| 四川盆地震旦系灯影组葡萄状白云岩成因 |
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| 引用本文： | 张杰,Brian Jones,潘立银,周进高,秦玉娟,郝毅,武明德.四川盆地震旦系灯影组葡萄状白云岩成因[J].古地理学报,2014,16(5):715-725. |
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| 作者姓名： | 张杰 Brian Jones 潘立银 周进高 秦玉娟 郝毅 武明德 |
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| 作者单位： | 1.中国石油杭州地质研究院,浙江杭州 310023;2.中国石油集团公司碳酸盐岩储层重点实验室,浙江杭州 310023;3.Department of Earth and Atmospheric Sciences,University of Alberta,Edmonton,Alberta T6G 2E3,Canada;4.青海省环境地质勘查局,青海西宁 810007 |
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| 基金项目： | 国家科技重大专项，中国石油杭州地质研究院科技攻关项目(编号21129 |
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| 摘 要： | 四川盆地震旦系灯影组发育巨厚的白云岩,其中灯影组二段和四段发育大量具有各种形态的葡萄状白云岩,其直径最长可达75cm,有的平行于层面,有的穿层。剖面资料表明,葡萄状白云岩发育多期等厚环边胶结物,中部残留大量未充填的不规则洞穴,这成为与岩溶喀斯特作用相关的地下溶蚀作用的证据。围岩泥晶白云石为早期海水中原生结晶的产物,后来的胶结物可划分为4期: (1)自泥晶化白云石(部分样品中可见)作为最早的一期胶结物,由于各种生物化学作用和生物作用的影响而紧贴着围岩发育;(2)第2期胶结物纤维状白云石可能为海水中直接沉淀的产物,经历后期成岩作用后,具有完全有序的结构,晶胞参数接近理想值;(3)细—中晶白云石为第3期胶结物,包含纤维状白云石溶蚀残余,形成于构造抬升之后的近地表大气淡水环境;(4)第4期胶结物中—粗晶白云石为埋藏环境下直接结晶的产物,充填了孔洞中心,残留部分未充填孔洞。灯影组受到了岩溶喀斯特作用、胶结作用以及白云石化作用等成岩作用的影响,其中与葡萄状白云岩有关的岩溶喀斯特作用对于灯影组储集层的发育至关重要。对灯影组葡萄状白云岩的研究,不仅有助于深入探讨灯影组储集层成因和演化及灯影组白云岩的成因,而且有助于指导四川盆地前寒武系油气勘探。
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| 关 键 词： | 葡萄状白云岩 灯影组 胶结物 晶胞参数 岩溶喀斯特 四川盆地 |
| 收稿时间： | 29 July 2013 |
Origin of botryoidal dolostone of the Sinian Dengying Formation in Sichuan Basin |
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| Zhang Jie,Brian Jones,Pan Liyin,Zhou Jingao,Qin Yujuan,Hao Yi,Wu Mingde.Origin of botryoidal dolostone of the Sinian Dengying Formation in Sichuan Basin[J].Journal of Palaeogeography,2014,16(5):715-725. |
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| Authors: | Zhang Jie Brian Jones Pan Liyin Zhou Jingao Qin Yujuan Hao Yi Wu Mingde |
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| Institution: | 1.PetroChina Hangzhou Research Institute of Geology,Hangzhou.310023,Zhejiang;2.Key Laboratory of Carbonate Reservoir,CNPC,Hangzhou.310023,Zhejiang;3.Department of Earth and Atmospheric Sciences,University of Alberta,Edmonton,Alberta T6G 2E3,Canada ;4.Qinghai Exploration Bureau of Environment Geology,Xining.810007,Qinghai |
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| Abstract: | Sinian Dengying Formation (up to 1000m) in Sichuan Basin is composed of fine crystalline dolostones. In some parts of the formation(mainly in Members 2 and 4) distributed various shaped botyroidal masses of dolomite,up to 75cm long in maximum. They are either parallel to bedding or cutting across bedding. Those cross sections reveal that isopachous bands of various types of dolomite are developed as cements. Large amount of irregular shaped cavities are still present in the central parts of some larger bodies, which formed as a result of subterranean dissolution that was associated with karst development. The surrounding micritic dolostone was originally deposited from seawater protocrystallization, and the subsequent cements can be divided into four stages:(1)the dolomitized automicrite in some samples was the 1st stage cement,which formed close to the surrounding micritic dolostone due to various physiochemical and possible biological influences;(2)the 2nd stage fibrous dolomite had an absolute ordering crystal structure and nearly ideal crystal cell parameter,which may have originated from marine waters and adjusted to be ordered during the late diagenesis;(3)the 3rd stage fine- to medium-crystal dolomite including residual of fibrous dolomite crystals dissolved in a near-surface meteoric environment after tectonic uplift;(4)the 4th stage medium-coarse crystal dolomite primarily precipitated under a burial environment and partially filled the central parts of the cavities, with some unfilled cavities. It is apparent that the Dengying Formation was subject to multiple phases of diagenesis including karst development,precipitation of various cements,and multiple episodes of dolomitization. Except the paleokarstification,all of the other processes critically reduced the porosity of the petroleum reservoir that developed in the Dengying Formation. The paleokarstification which related to botryoidal dolostone has crucial importance to the Dengying Formation reservoir. The study of botryoidal dolostone in Sinian Dengying Formation conduces to understand the reservoir origin and evolution of the Dengying Formation dolostone,and guide the Precambrian petroleum development of Sichuan Basin |
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| Keywords: | botryoidal dolostone Dengying Formation cement crystal cell parameter Palae-okarstification Sichuan Basin |
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