Processes of formation of fluorite-leucophane-melinophane-eudidymite ores of the Ermakovka F-Be deposit (western Transbaikalia)     

L.B. Damdinova  B.B. Damdinov  N.V. Bryanskii 《Russian Geology and Geophysics》2018,59(8):1022-1038

Fluorite-leucophane-melinophane-eudidymite ores of zone XVIII of the Ermakovka F-Be deposit were studied by geological, mineralogical, and thermobarogeochemical methods. Contents of Be and impurity elements (Li, Na, Mg, Al, Si, Cl, K, Mn, Fe, Cu, Zn, Nb, Mo, Ag, Sn, W, and Pb) in fluid inclusions in fluorite of this zone have been first determined by LA-ICP-MS. It is shown that fluorite-leucophane-melinophane-eudidymite ores were formed by alkaline high-F low-salt (6.0-12.5 wt.% NaCl equiv) solutions with a relatively low content of Be (0.0002-1.04 g/kg of solution). Fluorite and beryllium minerals were deposited in ores in a wide range of P-T conditions. The early fluorite-phenakite paragenesis formed at high temperatures (480-650 °C) and high pressures (> 3 kbar). At the late low-temperature stage, phenakite was replaced by Na-Be silicates (eudidymite and melinophane-leucophane) at < 220 °C and < 770 bars. The Be-ore deposition was due to the destruction of a predominant beryllium fluoride-carbonate complex as a result of the crystallization of fluorite during the metasomatic replacement of limestones. Eudidymite and melinophane-leucophane formed at low temperatures under high activity of Na and Ca and low activity of Be and F in highly alkaline solutions.  相似文献   

广西岑溪地区糯垌岩体中岩石包体的岩石学、地球化学特征及其意义     

秦亚  杨启军  李程  周叔齐  许浩天 《世界地质》2018,37(3):777-790

为探讨广西岑溪地区糯垌岩体及其岩石包体的成因,对糯垌岩体的岩石包体进行详细的岩相学、LA—ICP—MS锆石U—Pb年代学和地球化学分析。岩相学研究表明糯垌岩体的岩石包体主要为斑状黑云母钾长花岗岩、黑云斜长片麻岩、黑云二长片麻岩、二长变粒岩、钾长变粒岩和花岗闪长岩,按成因分为捕掳体和残浆包体两类。斑状黑云母钾长花岗岩包体(样品F16—7—6)和黑云斜长片麻岩包体(样品F16—13—4)的LA—ICP—MS锆石U—Pb定年结果分别为(152. 3±2. 2) Ma和(252. 7±4. 4)Ma;斑状黑云母钾长花岗岩与寄主岩石形成时代一致,黑云斜长片麻岩与大冲花岗闪长岩的侵位时代一致。岩石包体和寄主岩石在hark图解、稀土元素配分曲线和微量元素蛛网图中具有相似的演化趋势,表明寄主岩石经历了一定程度的同化混染作用。  相似文献   

新能源矿产调查工程进展   总被引：1，自引：1，他引：0       下载免费PDF全文

张家强  毕彩芹  李锋  单衍胜  仝立华  徐银波  唐跃  袁远  宁树正  周凤英 《中国地质调查》2018,5(4):1-16

近年来,由中国地质调查局油气资源调查中心牵头组织实施的“新能源矿产调查工程”,按照工程总体部署,主要开展了黔西、川南、新疆准南、东北三江等地区煤层气地质调查,松辽盆地西斜坡、柴达木盆地北缘油砂、油页岩地质调查,全国液化、气化等特殊用煤资源潜力调查、综合评价与信息系统建设等工作,获取了大量基础数据,取得了川高参1井、杨煤参1井等一系列突破性成果和重要进展,初步掌握了我国煤层气、油页岩、油砂等非常规油气资源以及特殊用煤资源家底。该工程取得的成果在煤层气等行业领域产生重要影响,提振了煤层气勘探开发信心,推动了科技创新与地质调查深度融合,促进了非常规油气学科的发展。  相似文献   

Genetic mechanisms of coalbed methane in typical districts from Huaibei Coalfield,Eastern China     

Li Tong  Feng Zhou  Yafei Wang  Shuying Li  Lingxiao Jia 《Geodinamica Acta》2018,30(1):241-248

Taking insight into genetic mechanisms of coalbed methane (CBM) can provide an effective approach for evaluating the value of CBM resources. In this study, the geo-temperature and the thermal subsidence history were used to investigate the effect of the present geothermal field characteristic on the genetic mechanisms of CBM at the Huaibei Coalfield. The results showed that the Permian coal strata in the study areas had a relatively low geo-temperature (< 50°C), high vitrinite reflectance (R_o,max; 0.75%-1.2%) and a coal rank typical of intermediate-high metamorphic bituminous. Comprehensive analyses of the characteristics of the present geothermal field indicate that the CBM at the Huaibei Coalfield are dominated by secondary biogenic gases. Furthermore, the genetic mechanism towards CBM was further proposed based on the tectonic evolution history: (1) Tectonic thrusting contributed to R_o,max values ranging from 0.5% to 3.0%, with maximum geo-temperatures of 140–180°C, which resulted in the generation of thermogenic CBM. (2) An extensional regime contributed to gradual uplift of the Permian coal-bearing strata, with the gradual escape of CBM at burial depths greater than 700m. (3) A large number of faults and hydrodynamic environments greatly promoted the microbial degradation of the early thermogenic gases, resulting in generation of secondary biogenic gases.  相似文献   

