东昆仑黑海地区沙松乌拉组变质碎屑岩的地球化学特征及其对物质来源的约束

Geochemical Characteristics of Meta Clastic Rocks of Shasongwula Formation in the Black Sea Area in Eastern Kunlun Mountains and Their Constraints on Material Sources

摘要:

沙松乌拉组是整个东昆仑地区早古生代最早的海相沉积，是原特提斯洋盆打开时的沉积记录。对沙松乌拉组的物质来源进行研究，可以为恢复和反演东昆仑地区早古生代构造格局提供依据。本文在野外地质调查的基础上，对沙松乌拉组的岩石地球化学特征进行了研究。通过系列判别图解，得到沙松乌拉组的岩石类型为杂砂岩、岩屑砂岩，源岩主要为长英质及部分古老沉积组分；得到物源区大地构造环境主要为大陆岛弧和活动大陆边缘，少量物源来自被动大陆边缘。分析前期通过碎屑锆石法得到的小庙群、万宝沟群、晋宁期岩浆岩及白沙河组物源区的形成环境及岩石性质，与地球化学判别结果较为吻合。

Abstract:

Shasongwula formation is the earliest marine deposit of eastern Kunlun in early Paleozoic, which is the sedimentary record of original Tethys ocean basin. By studying the provenance of Shasongwula formation, it can provide a basis for the restoration and inversion of the early Paleozoic tectonic pattern in eastern Kunlun. According to the field geological survey, geochemical analysis and research on Shasongwula formation has been carried out. Through series of discriminant diagrams, it is showed that the rock types of Shasongwula formation are graywackes and lithic sandstone. Its source rocks are mainly felsic and some ancient sedimentary components. The tectonic environment of its provenance area is mainly continental island arcs and active continental margins, with a small amount of provenance from passive continental margins. The formation environment and rock properties of the provenance areas of Xiaomiao group, Wanbaogou group, Jin'ning magmatic rocks and Baishahe formation obtained by detrital zircon method in the early stage have been analyzed, which are in good agreement with geochemical discrimination results.