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1.
水银洞金矿床曾被认为是滇黔桂地区最有代表性的微细浸染型金矿(卡林型金矿),然而矿床的金品位明显高于一般意义上的卡林型金矿床,且金矿体与气液爆破角砾岩关系密切.气液爆破角砾岩呈垂直筒状产状,两侧断裂矿化带呈向上扩张的"喇叭口"状成矿空间,富金矿体紧密围绕角砾岩筒分布.根据野外和显微镜观察,角砾岩块成分复杂与显著磨圆.气液角砾岩筒的角砾岩显著富集金、稀土、亲地幔过渡元素Ti、Cr、Ni、Co、V等,以及Zr、Hf等,明显地区别于围岩,反映出深源流体快速上升的气液爆破角砾岩的特征,角砾岩筒实际上具备含金成矿流体的上涌通道的功能.岩筒中早期角砾岩的角砾含Au达18×10–6,属于深部金矿体的爆破碎块,显示出水银洞金矿床可观的深部找矿勘探前景. 相似文献
2.
The Luoboling Cu–Mo deposit in the Zijinshan Orefield, Fujian province, southeastern China, is a large porphyry deposit hosted by the Sifang granodiorite and the Luoboling granodiorite porphyry. The largest Cu–Mo orebody is saddle-shaped with various types of hydrothermal veinlets. Intensive hydrothermal alteration in the deposit is characterized by outward zoning from potassic, overprinted by phyllic alteration, to phyllic and alunite–dickite alteration. Based on the mineral assemblages and crosscutting relationships of veins, the ore-forming process can be divided into three stages, namely: an early-stage K-feldspar + quartz ± magnetite ± molybdenite veins associated with potassic alteration; a middle-stage quartz + molybdenite + chalcopyrite + pyrite veins in phyllic zone; and a late-stage quartz ± gypsum veins in the phyllic and alunite–dickite alteration zones. Six molybdenite separates yield a Re−Os isochron age 104.6 ± 1.0 Ma, which is identical to the age of emplacement of the Sifang and Luoboling granodiorite porphyries. Three types of fluid inclusions (FIs) were observed at the Luoboling deposit: 1) NaCl–H2O (aqueous), 2) daughter mineral-bearing and 3) CO2–H2O fluid inclusions. FIs of the early and middle stages are predominantly vapor-rich aqueous and daughter mineral-bearing inclusions, together with minor CO2-rich and liquid-rich aqueous inclusions; whereas the late-stage minerals only contain liquid-rich aqueous inclusions. Homogenization temperatures and salinities of FIs trapped in the early-stage minerals range from 420 to 540 °C and 0.4 to 62.9 wt.% NaCl equiv., respectively. FIs of the middle-stage yield homogenization temperatures of 340 to 480 °C and salinities of 0.5 to 56.0 wt.% NaCl equiv. CO2 content and the oxygen fugacity (indicated by daughter minerals) of FIs trapped in middle-stage minerals are lower than those in the early stage. The liquid-rich aqueous inclusions of the late-stage homogenize at temperatures of 140 to 280 °C, yielding salinities of 0.4 to 8.4 wt.% NaCl equiv. The minimum estimated pressures of the three stages are 30–70 MPa, 10–40 MPa and 1–10 MPa, respectively, corresponding to minimum ore-forming depths of 1–2.8 km. Fluids trapped in early, middle and late stages yield δD values of − 67‰ to − 54‰, − 54‰ to − 70‰, and − 62‰, and δ18O values of 5.4‰ to 6.7‰, 2.8‰ to 4.2‰, and − 2.1‰, respectively. Fluid boiling, which resulted in the formation of stockworks and the precipitation of sulfides, occurred in the early and middle stages. The fluids subsequently evolved into a low temperature, low salinity system in the late stage, along with an input of meteoric water. The Luoboling porphyry Cu–Mo system was developed in a transition from continental arc to back-arc extension region, which was related to the westward subduction of the paleo-Pacific plate beneath the Huanan Orogen. 相似文献
3.
通过系统采集紫金山铜金矿床4~11线共41个钻孔的岩矿样,绘制原生晕剖面图,建立垂向元素分带序列、矿体剥蚀程度准则,结合深部指示元素的特征,进行隐伏矿预测。该矿床金矿近矿晕为Au-Ag-Zn1,尾部晕为BiGa-Mo-Sn-Ti-Co-Ni-W1-V;铜矿前缘晕为Hg-Sb-As,近矿晕为Cu-Pb1-Zn2,尾部晕为Be-W2。矿体剥蚀程度评价表明,高硫型铜矿体往深部已尖灭。深部F-Mn-Pb2-Zn3的异常形态和元素组合符合典型斑岩矿床的外带特征,斑岩体延伸至矿床周边;深部的蚀变矿物组合、金属矿物组合、流体包裹体特征等均表明深部可能存在斑岩铜(钼)矿床。 相似文献
4.
