Geology and Geochemistry of K-feldspar Veins in Lamprophyre at the Zhenyuan Gold Deposit,Yunnan,Southwest China:Implications for Gold Mineralization

Lamprophyres typically appear in hydrothermal gold deposits.The relationship between lamprophyres and gold deposits is investigated widely.Some researchers suggest that the emplacement of lamprophyres triggers gold mineralization,whereas others hypothesize that the formation of lamprophyres increases the fertility of mantle sources and ore-forming fluids.K-feldspar veins,with ages between those of lamprophyres and gold deposits,appear in lamprophyres in Zhenyuan.Therefore,K-feldspar veins are ideal for investigating the relationship between lamprophyres and gold deposits.Phlogopite in K-feldspar veins has lower Mg#,Ni,and Cr contents and higher TiO2,Li,Ba,Sr,Sc,Zr,Nb,and Cs contents than phlogopite in lamprophyres.The in-situ Sr isotopic values of apatites(0.7063–0.7066)in K-feldspar veins are within the range for apatites(0.7064–0.7078)from lamprophyres.High large-ion lithophile element concentrations and low Nb and Ta concentrations in phlogopite from lamprophyres,in addition to high(87Sr/86Sr)i values of apatite(0.7064–0.7078),indicate that the magma parental to these phlogopite and apatite crystals is derived from an enriched mantle.Kfeldspar veins are genetically correlated with lamprophyres,whereas sulfide mineral assemblage and trace element compositions of pyrite in K-feldspar veins suggest that K-feldspar veins in lamprophyres are not directly related to gold mineralization of the Zhenyuan deposit.

Rb-Sr Isotopic Chronology of the Au-Bearing Quartz Veins in Gold Deposits in the Eastern Part of North China Platform

In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope data (including four gold deposits previously studied and two gold deposits in this work) of Au\|bearing quartz veins of the representative gold deposits in six important gold ore\|concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig (2.90 version). The results show that the representative gold deposits in the six gold ore\|concentrated areas were formed during the Mesozoic.

Characteristics of Gold and Its Mineralization Style in the Boulon Djounga Eastern Perimeter of Liptako Mining Company (Central Southwestern Niger)

The Boulon Djounga eastern perimeter is part of the Tiawa operating permit of the Société des Mines du Liptako (SML), located in the central southwestern part of Liptako (Niger). In this study, we used field data, Reverse Circulation (RC) surveys and chemical analyzes of gold to determine the characteristics of gold and its mineralization style. The eastern perimeter of Boulon Djounga is represented by a succession of metabasalts and metasediments both intersected by intrusions of quartz and dolerite dykes, and covered by sandstone and clayey rocks. Gold is present in low contents (0.00 - 0.30 ppm) in the sedimentary cover and in medium (0.30 - 1.00 ppm) or high contents (1.00 - 4.534 ppm) in the metasediments, and in the gray quartz veins and locally in the volcanics. It exists in a disseminated state or in a concentrated state in the surrounding areas in the form of discrete grains associated with sulphurous minerals (pyrite: FeS2, chalcopyrite: CuFeS2 or arsenopyrite: FeAsS). The presence of gold in the quartz veins, and the NE-SW and NW-SE orientations of the ore bodies suggest that the eastern Boulon Djounga gold mineralization would be established during a late magmatic extensive phase.

U-Pb SHRIMP Dating of Zircon from Quartz Veins of the Yangshan Gold Deposit in Gansu Province and Its Geological Significance

The Yangshan gold deposit is a super-large fine-grained disseminated gold deposit located in southern Gansu Province. Its metallogenic age has been determined by using the cathodoluminescence image and ion probe U-Pb dating techniques. It is found that zircons from quartz veinlet of the fine-grained disseminated gold ore show characters of magmatic origin with prism idiomorphism, oscillatory zoning and dominant Th/U ratios of 0.5-1.5. Three main populations of zircons are obtained, giving average 206Pb/238U ages of 197.6±1.7 Ma, 126.9±3.2 Ma and 51.2±1.3 Ma respectively. The first age corresponds to the K-Ar age of the plagiogranite dike, while the latter two ages indicate that buried Cretaceous and Tertiary intrusives exist in the orefield, suggesting that the Yangshan gold deposit was genetically related to the three magmatic hydrothermal activities. By contrast, zircons from coarse gold-bearing quartz vein in the mining area are much older than the host rock, indicating that the vein was formed earlier and was not contaminated by later magmatic fluids. It is concluded that the coupling of multiperiodic hydrothermal activities in the mining area has contributed a lot to mineralization of the Yangshan gold deposit.

