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991.
The solubility of gold and quartz in 0.01, 0.10 and 1. 00 mol/kg NaCl solutions with various pH was determined in the presence
of the NNO oxygen buffer at 300°C and 50 MPa using a flexible gold cell hydrothermal apparatus. The Au speciation in the SiO2-NaCI-H2O system was inferred and the equilibrium constants for the following dissolution reactions were obtained: Au+H2O = AuOH0+1/2H2, logK(AuOH0) = -7.92 ± 0.25; Au+Cl-+H2O = AuOHCl-+1/2H2, logK(AuOHCl-) = - 7. 56 ± 0.65. The present study suggests that Au as AUOH0 and AuOHCl- is basically transported in ore-forming solutions under geologically realistic conditions of acidity, chloride molality and
oxygen fugacity. The reason for the common association of Au with SiO2 in hydrothermal gold deposits is discussed.
Project supported hy the National Natural Science Foundation of China. 相似文献
992.
新疆预须开普台铁铜矿床成因探讨 总被引:1,自引:1,他引:1
根据矿床地质地球化学等方面的研究,认为该矿床成矿物质来源于深部地壳或上地幔;通过海底火山同流作用,在酸性相对还原的热学沉积盆地中沉积成矿。成矿流体来源岩浆水,并有海水混入。红碧玉、重晶石等具有喷流岩的特征。矿床成因属于海底火山喷流一热水沉积矿床。 相似文献
993.
The geochemistry of wall rock alteration in turbidite-hosted gold vein deposits, central Victoria, Australia 总被引:3,自引:0,他引:3
Gold deposits hosted in Ordovician to Devonian turbidites in central Victoria, Australia, consist of steeply dipping quartz vein systems hosted mainly by reverse faults. Wall rock alteration of the host metasandstones, metasiltstones and shales (or slates) extends at least 20 m from the veins in the Bendigo-Ballarat zone (BBZ) and 10 m in the Melbourne zone (MZ) deposits. Alteration minerals include carbonates (ankerite, siderite and dolomite) chlorite, seriate, arsenopyrite, pyrite, chalcopyrite and sphalerite, with less common barite, albite and biotite in the BBZ and carbonates (siderite, ankerite, dolomite and ferromagnesite), sericite, chlorite, arsenopyrite, pyrite, and stibnite with less common chalcostibite in the MZ. SiO2, Na2O, MgO and Sr with P2O5 commonly decreasing during alteration while CO2, S, As, Sb, Au, V, Al2O3, Ga, K2O and Rb with Ni and Cr commonly increase. TiO2, FeO, Fe2O3, MnO, Th, U, Nb, La, Ce, and Sc showed little change. Concentrations of Zn, Cu, Pb, and Ca are variable.The relatively large decrease of SiO2 could account for most, if not all, quartz present in the ore veins. The Na2O and MgO could have crystallized in the veins in the very minor albite and chlorite present. The addition of V in all and Ni and Cr in most deposits probably reflects a source enriched in these elements such as underlying greenstones. The source of both the volatile (S, As, Sb) and lithophile (K2O and Rb) elements as well as Au is unknown, but they could have been derived from a magmatic source or from the metamorphism of Cambrian greenstones. CO2, present as carbonate, was derived mainly by the reaction of graphite, originally present in the sediments, with the ore solutions. Al2O3, the only other major element after SiO2, probably increased mainly due to the decrease of the latter. 相似文献
994.
995.
996.
热液矿床的矿体主要受断裂空间的控制.这些破裂空间的产生直接受控于构造应力偏张量的作用.应力偏张量为零的深度是构造动力驱动矿液运移的极限深度.应力偏张量等于岩石极限强度的叠加部位是矿化的极限深度. 相似文献
997.
北部湾盆地地温异常影响因素探讨 总被引:1,自引:0,他引:1
北部湾盆地地温场的不均一性除与基岩埋深有一定关系外,在很大程度上与活动热流体有关。含油气钻孔或含油气构造带大多分布在地温梯度和热流值较高的部位。压实作用及烃的生成所产生的压力促使热流体沿同生断裂以“幕式喷发”的方式发生运移,而流体所携带的巨大热量却不受盖层和构造圈闭等因素的影响向上传递,从而导致在地表(海底)形成高热流异常。 相似文献
998.
Ji Kejian Wang Liben Lu Fengxiang Wang Wuyi Zhang Jianhua Institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing 《《地质学报》英文版》1993,67(2)
Primary haloes of hydrothermal deposits were previously considered as positive haloes. Although it has been recently suggested that primary haloes incude positive and negative ones, almost all the research work on primary haloes has still focused on positive haloes for various reasons. In order to understand the source of ore substances a number of large hydrothermal deposits related to magmatism including porphyry, skarn and vein type deposits have been studied. It has been found that negative haloes exist on the peripheries of positive haloes of a mineral deposit. On the basis of the study the authors propose the concept of the geochemical field system of ore-forming elements of hydrotherreal deposits, i. e., with the orebody as the centre outwards there occur the mineralized field, positive halo field, depleted field and background field successively. 相似文献
999.
The Shimen realgar deposit is characterized by the pipi-shaped orebody and the development of silica sinter and hydrothermal explosive breccia which are typical of hot spring activity.Very similar trace-element associations are noticed between the silica cap and the breccia and modern hot spring waters in the area.The chemistr of ore-forming solutions is also well comparable with that of modern hot spring.,The spring system that gave rise to the mineralization was charged by ground waters heated through thermal conducting systems in the deep crust and,to a lesser extent,by geothermal gradient.ΔD,δ^18O,δ^13CCH4andδ^13CH4andδ^13CCO2values and ^40Ar/^36Ar and 3^He/^4He ratios indicate that the spring system is of crustal derivation.The ore-forming metals were supplied by surrounding strata,particularly those underlying the ore deposits.The mechanim of ore deposition is thought to be hydrothermal explosion and accompanying boiling and abrupt changes in pH and Eh.Located in northwest Hunan,the Shimen realgar deposit is the leading arsenic producer in the country,However,regardless of its long mining history,the genesis of this deposit has long been a puzzle.It was considered to be postmagmatic epithermal in the leading arsenic producer in the puzzle.It Was considered to be postmagmatic epithermal in origin,but this is trongly challenged by filling(metasomatism)in karst environment proposed later by Zhou Zhiquan(1986)also encounters a number of difficulties.For example,why can the pipi-shaped orebody vertically extend up to several hundreds meters without any compatible development in the lateral dimension? A hot spring genesis is suggested in the present paper based on geological observations and laboratory studies conducted by the authors in recent years. 相似文献
1000.
西秦岭太阳顶群硅质岩的岩石学及地球化学特征 总被引:2,自引:0,他引:2
本文详细论述西秦岭太阳顶群(寒武—奥陶系)硅质岩的岩石学、矿物学和化学成分特征,重点讨论球粒硅质岩的成因。通过微量元素、稀土元素及硅同位素分析,查明硅质具有深部来源的特征,并指出喷溢到浅水盆地底部的海底热水的硅化作用是其主要的形成机制。 相似文献