鄂尔多斯盆地西南部古构造指示的构造-沉积过程及砂岩型铀成矿意义  

Tectonic-sedimentary Process and Significance of Sandstone-type Uranium Mineralization Indicated by the Paleotectonic Reconstruction in the Southwestern Ordos Basin

作　　者：刘持恒 李子颖[1] 贺锋[1] 李西得[1] 刘坤鹏 李元昊 张字龙[1] LIU Chiheng;LI Ziying;HE Feng;LI Xide;LIU Kunpeng;LI Yuanhao;ZHANG Zilong(CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology,Beijing Research Institute of Uranium Geology,Beijing 100029,China;Research Institute No.203,CNNC,Xi’an,Shaanxi 710086,China;School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an,Shaanxi 710065,China)

机构地区：[1]核工业北京地质研究院中核集团铀资源勘查与评价技术重点实验室,北京100029 [2]核工业二〇三研究所,陕西西安710086 [3]西安石油大学地球科学与工程学院,陕西西安710065

出　　处：《铀矿地质》2024年第1期29-40,共12页Uranium Geology

基　　金：中核集团集中研发项目(编号:中核科发2021-143号);中国核工业地质局项目(编号:202201-8);中国铀业有限公司—东华理工大学核资源与环境国家重点实验室联合创新基金(编号:2022NRE-LH-16);中核集团青年英才项目(编号:QNYC2301)联合资助。

摘　　要：鄂尔多斯盆地自晚中生代以来长期处于多个板块汇聚的中心,在多期构造作用下,引起了盆地内部地层的变形和叠加。因此,通过恢复鄂尔多斯盆地西南部下白垩统不同地质历史时期的古构造特征,可以更好地理解该地区的构造-沉积与铀成矿过程。文章利用钻孔分层数据和地震剖面解释成果,采用了单一岩性逐步回剥的算法进行地层去压实校正,参考了前人的剥蚀量数据,从而恢复了鄂尔多斯盆地早白垩世末的古构造特征。早白垩世末的古构造图显示,在该时期下白垩统中并不存在现今的天环坳陷结构,华池环河组的顶面古构造特征与下部层位相比发生了显著变化。这些现象表明,华池环河组和罗汉洞组之间存在明显的二级层序界面,其转变的动力背景可能源自六盘山裂谷盆地的初始裂陷和相应的岩浆侵位作用。天环坳陷结构的初步形成可追溯到晚侏罗世末的挤压改造,在中新世晚期再次经历了叠加改造并最终定型。研究区的古构造条件及其演化过程指示了该区域存在“渗出”铀成矿作用。Ordos Basin has been a focal point of multiple plate convergence since the Late Mesozoic era and experienced the intra structural deformation and layer superposition from the various tectonic forces over times.Therefore,investigating the paleotectonic features of the Lower Cretaceous in the southwestern part of the Ordos Basin during different geological periods is crucial to comprehende the tectonic-sedimentary processes and uranium mineralization in the region.This study trys to reconstruct the paleotectonic features of the late Early Cretaceous in the Ordos Basin by utilizing borehole layering data,seismic profile interpretation results,and gradual back-stripping algorithm for stratigraphic de-compaction correction.Reference data from previous studies on stripping volume were also considered.The paleotectonic map of the late Early Cretaceous revealed that the Tianhuan depression structure,as observed in the present-day was not formed during that period.Furthermore,significant changes were noted in the paleotectonic features of the top surface of the Huachi-Huanhe Formation compared to the underlying strata.These observations suggested the presence of a distinct secondary stratigraphic interface between the Huachi-Huanhe Formation and the Luohandong Formation.The dynamics of this transformation may have originated from the initial rifting of the Liupanshan Rift Basin and associated magmatic intrusion.The Tianhuan depression structure in the Pre-Cretaceous initially formed by the end of the Late Jurassic and experienced further superposition in the Late Miocene,while the Tianhuan depression during the Lower Cretaceous formed exclusively in the Late Miocene.The paleotectonic conditions of the study area and their evolutionary process indicate the possibility of"oxudation"uranium mineralization in the region.

关 键 词：鄂尔多斯盆地 古构造 砂岩型铀矿 构造演化 层序 

分 类 号：P619.14[天文地球—矿床学]