论文部分内容阅读
对东昆仑东段布青山得力斯坦地区出露的上二叠统格曲组砾岩层进行砾石成分、砾度统计及系统的LA-ICP-MS锆石UPb年龄谱分析。结果表明,格曲组砾岩层砾石成分以石英岩和花岗岩为主,硅质岩和基性岩次之,砂岩和灰岩较少,砾石的分散系数为1.54~2.02,该套砾岩为近源快速堆积的产物。砾岩碎屑锆石U-Pb年龄可分为3组:1早奥陶世—晚志留世年龄组为499~409Ma,峰值年龄为426Ma,对应早古生代末期原特提斯洋向北俯冲碰撞产生的一系列构造岩浆事件;2新元古代年龄组为744~619Ma,峰值年龄为744Ma,对应于全球Rodinia超大陆裂解事件;3古元古代年龄组为2443Ma,对应东昆仑地区古元古代构造岩浆热事件。结合碎屑锆石年龄及沉积学特征综合分析,花岗质砾石来源于北侧东昆仑造山带加里东期岩浆弧,沉积岩砾石则可能来自造山带早期的沉积地层,石英岩及其他变质岩砾石则多来自东昆仑基底变质岩系。综合判别,格曲组为一套沉积于活动大陆边缘环境的滨浅海相磨拉石建造,代表南侧古特提斯洋向北俯冲开始的构造阶段,是初始俯冲的沉积构造响应。
Gravel composition, gravel statistics and LA-ICP-MS zircon UPb age distribution of the Upper Permian Guli conglomerate layer exposed in the Upper Stellenbosch of eastern Kunlun Mountains were analyzed. The results show that gravel in conglomerate is dominated by quartzite and granite, with less siliceous rocks and basic rocks, less sandstone and limestone, the gravel dispersion coefficient is 1.54-2.02, and the conglomerate is near The source of rapid accumulation of products. The U-Pb ages of conglomerate detrital zircons can be divided into three groups: 1 The Early Ordovician-Late Silurian age group is 499-409Ma and the peak age is 426Ma, corresponding to the early Tethys Ocean subduction of the Early Paleozoic A series of tectonic magmatic events resulted from the collision; 2 Neoproterozoic age group 744 ~ 619Ma, peak age 744Ma, corresponding to the global Rodinia supercontinental cracking event; 3 ancient age ancient group 2443Ma, corresponding to the Eastern Kunlun area Paleoproterozoic Tectonic magmatic event. Based on the analysis of age and sedimentary characteristics of detrital zircons, the granitic gravel is derived from the Caledonian magmatic arc of the East Kunlun orogenic belt on the north side. Sedimentary rock gravels may come from the early sedimentary strata of the orogenic belt, quartzite and other metamorphic gravels Mostly from the East Kunlun basement metamorphic rocks. Synthetically, the Songliao Formation is a sedimentary structure of shallow foreshore facies deposited on the margin of the active continental margin, representing the tectonic stage of the northward tectonic subduction of the southern Tethys Ocean, which is the sedimentary tectonic response of the initial subduction.