Geochemistry, Zircon Geochronology and Hf Isotopes of Lujiazhai Granites from the Dabie Orogen: Evidence for the Neoproterozoic Magmatism along the Northeastern Margin of Yangtze Block
详细信息
- 责任者：Sun Yang (Faculty of Earth Sciences ; China University of Geosciences ; Wuhan 430074 ; China) ; Ma Changqian
- 刊名：Earth Science Frontiers
- 出版年：2011
- 卷期：18(2)
- 关键词：花岗岩 ; granite ; 铀—铅计时 ; U-Pb dating ; 铪同位素 ; hafnium isotopes ; 岩浆作用 ; igneous processes ; 大别山 ; Dabie Mountains ; 扬子地台 ; Yangtze Platform
- 页码：p.85-99
- 图表：8 illus., 4 tables, 93 refs.
- 分类号：0801
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
摘要
The Lujiazhai granitic pluton located in the southern Dabie Orogen was studied. LA-ICP-MS zircon U-Pb dating gave the age of (816±17) Ma for the Lujiazhai granites, revealing that the pluton was emplaced in the Neoproterozoic. All bulk samples are high in SiO2 (69.13%~75.47%), with moderate A/CNK values (0.98~1.01, averaged at 1.0), inferring an I-type granite affinity. The concentration of total rare earth elements (REEs) varies in the range of 27.43×10-6 to 160.66×10-6. The Lujiazhai granites are characterized by an enriched LREE pattern with slightly negative to positive Eu anomalies. The authors propose that since Early Neoproterozoic, the northeastern margin of the Yangtze block might have been under an active continental margin setting induced by subduction of an oceanic plate. In this tectonic regime, the Lujiazhai granites were derived by partial melting of ancient crustal materials induced by the underplating or intracrustal heating of hot mantle-derived magmas.
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