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Adakitic Granites within the NE Jiangxi Ophiolites,South China Geochemical and Nd Isotopic Evidence

LI Wu-xian, LI Xian-hua   

  1. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
  • Received:2004-06-20 Revised:2004-06-20 Online:2004-06-20 Published:2004-06-20

Abstract: The geochemistry and Nd isotope compositions of Xiwan albite gmaites within NE jiangxi ophiolites were reported in this paper.The granites share some geochemical similarities with modem adakite,including high Al203(15% ~17%),Sr(383 x 10-6~920 x 10-6),Sr/Y(166~444)and high εNd(t)values(+4.9~+6.0).Compared with the typical adakites,these granites are lower in HREE(Yb:0.14×1O-6~0.21×10-6),MREE(Sm=0.6 x 10-6~1.2 x 10-6)and Y(1.66 x 10-6~2.81 x 10-6)contents but higher in Na20/K20(12~37)and Na20/CaO(2.7~3.6)ratios.Geological and geochemical features suggest that they were generated by lower degree of partial melting of subducting spillitized oceanic crest at pressure high enough to stabilize garnet and amphibole but the plagioclase absent.The scenario is similar to the formation of the modem adakite in circum-Pacific margin.