四川盆地西部栖霞组热液白云岩中的自生非碳酸盐矿物.docx

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1、四川盆地西部栖霞组热液白云岩中的自生非碳酸盐矿物黄思静李小宁黄可可兰叶芳吕杰王春梅(油气藏地质及开发工程我国重点试验室(成都理工高校)，成都610059)摘要热液环境是碳酸盐重要的成岩环境之一，MVT铅锌矿床和某些白云岩储层都与之有关。通过薄片观看、扫描电镜和能谱分析，在四川盆地西部中二叠统栖霞组白云岩地层中发觉了一些自生非碳酸盐矿物和焦沥青，包括伊利石、萤石、氟磷灰石、石英、重晶石和黄铁矿等，它们赋存于具不同结构的白云石的晶间/晶内孔隙和溶解孔隙中，尤其是非平直晶面鞍形白云石的溶解孔隙中。赋存自生矿物的白云石主晶的包裹体均一化温度主要分布在8018(C之间，最高可达240以上。白云石溶解空间

2、中萤石、氟磷灰石(也包括方解石)等以Ca作为阳离子自生矿物的存在，反映热液白云石沉淀后温度降低造成的流体性质的转变和白云石的溶解，热液蚀变作用还造成了伊利石的形成和黏土矿物的强迫热演化，白云石晶间焦沥青的存在则代表了有机质因热蚀变而发生的强迫成熟和过成熟。川西栖霞组碳酸盐岩的热液蚀变作用发生在距今259 Ma左右(中二叠世末)的东吴运动期间，与峨眉山玄武岩有关的热大事伴生。该期间古热流达6()8()mWn,甚至更高，持续时间约6 Ma,此时栖霞组白云岩地层的埋藏深度V50() m,因而热液蚀变过程与地热增温无关。白云岩地层中各种自生矿物和非正常有机质热演化形成的焦沥青的存在为川西栖霞组碳酸盐岩

3、所经受的热液环境成岩作用供应了依据。关键词四川盆地西部；栖霞组；热液蚀变；萤石；氟磷灰石；重晶石；有机质强迫成熟；黏土矿物的强迫热演化Authigenic noncarbonate minerals in hydrothermal dolomite ofMiddle Permian Qixia Formation in the west of Sichuan Basin9ChinaHUANG Si-jing, LI Xiao-ning, HUANG Ke-ke, LAN Ye-fang, LU Jie, WANG Chun-meiState Key Laboratory of Oil and

4、Gas Reservoir Geology and Exploitation, Chengdu University ofTechnology, Chengdu 610059, ChinaAbstract: The hydrothermal environment is an important diagenetic environment. MVT lead andzinc ore deposits and some dolomite reservoirs are related to hydrothermal environments. Basedon thin section exami

5、nation, scanning electron microscopy and the energy dispersion X-rayanalysis, some authigenic noncarbonate minerals, including illite, fluorite, fluorapatite, quartz,barite and pyrite, and pyrobitumen are identied in the Middle Permian Qixia Formation on thewest of Sichuan Basin. These minerals occu

6、r in the intercrystalline/intragranular pores anddissolution pores in dolomites with different textures, especially in the dissolution pores ofnonplanar-saddle dolomite. Fluid inclusion homogenization temperatures of host dolomites mainlyrange from 80 to 180, up to 240 or higher. The occurrence of a

7、uthigenic minerals takingCa2+ as the cation, such as fluorite, fluorapatite and also calcite in the dissolution space ofdolomite, reveals that the fall of temperature after the hydrothermal dolomite precipitation causesthe change of fluid nature and dissolution of dolomite. The hydrothennal alternat

8、ion also leads tothe formation of illite owing to forced thermal evolution of clay minerals. Pyrobitumen existingbetween dolomite crystals represents the forced maturation and over maturation of organic matterdue to hydrothermal alternation. The hydrothermal alternation of carbonate rocks from Qixia

9、Formation in the west of Sichuan Basin occurred during Dongwu Movement about 259 Ma B.R(the late stage of Middle Permian), associated with the thermal events related to the Emeishanbasalt eruption with paleoheat flow up to or higher than 60-80 mWm2 and duration time of about6 Ma. The buried depth of

10、 the dolomite strata in Qixia Formation was less than 500 meters at thatperiod, so the process of hydrothermal alteration had nothing to do with geothermal gradientfunction. Various authigenic minerals and pyrobitumen formed by abnormal thermal evolution oforganic matter in the dolomite strata provi

11、de evidences for the hydrothermal environmentdiagenesis experienced by carbonates from Qixia Formation in the west of Sichuan Basin.Key words: west of Sichuan Basin; Qixia Formation; hydrothermal alternation; fluorite;fluorapatite; barite; forced maturation of organic matter; forced thermal evolutio

12、n of clay minerals下刚果盆地A区块下白垩统Albian阶沉积层序与古地理演化于水I文华国2郝立华I郝立业I程涛I郑荣才2（1.中海石油争论中心，北京100049；2.油气藏地质及开发工程我国重点试验室（成都理工高校），成都610059）摘要通过对西非被动大陆边缘下刚果盆地中的A区块沉积相和层序地层分析，确定Albian阶主要为一套具“间断-交叉”混积机理的碳酸盐岩混杂陆源砂、泥沉积，可划分出5个三级层序，经受了从混积缓坡一周缘混积台地一裂开混积台地一深水混积陆棚深海盆地（深水扇）的沉积演化全过程，对应于威尔逊构造旋同中后裂谷拗陷阶段向大陆漂移的过渡阶段，其中发育主力储、产层的

13、SQ2-SQ3层序为型周缘混积.裂开台地沉积层序，可进一步划分为TST和HST两个体系域。解析了混积碳酸盐岩层序地层与沉积充填响应特征，建立了争论区混积碳酸盐岩“滑脱-盐拱-转换”多因素联控的沉积演化模式，提出SQ3层序时期的盐拱构造顶部呈帚状分布和垂向偏转加积发育的裂开混积台缘浅滩为最有利的储集微相类型；以TST和HST体系域作为编图单元，编制了 SQ2和SQ3层序各体系域的岩相古地理图并研讨了有利储集相带展布规律，认为A区块Albian阶SQ2-HST SQ3-TST和SQ3-HST三个体系域中猜测出的叠置台缘浅滩，应成为今后的勘探重点。关键词沉积-层序；混积碳酸盐岩；浅滩；沉积演化模式；

14、层序岩相古地理；Albian阶；下刚果盆地Sedimentary sequence and paleogeographic evolution of AlbianStage, Lower Cretaceous in Block A of Lower Congo BasinYU Shuil, WEN Hua-guo2, HAO Li-hua, HAO Li-ye1,CHENG Tao, ZHENG Rong-cai21 .Petroleum Research Center of CNOOC, Beijing 100049, China；2.State Key Laboratory of Oil

15、and Gas Reservoir Geology and Exploitation, Chengdu Universityof Technology, Chengdu 610059, ChinaAbstract: Lower Congo Basin is located on the passive continental margin of West Africa. Thispaper studies the sedimentary facies and sequence stratigraphy of Block A, ascertains that Albianis a set of

16、carbonate rocks mixed with terrigenous sand and mud forming in a mixed mechanism ofu intermittence-cross n diamictic process. Albian can be divided into five third-order sequences inthe area. The whole sedimentary and evolutionary process of the strata has undergone thesedimentary ramp- peripheral diamictic platformf