豫西济源盆地中生代泥岩地球化学特征对物源区的指示

发布时间：2018-04-19 17:03

本文选题：济源盆地 + 沉积物　；参考：《地球科学》2017年01期

【摘要】：秦岭造山带印支期造山作用控制着济源盆地的形成与演化,对盆地中沉积物物源进行研究,有利于恢复造山带造山-隆升的细节.通过对济源盆地中生代泥岩地球化学的系统分析,发现样品的CIA(化学风化指数)校正值在早-中三叠世、晚三叠世、早-中侏罗世和中侏罗世后期的平均值分别为68.5、76.4、86.0和73.7,这一演化特征可能反映其经历了古气候控制的化学风化过程.但是三叠纪样品CIA值明显过低,可能与源区活动的构造背景相关;ICV(成分变异指数)值显示沉积物具有初次沉积的特征,反映了源区早期发生过弧-陆碰撞或具备陆缘弧特征的克拉通基底隆升.而早-中侏罗世样品表现为高的CIA值,ICV值显示沉积物具有再循环特征,其初次沉积可能发生在弧后盆地中,后随造山带的隆升,被剥露再搬运而沉积下来.泥岩物源区构造环境判别结果显示,沉积物主要来自活动大陆边缘和被动大陆边缘,且含有较多大陆岛弧(陆缘弧)的信息.由此说明,中生代济源盆地盆缘构造活动经历了由克拉通基底隆升到造山带剥露的过程,这一过程与秦岭造山带印支期的造山作用密切相关.
[Abstract]:The Indosinian orogeny of the Qinling orogenic belt controls the formation and evolution of the Jiyuan basin. The study of the sediment provenance in the basin is beneficial to the restoration of the details of the orogenic orogeny and uplift of the orogenic belt.Based on the systematic analysis of Mesozoic mudstone geochemistry in Jiyuan Basin, it is found that the CIA (Chemical weathering Index) correction values of the samples are in the Early-Middle Triassic and the late Triassic.The average values of early to middle Jurassic and late Middle Jurassic are 68.5 ~ 76.4N ~ 86.0 and 73.7respectively, which may reflect the chemical weathering process controlled by paleoclimate.However, the CIA value of Triassic samples is obviously too low, which may be related to the tectonic background of the source area.It reflects the early arc-continent collision or the uplift of the craton basement with the characteristics of the continental margin arc in the source region.The early and middle Jurassic samples showed a high CIA value and a high CIA value, which indicated that the sediments had the characteristics of recirculation, and their initial deposits may have occurred in the back-arc basin, and then deposited along with the uplift of the orogenic belt, which were stripped and transported.The result of judging the tectonic environment of mudstone provenance shows that the sediments mainly come from active continental margin and passive continental margin and contain more information of continental island arc (continental margin arc).It is concluded that the tectonic activity of the basin margin of Jiyuan basin in Mesozoic has experienced a process from the uplift of craton basement to the exfoliation of orogenic belt, which is closely related to the orogeny of the Indosinian period of the Qinling orogenic belt.
【作者单位】：河南理工大学资源环境学院;中国地质大学生物地质与环境地质国家重点实验室;
【基金】：国家自然科学基金项目(No.41440016) 河南省基础与前沿技术研究计划项目(No.152300410211)
【分类号】：P588.2

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