鄂尔多斯盆地中部寒武纪岩相古地理研究  

Lithofacies Paleogeography of the Cambrian in the Central Ordos Basin

作　　者：郑萌 梁积伟[1] 冯振伟 冯昆明 宗浩 李汉林 常小斌 Tsogochir Tungalag ZHENG Meng;LIANG Jiwei;FENG Zhenwei;FENG Kunming;ZONG Hao;LI Hanlin;CHANG Xiaobin;Tsogochir Tungalag(School of Earth Sciences and Resources,Chang’an University,Xi’an 710064,Shaanxi,China;PetroChina Changqing Oilfield Co,No.9 Oil Production Plant,Xi’an 710200,Shaanxi,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710064 [2]中国石油长庆油田公司第九采油厂,陕西西安710200

出　　处：《西北地质》2023年第6期352-368,共17页Northwestern Geology

基　　金：第二次青藏高原科学考察研究国家专项“碰撞以来高原古地理格局与构造地貌演化”(2019QZKK0704);中国地质调查局项目(0716-1641DK900365/07);国际地科联国际地层对比计划(IGCP652)联合资助。

摘　　要：鄂尔多斯盆地寒武系是一套海相沉积地层,岩性以碳酸盐岩为主夹少量碎屑岩。近年来,该地区的寒武系被认为具有很大的勘探潜力,但迄今为止尚未发掘到大型储层。以往的研究主要集中在东、西和南部,而中部的研究严重缺乏,这阻碍了该区油气勘探的突破。笔者通过对56个钻孔岩心和13条野外露头进行单井划分,根据120块镜下薄片和岩石组合特征,识别出2种沉积相:斜坡相和台地相2种沉积相。在此基础上,开展联井对比,以盆地中部为中心划分出东西、南北2条贯穿盆地的连井剖面,探讨不同时期的沉积厚度和沉积相变规律。研究认为,鄂尔多斯盆地寒武系形成于海侵背景下,在经历了辛集期后,海水从盆地的西部和南部向内部推进。到张夏期,海进达到鼎盛,盆地绝大部分区域被海水淹没,只留下零星低矮的古陆。到三山子期,海进由盛转衰,开始发生海退。笔者重建了“一隆四凹”的古地理沉积格局,还原了盆地中部寒武纪构造沉积演化过程。The Cambrian System in the Ordos basin is a set of marine sedimentary formations dominated by carbonate rocks and interbedded with a small amount of clastic rocks.In recent years,the Cambrian System in this area has been considered to have great exploration potential,but so far no large reservoirs have been discovered.Previous research has mainly focused on the eastern,western,and southern parts,while research on the central part has been severely lacking,which has hindered breakthroughs in oil and gas exploration in the region.In this study,single-well divisions were conducted on 56 drill cores and 13 outcrop sections,and based on the characteristics of 120 thin sections and rock combinations,two sedimentary facies were identified:slope facies and platform facies.Based on this,inter-well comparisons were carried out,and two cross-well sections run-ning through the east-west and north-south of the basin were delineated with the center of the basin as the focus,to explore the sedimentary thickness and facies changes in different periods.The study suggests that the Cambrian in the Ordos basin was formed under a transgression background,and after the Xijian period,seawater advanced from the western and southern parts of the basin towards the interior.By the Zhangxia period,the sea had reached its peak and most of the basin was submerged by seawater,leaving only sporadic low-lying ancient land.During the sedimentation period of the Sanshanzi Formation,the sea transgressed to regress.This study also reconstructed the paleogeographic pattern of“one uplift and four depressions”and restored the tectonic and sedimentary evolution process of the Cambrian period in the central part of the basin.

关 键 词：岩相古地理 寒武系 鄂尔多斯盆地 构造沉积演化 

分 类 号：P618.13[天文地球—矿床学]