古地理学报2024，Vol.26Issue(1)：119-131,13.DOI:10.7605/gdlxb.2024.01.004
鄂尔多斯盆地怀远运动期不整合类型及其分布特征
Distribution characteristics of different Huaiyuan unconformities in Ordos Basin
摘要
Abstract
The Huaiyuan Movement is an important tectonic event in the early Paleozoic of the North China Platform,resulting in a regional unconformity.Based on outcrop data,geological maps,drilling data and new seismic data,the identification marks,types and distributions of unconformities formed dur-ing the Huaiyuan movement in the Ordos Basin were analyzed.The results show that(1)sandy conglo-merate and weathered crust developed near the unconformity surface;additionally,high acoustic time,high gamma values,high content of trace elements(U,Th and K),high thorium-uranium ratios,low resistivity,and low density of logging curves occurred near the unconformity surface.The seismic response of the unconformity is characterized by a strong phase,and there are obvious differences in amplitude in-tensity,frequency and continuity in the wave groups on both sides of the unconformity.In addition,the truncation point reflections can be observed in local domain.(2)The Huaiyuan movement caused both parallel-unconformity and low-angle cutting unconformity in the basin.The former was widely distributed in the basin and its periphery areas,and the latter was distributed near the paleo-uplift in the basin.(3)The Ordos Basin and its periphery areas were affected by three stages of the Huaiyuan tectonic move-ment:during the depositional period of the Zhangxia Formation in the Middle Cambrian,uplift first oc-curred in the southeast region of the basin and then moved to the northwest direction;at the end of the Sanshanzi Formation deposition period in the late Cambrian,paleo-uplifts developed in the basin,and they were subjected to erosion;at the end of the late Cambrian,before the Ordovician Majiagou Formation was deposited,the negative drift of carbon isotopes first occurred in the bottom layer of Majiagou Forma-tion due to the influence of global sea level decline.These results provides a reference for the research of new fields of oil and gas exploration in Lower Paleozoic in the Ordos Basin.关键词
鄂尔多斯盆地/奥陶系/削截/不整合/怀远运动Key words
Ordos Basin/Ordovician/truncation/unconformity/Huaiyuan movement分类
地质学引用本文复制引用
毛丹凤,何登发,包洪平,魏柳斌,成祥,苟钧壹,石婧,许艳华..鄂尔多斯盆地怀远运动期不整合类型及其分布特征[J].古地理学报,2024,26(1):119-131,13.基金项目
中国石油长庆油田公司科技攻关项目(编号:ZDZX2021-01)资助.Financially supported by the project of Tackling the Science and Technological Key Problems in PetroChina Changqing Oil and Gas Field Company(No.ZDZX2021-01) （编号:ZDZX2021-01）
