Geochemistry, Zircon U-Pb Geochronology and Hf-O Isotopes of the Banzhusi Granite Porphyry from the Xiong’ershan Area, East Qinling Orogen, China: Implications for Petrogenesis and Geodynamics

• Main Authors: Bin Wang, Xinkai Hu, Li Tang, Jingchao Li
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Minerals
• Subjects: geochemistry; zircon U-Pb geochronology; zircon Hf-O isotopes; Banzhusi granite porphyry; East Qinling
• Online Access: https://www.mdpi.com/2075-163X/9/9/538

The Banzhusi granite porphyry is located in the Xiong’ershan area, East Qinling orogenic belt (EQOB). This study presents an integrated whole-rock geochemistry and zircon U-Pb-Hf-O isotope analysis of the Banzhusi granite porphyry. These rocks have metaluminous, high-K alkali-calcic and shoshonitic features and show significant enrichment in light rare earth elements (LREEs) over heavy rare earth elements (HREEs) with negative Eu anomalies. These samples are also greatly enriched in Rb, Ba, K, Pb, Th and U and depleted in Nb, Ta, P and Ti, and they mostly overlap the ranges of the Taihua Group tonalite−trondhjemite−granodiorite (TTG) gneiss. Magmatic zircons from three samples of the Banzhusi granite porphyry yield U-Pb ages of 125.1 ± 0.97 Ma, 128.1 ± 1.2 Ma and 128.2 ± 1.3 Ma. The Hf-O isotope features of zircons from the three samples are very similar (δ¹⁸O_zircon = 4.84‱ to 6.51‱, εHf_(t) = −26.9 to −14.4). The co-variations of geochemical and isotopic data in these granite porphyries imply that the Banzhusi granite porphyry resulted from the mixing of the partially melted Taihua Group and mantle-derived material in a post-collisional setting from 128−125 Ma.