斑岩铜矿床研究进展   总被引：1，自引：0，他引：1  

张云国  周朝宪 《地球科学进展》2011,26(11)

斑岩铜矿不但形成于环太平洋成矿域,还形成于特提斯成矿域和中亚成矿域（古亚洲洋成矿域）。成矿物质来源于深部,经过“洋壳一地幔熔岩流”、“原始岩浆”、“浅部富矿岩浆”和“岩浆结晶一成矿”4个阶段,其中在“原始弧岩浆”阶段,通过MASH过程,有大量成矿物质和能量的聚集。成矿流体为富H2O、高温、高压、高盐度、强氧化性、高氧逸度的富矿气液相流体,这些特点有利于成矿物质在岩浆一热液分离过程中向流体富集,并以氯络合物的形式运移。随着成矿流体的上侵,温度和压力的降低是成矿物质沉淀的主要影响因素。磁铁矿的结晶为成矿流体提供了大量的S2-离子,也是导致成矿物质沉淀的主要因素。斑岩型蚀变带从里向外为石英内核、钾化带、SCC带和泥化带,铜矿化主要发育在矿化带外围以及SCC带。目前,斑岩铜矿成矿模型主要有经典模型、系统模型和多阶段叠加模型。  相似文献   

新疆北山地区坡十镁铁-超镁铁岩体的岩石学特征及其对成矿作用的指示   总被引：6，自引：4，他引：2  

苏本勋  秦克章  唐冬梅  邓刚  肖庆华  孙赫  卢鸿飞  代玉财 《岩石学报》2011,27(12):3627-3639

新疆北山地区的坡十镁铁-超镁铁岩体在钻孔剖面上主要由辉长岩、纯橄岩和二辉橄榄岩组成,各岩相在矿物含量上具有渐变过渡的关系,主要组成矿物橄榄石、单斜辉石和尖晶石的化学成分显示系统的变化,而底部的二辉橄榄岩中的矿物成分具有“边缘反转”现象.这些特征表明坡十岩体的形成主要受结晶分异作用控制,亦有明显的壳源混染痕迹.以反应边形式出现在辉石边部的角闪石的出现,尖晶石的分解现象,以及角闪石和金云母化学成分剖面上的系统变化揭示该岩体经历了堆晶后自上而下程度减弱的蚀变反应.在早期结晶的矿物相(橄榄石和尖晶石)中发现有硫化物颗粒或细脉产出,表明在岩浆演化的早期阶段确实发生了硫化物熔离的现象.硫化物总与含水矿物(金云母)或蚀变矿物(角闪石和蛇纹石)相伴生的特点显示铜镍硫化物的形成和沉淀不仅与壳源混染有关,而且也与堆晶后的蚀变反应密切相关.  相似文献   

内蒙古达来庙地区1:5万矿调遥感蚀变信息提取     

王弢  刘颖曙  章培春 《西部资源》2011,(6):80-82

本文探讨了内蒙古达来庙矿调工作区乌兰德勒、准苏吉花、阿敏乌苏等钼矿床围岩蚀变的特征及遥感识别方法。通过采用主成分分析、比值以及主成份变换法等多种蚀变异常提取方法,提取了与钼矿化有关的围岩蚀变信息。经野外实地验证,发现了两个具有重要找矿价值的找矿靶区,经进一步勘查矿床规模已达中型。  相似文献   

Geologic remote sensing for geothermal exploration: A review     

《International Journal of Applied Earth Observation and Geoinformation》2014

This paper is a comprehensive review of the potential for remote sensing in exploring for geothermal resources. Temperature gradients in the earth crust are typically 25–30 °C per kilometer depth, however in active volcanic areas situated in subduction or rift zones gradients of up to 150 °C per kilometer depth can be reached. In such volcanic areas, meteoric water in permeable and porous rocks is heated and hot water is trapped to form a geothermal reservoir. At the Earth's surface hot springs and fumaroles are evidence of hot geothermal water. In low enthalpy systems the heat can be used for heating/cooling and drying while in high enthalpy systems energy is generated using hot water or steam. In this paper we review the potential of remote sensing in the exploration for geothermal resources. We embark from the traditional suite of geophysical and geochemical prospecting techniques to arrive at parameters at the Earth surface that can be measured by earth observing satellites. Next, we summarize direct and indirect detection of geothermal potential using alteration mineralogy, temperature anomalies and heat fluxes, geobotanical anomalies and Earth surface deformation. A section of this paper is dedicated to published remote sensing studies illustrating the principles of mapping: surface deformation, gaseous emissions, mineral mapping, heat flux measurements, temperature mapping and geobotany. In a case study from the La Pacana caldera (Chili) geothermal field we illustrate the cross cutting relationships between various surface manifestations of geothermal reservoirs and how remotely sensed indicators can contribute to exploration. We conclude that although remote sensing of geothermal systems has not reached full maturity, there is great potential for integrating these surface measurements in a exploration framework. A number of recommendations for future research result from our analysis of geothermal systems and the present contributions of remote sensing to studying these systems. These are grouped along a number of question lines: ‘how reproducible are remote sensing products’, ‘can long term monitoring of geothermal systems be achieved’ and ‘do surface manifestations link to subsurface features’?  相似文献   