REE geochemistry of auriferous quartz carbonate veins of Neoarchean Ajjanahalli gold deposit,Chitradurga schist belt,Dharwar Craton,India

REE composition of the carbonates of the auriferous quartz carbonate veins（QCVs） of the Neoarchean Ajjanahalli gold deposit.Chitradurga schist belt.Dharwar Craton,is characterized by U-shaped chondrite normalized REE patterns with both LREE and HREE enrichment and a distinct positive Eu anomaly.As positive Eu anomaly is associated with low oxygen fugacity,we propose that the auriferous fluids responsible for gold mineralization at Ajjanahalli could be from an oxygen depleted fluid.The observed positive Eu anomaly is interpreted to suggest the derivation of the auriferous fluids from a mantle reservoir.The location of Ajjanahalli gold deposit in a crustal scale shear zone is consistent with this interpretation.

Auriferous Quartz Veins from the Dongping Gold Deposit, NW Hebei Province and Metallogenesis—Fluid Inclusion Rb-SrIsochron Evidence

The Dongping gold deposit, situated on the northern margin of the North China Platform, is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies. It is hosted in the inner contact zone of an alkaline intrusion which was intruded into Archean metamorphic rocks and was formed not later than the Hercynian peried. Auriferous quartz veins of the deposit are dated with the fluid inclusion Rb-Sr isochron method at 103 ±4Ma, indicating that the gold deposit was formed in the Yenshanian period. 87Sr/86Sr sourcetracing shows the ore-forming materials came dominantly from alkaline intrusions. These results, combined with other isotope and REE data, suggest that the Dengping gold deposit is not a traditional magmatic hydrothermal deposit, but a reworked hydrothermal deposit related to heated and evoved meteoric water.

Fluid Inclusions in the Gold-Bearing Quartz Veins at Um Rus Area, Eastern Desert, Egypt

Fluid inclusions in the gold-bearing quartz veins at the Um Rus area are of three types: H\-2O, H\-2O-CO\-2 and CO\-2 inclusions. H\-2O inclusions are the most abundant, they include two phases which exhibit low and high homogenization temperatures ranging from 150 to 200℃ and 175 to 250℃, respectively. The salinity of aqueous inclusions, based on ice melting, varies between \{6.1\} and 8 equiv. wt% NaCl. On the other hand, H\-2O-CO\-2 fluid inclusions include three phases. Their total homogenization temperatures range from 270 to 325℃, and their salinity, based on clathrate melting, ranges between \{0.8\} and \{3.8\} equiv. wt% NaCl. CO\-2 fluid inclusions homogenize to a liquid phase and exhibit a low density range from \{0.52\} to \{0.66\} g/cm\+3. The partial mixing of H\-2O-CO\-2 and salt H\-2O-NaCl fluid inclusions is the main source of fluids from which the other types of inclusions were derived. The gold-bearing quartz veins are believed to be of medium temperature hydrothermal convective origin.

