GIN: 0cm 0cm 0pt; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-outline-level: 2" class=MsoNormal>g: 18.0pt; mso-bidi-font-family: 宋体" lang=EN-US>Petrogenesis of Late Cretaceous Adakite-Like Rocks in Mamba from the Eastern gs" />
详细信息
- 责任者：Meng Fanyi (State Key Laboratory of Geological Processes and Mineral Resources ; School of Earth Science and Mineral Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Zhao Zhidan
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(7)
- 关键词：埃达克岩 ; adakite ; 冈底斯山 ; Gangdise Range
- 页码：p.2180-2192
- 图表：8 illus., 3 tables, 60 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
This paper firstly reports a systematic study of petrology,LA-ICPMS U-Pb zircon dating and Hf isotopes,whole rock elements and Sr-Nd isotopic data of the Late Cretaceous Mamba granodiorite in the eastern Gangdise.The zircon U-Pb age of Mamba granodiorite is 88.3 Ma.The rocks are high-K calc-alkaline metaluminous,with SiO2 ranging from 66.4% to 68.5%,K2O from 3.1% to 4.1%,and A/CNK from 0.90 to 0.99.The rocks show typical adakitic features,with slightly negative Eu anomalies（δEu = 0.83~0.91）,strongly enriched in LREE,high（La/Yb）N（25.3~46.6）,high Sr contents（725×10-6~766×10-6）and high Sr/Y（52.2~65.2）.The Mamba adakites have homogeneous Nd-Sr compositions（εNd（t）=-4.1~-4.3,87Sr/86Sr=0.706 71~0.706 72）.In situ Hf isotopic analyses of zircon by LA-ICPMS yield initial εHf（t）values ranging from-3.4 to-1.2,corresponding to an ancient Hf crustal model ages of 1.21.4 Ga.Together with the geochemical results,including major,trace elements and isotopes,with that field occurrences that containing dioritic enclaves in the host rock,the authors interpret the Mamba adakites as the partial melting of ancient mafic lower crust,and later mixed with mantle-derived material.