【摘要】 本文通过雅鲁藏布江缝合带南侧江孜和岗巴地区晚白垩世-古近纪沉积地层的碎屑岩岩石学、地球化学和铬尖晶石电子探针分析,揭示了碰撞前后沉积盆地的物源区变化,提供了盆地和造山带早期的演化历史。江孜地区上白垩统宗卓组属于弧-陆或陆-陆碰撞背景下的海沟沉积。日朗砾岩中的岩屑质长石砂岩地球化学特征反映有大洋岛弧物质的注入,物源区为大洋岛弧或增生楔。上古新统-下始新统甲查拉组长石质岩屑砂岩反映了冈底斯岛弧和再循环造山带物源区特征,是陆-陆碰撞背景下形成的周缘前陆盆地的前渊沉积。岗巴地区古新统基堵拉组石英砂岩表现为印度大陆内部物源区特征,而始新统遮普惹组岩屑砂岩为再循环造山带和冈底斯岛弧物源区。沉积特征和物源区综合研究表明,雅鲁藏布江周缘前陆盆地在古新世期间开始发育,它指示了印度与欧亚板块的初始碰撞时间。更多还原

【Abstract】 We focus on the upper Cretaceous-Palaeogene terrigenous sequences in the Tethyan Himalaya near the Gyangze and Gamba.Our research presents detrital petrology and geochemistry and Cr-spinel electron microprobe data,which together illustrate significant provenance change at the Paleocene and provide the early history of the basin and orogen belt. The latest Cretaceous Zongzhuo Formation in Gyangze was deposited in trench.The Rilang conglomerates unite is lithic arkose which was derived from transitional arc,and geochemistry shows input of ocean island arc materials.Its provenance is ocean island arc or accretionary prism. Late Paleocene-early Eocene Jiachala Formation is feldspathic indicating a mixing provenance of Gangdese magmatic arc and recyled orogen provenances,which deposited in a foredeep responded the India-Asia collision.The early Paleocene Judula Formation in Gamba is composed of quartz sandstone from interior India.In contrast,the Eocene Zhepure Formation consisting of lithic sandstone is characterized of active continental margin.We propose the development of the Yalu-Zangbo peripheral foreland basin and the onset of India-Asia collision occurred at 65-55 Ma in the central Tethyan Himalaya.更多还原