金红石中锆含量温度计及其微量元素地球化学特征

Zack et al.(2004a)、Watson et al.(2006)以及Tomkins et al.(2007)(在2GPa条件下)的金红石中锆含量温度计计算结果显示,徐淮地区中生代侵入杂岩所含榴辉岩类包体所经历的榴辉岩相变质的温度范围分别为776～1099℃(平均898℃)、663～923℃(平均750℃)和714～981℃(平均804℃),这些温度结果可能并非榴辉岩相峰期变质温度;其角闪岩相退变质作用过程中保存的温度范围分别为555～777℃(平均697℃)、541～663℃(平均6170C)和588～714℃(平均667℃),这些结果不能代表角闪岩相退变质再平衡后的温度,而只能代表角闪岩相退变质作用过程中某-阶段的温度.微量元素地球化学特征研究表明,榴辉岩类包体所含金红石中的某些微量元素(如Nb、Ta、Cr、Fe、V等)含量与其原岩有继承和对应关系,其原岩主要为镁铁质岩石;榴辉岩类包体与其寄主岩石中部分高价态/高场强元素(HFSE)呈相互消长的关系.榴辉岩的形成与扬子地块和华北地块之间的俯冲,碰撞作用有关.

Zr-in-rutile thermometry and geochemical characteristics of trace element in rutile from eclogite inclusions of Mesozoic intrusive complexes in Xuzhou-Huainian area, China

The calculate results of temperature to eclogite inclusions from Mesozoic intrusive complexes in Xuzhou-Huainian area, China, make use of zircon-in-rutile thermometry of Zack et al. (2004a) , Watson et al. (2006) and Tomkins et al. (2007) (under 2GPa) ,indicate that it underwent metamorphic temperature of eclogite facies range from 776 to 1099X (average 898X1 ) ,from 663 to 923X (average 750℃ )and from 714 to 981℃ (average 804℃ ),respectively. These calculate results of temperature may be not peak metamorphic temperature of eclogite facies; and the temperature was kept in the course of the amphibolite facies retrogressive metamorphism are 555 ～ 777℃ (average 697℃) ,541 ～ 663℃ ( average 617℃) and 588 ～ 714℃ ( average 667℃) , respectively. The results do not represent the equilibrium temperature after amphibolite facies retrogressive metamorphism, but represent certain temperature in the course of the amphibolite facies retrogressive metamorphism. The research on geochemical characteristics of trace element in rutile from eclogite inclusions shows that the components of some trace elements(e. g. Nb,Ta,Cr,Fe, V,etc. )inherited the original matter which dominant are mafic rock, which high electrovalency element or/and high field strength element emerge the decrease and increase between eclogite inclusions and its host magmatic complex. The eclogite was resulted from the subduction-collision action between the Yangtze block and the North China block.