青海南部治多—杂多地区石炭纪—三叠纪砂岩地球化学特征与构造背景探讨

Discussion on the Tectonic Setting and Geochemical Characteristics of Sandstones from Carboniferous to Triassic in Zhidoi-Zadoi Area,Southern Qinghai

选取青海南部治多—杂多地区石炭纪—三叠纪的砂岩、粉砂岩样品,进行主量元素地球化学分析,利用分析结果判别物源区大地构造背景,探讨北羌塘盆地的性质及演化。研究结果表明:北羌塘中段的治多—杂多地区物源区大地构造背景早石炭世为被动大陆边缘;早中二叠世为被动大陆边缘、活动大陆边缘和大陆岛弧;晚三叠世为被动大陆边缘、活动大陆边缘和大陆岛弧。结合地层学、沉积学和岩石学,治多—杂多地区的沉积盆地经历了早石炭世被动陆缘克拉通盆地—早中二叠世裂陷盆地和早中三叠世被动边缘克拉通盆地—晚三叠世弧后前陆盆地的两个演化旋回,体现了金沙江缝合带和甘孜—理塘缝合带成生发展在研究区内的沉积响应。

The major element geochemical analysis of sandstone and sihstones samples were performed for tectonic setting discrimination and discussion the nature and evolution of northern Qiangtang basin in Zhidoi-Zadoi area, southern Qinghai. The result of study indicates that the tectonic settings of provenances are passive continental margin in the Early Carboniferous, passive continental margin, active continental margin and continental island arc in the Early and Middle Permian, passive continental margin, active continental margin and continental island arc in the Late Triassic. Along with the stratigraphy, sedimentology and petrology, the nature of basin evolved from craton basin in the Early Carboniferous to rift-basin in the Early and Middle Permian and passive continental margin basin in the Early and Middle Triassic to back-arc basin in the Late Triassic, and this is sedimentation responding to evolvement of Jinshajiang suture belt and Garze-Litang suture belt in study area.