An Integrated Geoscientific Approach to Define Zones of Gold Mineralization <br/>—A Case Study in North Sudan

The study area is located in Bayuda desert lying about 400 km from Khartoum in the state of River Nile, North Sudan. The present study aimed to identify gold mineralized zones through an integrated geoscientific approach. The approach integrated the results of geospatial studies, geological mapping, field observations and geochemical data. Remote sensing studies using ASTER and Quickbird data helped to identify the zones of chloritic, sericitic and phyllic alteration signatures and gossan rich zones. Geological mapping and field observations confirmed the presence of gold mineralization along the quartz veins which shared the litho contacts of biotite muscovite schist, biotite muscovite gneiss and silicate gneiss. These gold bearing potential areas were found to be structurally controlled and most of the mineralizations were along the proximity of shear-zones, faults and folds. The gold assay values obtained from the chemical analysis of stream sediment and pitting-trenching samples also confirmed the results of remote sensing and geological mapping. Integration of all these data helped to identify drill holes’ locations in the study area for further exploration. This focused plan facilitated cost and time optimization in exploration activities.

Genesis and mineralization of gold-bearing quartz veins in the Xiao Qinling area,central China

Gold-bearing quartz veins of the Taihua Group consisting of Archean metavolcanic rocks are a main gold deposit type in the Xiao Qinling area,one of the three biggest gold production areas in China.The quartz veins experienced strong alteration characterized by a typical mesothermal hydrothermal altered mineral assemblage.The grade of gold is affected by the contents of sulphides,e.g.galena,pyrite and chalcopyrite.Results of minor elements analysis for the of gold-bearing quartz veins indicate higher contents of Au and high contents of Ag,Pb,Cu,Cd,W,and Mo.Abundant fluid inclusions were found in the gold-bearing quartz veins.Three types of fluid inclusions were identified:(1) aqueous inclusions;(2) CO 2-bearing inclusions;and(3) daughter crystal-bearing fluid inclusions.Homogenization temperatures ranged from 110 to 670℃ with low and high peaks appearing at 160 180℃ and 280 300℃,respectively.The salinity of aqueous inclusions varies between 1.8 wt% and 38.2 wt% NaCl.The homogenization temperature and salinity show a positive correlation.The H and O isotopes of fluid inclusions in the gold-bearing quartz veins indicate that magmatic solution and metamorphic hydrothermal solution,together with meteoric water,were involved in the formation of gold-bearing fluid.Mesozoic magma activities related to granite intrusions should be the main source of CO 2 fluid with higher temperature and salinity.

Geology and fluid inclusion of Wadi Sharis Neoproterozoic orogenic gold deposits in northwestern Yemen

The Wadi Sharis orogenic gold deposit in northwestern Yemen is related to the fault and shear zones vein at medium depth in the crust in the Neoprotcrozoic meta-sedimentary and meta-volcanosedimentary succes- sion of greenschist to amphibolite facies metamorphism. Three distinct fluid inclusion types have been identified in the gold-bearing quartz sulphide veins of the deposit： （1） type I： vapour-liquid two-phase （VH2O-LH2O ）, （2） type II ： three-phase CO2 （ VCO2 - LH2O - LCO2 ） and （3） type III： vapour-rich （LCO2 - VCO2 ） inclusions. Six analysis of individual fluid inclusion indicate the fluid inclusions comprise mainly of H2O and CO2. Forma- tion P-T conditions recorded by fluid inclusions in quartz crystals correspond to 180℃-380℃ and up to 130 MPa, as indicated by high-density CO2 bubbles （up to 0. 98 g/cm3 ） observed in some inclusions. The esti- mated crystallization pressures correspond to approximately 4-10 km of overburden, assuming a lithostatic load. The salinity ranges from 0 to 22 wt%. The deposit holds at 0.2-5 g/t Au and contains low-moderate salinity.

Gold Veins Location in Deposits Originated by a Slanting Magma Intrusion Dike

The location of gold veins, due to a slanting magma dike intrusion in a cold rock, considering earth surface effects is determined. The 400°C and 500°C isotherm evolution resulting from this magma intrusion are studied considering a 2-D model. In this analysis, it is shown that the isotherm envelopes are the most important surfaces. Analytic solutions have been found as a function of the angle a between the dike and the vertical planes. The present results are more general than previous ones in the contest of vertical dikes. Magma convection has been considered in a simplified way. The agreement found that the results in the work the actual vein sites at the gold mine, called Colombia, in the auriferous area of El Callao, located 180 Km south of Ciudad Guayana in Bolivar state, Venezuela, are much better than in previous works.

