东昆仑花石峡北部上二叠统格曲组砂岩碎屑锆石LA-ICP-MS U-Pb年龄及其构造意义

发布时间：2018-01-30 01:53

本文关键词： 上二叠统格曲组东昆仑碎屑锆石LA-ICP-MS U-Pb测年构造演化　出处：《地质通报》2017年Z1期 　论文类型：期刊论文

【摘要】：东昆仑南缘上二叠统(乐平统)格曲组为一套由砾岩、砂岩、钙质泥岩构成的扇三角洲-浅海碳酸盐台地相沉积组合,在区域地质演化分析上具有重要的意义。经测定,格曲组砂岩的碎屑锆石LA-ICP-MS U-Pb年龄的范围为412~2448Ma,包括1869~1602Ma、1396Ma~1270Ma、1197~877Ma和572~412Ma四个年龄区间,指示物源区先后经历了古元古代早期的构造-岩浆事件、古元古代晚期的汇聚事件、中元古代的裂解事件、中元古代晚期—新元古代早期的构造-岩浆-变质事件和新元古代晚期—早古生代的裂解-扩张-汇聚事件。其中,与新元古代—早古生代洋陆转化相关的产物是格曲组的主要物源。格曲组砂岩碎屑锆石年龄组成表明沉积盆地具有前陆盆地"冷盆地"的特征。相对于格曲组,下中二叠统存在大量大于2000Ma的年龄信息,而下三叠统开始出现了大量海西末期-印支期的年龄信息。碎屑锆石年龄组成出现两次明显的变化,分别为格曲组和洪水川组底部不整合所代表的构造运动的沉积响应,表现出较好的构造-沉积耦合关系。
[Abstract]:The Upper Permian (Leping) Gequ formation in the southern margin of East Kunlun is a fan deltaic shallow sea carbonate platform assemblage composed of conglomerate sandstone and calcareous mudstone. It is of great significance in the analysis of regional geological evolution. The range of LA-ICP-MS U-Pb age of detrital zircon from Gequ formation sandstone is 412 ~ 2448 Ma. It consists of four ages: 1869 / 1602 Ma / 1396 Ma / 1270 / 1 197 / 877 Ma and 5722 / 412Ma. The origin of the indicator has experienced early Paleoproterozoic tectonic-magmatic events, late Paleoproterozoic convergence events, and Mesoproterozoic pyrolysis events. The tectonic-magmatic metamorphic events of the late Mesoproterozoic to the early Neoproterozoic and the split-extension-convergence events of the late Neoproterozoic to the early Paleozoic. The products related to the oceanic land transformation in Neoproterozoic and early Paleozoic are the main provenances of the Gequ formation. The zircon age composition of the sandstone in the Gequ formation indicates that the sedimentary basin has the characteristics of "cold basin" in Foreland basin. The Lower Middle Permian contains a large amount of age information larger than 2000 Ma, while the Lower Triassic begins to show a large amount of Hercynian-Indosinian age information. There are two obvious changes in the age composition of detrital zircons. The sedimentary response of the tectonic movement represented by the unconformity at the bottom of the Gequ formation and the Hongchuan formation respectively shows a good tectonic-sedimentary coupling relationship.
【作者单位】：中国地质大学(北京) 地球科学与资源学院;中国人民武装警察部队黄金第九支队;中国人民武装警察部队黄金第二支队;
【基金】：中国地质调查局项目《东昆仑成矿带地质矿产调查评价成果集成》(编号:12120113028800)、《秦-祁-昆重要结合带组成、成因及演化研究》(编号:1212011121258) 中央高校基本科研业务费专项资金(编号:2652014005)
【分类号】：P534.46;P597.3
【正文快照】： 昆仑造山带演化过程具有多岛洋、软碰撞、多旋回、构造迁移等特殊性和复杂性[1]。已有研究认为,东昆仑在青白口纪汇聚作用之后形成统一的块体,此后经历了2个主要洋陆转化阶段,即南华纪—早古生代洋陆转化阶段和晚古生代—早中生代的洋陆转化阶段[2-6]。在晚古生代洋陆转化阶段

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