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  

LA-ICP-MS U-Pb dating of detrital zircons from the Upper Permian Gequ Formation on the southern margin of the East Kunlun Mountains and its tectonics implications

作　　者：黄晓宏[1,2] 张海军[1] 王训练[1] 王勋[1] 王振义[3] 戚宜建 

机构地区：[1]中国地质大学(北京),地球科学与资源学院,北京100083 [2]中国人民武装警察部队黄金第九支队,海南海口571127 [3]中国人民武装警察部队黄金第二支队,内蒙古呼和浩特010010

出　　处：《地质通报》2017年第2期258-269,共12页Geological Bulletin of China

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)

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。The Upper Permian(Lopingian) Gequ Formation on the southern margin of the East Kunlun Mountains is composed of conglomerates, sandstones and calcareous mudstones of fan delta-sea carbonate plateau. It is of important significance for the analyzing of regional tectonic evolution. This paper reports the detrital zircon ages for sandstone from the Gequ Formation in the area north of Huashixia. The sandstone sample has ages of 412~2448Ma, which can be mainly divided into four age ranges, i.e., 1869~1602Ma, 1396~1270Ma, 1197~877Ma and 572~412Ma. The age ranges indicate that the source regions of the Gequ Formation experienced complex multi-phase geological events, which included the Early Paleoproterozoic tectono-magmatic event, Late Paleoproterozoic assembly event, Mesoproterozoic rifting event, Late Mesoproterozoic-Early Neoproterozoic tectono-magmatic event and Late Neoproterozoic-Early Paleozoic rifting-extension-assembly event. Magmatic rocks formed during Late Neoproterozoic-Early Paleozoic constituted the main provenance of the Gequ Formation. According to the detrital zircons ages, basin of the Gequ Formation was a'cold basin'similar to foreland basin. Contrast to the Upper Permian, there were many >2000Ma ages in the Lower-Middle Permian, and the dated zircons yielded Hercynian-Indosinian ages, which was first found in the Lower Triassic.The two significant changes were the sedimentary response to the unconformities between Upper Permian and Lower-Middle Permian, Lower Triassic and Upper Permian and the tectonic events represented by them, exhibiting a good tectono-depositional coupling relationship.

关 键 词：上二叠统 格曲组 东昆仑 碎屑锆石LA-ICP-MSU-Pb测年 构造演化 

分 类 号：P534.46[天文地球—古生物学与地层学] P597.3[天文地球—地质学]