辽东半岛五龙金矿外围电性特征及找矿意义

辽东五龙金矿经过80余年的开采,矿山资源储备严重下滑,后备资源不足问题日益突出,亟需查明矿区深部和外围矿产资源。通过在v163号脉西北和东南两侧以及100号断裂南侧开展瞬变电磁法测量工作,构建了相应的二维和三维地电模型,分析了矿区低阻异常特征;结合前人研究成果,推断出金矿成因类型和下一步找矿方向。研究结果表明:v163号脉西北方向P0剖面上低阻区是由包括163号脉西北段的细粒闪长岩脉群引起的,属于石英脉型成矿的可能性较大;100号断裂南侧三维地电模型中的低阻区域与大孤顶子金矿矿化点相对应,该低阻区向北侧深部规模增大,异常未封闭,表明该区域北侧深部具有良好的找矿前景,值得进一步开展研究工作;v163号脉东南方向的三维地电模型中,低阻异常值在数量级上明显低于前二者,推测为蚀变带引起,后经工程验证孔揭露,该区域纵向存在多层不连续的硅化蚀变岩,最大厚度为41m,蚀变类型有硅化、绢云母化、绿泥石化以及不同程度的黄铁矿化。研究表明,五龙金矿不仅存在石英脉型金矿体,还有蚀变岩型金矿体,后者可能是该矿区下一个找矿的主要方向。

高精度磁测在柴达木盆地北缘三角顶金矿床找矿中的应用

三角顶金矿床位于柴北缘结合带滩间山岩浆弧,是区域造山型金矿成矿事件响应的产物;研究区主要出露寒武系—奥陶系滩间山群火山岩组,岩性主要为玄武岩、硅质岩等;岩浆活动强烈,主要为晚泥盆世花岗闪长岩、二长花岗岩等,岩体中发育辉绿岩脉、石英脉等;基性—酸性岩中磁性由强变弱,其中辉长岩、二长花岗岩磁化率最高分别为8815.6×10^(-6)×4π·SI、5992.4×10^(-6)×4π·SI,可能由磁铁矿化、黄铁矿化引起强磁化率;磁异常呈锯齿状不规则跳跃,强度中等,梯度变化大,幅值为-733~820 nT;高精度磁法测量对与金矿成矿关系密切的断裂构造、破碎蚀变带等地质体有较好的分辨效果,经高精度磁法探测出局部异常呈串珠状分布,沿异常轴部存在断裂构造。经部分工程验证,在区内圈定构造蚀变带12条、金矿体7条、金矿化体40余条,M18-2异常与区内化探异常、深部工程验证等找矿信息相吻合,为区内进一步金矿找矿方向提供了依据。

夹皮沟成矿带小北沟金矿床成矿流体特征及其地质意义

小北沟金矿床地处夹皮沟成矿带中部,为石英脉-蚀变岩型金矿床。矿区赋矿围岩主要为高角闪岩-麻粒岩相斜长角闪岩,含金石英脉呈小而不连续的平行细脉或透镜体状产于NW向叠加于早期韧性剪切带之上的次级脆性剪切裂隙之中,其上、下盘旁侧及尖灭处发育少量低品位蚀变岩型(蚀变糜棱岩、片糜岩)矿体。主成矿阶段流体包裹体研究表明,矿石中石英主要发育CO_(2)、富CO_(2)、含CO_(2)及气液两相四种类型原生流体包裹体,测温结果显示包裹体均一温度为226.8~362.5℃,盐度(w(NaCl))为3.57%~11.95%,密度为0.65~0.91 g/cm^(3);成矿流体总体属中低温、中低盐度和低密度的富CO_(2)的CO_(2)-H_(2)O-NaCl体系,成矿压力为70~206 MPa,成矿深度约为9.8 km。包裹体O同位素δ^(18)O_(V-SMOW)值为10.8‰~11.3‰,H同位素δD_(V-SMOW)值为-102.8‰~-96.7‰,C同位素δ^(13)C_(V-PDB)值为-20.6‰~-8.3‰,反映主成矿阶段成矿流体来源具幔源属性。矿石中CO_(2)和富CO_(2)包裹体CO_(2)相均一温度为-24.7~26.6℃,明显低于邻近其他矿床(如三道岔金矿床为21.9~29.7℃,二道沟金矿床为23.8~30.9℃等),暗示其成矿深度较深。小北沟金矿床的地质、流体包裹体和H-O-C同位素特征共同揭示该矿床属于中温热液脉型金矿床,处于深大断裂的脆性区构造层次向韧脆性区构造层次过渡部位,深部仍应有一定的进一步找矿前景,但矿石类型可能由石英脉型转为构造蚀变岩型或蚀变糜棱岩型。

