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TRACE ELEMENT GEOCHEMISTRY AND TECTONIC SETTING OF GREENSCHISTS IN THE CENTRAL PART OF FUJIAN PROVINCE

Wang He-nian, Sun Cheng-yuan,   

  1. Department of Earth Sciences and State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing, 210093
  • Received:1998-12-20 Revised:1998-12-20 Online:1998-12-20 Published:1998-12-20

Abstract: The Precambrian greenschists of the Longbeiqi Group in the central part of Fujian province are distributed along the Zhenghe-Daipu fult belt. Major chemical compositions of the greenschists indicate that they were originated from picrite-basalt and basalt. The Precambrian metamorphic acidic volcanics are generally associated with the basic ones, and demonstrate a “biomode” feature of the continental rift volcanic rocks. The geochemical characteristics of trace elements of the greenschists are different from MORB and VAB in higher contents of LILE,such as K, Rb,Ba, Zr and Ti;The chondrite-normalized REE patterns are enriched in LREE with a small Eu anomaly. Based on the Ti-Zr-Y and Ti-Zr-Nb diagrams, the grecnschist is identified as within plate tholeiite (WPT). Consequently,the greenshists in the central Fuijan province are considered to be derived from the continental tholeiite formed in a continental rift tectonic setting. Our results may have important significance for further studies of Zhenghe-Daipu fault belt, as well as the tectonic evolution of South East China.