The Xinan Cu–Mo deposit, newly-discovered in the Zijinshan Au–Cu–Mo Orefield (the largest porphyry–epithermal system in SE China), is featured by the presence of abundant multi-phase granitoids, which reflects the complex Mesozoic tectono-magmatic evolution in the region.New and published LA-ICP-MS zircon U–Pb age data reveal that the Mesozoic Zijinshan magmatism occurred in two major phases: (1) Middle to Late Jurassic (ca. 169–150 Ma), forming the Zijinshan complex granite and the Xinan monzogranite; (2) late Early Cretaceous to earliest Late Cretaceous (ca. 112–98 Ma), forming the Shimaoshan volcanic rocks, Sifang granodiorite, and the Xinan (fine-grained) granodiorite porphyry, porphyritic granodiorite and late aplite dykes. Additionally, a possible earliest Cretaceous magmatism (ca. 141 Ma) may have occurred based on inherited zircon evidence. Major and trace element geochemistry indicates that all the Zijinshan igneous rocks show subduction-related geochemical affinities. Zircon Ce4 +/Ce3 + values of the late Early Cretaceous to earliest Late Cretaceous granitoids (Ce4 +/Ce3 + = 190–1706) are distinctly higher than the Middle to Late Jurassic ones (Ce4 +/Ce3 + = 27–457), suggesting that the former were derived from more oxidized parental magma. The Middle to Late Jurassic Zijinshan complex granite and monzogranite have εHf (t) values of − 8.02 to − 10.00, with the two-stage Hf model ages (TDM2) of 1.72 to 1.84 Ga (similar to the Paleoproterozoic metamorphosed Cathaysia Block basement), suggesting that they were derived from partial melting of the basement. The late Early Cretaceous to earliest Late Cretaceous Sifang granodiorite and Xinan (fine-grained) granodiorite porphyry, porphyritic granodiorite and aplite dykes contain higher and wider range of εHf (t) values (0.66 to − 6.05), with TDM2 of 1.12 to 1.56 Ga, indicating that they were also partial melting product of the Cathaysia basement but with more mantle and/or juvenile mafic lower crustal input. We propose that the Zijinshan Orefield was in a compressive, Pacific subduction-related tectonic setting during the Middle to Late Jurassic. The regional tectonic regime may have changed to extensional in the late Early Cretaceous to earliest Late Cretaceous, during which the Pacific plate subduction direction change and the accompanying subduction roll-back and slab window-opening occurred. The tectonic regime transition, high oxygen fugacity and mantle/mafic lower crustal materials involvement in the late Early Cretaceous to earliest Late Cretaceous may have generated the Zijinshan porphyry-related Au–Cu–Mo mineralization. 相似文献
5.
造山型金矿床指造山过程中形成的后生脉状金矿床,受构造、建造双重控制,是全球最重要的金矿勘查类型。按容矿岩石建造的不同,造山型金矿可分为绿岩带型（包括绿片岩型、BIF型和花岗- 片麻岩型3个亚类型）、浊积岩型、碳酸盐岩型和浅成侵入岩型,构成了造山型金矿床完整的成矿谱系。不同类型之间具有紧密的时空和成因联系,可互为找矿标志。绿岩组合和浊积岩系具有高的金丰度,既是容矿岩系,也是重要的矿源层,多类型造山作用驱动大规模区域性流体活动,造就了造山型金矿省/巨型成矿带,岩浆流体叠加和“热机效应”是形成超大型金矿床的重要因素。构建了多源区域性流体+岩浆流体叠加的地壳连续成矿模型和造山型金矿区域成矿模式,强调了多旋回造山作用对造山型金矿的成矿意义。“富金矿源层+剪切变形带+浅成侵入岩”组合是大型金矿系统的勘查选区标志,靶区优选的目标是获取找矿潜力大的优质矿权;矿权区勘查的优先目标是发现可规模化露天开采的矿床（体）,通过化探异常评价和浅钻追索次生富集带,可快速发现主矿体;矿区深部找矿（深度>300 m）潜力巨大,主攻目标是资源量大、品位高的热液通道相的厚板状或筒状矿体。 相似文献
6.
紫金山矿集区地质特征、矿床模型与勘查实践 总被引：8，自引：7，他引：1
紫金山矿集区位于福建省上杭县城北约15 km处,是一个典型的与陆相火山活动有关的斑岩-浅成低温热液型铜钼金矿床成矿系统,分布于长14 km、宽4km范围中,已探明高硫化浅成中低温热液型特大型金、铜矿床各1处,低硫化热液型大型银多金属矿床2处,斑岩型铜钼矿床1处,中小型铜、金矿床3处.文章结合近年来在该矿集区找矿取得的重大进展,介绍了创新性地质找矿的实践经验:一是开展三维地质建模;二是开展蚀变矿物短波红外光谱测试和解译,建立蚀变找矿模型;三是注重物化探资料的应用和二次开发,建立物化探找矿模型;四是以大量真实的生产技术经济指标为基础,以资源利用最大化为原则,开展矿床动态评价,指导成矿预测,提高找矿效率. 相似文献
7.