试析金矿床的成矿规律及其找矿预测

黄金作为我国的关键资源之一,对于国家的发展扮演着至关重要的角色。当前,我国在化工和通信等多个领域都在积极利用黄金资源,而黄金的价格波动对我国经济的走向也有着显著的指示作用。因此,金矿的开采对于推动我国经济的增长和现代化建设具有不可或缺的作用。然而,黄金生成条件多样,地质结构复杂。为了有效地进行金矿开采,工作人员必须具备坚实的理论基础和实践经验,理解金矿的形成规律和特点。又由于黄金的形成周期漫长,决定了金矿资源的有限性。为了延长金矿的服务年限并提高其利用效率,必须加强金矿的勘探工作。只有通过增强勘探力度,才能充分开采出符合我国经济建设和发展需求的黄金资源,从而更好地促进国家经济的持续发展。

pp60c-src在高静水压培养的人脐静脉内皮细胞增殖中的作用

目的 :探讨短期高压刺激是否诱导人脐静脉内皮细胞 (HUVECs)增殖以及pp60c -src所起的作用。方法 :分大气压 (AP ,0mmHg) ,中压 (MP ,12 0mmHg)和高压培养 (HP ,180mmHg) 3组 ,各组分别用卡托普利 (Cap ,10μmol/L)和厄贝沙坦 (Irb ,10 μmol/L)进行干预。测定 β -N -乙酰氨基己糖苷酶活性以反映细胞增殖。用Westernblotting法测定细胞内pp60c -src含量。结果 :① 2h时各组氨基己糖苷酶活性相似 ;中、高压组 4h时酶活性明显增高 (0 118± 0 0 0 3vs 0 14 5± 0 0 18和 0 14 4± 0 0 19,P <0 0 1) ,而大气压组 8h才见增高。 12h时各组酶活性相近。与此相应 ,2h时中、高压组pp60c -src明显高于大气压组 (0 12± 0 0 3vs 0 16± 0 0 2和 0 19± 0 0 6,均P <0 0 5) ,而大气压组 4h后才缓慢增加至中、高压组水平。② 12h时大气压组Cap与Irb对细胞数无影响 ,而在中、高压组两药使细胞增加 (MP组 0 189± 0 0 0 6vs 0 2 0 2± 0 0 0 5和 0 2 0 7± 0 0 0 3 ,P <0 0 5;HP组 0 193± 0 0 0 4vs 0 2 13± 0 0 0 4和0 2 2 1± 0 0 0 4,P <0 0 5)。但Cap与Irb干预组pp60c -src含量与对照组相似。结论 :压力刺激促使HUVECs早期 (4h)增殖 ,pp60c

