二连盆地塔北凹陷反转构造特征与砂岩型铀矿之间的关系  

Relationships between inverted structures and sandstone-hosted uranium deposits in the Tabei Sag,Erlian Basin

作　　者：陈念楠 李满根[1,2] 宋志杰 关宝文 段建兵 李西得[3] 刘武生[3] 范鹏飞 刘颖[1] CHEN Nian-Nan;LI Man-Gen;SONG Zhi-Jie;GUAN Bao-Wen;DUAN Jian-Bing;LI Xi-De;LIU Wu-Sheng;FAN Peng-Fei;LIU Ying(School of Earth Sciences,East China University of Technology,Nanchang 330013,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌330013 [2]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [3]核工业北京地质研究院,北京100029

出　　处：《物探与化探》2025年第1期22-31,共10页Geophysical and Geochemical Exploration

基　　金：中国核工业地质局项目(地LCEQ01);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(2022NRE-LH-12);核资源与环境国家重点实验室自主基金(2020Z13);江西省教育厅科学技术研究项目(GJJ2200710)。

摘　　要：通过地震反射剖面和钻井等资料,厘定了二连盆地塔北凹陷反转构造类型和样式,进而探讨了构造反转成因机制及其与砂岩型铀矿之间的关系。结果显示:塔北凹陷东部和西部遭受了不同程度的正反转构造作用,东部发育典型的反转构造样式,西部巴彦乌拉、芒来等地区沿反转断层F 1上盘的赛汉组被抬升,近乎被完全剥蚀,原有的反转构造几何形态被破坏。在早白垩世赛汉组晚期(113~98.9 Ma)及晚白垩世—古新世初(66~42 Ma),古太平洋板块俯冲方向由NW转为NWW向,二连盆地塔北凹陷应力状态由伸展转变为挤压反转,形成一系列压性、压扭性构造,赛汉组及上白垩统被抬升剥蚀,形成区域性的角度不整合。构造反转作用一方面造成塔北凹陷赛汉组沉积体系由湖相转变为河流相,另一方面导致赛汉组与上覆地层差异性升降并遭受不均衡剥蚀,形成剥蚀天窗,有利于含铀、含氧流体向深部深入和流动,控制了层间氧化带的形态和发育,促进了铀矿富集。Using seismic reflection profiles and drilling data,this study determined the types and styles of inverted structures in the Tabei Sag,Erlian Basin.Accordingly,this study explored the genetic mechanisms of the inverted structures and their relationships with sandstone-hosted uranium mines.The results indicate that the eastern and western parts of the Tabei Sag experienced different degrees of normal and inverted tectonism.As a result,the eastern part exhibits typical inverted structural styles.In contrast,in the western part,the Saihan Formation on the hanging wall of inverted fault F 1 in the Bayanwula and Manglai area was uplifted and almost completely eroded,with the original geometries of inverted structures being destroyed.During the late depositional stage of the Early Cretaceous Saihan Formation(113~98.9 Ma)and from the Late Cretaceous to the Early Paleocene(66~42 Ma),the subduction direction of the Paleo-Pacific Plate shifted from NW to NWW.This change altered the stress regime in the Tabei Sag from extension to compressional inversion,leading to the formation of a series of compressional and compressional-torsional structures.Consequently,the Saihan Formation and the Upper Cretaceous strata were uplifted and eroded,resulting in the formation of regional angular unconformities.The structural inversion transformed the sedimentary system of the Saihan Formation in the Tabei Sag from lacustrine to fluvial facies.Meanwhile,it caused differential uplift and uneven erosion of the Saihan Formation and its overburden,leading to the formation of erosion windows.This facilitated the infiltration and migration of uranium-and oxygen-bearing fluids toward deep parts.These processes controlled the morphologies and development of interlayer oxidation zones,thereby promoting the enrichment of uranium deposits.

关 键 词：反转构造 成因机制 砂岩型铀矿 塔北凹陷 二连盆地 

分 类 号：P632[天文地球—地质矿产勘探]