塔里木盆地孔雀河地区东南部寒武—奥陶系稀土元素特征及其地质意义

采集了塔里木盆地孔雀河斜坡地区东南部寒武—奥陶系砂岩、泥岩及泥灰岩等沉积岩样品,对其稀土元素地球化学特征进行了系统研究,结果表明:研究区样品稀土含量总体表现正常.稀土元素配分模式轻稀土段曲线明显"右倾",重稀土段则较为"平坦",总体为轻稀土富集、重稀土亏损型,且受成岩作用影响不明显.根据稀土元素组合及其比值特征,结合研究区构造运动的影响,综合分析了孔雀河斜坡东南部寒武—奥陶系沉积岩源岩,源岩以北部沉积岩为主,少部分来自构造活动导致的花岗岩侵入体.与不同构造环境杂砂岩的稀土元素特征的对比结果及δCe的特征表明,孔雀河斜坡地区东南部寒武—奥陶系源区属性为大陆边缘背景.

Geochemical characteristic of the rare earth elements in Cambrian-Ordovician in the southeast of Kongquehe slope in Tarim Basin and its geological significance

The geochemical characteristics of REE (rare earth element) in the Cambrian-Ordovician sandstone,mudstone and marl in the southeast of Kongquehe slope in Tarim Basin are studied.The results show that the content of REE in the studied area is normal mostly.The distribution patterns of the rare earth elements indicate that LREE in the sedimentary rocks is rich and HREE is lack.The LREE segment of the distribution pattern curves is inclining-to-right,and the HREE segment is flat.The source rock of the sedimentary rocks in the studied area is studied according to the combination of the rare earth elements and the characteristics of their ratios,and the effects of the tectonic movement,and it is shown that the source rock is mainly from the northern sedimentary rock,and a small part of it comes from the granite intrusion resulted from tectonic activity.According to the comparative results of the geochemical characteristics of REE in the studied area with those of REE in the graywackes from different structural environment and the characteristics of δCe,it is held that the Cambrian-Ordovician sedimentary rock in the southeast of the Kongquehe slope is the tectonic background of continental margin.