| 塔里木盆地西北部寒武系纽芬兰统玉尔吐斯组混积岩早成岩期岩溶特征及其地质意义 |
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| 引用本文： | 金值民,谭秀成,唐浩,沈安江,李飞,乔占峰,罗思聪,郑剑锋,王小芳.塔里木盆地西北部寒武系纽芬兰统玉尔吐斯组混积岩早成岩期岩溶特征及其地质意义[J].古地理学报,2021,23(1). |
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| 作者姓名： | 金值民 谭秀成 唐浩 沈安江 李飞 乔占峰 罗思聪 郑剑锋 王小芳 |
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| 作者单位： | 油气藏地质及开发工程国家重点实验室,西南石油大学,四川成都 610500;中国石油集团碳酸盐岩储层重点实验室西南石油大学分室,四川成都 610500;中国石油集团碳酸盐岩储层重点实验室,浙江杭州 310023 |
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| 基金项目： | 国家科技重大专项(编号:2016ZX05004002-001)资助。 |
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| 摘 要： | 通过塔里木盆地西北部阿克苏-柯坪-乌什地区露头剖面的宏微观工作发现,寒武系纽芬兰统玉尔吐斯组存在3期稳定发育的古暴露面,并具有(1)铁质结壳层、(2)近地表喀斯特(塑形)角砾、(3)溶沟、溶缝及囊状溶洞、(4)岩溶系统内的角砾、陆源碎屑充填物、(5)暴露面之上的地层超覆等暴露标志。综合分析认为研究区玉尔吐斯组并非连续沉积,内部存在多个沉积间断,并与肖尔布拉克组为区域性不整合接触。同时,在与灰岩和白云岩早成岩期岩溶特征对比分析的基础上,指出先期渗滤条件较差的混积岩(硅质碎屑-碳酸盐混合沉积)早成岩期岩溶以充填程度较高的溶沟、溶缝和小型溶洞发育为特征,且水平潜流岩溶带发育不成熟;以此区别于灰岩和云岩型早成岩期岩溶发育的相控溶蚀孔洞、岩溶花斑和近原地角砾化等典型特征。研究结果表明开放条件下的早成岩期暴露岩溶特征及储集层优化与否更多受岩石组构特征控制,由此推断在相对封闭的埋藏条件下,先期致密化的岩石难以经历岩溶改造形成相控的孔洞型储集层。这一认识不仅对深埋条件下储集层的形成和保持具有重要的借鉴意义,也为早成岩期岩溶地质理论的丰富和发展提供了新的材料。
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| 关 键 词： | 玉尔吐斯组 混积岩 硅质碎屑-碳酸盐混合沉积 早成岩期岩溶 沉积间断 岩溶改造 |
Eogenetic karst characteristics and its geological significance of mixed rocks in the Cambrian Terreneuvian Yuertus Formation in northwestern Tarim Basin |
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| Jin Zhi-Min,Tan Xiu-Cheng,Tang Hao,Shen An-Jiang,Li Fei,Qiao Zhan-Feng,Luo Si-Cong,Zheng Jian-Feng,Wang Xiao-Fang.Eogenetic karst characteristics and its geological significance of mixed rocks in the Cambrian Terreneuvian Yuertus Formation in northwestern Tarim Basin[J].Journal of Palaeogeography,2021,23(1). |
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| Authors: | Jin Zhi-Min Tan Xiu-Cheng Tang Hao Shen An-Jiang Li Fei Qiao Zhan-Feng Luo Si-Cong Zheng Jian-Feng Wang Xiao-Fang |
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| Affiliation: | (State Key Laboratory of Oit and Cas Resertoir Geology and Eixploitation,Southuest Petroleum University,Chengdu 610500 China;Research Branch of Souhuwest Petroleum University,Key Laboratory of Carbonate Reservoirs,CNPC,Chengdu 610500,China;Key Laboratory of Carbonate Reservoir,CNPC,Hangzhou 310023,China) |
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| Abstract: | Based on macro-and micro-scale studies on the outcrop profiles in the Akesu-KepingWushi areas in Northwestern Tarim Basin,three distinct subaerial exposed surfaces within the Yuertus Formation of the Cambrian Terreneuvian Series have been identified and are characterized as follows:( 1) ferruginous crust,( 2) near-surface karst( plastic) breccia,( 3) karst trench,fissure and cystic cave,( 4) breccia and terrigenous clastics filled in Karst system,and( 5) sediments onlapped onto the exposed surfaces. The comprehensive analysis shows that the Yurtus Formation in the study area is not continuously deposited,but presents several internal sedimentary hiatus and a regional unconformable contact with the overlying Xiaoerbulake Formation. Meanwhile,based on a comparative analysis of eogenetic karst characteristics between limestone and dolomite,it is suggested that the mixed rocks( mixed siliciclasticcarbonate sediments) with poor percolation conditions are characterized by the development of small karst caves and immature horizontal underflow zone. This can be used to distinguish the typical characteristics of facies-controlled karst caves,variegated karst,and near-in-situ brecciation of limestone from dolomitetype in early diagenetic stage. The findings show that the karstification and reservoir optimization in the early diagenetic stage under open conditions are more controlled by the rock fabric,so it is inferred that under relatively closed burial conditions,the early densified rocks are difficult to undergo karst modification to form facies-controlled vuggy reservoirs. This result not only has an important reference for the formation and maintenance of reservoirs under deep burial conditions,but also provides new materials for the supplement of eogenetic karst geological theory. |
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| Keywords: | Yuertus Formation mixed rock mixed siliciclastic-carbonate sediment eogenetic karst sedimentary discontinuity karst reconstruction |
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