贵州岩溶地区煤层气钻井关键技术     

谢国毅  刘虎  毛志新 《探矿工程》2018,45(5):46-49

贵州省煤层气资源十分丰富,在前期的煤层气勘探开发过程中,出现了诸多钻井难点,一开钻进过程中容易遇碰到溶洞,存在井漏和井口失返现象;地层倾角大,可钻性差。二开钻井机械钻速低;煤层多而薄,机械强度低,岩心采取率低。这些钻井难点严重制约了贵州岩溶地区煤层气勘探和开发的进程。本文通过分析贵州岩溶地区地层特征和钻井难点,并通过多年的工程实践,总结出了一套适合贵州岩溶地区的煤层气钻井关键技术,包括一开空气钻井技术、二开快速钻井技术和绳索取心钻进技术等。本文的研究成果不仅适合贵州岩溶地区煤层气勘探和开发,对其他地区的煤层气勘探和开发也有借鉴意义。  相似文献   

Genesis of the Dalingzi Pb-Zn Deposit in the Western Margin of Yangtze Plate: Constraints from Fluid Inclusions and Isotopic EvidenceEI北大核心CSCD     

Wang H.  Wang J.  Zhu X.  Li Y.  Zhen S.  Sun H.  Cheng X.  Han Y.  Sun Z.  Jiang B. 《大地构造与成矿学》2018,(4):681-698

The Daliangzi Pb-Zn deposit is a large deposit hosted in the Sinian Dengying Formation dolostone, located in the Sichuan-Yunnan-Guizhou ore concentration area. Ore minerals are mianly sphalerite, galena, and gangue minerals consist of dolomite, quartz and calcite. The metallogenic stages may be divided into sphalerite-pyrite-carbon stage, sphalerite-galena stage and galena-chalcopyrite-carbonate stage. The ore-forming fluid is basin brine, which is characterized by medium-low temperature of 117.5 ℃ to 320.3 ℃ and medium salinity of 5.11% NaCleqv to 18.96% NaCleqv, moreover, the abundant CH4 and pitch in the fluid inclusions indicate that the participation of organic matter in the mineralization. The δ13CV-PDB and δ18OSMOW values of the Dengying Formation dolostone are similar to that of marine carbonate, revealing that the dolostone belongs to marine carbonate. Both the δ13CV-PDB and δ18OSMOW values of hydrothermal calcites are lower than that of the Dengying Formation dolostone, which may result from dissolution of the Dengying Formation dolostone. The δ34S values of ore minerals are mainly in the range of 9.8‰-20.8‰, indicating the sulfur may come from thermochemical reduction of marine sulfate in the Dengying Formation. The 207Pb/204Pb versus 206Pb/204Pb diagram manifests that Pb is crustal origin, and likely comes mainly from the wall rocks and less from the basement. (87Sr/86Sr)i ratios of sphalerites and hydrothermal calcite are higher than that of the Dengying Formation dolostone, indicating that the ore-forming fluid flew through the basement. In conclusion, the ore-forming fluid was basin brine, which extracted the metallogenic materials, Pb and Zn, from the basement and wall rocks. When the ore-forming fluid reached the "black fractured zones", carbonized tectonic breccia zone, S2- was produced by the thermochemical reduction reaction under the influence of the organic matter, and interaction between the S2- and Pb2+, Zn2+, resulted in the precipitation of ore metals. © 2018, Science Press. All right reserved.  相似文献   

青海驼路沟钴矿床流体包裹体及成矿物理化学条件     

朱华平  孙丰月  李碧乐  王力 《地球科学与环境学报》2007,29(4):351-355

应用均一法、激光拉曼显微探针法研究驼路沟钴矿床的流体包裹体,发现其包裹体类型多样,以气液两相包裹体和富二氧化碳包裹体为主,测得均一温度为220℃~300℃,众值为275℃,成矿流体形成于中低温环境。通过对其他热力学参数计算,确定出驼路沟钴矿床成矿流体具有中低盐度、低密度、弱还原-还原性的特点。包裹体气、液相成分分析表明其与现代海底热液沉积物的流体成分类似,进一步佐证了驼路沟钴矿床为热水喷流沉积成因。  相似文献   

Role of fluids in migmatites: CO₂-H₂O fluid inclusions in leucosomes from the Deep Freeze Range migmatites (Terra Nova Bay, Antarctica)     

