论文部分内容阅读
藏夏河组是指发育于北羌塘盆地北部的一套砂、泥质互层的复理石相沉积地层,其时代为晚三叠世诺利期.由于其形成时间正是羌塘地体与可可西里-松潘地体沿金沙江缝合带进行碰撞、缝合的时期,因此该套地层对于探讨晚三叠世藏北地质演化具有重要的指示意义.通过对北羌塘盆地多色梁一带藏夏河组砂岩进行X射线衍射,全岩常量、稀土和微量元素分析,以及锆石裂变径迹等方法分析该套砂岩的物源、沉积构造背景,进而探讨晚三叠世羌塘盆地的性质.研究结果表明,其岩石类型为杂砂岩,物源主要为长英质火成物质,另有少量古地壳再循环物质加入,沉积大地构造背景为活动大陆边缘与大陆岛弧.结合前人研究资料,推断晚三叠世北羌塘盆地的性质可能为前陆盆地,藏夏河组为一套造山前或同造山期形成的复理石沉积建造.
Cangxiahe Formation refers to a sandstone and argillaceous interbedded complex facies sedimentary stratum developed in the northern part of North Qiangtang Basin and dated to the Late Triassic Noriellian Period.Due to the formation time of the Qiangtang terrane And the Kekexili - Songpan terrain during the collision and suture along the Jinshajiang suture zone, so this set of strata is of great significance for the exploration of the geological evolution of the northern Triassic in northern Tibet.Through the North Qiangtang basin along the Cangsha River Group sandstone was analyzed by X-ray diffraction, total rock mass, rare earth and trace element analysis, and zircon fission track method to analyze the provenance and sedimentary tectonic setting of the sandstone, and to explore the nature of Late Triassic Qiangtang Basin. The results show that the rock type is composed of miscellaneous sandstone, the source of which is mainly the felsic magma and a small amount of reclaimed material from the ancient crust, and the tectonic setting of the sedimentary earth is the active continental margin and continental island arc.Based on the previous research data, It is inferred that the characteristics of the northern Qiangtang basin in the Late Triassic may be that the foreland basin and the Cangxiahe Formation were deposited as a set of dolomitic dolomite sediments that were formed before orogenic orogenic orogeny.