鄂尔多斯盆地西缘徐庄组风暴沉积特征及沉积模式  

Sedimentary Characteristics and Model of Storm Deposits in the Xuzhuang Formation at the Western Margin of the Ordos Basin

作　　者：师宇翔 路向伟[3] 李国斌[4] 方泽鑫 徐凯 杨永祯 张寰萌 郭岭[1,2] SHI YuXiang;LU XiangWei;LI GuoBin;FANG ZeXin;XU Kai;YANG YongZhen;ZHANG HuanMeng;GUO Ling(State Key Laboratory of Continental Dynamics,Northwest University,Xi’an 710069,China;Department of Geology,Northwest University,Xi’an 710069,China;The 6th Oil Production Plant,Changqing Oilfield Company,PetroChina,Xi’an 710299,China;PetroChina Research Institute of Petroleum Exploration&Development-Northwest(NWGI),Lanzhou 730020,China)

机构地区：[1]西北大学大陆动力学国家重点实验室,西安710069 [2]西北大学地质学系,西安710069 [3]中国石油天然气股份有限公司长庆油田分公司第六采油厂,西安710299 [4]中国石油勘探开发研究院西北分院,兰州730020

出　　处：《沉积学报》2024年第4期1354-1369,共16页Acta Sedimentologica Sinica

基　　金：长庆油田重大科技专项(ZDZX2021-03);国家自然科学基金项目(42130206,41302076);大陆动力学国家重点实验室团队重点课题(201210128)。

摘　　要：【目的】鄂尔多斯盆地西缘寒武系砾屑灰岩发育,并发育典型的风暴沉积构造。然而,关于其沉积环境、形成过程及地质意义仍缺乏系统研究。【方法】通过对乌海摩尔沟、乌海老石旦、环县阴石峡、同心青龙山四条剖面实地观测以及薄片观察,详细研究了鄂尔多斯盆地西缘徐庄组砾屑灰岩发育特征以及典型的风暴沉积特征。【结果】(1)研究区徐庄组发育渠模、底冲刷面、丘状交错层理和平行层理等风暴沉积构造。(2)研究区徐庄组发育四种砾屑灰岩岩相,即颗粒支撑砾屑灰岩相,泥质充填砾屑灰岩相,放射状砾屑灰岩相和基质支撑砾屑灰岩相。(3)研究区徐庄组发育五种典型的风暴沉积序列。(4)综合研究区寒武纪陆表海环境与沉积相带以及前人研究成果,对砾屑灰岩成因进行分析并对其形成过程进行探讨,认为风暴浪与地震作用为砾屑灰岩形成的动力条件,古板块位置处于低纬度的风暴带,是风暴作用频发的原因。(5)研究区风暴沉积的发育揭示了鄂尔多斯盆地在寒武纪徐庄组时期位于赤道附近的低纬度地区,与通过古地磁学所恢复的华北板块在同时期所处位置形成相互印证。【结论】研究区风暴沉积的研究及沉积模式的建立,对鄂尔多斯盆地寒武纪时期古环境及古地理恢复具有重要意义。此外,研究区砾屑灰岩成因示意图揭示了砾屑灰岩的形成过程。[Objective]Gravelly limestone is developed in Cambrian strata at the western margin of the Ordos Basin,and typical storm sedimentary structures are developed.However,there is still a lack of systematic research on its sedimentary environment,formation process,and geological significance.[Methods]This detailed study of the development of gravelly limestone and typical storm deposits in the Xuzhuang Formation at the western margin of the Ordos Basin was conducted by means of field observation and thin section observation of four sections:Wuhai Moer⁃gou,Wuhai Laoshidan,Huanxian Yinshixia and Tongxin Qinglongshan.[Results]The following conclusions have been made:(1)storm sedimentary structures(e.g.,channel mold,bottom scouring surface,mound cross-bedding and parallel bedding)are developed in the study area.(2)There are four gravelly limestone facies are categorized by shape,arrangement and infill characteristics(e.g.,particle-supported gravelly limestone facies;argillaceous filled gravelly limestone facies;radial gravelly limestone facies and matrix-supported gravelly limestone facies).(3)In ad⁃dition,five typical storm sedimentary sequences of the Xuzhuang Formation of the Middle Cambrian are identified at the western margin of the Ordos Basin from field-measured data,and a storm sedimentary model of the study area is established.(4)The study area was located in an epicontinental sea environment during the Cambrian and combined with previous research results,the genesis of gravel limestone is analyzed and the formation process is illustrated.It is considered that the storm wave and seismic action are the dynamic conditions for the formation of gravel limestone.Storm waves and earthquakes were the dynamic conditions for the formation of gravelly limestone.The ancient plate was located in a tropical storm belt,which was the reason for frequent storms.(5)The development of storm deposits in the study area reveals that the Ordos Basin was located in a low-latitude area near the equator during the Cambrian Xuzhuang F

关 键 词：砾屑灰岩 风暴沉积 鄂尔多斯盆地 徐庄组 

分 类 号：P512.2[天文地球—地质学]