Tectonic Setting of the Baitutang Ophiolite at the Northern Margin of South Tianshan Belt

There exposed part of the Ophiolitic Melange in Baitutang,the norht of the South Tianshan in Xinjiang. To understand the ultrabasic rocks forming environment, this paper focuses on the 9 samples of this area are tested by the study of geochemical method.Research and analysis of the geochemical results that the serpentinite in the area with low SiO₂,TiO₂,CaO,K₂O,Na₂O,MgO, Al₂O₃ for the characteristics,with high concentration of compatible elements Cr, Co, and Ni, depleted in incompatible elements, and large ion lithophile element content is low, the overall features similar to the Ocean lherzolite, features representing the mantleresidue.The basalts possess high TiO₂ and MgO contents,not only low Al₂O₃ and K₂O,but also Na₂O>K₂O.Compared with MORB, the elements of Nb, Ta apparent are loss. Compared with the primitive mantle, with slow features similar to the N-MORB's losses, The geochemical characteristics of the main elements and trace elements show that rock should be formed in the tectonic environment similar to mid-ocean ridge,and the magma derived from depleted mantle zone.