G. GIORGETTI  M.-L.E FREZZOTTI  R. PALMERI  E. A. J. BURKE 《Journal of Metamorphic Geology》1996,14(3):307-317

ABSTRACT The metasedimentary sequence of the Deep Freeze Range (northern Victoria Land, Antarctica) experienced high-T/low-F metamorphism during the Cambro-Ordovician Ross orogeny. The reaction Bt + Sil + Qtz = Grt + Crd + Kfs + melt was responsible for the formation of migmatites. Peak conditions were c. 700–750° C, c. 3.5–5 kbar and x_H2Oc. 0.5). Distribution of fluid inclusions is controlled by host rock type: (1) CO₂-H₂O fluid inclusions occur only in graphite-free leucosomes; (2) CO₂–CH₄± H₂O fluid inclusions are the most common type in leucosomes, and in graphite-bearing mesosomes and gneiss; and (3) CO₂–N₂–CH₄ fluid inclusions are observed only in the gneiss, and subordinately in mesosomes. CO₂–H₂O mixtures (41% CO₂, 58% H₂O, 1% Nad mol.%) are interpreted as remnants of a synmig-matization fluid; their composition and density are compatible P–T–a_H2O conditions of migmatization (c. 750° C, c. 4 kbar, x_H2Oc. 0.5). CO₂-H₂O fluid in graphite-free leucosomes cannot originate via partial melting of graphite-bearing mesosomes in a closed system; this would have produced a mixed CO₂–CH₄ fluid in the leucosomes by a reaction such as Bt + Sil + Qtz + C ± H₂O = Grt + Crd + Kfs + L + CO₂+ CH₄. We conclude that an externally derived oxidizing CO₂-H₂O fluid was present in the middle crust and initiated anatexis. High-density CO₂-rich fluid with traces of CH₄ characterizes the retrograde evolution of these rocks at high temperatures and support isobaric cooling (P–T anticlockwise path). In unmigmatized gneiss, mixed CO₂–N₂–CH₄ fluid yields isochores compatible with peak metamorphic conditions (c. 700–750° C, c. 4–4.5 kbar); they may represent a peak metamorphic fluid that pre-dated the migmatization.  相似文献   

Halogen contents of eclogite facies fluid inclusions and minerals: Caledonides,western Norway     

H. Svensen  B. Jamtveit  D. A. Banks  H. Austrheim 《Journal of Metamorphic Geology》2001,19(2):165-178

Primary multiphase brine fluid inclusions in omphacite and garnet from low‐ to medium‐temperature eclogites have been analysed for Cl, Br, I, F, Li and SO₄. Halogen contents and ratios provide information about trapped lower crustal fluids, even though the major element (Na, K, Ca) contents of inclusion fluids have been modified by fluid–mineral interactions and (step‐) daughter‐crystal formation after trapping. Halogens in the inclusion fluids were analysed with crush–leach techniques. Cl/Br and Cl/I mass ratios of eclogite fluids are in the range 31–395 and 5000–33 000, respectively. Most fluids have a Cl/Br ratio lower than modern seawater and a Cl/I ratio one order of magnitude lower than modern seawater. Fluids with the lowest Cl/Br and highest Cl/I ratios come from an eclogite that formed by hydration of granulite facies rocks, and may indicate that Br and I are fractionated into hydrous minerals. Reconstructions indicate that the inclusion fluids originally contained 500–4000 ppm Br, 1–14 ppm I and 33–438 ppm Li. Electron microprobe analyses of eclogite facies amphibole, biotite, phengite and apatite indicate that F and Cl fractionate most strongly between phengite (F/Cl mass ratio of 1469 ± 1048) and fluid (F/Cl mass ratio of 0.008), and the least between amphibole and fluid. The chemical evolution of Cl and Br in pore fluids during hydration reactions is in many ways analogous to Cl and Br in seawater during evaporation: the Cl/Br ratio remains constant until the a_H2O value is sufficiently lowered for Cl to be removed from solution by incorporation into hydrous minerals.  相似文献   

南极乔治王岛长城站地区火山岩中矿物包裹体的研究          下载免费PDF全文

王碧香  张元奇  杨崇辉 《极地研究》1991,3(1):14-21

本文主要讨论了长城站地区第三纪火山岩系的透辉石和斜长石中熔融包裹体的特征、均一温度、挥发组分、玻璃和子矿物的化学成分。透辉石中熔融包裹体均一温度为1070～1170℃,斜长石中熔融包裹体均一温度m≥1100℃。透辉石和斜长石熔融包裹体气泡中组分CO_2为45～93％,H_2S为微量～35％,CH_4为2～20％和CO为2～14％,少量为N_2,O_2,H_2O和H_2。这些组分从火山喷发早期至晚期呈规律性变化。对熔融包裹体的玻璃和子矿物进行成分测定,其子矿物为钙铁橄榄石。  相似文献