10.6084/m9.figshare.7730510.v1
Min Liu
Min
Liu
Shaocong Lai
Shaocong
Lai
Da Zhang
Da
Zhang
Renzhi Zhu
Renzhi
Zhu
Jiangfeng Qin
Jiangfeng
Qin
Guangqiang Xiong
Guangqiang
Xiong
Middle Permian high Sr/Y monzogranites in central Inner Mongolia: reworking of the juvenile lower crust of Bainaimiao arc belt during slab break-off of the Palaeo-Asian oceanic lithosphere
Taylor & Francis Group
2019
High Sr/Y granitoids
Bainaimiao arc belt
Collision
Middle Permian
Palaeo-Asian ocean
Slab break-off
2019-02-17 16:12:06
Dataset
https://tandf.figshare.com/articles/dataset/Middle_Permian_high_Sr_Y_monzogranites_in_central_Inner_Mongolia_reworking_of_the_juvenile_lower_crust_of_Bainaimiao_arc_belt_during_slab_break-off_of_the_Palaeo-Asian_oceanic_lithosphere/7730510
<p>The high Sr/Y geochemical feature of granitoids can be attributed to various mechanisms, and elucidating genesis of high Sr/Y granitoids provides insights into the material recycling and magmatic processes at depth. In southeastern Central Asian Orogenic Belt (CAOB), many Middle Permian granitoids exhibit high Sr/Y ratios, but their origins remain unclear, inhibiting a comprehensive understanding of the magmatic response to the final closure of the Palaeo-Asian ocean. Here we present new zircon U-Pb ages, Lu-Hf isotopes and whole-rock geochemical data for the Middle Permian high Sr/Y monzogranites from central Inner Mongolia, southeastern CAOB. LA-ICP-MS zircon U-Pb data shows that these high Sr/Y rocks were emplaced during 273–261 Ma. They are calc-alkaline, sodium-rich and metaluminous to weakly peraluminous, with enriched large-ion lithophile elements (Rb, Th, K and Pb) and depleted high field strength elements (Nb, Ta, P and Ti), suggesting a mafic lower crustal source rather than evolved potassic crustal materials. Their relatively low (Gd/Yb)<sub>N</sub> (1.1–2.0), (Dy/Yb)<sub>N</sub> (1.0–1.3), Nb/Ta (7.9–10.9) ratios and flat heavy rare earth element patterns are characteristics of derivation from a relatively shallow depth with amphibolite as dominant residue. They also have highly variable <i>ε</i><sub>Hf</sub>(t) values (−8.2 to +10.0) and <i>T</i><sub>DMC</sub> (1814 to 649 Ma), similar to those of the Early Palaeozoic high Sr/Y intrusions along the Bainaimiao arc belt. Combined with data from literatures, we suggest that the high Sr/Y monzogranites in this study were probably generated by reworking of the newly underplated juvenile high Sr/Y lower crust of the Bainaimiao arc belt. Moreover, taking into account the regional investigations, the sublinear distributed Middle Permian magmatic rocks in the southeastern CAOB were likely associated with the incipient slab break-off of the Palaeo-Asian oceanic lithosphere following initial collision between the North China craton and the South Mongolia terranes.</p>