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Chinese Journal of Geochemistry

, Volume 10, Issue 3, pp 244–256 | Cite as

Petrochemistry, age and petrogenesis of the Shexian pluton in southern Anhui

  • Xing Fengming
  • Xu Xiang
  • Ren Siming
  • Li Yingyun
Article
  • 26 Downloads

Abstract

The Shexian gneissic granodiorite in southern Anhui trends NE 55° from Shexian in the west to Guitoujian in the east with a length of 22 km and an outcrop area of 32 km. It was considered formerly to be Caledonian on the basis of a biotite K-Ar age of 474 Ma (1982). However, new evidence indicates that it may be Early Jinning in age as shown by: (1) it is found intruding into the Mid-Proterozoic Shangxi Group and is unconformably overlain by the Sinian Xiuning Formation, and (2) a zircon U-Th-Pb age of 928 Ma is obtained for the pluton.

The pluton is composed of plagioclase (An=27.37%), K-feldspar(14%), biotite(16%) and quartz(32%). Accessory minerals are ilmenite (150g/T), xenotime (15g/T). garnet(25g/T), monazite(10g/T), zircon (20g/T) and apatite (104g/T). Petrochemical characteristics of the intrusion are:(l) Al-enrichment (A/NKC=1.30); (2) H2O enrichment (H2O= 1.74%); and (3) low oxidation index (f ’=0.10). It belongs to the continental crust transformation type as evidenced by: (1) MF and Mg/Y values of biotite are 0.41 and 0.31 respectively; (2) (87Sr/86Sr)=0.71119; (3) δ Eu=0.52; and (4) A/NKC=130. The Shexian pluton is therefore considered as a product of melting of phyllite at depth in the light of similarities in trace element and REE contents with the phyllite of the Banxi Group. Calculations of REE batch partial melting indicate that it may have resulted from 75% melting of the Banxi phyllite.

Keywords

Continental Crust Isochron Outcrop Area Undulatory Extinction Plutonic Body 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Institute of Geochemistry, Chinese Academy of Sciences 1991

Authors and Affiliations

  • Xing Fengming
    • 1
  • Xu Xiang
    • 1
  • Ren Siming
    • 1
  • Li Yingyun
    • 1
  1. 1.Institute of Geological Sciences of Anhui ProvinceHefei

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