Petrogenesis and tectonic setting of the Huhetaoergai granitic pluton in the northern Ya-Gan Fault zone, northern Alxa, China: constraints from whole-rock geochemistry, zircon U-Pb ages, and Hf isotope compositions

摘要

This study presents a new data set that contains zircon U-Pb ages, whole-rock geochemistry, and Hf isotopes of the Huhetaoergai granitic pluton in the northern Ya-Gan Fault zone, northern Alxa, China. The Huhetaoergai pluton is composed of medium- to coarse-grained biotite monzogranite and coarse-grained biotite monzogranite with K-feldspar megacrysts, with U-Pb zircon ages of 220.5 +/- 1.9 Ma and 226.5 +/- 2.4 Ma, respectively. Granitoids are I-type granites with high epsilon(Hf)(t) values (9-11.05). These features indicate that the granitoids were generated from partial melting of juvenile crust and experienced an obvious fractional crystallization process. We speculate that the granitoids of the Huhetaoergai pluton were formed in an intraplate extensional environment during the post-collision process, indicating a crustal stretching and thinning event in the northern Ya-Gan Fault zone.