鄂尔多斯盆地印支期不整合面类型及分布特征  

Types and distribution characteristics of the Indosinian unconformities in the Ordos ba

作　　者：许艳华 何登发[1] 毛丹凤 成昌宇 XU Yanhua;HE Dengfa;MAO Danfeng;CHENG Changyu(School of Energy,China University of Geosciences(Beijing),Beijing 100083,China;School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《地质学报》2024年第12期3630-3646,共17页Acta Geologica Sinica

基　　金：中国石油长庆油田公司科技攻关项目(编号ZDZX2021-01);中央高校基础研究经费项目(编号2-9-2021-071)联合资助的成果。

摘　　要：印支期(中三叠世—早侏罗世)代表了中国关键的变形期和岩浆发育期,该时期华北克拉通构造-沉积格局发生重大转变。大量的地层记录被保存在相对稳定的鄂尔多斯盆地,为探讨印支运动对克拉通内盆地的改造提供了可能。本文通过研究区内10条地震剖面、105口钻井和28个野外露头,从井、震、野外剖面三方面精细刻画了印支期不整合面的类型、分布、演化和成因。研究表明:(1)印支期不整合面存在岩性突变、底砾岩发育、测井值(AC与GR)突变、地震强振幅反射等特征,据此划分出4种不整合面类型,即高角度不整合面(Ⅲ)、低角度不整合面(Ⅱ)、平行侵蚀不整合面(Ⅰ1)和平行不整合面(Ⅰ2);盆地中心以平行不整合面为主,向南、北缘过渡为低角度、高角度不整合面;(2)不整合面广泛分布于华北克拉通西缘和中部,并经历2期演化阶段,形成了纸坊组—铜川组之间的低角度不整合面和延长组—侏罗系复合不整合面;(3)华北克拉通南北缘双向挤压构造环境和干旱气候伴随季节性降雨促使形成了“下削上超”的角度不整合面与平行侵蚀不整合面共存的特征;构造-气候因素导致了鄂尔多斯盆地南部角度不整合面与北部复合成因不整合面的形成。本研究厘定了印支运动形成的两期区域不整合面,确定了印支期不整合面的构造-气候复合成因。The Indosinian period in China is characterized by significant tectonic deformation and magmatic activity,leading to major changes in the tectonic pattern of the North China Craton.The Ordos basin,known for its stable geological conditions,has preserved extensive stratigraphic records,providing critical insights into the basins evolution during the Indo-China movement.This study integrates data from 10 regional seismic profiles,105 wells,and 28 outcrops to provide a detailed description of the types,distribution,evolution,and genesis of the Indosinian unconformities.This multi-faceted analysis incorporates well logs,seismic data,and outcrop observations.Our findings reveal the following:①Indosinian unconformities are characterized by distinct lithological changes,basal conglomerate deposition,alterations in log values(AC and GR),and strong amplitude reflections on seismic data.Four distinct types of unconformities were identified:High-angle(Ⅲ),low-angle(Ⅱ),parallel(Ⅰ2),and parallel erosion(Ⅰ1).Parallel unconformities dominate the central basin,transitioning to low-angle unconformities in the south and high-angle unconformities in the north.②The unconformity is extensively present in the western and central regions of the North China Craton and has experienced four stages of evolution.This resulted in the development of a low-angle unconformity between the Zhifang and Tongchuan Formations,as well as between the Yanchang Formation and Jurassic polygenetic unconformity.③A compressional tectonic setting along the northern and southern margins of the North China Craton,coupled with a dry,seasonally rainy climate,facilitated the development of truncation,onlap,and erosion unconformities.These processes ultimately resulted in the formation of angular unconformities in the south and polygenetic unconformities in the north.This analysis supports the hypothesis that the Indo-China movement triggered two distinct phases of regional unconformities.Polygenetic unconformities resulted from the synergistic effects

关 键 词：鄂尔多斯盆地 印支期 不整合面 古地貌 秦岭造山带 

分 类 号：P548[天文地球—构造地质学]