Gas Sources of Natural Gas Hydrates in the Shenhu Drilling Area, South China Sea: Geochemical Evidence and Geological Analysis     

ZHU Youhai  HUANG Xi  FU Shaoying  SU Pibo 《《地质学报》英文版》2013,87(3):767-776

The Shenhu gas hydrate drilling area is located in the central Baiyun sag, Zhu Ⅱ depression, Pearl River Mouth basin, northern South China Sea. The gas compositions contained in the hydrate-bearing zones is dominated by methane with content up to 99.89% and 99.91%. The carbon isotope of the methane (δ13C1 ) are 56.7‰ and 60.9‰, and its hydrogen isotope (δD) are 199‰ and 180‰, respectively, indicating the methane from the microbial reduction of CO2 . Based on the data of measured seafloor temperature and geothermal gradient, the gas formed hydrate reservoirs are from depths 24-1699 m below the seafloor, and main gas-generation zone is present at the depth interval of 416-1165 m. Gas-bearing zones include the Hanjiang Formation, Yuehai Formation, Wanshan Formation and Quaternary sediments. We infer that the microbial gas migrated laterally or vertically along faults (especially interlayer faults), slump structures, small-scale diapiric structures, regional sand beds and sedimentary boundaries to the hydrate stability zone, and formed natural gas hydrates in the upper Yuehai Formation and lower Wanshan Formation, probably with contribution of a little thermogenic gas from the deep sedments during this process.  相似文献   

鄂尔多斯盆地宜川—黄陵地区马家沟组流体包裹体特征及其意义     

曹青  赵靖舟  赵小会  张涛  王宝清 《地球科学进展》2013,28(7):819-828

通过单偏光、荧光显微镜和显微冷热台测温观察等方法,对宜川—黄陵地区下古生界马家沟组流体包裹体进行系统研究,归纳流体包裹体岩相学、均一温度和冰点温度等特征,结合盆地热演化史分析推测储层内烃类充注史。综合分析结果显示研究区马家沟方解石内发现的沥青包裹体证明早期形成古油藏已遭受改造破坏;研究区马家沟组顶部古油藏的形成时间在早侏罗世—中侏罗世,而气藏的形成时间在早白垩世。  相似文献   

安徽天井山金矿成矿流体特征及成矿过程初探   总被引：6，自引：0，他引：6  

姜妍岑  谢玉玲  唐燕文  李应栩  王爱国  曾献育  李媛  刘保顺 《岩石矿物学杂志》2013,32(3):329-340

本文在矿床地质调研的基础上,通过主要矿石和蚀变岩石的岩矿相、SEM/EDS、流体包裹体岩相学、显微测温和成分分析,对天井山金矿成矿流体特征、流体来源及成矿过程进行了研究.结果表明,金矿化主要发育于石英脉中,少数产于蚀变围岩中,矿区蚀变以硅化、绢云母化最为发育,另发育含铁碳酸盐化、绿泥石化、黄铁矿化、黄铜矿化、方铅矿化、闪锌矿化等.金矿化发生于石英脉形成后的脆性变形阶段,与之相关的蚀变以绢云母化为主,其次为含铁碳酸盐化和硫化物矿化.金主要以自然金的形式与绢云母共生于石英脉的裂隙中或蚀变围岩中.通过与绢云母同期的流体包裹体研究表明,与金矿化有关的成矿流体为富水、含CO2的中高温(286～380℃)、低盐度流体(3.0％～5.1％,NaCleq,质量分数),单个流体包裹体的LA-ICP-MS成分分析表明,成矿流体中富含Pb、Zn、Cu、Bi、Mo、Sb等金属元素.综合流体包裹体中水的H同位素组成和流体成分特征,成矿流体主要为岩浆水的贡献.含CO2的岩浆流体沿活化的先期断裂上升并发生流体沸腾,在流体沸腾过程中CO2进入气相而改变了流体的pH值,造成金和其它金属硫化物的沉淀,同时形成石英裂隙中和围岩中的绢云母化、含铁碳酸盐化等蚀变.  相似文献   

硅铍石的包裹体及其形成条件研究     

高诗佳  白峰 《岩石矿物学杂志》2013,32(2):180-188

对硅铍石样品进行放大观察,可见大量杂乱分布的黄色透明针状固态包裹体、少量红色不透明粒状固态包裹体,气液包裹体和愈合裂隙普遍存在.通过激光拉曼光谱分析,测得硅铍石样品中气液包裹体的液态部分为含有CO2等气体的NaCl盐水溶液,气态部分的化学成分为CO2、水蒸气等.对硅铍石样品中气液包裹体的气体比和充填度进行估测,利用冷热台测出其均一温度和冰点分别为378.9～ 425.5℃和-12.1～-6.3℃.经过计算,得出硅铍石的近似形成温度为378.9～ 425.5℃,近似形成压力为234.44～428.56 MPa.  相似文献   

