鄂尔多斯盆地马家沟组准层状岩溶角砾岩特征及其成因  

Characteristics and genesis of quasi-stratified karst breccia of the Majiagou Formation in Ordos Basin

作　　者：张欣玥 李凌[1,2] 张道锋 易刚[4] 吴东旭 钟寿康 杨梦颖 熊鹰 肖笛[1,2] 谭秀成 ZHANG Xinyue;LI Ling;ZHANG Daofeng;YI Gang;WU Dongxu;ZHONG Shoukang;YANG Mengying;XIONG Ying;XIAO Di;TAN Xiucheng(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Research branch of southwest petroleum university,key laboratory of carbonate reservoirs,CNPC,Chengdu 610500,China;Research Institute of Exploration and Development,Changqing Oilfield Company of PetroChina,Xi'an 710021,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,Sichuan;PetroChina Hangzhou Research Institute of Geology(HIPG),Hangzhou 310023,China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [2]中国石油集团碳酸盐岩储层重点实验室西南石油大学研究分室,四川成都610500 [3]中国石油长庆油田分公司勘探开发研究院,陕西西安710021 [4]西南石油大学地球科学与技术学院,四川成都610500 [5]中国石油杭州地质研究院,浙江杭州310023

出　　处：《古地理学报》2022年第4期663-679,共17页Journal of Palaeogeography：Chinese Edition

基　　金：中国石油集团公司上游领域基础性前瞻性项目(编号:2021DJ0501)资助。

摘　　要：鄂尔多斯盆地奥陶系马家沟组广泛发育岩溶角砾岩,结构特征复杂。近期研究发现,这些角砾岩的组构和分布特征难以能单纯地用经典的风化壳岩溶模式解释,各类角砾岩的成因机理值得进一步探究。文中基于大量岩心及薄片观察,对苏里格气田东区奥陶系马家沟组上组合不同层位角砾岩进行归纳和判识,明确其空间展布和序列结构特征,分析形成机理。研究发现:(1)根据成因与发育环境,苏格里气田东区奥陶系马家沟组上组合角砾岩可划分为5类,分别是近原地解离角砾岩(B1)、近地表堆积角砾岩(B2)、洞穴堆积角砾岩(B3)、洞顶(壁)碎裂角砾岩(B4)和坍塌角砾岩(B5),它们具有纵向多层叠置、横向可对比的“准层状”特征;(2)不同类型角砾岩的纵向配置和演化与周期性的向上变浅沉积序列和暴露溶蚀有关,共归纳为3种类型,即B1主发育型、B2-B3-B4组合发育型、B5主发育型;(3)准层状角砾岩形成于早成岩期,受控于古地貌起伏背景下的高频海平面变化,由暴露溶蚀透镜体横向迁移连片和纵向多旋回叠置而成。研究结果不仅有助于了解鄂尔多斯盆地马家沟组多样化的岩溶角砾岩特征与成因,也为白云岩早成岩期岩溶研究提供了新的素材。Karst breccia with complex structural characteristics is widely developed in the Ordovician Majiagou Formation in Ordos Basin.It is found that the classical model can not explain the fabric and distribution characteristics of breccia,and the genetic mechanism is required further studied.Based on observation of cores and thin sections,different types of breccias of upper Ordovician Majiagou Formation in the eastern Sulige Gas Field are summarized and identified to clarify the spatial distribution,sequence structure characteristics and the formation mechanism.The results showed that(1)five types of breccia can be identified according to the occurrence and origin,including nearly in situ dissociation breccia(B1),near surface accumulation breccia(B2),cave accumulation breccia(B3),height(wall)fractured breccia(B4)and solution breccia(B5).They are multilayer overlapping in the vertical direction and have the“quasi stratified”characteristics which can be comparable in the horizontal direction;(2)The vertical configuration and evolution of different breccias are related to the periodical upward shallower sedimentary sequence and exposure dissolution,which can be classified into three types:main development type of B1,combined development type of B2-B3-B4 and main development type of B5;(3)The quasi-stratified breccia formed in the early diagenetic stage and was controlled by the high frequency sea level change under the background of low geomorphic relief,the multi-cycle superposition in the vertical direction,transverse migration and interlocking process of exposed dissolution lens.The research is helpful for understanding the characteristics and genesis of diversified karst breccia in Majiagou Formation,Ordos Basin,which also provides new materials for the study of dolomite karstification at the early diagenesis period.

关 键 词：岩溶角砾岩 早成岩期岩溶 高频层序 马家沟组 苏里格气田 鄂尔多斯盆地 

分 类 号：P588.245[天文地球—岩石学]