首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Chronology and petrogenesis of the Hejiazhuang granitoid pluton and its constraints on the Early Triassic tectonic evolution of the South Qinling Belt
Authors:PengTao Yang  ShuWen Liu  QiuGen Li  ZongQi Wang  Fan Zhang  Wei Wang
Institution:1. Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing, 100871, China
2. Key Laboratory of Crustal Dynamics, Institute of Crastal Dynamics, China Earthquake Administration, Beijing, 100085, China
3. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037, China
Abstract:The Hejiazhuang pluton is located in the South Qinling Tectonic Belt (SQTB) in the north side of the Mianxian-Lueyang Suture Zone, and consists dominantly of granodiorites. LA-ICP-MS zircon U-Pb dating and Lu-Hf isotopic analyses reveal that these granodiorites of the Hejiazhaung pluton emplaced at ~248 Ma, and show a large variation in zircon ?Hf(t) values from ?4.8 to 8.8. These granodiorite samples are attributed to high-K to mid-K calc-alkaline series, and characterized by high SiO2 (66.6%–70.0%), Al2O3 (15.04%–16.10%) and Na2O (3.74%–4.33%) concentrations, with high Mg# (54.2–61.7). All samples have high Sr (627–751 ppm), Cr (55–373 ppm) and Ni (17.2–182 ppm), but low Y (5.42–8.41 ppm) and Yb (0.59–0.74 ppm) concentrations with high Sr/Y ratios (84.90–120.66). They also display highly fractionated REE patterns with (La/Yb)N ratios of 18.9–34.0 and positive Eu anomalies (δEu=1.10–2.22) in the chondrite-normalized REE patterns. In the primitive mantle normalized spidergrams, these samples exhibit enrichment in LILEs but depletion in Nb, Ta, P and Ti. These geochemical features indicate that the granodioritic magma of the Hejiazhuang pluton was derived from the partial melting of hybrid sources comprising the subducted oceanic slab and sediments, and the melts were polluted by the mantle wedge materials during their ascent. The emplacement ages and petrogenesis of the Hejiazhuang pluton prove that the initial subduction of the Mianlue oceanic crust occurred at ~248 Ma ago, and the SQTB was still under subduction tectonic setting in the Early Triassic.
Keywords:granodiorites in Hejiazhuang pluton  zircon U-Pb-Hf isotopic systematics  petrogenesis and tectonic setting  evolution of South Qinling Tectonic Belt
本文献已被 CNKI SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号