发布时间：2019-12-25 浏览次数：33
Post-conference field trip “Post-collisional granitoids and migmatites in the Dabie orogen, east-central China” was held in October 19, 2019 to October 22, 2019 in the Dabie orogen. The four-day field trip was guided by Profs. Yong-Fei Zheng, Zi-Fu Zhao, Ren-Xu Chen, Xiao-Ying Gao and Li-Qun Dai from University of Science and Technology of China. There are 24 participants from Australia, Canada, Switzerland, Japan, Czech Republic, Brazil, and China, including Profs. Peter Cawood, William Collins, Roberto Weinberg, Catherine Annen, and Di-Cheng Zhu.
The Dabie-Sulu orogenic belt is one of the typical collisional orogens in the world. It was produced by northward subduction of the South China Block beneath the North China Block in the Triassic. It is not only one of the largest-exposed and best-preserved ultrahigh-pressure (UHP) metamorphic terrane in the world, but also one of the areas that have intense magmatism in the post-collisional stage after the formation of UHP metamorphic rocks by the continental deep subduction. It is the ideal target to study both reworking and recycling of the deeply subducted continental crust at the convergent continental boundary.
The participants of the post-conference field trip visited 10 sites of post-collisional granitoids and contemporaneous migmatites as well as a porphyry Mo deposit that is hosted by the post-collisional granitoid in the Dabie orogen. The granitoids in the Dabie orogen were produced by crustal anataxis in the Early Cretaceous rather than in the Triassic. Nevertheless, these rocks show geochemical inheritance from the subducted continental crust of the South China Block. They were developed on the basis of the collisional orogen and thus were the melting product of the deeply subducted continental crust in the post-collisional stage. Therefore, the same crustal rocks from the subducted continental lithosphere would have serve as the protolith of granite-migmatite-granulite associations in the Dabie orogen. This enables us recognition of crustal anataxis in the collisional orogen after its root was removed for continental rifting. The geologists had hot discussion on the origin and evolution of these granitoids and contemporaneous migmatites in the Dabie orogen.
Group photo at the outcrop of Yanzihe migmatite
Group photo at the Tianzhushan Mountain
Investigating the Shapinggou granitoid and associated Mo deposit
Investigating the Yanzihe migmatite
Discussion at the Shapinggou granitoid and Mo deposit
Prof. Zi-Fu Zhao is introducing the Tianzhushan granitoid
Discussing the genesis of post-collisional magmatic rocks at the Baimajian granitic pluton
Prof. Zi-Fu Zhao is introducing the Zhubuyuan granitoid
Prof. Ren-Xu Chen is introducing the Qingtian migmatite
Discussion at the Tianzhu Mountain