RES2DINV在粤北某铅锌矿区激电测深反演中的应用     

韦乙杰  袁忠明 《物探与化探》2013,(5):827-829

在粤北某铅锌矿矿区进行的直流激电测深工作中,通过修改激电测量数据格式,用RES2DINV软件进行反演,推测了3个矿体的产状。后经钻探验证,推测结果跟钻探揭露结果基本一致。  相似文献   

Genesis of the Zhaokalong Fe-Cu Polymetallic Deposit at Yushu, China:Evidence from Ore Geochemistry and Fluid Inclusions     

LI Huan  XI Xiaoshuang  WU Chengming  Koichiro WATANABE 《《地质学报》英文版》2013,87(2):486-500

The ore types of the Zhaokalong Fe-Cu deposit are divided into two categories: sulfide-type and oxide-type. The sulfide-type ore include siderite ore, galena-sphalerite ore and chalcopyrite ore, whereas the oxide-type ore include magnetite ore and hematite ore. The ore textures and structures indicate that the Zhaokalong deposit is of the sedimentary-exhalative mineralization type. Geochemical analyses show that the two ore types have a high As, Sb, Mn, Co and Ni content. The REE patterns reveal an enrichment of the LREE compared to the HREE. Isotopic analysis of siderite ore reveal that the δ13CPDB ranges from 2.01 to 3.34 (‰) whereas the δ18O SMOW ranges from 6.96 to 18.95 (‰). The fluid inclusion microthermometry results indicate that homogenization temperatures of fluid inclusions in quartz range from 131 to 181℃, with salinity values of 1.06 to 8.04 wt% NaCl eq. The mineralizing fluid therefore belongs to the low temperature - low salinity system, with a mineralizing solution of a CO2-Ca2+(Na+, K+)-SO42-(F-, Cl-)-H2O system. The geochemical results and fluid inclusion data provide additional evidence that the Zhaokalong deposit is a sedex-type deposit that experienced two stages of mineralization. The sulfide mineralization probably occurred first, during the sedimentary exhalative process, as exhibited by the abundance of marine materials associated with the sulfide ores, indicating a higher temperature and relatively deoxidized oceanic depositional environment. After the main exhalative stage, hydrothermal activity was superimposed to the sulfide mineralization. The later stage oxide mineralization occurred in a low temperature and relatively oxidized environment, in which magmatic fluid circulation was dominant.  相似文献   

滇西云县-景谷火山弧带官房铜矿床成因:流体包裹体及年代学证据   总被引：4，自引：1，他引：3  

陈莉  王立全  王保弟  刘函 《岩石学报》2013,29(4):1279-1289

官房铜矿位于云县-景谷火山弧带北段,矿体主要呈浸染状、网脉状赋存于小定西组杏仁状玄武岩、玄武质角砾岩及其断裂破碎带中.本文采用LA-ICP-MS方法,首次获得小定西组玄武岩锆石U-Pb年龄为234.3±0.8Ma,表明赋矿地层小定西组形成于中三叠世,而不是前人一直认为的晚三叠世.通过矿石中石英、方解石的流体包裹体形貌特征、均一温度和成分的研究,并结合矿区矿石矿物特征,认为官房铜矿至少存在两期不同的成矿作用,即中三叠世火山-次火山热液成矿和后期(可能为新生代)地下水热液叠加改造.结合云县-景谷火山弧的形成演化过程,认为区域中三叠统小定西组玄武岩和芒怀组流纹岩构成了“双峰”式火山岩组合,官房铜矿产于中三叠世裂谷盆地的基性火山岩中,受海陆交互相的古地理环境制约,早期成矿具有VHMS型成矿特征,由于缺乏火山热液成矿流体聚集的“卤水池”,仅发育典型VHMS矿床下部火山通道相中的脉状-网脉状-角砾状矿体,缺少上部厚大的层状矿体,并经历了后期地下水热液的叠加改造.  相似文献   

