belt in the Chinese Tianshan Orogen. Tectonophyics. 2011, 499: 118-131 (Download Here)