摘要
调查研究发现，阿尔金南缘环形山榴辉岩呈透镜体状产于新元古代石榴石二长花岗片麻岩中，岩石经退变质作用，白眼圈构造发育，石榴石变少，石英及金红石等矿物较少，未见峰期矿物组合。绿辉石被次透辉石及角闪石替代，岩石为榴辉岩、榴闪岩及斜长角闪岩。主量及微量元素地球化学分析显示：主量元素Al2O3、TiO2、MgO、P2O5及稀土Nb/Ta、Zr/Hf、Zr/Nb、La/Nb、Y/Nb特征比值与洋脊玄武岩一致；稀土标准化模式图、微量元素原始地幔标准化图及MORB标准化图指示岩石具洋脊玄武岩特征，原岩可能为地幔岩经15%-30%的部分熔融形成。结合榴辉岩围岩年龄、变质作用等分析认为，该榴辉岩为似洋脊玄武岩的基性岩浆侵入花岗岩后，于500 Ma左右发生大陆俯冲折返形成。
On the south rim Altyn Tagh crater eclogite investigation found that eclogite was a lens-shaped garnet produced in early Neopro-terozoic granite gneiss, rocks experienced retrograde, white-circle structure development, less garnets, quartzesand rutile mineral, the peak mineral combination almost invisible, omphacite almost all replaced by salites and amphiboles, There are the eclogite, amphibole eclogite and amphibolite at present. The main elements and trace element geochemical analysis found that the stable main elements Al2O3, TiO2, MgO, P2O5 and rare earth Nb/Ta, Zr/Hf, Zr/Nb, La/Nb, Y/Nb characteristics ratio consistent with oceanic basalt. Rare earth standardized model diagram, primitive mantle normalized trace elements diagram and MORB standardization map also indicates the rock a mid ocean ridge basalt character-istics, and the original rock could be formed by 15%~30%partial melting of mantle rock. Based on the geochemical characteristics and com-prehensive analysis on host granite gneiss age, metamorphism grade, and regional contrast indicate that the eclogite is like ridge basalt magma penetrated the granite base, after the formation of continental subduction occurred at about 500Ma.
出处
《新疆地质》
CAS
CSCD
2015年第2期143-150,共8页
Xinjiang Geology
基金
国家自然科学基金(41103021
41272089)
中国地质调查局项目(1212011220861)资助
关键词
阿尔金
榴辉岩
大陆深俯冲
地球化学
Altyn Tagh
Eclogite
Continental deep subduction
Geochemistry