北秦岭松树沟榴闪岩锆石U-Pb定年、矿物包裹体和Lu-Hf同位素特征及其地质意义   总被引：6，自引：5，他引：1  

钱加慧  杨秀清  刘良  曹玉亭  陈丹玲  杨文强 《岩石学报》2013,29(9):3087-3098

采用LA-ICP-MS锆石U-Pb定年法对松树沟榴闪岩中的锆石进行年代学分析,得到锆石残留核的206Pb/238U加权平均年龄为729±24Ma,对应的Th/U比值为0.70~1.01;变质锆石的206Pb/238U加权平均年龄为496±9.1Ma,对应的Th/U比值为0.02~0.11。通过激光拉曼探针在变质锆石里寻找到斜长石、单斜辉石、石榴石、石英、榍石、磷灰石等矿物包裹体,结合岩石具有的石榴石变斑晶和单斜辉石+斜长石嵌晶,推测变质锆石可能生长于岩石的高压麻粒岩相变质阶段,不排除早期存在榴辉岩相变质的可能性,所获~496Ma的变质时代记录了一期与陆壳深俯冲相关的区域地质事件。利用LA-MC-ICP-MS法测定了变质重结晶锆石的176Hf/177Hf=0.282560~0.282663;以t=730Ma计算出εHf(t)=+8.6~+12.2;Hf模式年龄为867±43Ma。锆石残留核年龄和变质重结晶锆石的t DM(Hf)数值,表明该榴闪岩的原岩应老于729Ma,原岩物质从亏损地幔分离的时间不晚于867±43Ma。结合前人研究成果,认为松树沟榴闪岩是早期侵位的岩石遭受早古生代高压-超高压区域变质作用的产物。  相似文献   

吉林延边棉田金铜矿床成矿流体特征及矿床成因     

吴涛涛  陈跃军  张宇峰  张勇  赵宏光  王长兵  刘永俊  朱怀亮  吴国学 《世界地质》2013,32(1):15-23

棉田金铜矿床是受断裂构造和中性侵入体联合控制的以金、铜为主的多金属矿床。笔者在对该区地质调查的基础上,运用红外光谱分析和显微测温技术对成矿流体进行研究,发现该区围岩蚀变以绢云母化和青磐岩化最为普遍,并将成矿阶段分为4 个阶段: 黄铁绢英岩阶段、石英--黄铁矿阶段、多金属硫化物阶段和石英--碳酸盐阶段; 对应的均一温度为320℃ ～ 360℃、280℃ ～ 320℃、200℃ ～ 280℃和200℃ ～ 240℃; 其中主成矿阶段为第二、三阶段,主成矿温度为200℃ ～ 320℃,这也是热液中水和二氧化碳含量最高的阶段。流体盐度为1. 91 ～ 13. 40 ( wt%,NaCl) ,密度为0. 69 ～ 0. 95 g /cm3,具低盐度和低密度的特点; 成矿深度为0. 8 ～ 1. 5 km,具浅层成矿的特点; 氢氧同位素分析, δ18OH2O的值为－ 4. 7 × 10 － 3 ～ 5. 83 × 10 － 3,δDH2O的值为－ 89 × 10 － 3 ～ － 124 × 10 － 3,说明成矿流体主要为岩浆水,含少量大气水。综合研究表明,棉田金铜矿床属于浅成中温岩浆热液型矿床。  相似文献   

Synthesis of Fluid Inclusion Reference Materials in the H2O–NaCl–CH4 System     

Fabiano R. L. Faulstich  Reiner Neumann  Jacques Pironon  Aurelien Randi 《Geostandards and Geoanalytical Research》2013,37(4):393-402

In this study, we detail procedures to synthesise inclusions of fluids of known composition under diagenetic conditions – low temperatures (50–180 °C) and pressures (2–25 MPa) – hosted by quartz. Pre‐existing microcavities in polished quartz chips were used, decrepitated and rinsed before being healed in an autoclave. Each synthesis required around 4 weeks. A range of biphase liquid–vapour inclusions in the H₂O–CH₄–NaCl system, similar to natural ones, were synthesised in quartz, varying the content of all three components. The quartz chips were checked before and after synthesis by optical microscopy, microthermometry and Raman spectroscopy. The method was used to build a series of calibration curves relating methane‐to‐water count ratios to the methane content of aqueous fluid inclusions. Good correlation was obtained between Raman band area ratios and the expected CH₄ solubilities from equations of state. The chosen procedure's main advantages, compared with other published methods, are as follows: quicker healing of the microfractures at lower temperatures, larger inclusions, simple quartz sample preparation, control of fluid inclusion composition and the use of commercial reactors. Such reference material inclusions allow the calibration of Raman microspectrometers with the objective of PTX reconstruction of palaeofluid migration in petroleum reservoirs.  相似文献