大别造山带双庙关金矿床成矿流体特征与成因

湖北省麻城市双庙关金矿床是大别造山带中部新发现的金多金属矿床。本文在详细的野外地质调查和岩矿相学研究基础上,将成矿过程分为S1、S2、S3和S4四个阶段,其矿物组合分别为石英+钾长石±黄铁矿、石英+黄铁矿±黄铜矿、石英+黄铁矿+黄铜矿±金银碲化物和石英+碳酸盐,其中S3为主成矿阶段。四个成矿阶段的石英中发育富液两相(WL型)、富气两相(WV型)、含CO_(2)三相(C型)和含子矿物多相(S型)包裹体,其均一温度分别为226~445、234~422、258~392和152~215℃,盐度分别为2.8%~17.6%、2.9%~11.9%、1.9%~14.2%和1.2%~9.1%NaCl_(eqv),指示成矿流体主要为中-低温、中-低盐度和低密度的H_(2)O-CO_(2)-NaCl体系流体。S3阶段石英流体包裹体的δD_(V-SMOW)值为-89.3‰~-75.9‰,δ^(18)O_(H_(2)O)值为4.77‰~8.01‰;S2和S3阶段黄铁矿原位硫同位素数据δ^(34)S值为-3.6‰~1.6‰,指示成矿流体具有深源岩浆流体特征。综合分析认为,双庙关金矿床的成矿流体可能来源于岩浆热液,成矿过程中流体的不混溶作用是金沉淀的重要因素。

凤太矿集区八卦庙金矿区脉状铅锌矿化的物质来源研究:硫化物原位S-Pb同位素证据

秦岭造山带凤太矿集区内发育层状—似层状和脉状两种类型的铅锌矿化,部分脉状铅锌矿化伴生产于金矿床中,其成矿物质来源仍未得到较好的约束。论文以八卦庙金矿区的脉状铅锌矿体为主要研究对象,采用硫化物原位微区S-Pb同位素研究方法,探讨了脉状铅锌矿化的成矿物质来源。八卦庙金矿区的脉状铅锌矿化主要受NE和NW向断裂或裂隙控制,矿脉宽度通常为2~20 cm。矿石呈团块状或浸染状构造,其中矿石矿物以方铅矿和闪锌矿为主,另有少量黄铜矿和黄铁矿,脉石矿物有石英、白云母、绢云母和少量方解石、白云石等碳酸盐矿物。硫化物原位S-Pb同位素分析结果显示,矿石中闪锌矿的δ^(34)S值相对集中(15.03‰~17.11‰),而黄铜矿(14.76‰~19.91‰)和方铅矿(12.12‰~21.88‰)的δ^(34)S值则变化较大;方铅矿的铅同位素组成非常均一。通过与区内可能物质源区S-Pb同位素对比研究,认为八卦庙金矿区脉状铅锌矿化的成矿物质来自于围岩变质过程中释放的变质流体,并有印支期岩浆热液的贡献,总体具有与金矿化相似的成矿物质来源。金矿化和脉状铅锌矿化在八卦庙矿区共生富集但又独立产出,可能受铅锌和金元素在热液体系中明显不同的地球化学行为所控制。

安徽东至县方坑坞—杨树桥地区金矿化特征及成因探讨

安徽东至县方坑坞—杨树桥地区金多金属矿大地构造位置处于扬子准地台下扬子台坳的石台穹褶断束与江南台隆交接部位,受近东西向断裂控制。金矿(化)体主要产于休宁组与小安里组层间破碎带及邓家组与葛公镇组界面韧性剪切带中,呈脉状、网脉状,总体北倾。矿石矿物主要有自然金、褐铁矿、黄铁矿等,脉石矿物以石英为主,次为绢云母、绿泥石等。矿化类型为石英脉型金矿及含金构造蚀变岩型。找矿标志有构造、石英脉、蚀变、化探异常等。

东至县花山地区金矿体特征及金的成因探讨

花山金矿地区大地构造位置处于江南过渡带南部,江南深大断裂南侧,东至断裂西侧。矿体受近东西向断层控制,含矿岩石为早寒武世杨柳岗组条纹状泥灰岩、粘土页岩。主要矿石矿物为黄铁矿、毒砂、辉锑矿等。其中花岗闪长斑岩黄铁矿化发育,绢英岩化发育,并伴随较普遍的细脉浸染状金矿化,具有斑岩型金矿特征,在江南过渡带应把中酸性斑岩体作为寻找斑岩型金矿的重点。找矿标志有构造、岩性、蚀变等。