粤北棉花坑铀矿床热液蚀变与物质迁移研究   总被引：5，自引：2，他引：3  

吴德海  夏菲  潘家永  刘国奇  黄国龙  刘文泉  吴建勇 《岩石学报》2019,35(9):2745-2764

本文以粤北长江铀矿区棉花坑铀矿床的横向矿化蚀变剖面为研究对象,系统研究了代表性新鲜花岗岩、蚀变岩和矿石的主量、微量以及稀土元素地球化学特征,运用质量平衡计算方法探讨了各蚀变带组分的迁移规律,以期解决成矿物质来源、成矿流体来源及其性质等问题。结果表明,该矿化蚀变剖面具有明显的水平分带特征,可分为新鲜花岗岩带(Ⅴ带)、远矿碱交代蚀变带(Ⅳ带)、近矿绿泥石化蚀变带(Ⅲ带)、矿旁水云母化蚀变带(Ⅱ带)和矿化中心赤铁矿化蚀变带(Ⅰ带)。从侧缘碱交代带→矿化中心带,Si O2的带入率(0. 27%→0. 21%→0. 50%→0. 70%)整体上与U的带入率(4. 73%→8. 07%→39. 26%→98. 29%)呈正比,K+与Na+相互排斥呈现"钾钠不相容"现象,Mg O与Mn O呈现出"此消彼长"的迁移特征,是对流平衡迁移方式的表现。Th、Pb、Cs、Mo、As元素在矿化中心带的带入率最大,Ba、Sr、Co、V元素在矿化中心带迁出率最小,这对铀成矿(铀矿化)具有很好的指示作用。根据各蚀变带元素的含量、比值及迁移特征,结合前人的研究成果,认为矿床的成矿物质主要来源于赋矿围岩长江岩体,成矿流体在成分上富含挥发分和矿化剂(CO_2、F、H_2O等)、碱金属元素(K、Cs、Rb)和重稀土元素,性质上具相对高的氧逸度,其来源是地幔流体与经历了深循环大气降水的混合成因流体。挥发分和矿化剂(CO_2、F、H_2O等)的带入是矿床重要的矿质迁移机制,CO2的逸出伴随着氧化向还原过渡的环境是矿床重要的矿质沉淀机制。  相似文献   

Addressing ore formation and exploration     

Jean-Louis Vigneresse 《地学前缘(英文版)》2019,10(4):1613-1622

Common base and noble metals represent an important economic factor in the actual industrial development.For instance the world resources for copper are actually estimated for about the next 30 years only.The situation requires rethinking the way major ore deposits form,leading to new guides for exploration.The present paper briefly examines the processes leading to ore formation,in relation with granitic or granodioritic intrusions.It identifies the importance of metal enrichment during the magmatic stage.Within the magma chamber that forms porphyry intrusions,metals may incorporate to first formed crystals,becoming inert;concentrate into the residual melt of a mush;or segregate by diffusion into the exsolved magmatic volatile phase(MVP)into which they are transported and precipitated.A competition results between elements partitioning and diffusivity.Hence,a specific Peclet number for each metal(Cu,Au,Ag,Mo,W,Sn,and REE)controls the ratio between the diffusive and the advective flux.Metals diffusivity in the melt shows differential behavior relative to a threshold of about10 13 m2/s.Metals with slower diffusivity values(e.g.As)will not concentrate.Conversely,fast diffusive metals(Au,Ag,Cu)may rapidly incorporate the MVP,provided an adequate component(halogens or S)is attractive for metals.The chemistry of the MVP escaping the magma induces different alteration patterns.Their relative content in F,Cl or S,attested by the composition of biotites and apatites,links with the preferential content of metals in o re deposits,representing a valuable tool for exploration.Finally the model is replaced in a set of coupled mechanical-chemical instabilities,within a three phase material.  相似文献   

空间自相似性与地球物理和地球化学场的分解方法   总被引：8，自引：2，他引：8  

成秋明 《地球物理学进展》2001,16(2):8-17

场的分解是应用勘查地球物理和地球化学数据所必不可少的数理处理工作，这项工作往往是为了分解不同的场来研究和了解不同的地质以及相应的地质过程，比如划分不同岩石类型以及识别和圈定矿化蚀变睡.闰定地质过程所产生的同类型的地质体并不简单地对应于相同的场值和频率，场的分布特征往往还与地质体的几何形态，。埋藏深度以及与其周围地质体的相对差异有关。然而，由于地质过程往往具有多期次和空间相关性等特点，所产生的地质体或者相应的场往往会呈现空间自相似性或统计自相似性。这种自相似性可以帮助分解不同地质过程所产生的同类地质体，文中所介绍的多重分形（multifractal)滤波方法（S－A）根据场的能谱分布的不同空间自相似性形成不规则甚至分形滤波器，并将场分解为不同同的组份，如局部异常和背景场，应用该方法对多处地球化学和地球物理场的处理结果表明，该方法对区分与矿有关的局部异常与背景场是很有效的，对加拿大NOVA SCOTIA省西南部航空放射性铀钍钾（U-Tn-K)数据处理所分解的异常对反映岩体中与铀－钨－锡（U－W－Sn)矿化有关的围岩饰变具有明显的效果。  相似文献   

