碎屑金红石地球化学特征对库车坳陷中生代沉积物源的启示

本文主要对库车坳陷的库车河流域和巴音布鲁克盆地中生代砂岩样品进行了碎屑金红石微量元素电子探针分析。结果显示,巴音布鲁克地区侏罗纪砂岩中的碎屑金红石来自变质泥质岩和来自基性变质岩的比例大致相当,而库车坳陷中生代砂岩中碎屑金红石则主要来自变质泥质岩。两地金红石的变质级别以角闪岩相/榴辉岩相为主,并有一定比例麻粒岩相变质的金红石。库车坳陷中生代砂岩中麻粒岩相金红石的含量,从三叠纪至白垩纪呈现出低-高-低的特点,说明侏罗纪时期物源方向有所变化,可能有东南部物源的参与。白垩纪时期,库车河地区砂岩中麻粒岩相变质金红石含量减少,可能与南天山再度抬升隆起成为优势物源区有关。

Detrital rutile geochemistry as an provenance indicator for the Mesozoic sediments in Kuqa depression

In the present study we focused on electron microprobe analysis of detrital rutiles separated from Mesozoic sandstones along Kuqa river in the Kuqa depression and a Jurassic sandstone in the Bayanbulak Basin.The results show that the proportion of detrital rutiles in Jurassic succession in Bayanbulak Basin derived from metamafic and metapelitic rocks is approximately equal,whereas the detrital rutiles in Mesozoic sandstones along Kuqa river mainly come from metapelitic source.The metamorphic stages of rutiles are mainly amphibolite/elogite facies in both areas,and there are a certain amount of granulitic rutiles.Contents of granulite-facies rutiles in Kuqa depression change with time,with the highest content for Jurassic period,indicating an change for source supply,maybe an input from the southeast.While in the early Cretaceous,content of rutiles of granulite-facies decreased as South Tianshan became the main provenance area due to its rapid uplift during this period.