The Geochemistry Characteristics Of Basalts And Basaltic Andesites And Theier Tectionics Environment From The Takezale Ophiolitic Melange In XinJiang

The Takezale ophiolitic melange occurs in piedmont of Takezale Mountain in eastern Junggar in Xinjiang. The author has paid attention to the two kinds of lavas which locate the south-east end of the Kalamaili belt. Through the field investigate and the geochemistry experiment the author has contrasted the two kinds of lavas in the ophiolitic melange, made clear the tectonic background and summarized the geochemical characteristic and then discussed the formed environment and tectonic significance. The main conclusions of this thesis described as below:1.The REE distributions of the basalts show a LREE faint flat but HREE slightly depleted patterns, however, the basalt-andesites display a LREE enriched pattern relative to HREE and depleted in Eu clearly.2. The race element spider diagram indicates that they are both poor in Nb-Ta. Moreover, Ce-Sr-Zr-Ti-Tb-Y-Cr-Ni-Zn-Ta and Cs-Ba-Rb-Th-U-Pb are complemental to each other.3.In the Eu-Ti, Ho-Y and Zr- Sm et al. diagrams, the two lavas have their own linear relationship and they locate on the different ends of the same straight line, which suggests that the resources of the two lavas are similar.4. Basalts belong to islands-type ophiolite and basalt-andesites to calc-basalt and possess the characteristics of oceanic island-arc alkaline basalts.5.The ophiolitic melange is likely to form in a arc island circumstance influenced by a mantle plume.