Hydromechanical properties and alteration of natural fracture surfaces in the Soultz granite (Bas-Rhin, France)     

Judith Sausse   《Tectonophysics》2002,348(1-3)

Natural fractures are characterized by rough surfaces and complex fluid flows. A large distribution of apertures (residual voids) within their walls and the presence of contact points (in situ normal loads) produce heterogeneous flows (channeling). The resulting permeabilities, porosities or fluid–rock exchange surfaces cannot be realistically modeled by parallel and smooth plate models. Four natural fractures are sampled at different depths and degrees of alteration in the Soultz sandstone and granite (EPS1 drillhole, Soultz-sous-Forêts, Bas-Rhin, France). The fracture surfaces are measured with mechanical profilometry and maps of asperity heights (XYZ). Resulting local apertures (XYe) are then calculated. A statistical study of the surface profiles (XZ) show that the fractures are more or less rough and tortuous according to the types of alteration. Altered samples are characterized by smoother surfaces of fractures. Such differences imply that (i) the average fracture aperture is not representative for the whole fracture and that (ii) the different local apertures should be integrated in hydraulic and mechanical models. A hydraulic model (finite difference calculations) of fluid flow, taking into account the elastic closure (Hertz contact theory) of fractures with depth, is used. Maps of contact points and relative local loads within the fracture planes are compared to flow maps. They show different channeling of fluid flows. Strongly altered fractures are characterized by homogeneous fluxes despite the presence of numerous contact zones during the closure of fracture. By contrast, fresh fractures develop, increasing fluid flow channels with depth.Fracture closure (increasing normal stress) does not systematically increase the channeling of fluid flow. There is evidence for a general smoothing out of the irregularities of the fracture walls due to precipitation of secondary minerals, indicating that the cubic law can be commonly valid, also at great crustal depth but this validity depends on the degree of fracture alteration. Mineralogical and geochemical observations, thus, should be taken into account to perform more accurate permeability calculations and models of fluid circulation in fracture networks.  相似文献   

Influence of the alteration processes on the origin of uranium and europium anomalies in trachyte, central Eastern Desert, Egypt     

Y. H. Dawood  H. H. Abd El-Naby  A. A. Sharafeldin 《Journal of Geochemical Exploration》2004,81(1-3):15-27

El Atshan mining area, central Eastern Desert, represents one of the uranium occurrences related to alkaline volcanic rocks in Egypt. Based on the plot of total alkali elements versus silica, these rocks are classified as trachytes. The U and Eu anomalies appear to be derived from trachyte exposed to a long period of alteration and rock–fluid interaction. The trachyte has been subjected to two phases of alteration. The pronounced chemical changes include the mobility of Si, Na, Fe, U, Zn and REE and the immobility of Mg, Th, Hf, Ta and Sc. The late stage hydrothermal solutions caused the breakdown of the feldspars by losing sodium, potassium and partially silica and eventually formation of argillic alteration products, dissolution of iron-bearing sulphides, formation of iron-oxy hydroxides and corrosion of primary uranium minerals forming uranyl oxide hydrates. The acidic water percolating through the fractured trachyte rock leached not only available major or trace elements, but also REE. Eu originally incorporated in feldspars as Eu⁺² has been oxidized to Eu⁺³ and subsequently leached away leaving a negative anomaly in the host rock. The leached U and Eu were then transported most probably as carbonate complexes. The second phase of alteration occurred at the near surface profile when the late stage hydrothermal fluids cool to the temperature of meteoric water and may have mixed with it, the pH of the fluids would shift to more alkaline values and at these conditions U and Eu were precipitated into the fracture system mainly by being adsorbed on the clay minerals and probably coprecipitated with iron oxy-hydroxides.  相似文献   

铀的预富集系   总被引：2，自引：0，他引：2  

杜乐天  王玉明 《铀矿地质》1986,(1)

本文阐述了成矿阶段前预富集的重要性及其演化序列。预富集可大体分为:地层预富集,岩体预富集,蚀变带预富集,总称预富集系。不只铀成矿有此规律,其它如钨、锡、金、银、铜、钼、铌、钽、锂、铍、稀土等矿床也同样遵循这一规律。掌握预富集规律对区域成矿远景预测和评价是很重要的。所谓层控矿床,其实质也在于强调成矿的工业富集(尽管可以通过各种成矿作用来实现)仍然脱离不开它之前的预富集。地层预富集乃是地壳上一切矿床成矿前最重要最有决定意义的预富集。  相似文献