| 广东莲花山花岗岩体锆石U-Pb年龄、地球化学特征及地质意义 |
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| 关键词:Early Cretaceous Lianhuashan granitoids I-type granite crustal extension zircon U-Pb LA-ICP-MS Lu-Hf isotopes |
| 基金项目:国家自然科学基金项目(编号: 41822205; 42072239）;中国地质科学院基本科研业务费项目(编号: DZLXJK202005);中国地质调查局项目(编号: DD20190306) |
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| Zircon U-Pb Ages and Geochemical Constraints of the Lianhuashan Granitoids in Guangdong Province and Their Geological Implications |
| The Lianhuashan granitoids, located in the north of the Lianhuashan fault zone, are composed of massive Jurassic–Cretaceous granites. This paper presents a synthetical petrologic, geochemical and geochronological study and Lu-Hf isotopic analysis of the granitoids. LA-ICP-MS zircon U-Pb dating yielded ages of 146~139 Ma, indicating that the granitoids were mainly generated in Late Jurassic to Early Cretaceous period. The granitoids are metaluminous to weakly peraluminous (A/CNK=0.97~1.1), and have the data K2O+Na2O=6.1 wt%~8.1 wt% and K2O/Na2O=1.4~1.8. They are all depleted in Ba, Ta, Nb, Sr, P and Ti, and enriched in Rb, Th, U, K and Pb. All these features point to a major crustal source. The Lianhuashan granitoids show large variation in the SiO2 content (69.5 wt%~80.1 wt%), and the high SiO2 samples underwent strong fractional crystallization, exhibiting characteristics of highly fractionated I-type granites. All zircons from these samples show negative εHf(t) values from –4.5 to –2.0, recording a predominant contribution of partial melting of ancient crustal rocks. However, on the ages versus εHf(t) diagram, all the samples are plotted on the field between the evolution curve of chondrite and Cathaysia basement, indicating minor mantle contributions to the source of the Lianhuashan granitoids. Integrating regional tectono-magmatic records, the authors infer that the Lianhuashan granitoids were formed in a back-arc extension environment, which was associated with roll-back of the subducting Paleo-Pacific plate in the Late Jurassic to Early Cretaceous period. |
| YANG Hang,XIN Yu-jia,LI Jian-hua,ZHANG Pei-xing.2022.Zircon U-Pb Ages and Geochemical Constraints of the Lianhuashan Granitoids in Guangdong Province and Their Geological Implications[J].Acta Geoscientica Sinica,43(2):211-223. |
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