The Baolun gold deposit is a mesothermal orogenic gold deposit located in the southwestern part of Hainan Island, South China. The deposit comprises a series of NNW-trending quartz-sulfide lodes situated within a parallel array of fault zones traversing a sequence of variably foliated flysch siliciclastic rocks of the Lower Silurian. Detailed field mapping documented at least five phases of deformation in the deposit including NNW-trending folding of the Lower Silurian rocks (D1), development of NNW-trending, steeply dipping ductile shear zones with an oblique dextral sense corresponding to NNE-SSW shortening (D2), WNW-ESE shortening and extension associated with an early oblique sinistral ductile shearing along the NNW-trending fault zones (D3), ENE-WSW shortening (D4), and near N-S extension (D5). The gold-bearing quartz lodes cut the strata folded in the D1, show some laminar layering related to ductile shear in the D2 and are overprinted by brittle structures formed in the D3 to D5. 40Ar–39Ar dating on muscovite from an auriferous quartz lode yielded an age of 242 ± 2.5 Ma, which, together with the age of 232 ± 2.5 Ma for an aplite vein in the deposit, suggests that the mineralization may be related to a tectono-thermal event in the Triassic. In the context of the southern South China plate tectonics, the formation of the Baolun gold deposit is interpreted to be related to the oblique dextral ductile shearing (D2) along the NNW-trending fault zones during the Indosinian orogeny, in relation to the convergence between the Indochina and South China plates. 相似文献
8.
A Late Cretaceous to Early Oligocene episode of paleoweathering and supergene activity has been identified within the Jurassic-age (170 Ma) Humboldt mafic complex (HMC) and associated Boyer Ranch Formation of west-central Nevada, USA. This episode is responsible for significant subaerial weathering, erosion, oxidation and most importantly local supergene metal enrichment which could potentially have a major economic impact upon iron oxide copper-gold (IOCG)-style mineralization within the complex and in the Boyer Ranch Formation. Paleoweathering profiles that developed on the exposed Jurassic surface during this time now mark an angular unconformity (J-T unconformity) with a stratigraphically overlying, Tertiary (Oligocene) rhyolitic volcanic-volcaniclastic sequence.Differential uplift of the Jurassic surface is a direct result of the Middle and/or Late Jurassic Luning-Fencemaker compressional overthrust faulting event during which the entire complex was tectonically transported to its present location. The uplifted Jurassic paleosurface experienced one or more cycles of weathering, erosion, depression of the water table and uninterrupted supergene activity beginning at the end of the Cretaceous and possibly accelerating during the Paleocene-Eocene Thermal Maximum Event (∼56 Ma). Geochemically mature supergene Cu-oxide profiles developed over exhumed mineralized sections in terrains with favorable fault block movements. These paloweathering systems evolved from moderately acidic pH to near-neutral or slightly alkaline pH environments over time. High protolith reactivity and low hypogene pyrite concentrations modified acidity of supergene fluids thus limiting Cu mobility.Profiles that survived erosion were later buried and preserved by the Oligocene-age rhyolitic volcanic-volcaniclastic sequence before the onset of mid-Tertiary Basin and Range normal faulting. Subsequent partial unroofing of overlying Tertiary volcanic cover resulted in further erosion of some profiles. Erosional remnants mapped in the field include all or some components of the original supergene Cu-oxide profiles. Drilling results suggest profiles that remain buried are generally intact.Although this field-oriented study is considered preliminary, it concludes that known Jurassic-age IOCG-style mineral occurrences in the central HMC have been subjected to prolonged subaerial paleoweathering and supergene activity that has not been previously recognized. Where complete or nearly complete profiles are preserved, efficient cumulative Cu-enrichment to potentially ore grades has been documented in well defined oxide zones. These findings can be extrapolated to the entire J-T unconformity along which concealed and enriched deposits may exist. As such, the unconformity is considered a prime exploration target that is highly prospective for new discoveries of economically viable, supergene-enriched IOCG resources. 相似文献
9.
Transition metal isotopes are sensitive geochemical tracers of ore genesis. Here we present MC-ICP-MS analytical data of Cu isotope compositions from the Hongshan-Hongniu Cu deposit in Yunnan province. The δ65Cu values (δ65Cu = [(65Cu/63Cu)sample/(65Cu/63Cu)NIST976 − 1] × 1000) of seven whole-rock quartz monzonite porphyries and twenty-two chalcopyrite samples from the skarn ore-bodies display relatively narrow ranges from −0.15‰ to 0.38‰ and from −0.02‰ to 0.77‰, respectively. The overlap of δ65Cu values indicates a genetic relationship between the quartz monzonite porphyry and skarn ore-bodies. We also evaluate the spatial and temporal variations of Cu isotope compositions in the skarn ore-bodies by comparison with some well-documented porphyry deposits in the world. The quartz monzonite porphyry shows compositional zoning with the inner domain enriched in heavy Cu isotope and the skarn related to the porphyry depleted in heavy Cu isotope. The chalcopyrites that formed during the late stage of mineralization tend to be enriched in heavy Cu isotope, and this feature is analogous to porphyry deposits. The δ65Cu values of the quartz monzonite porphyry show typical features of hypogene mineralization, suggesting a potential scope for deep exploration and development in this deposit. 相似文献
10.
洒西钨铍矿床位于滇东南老君山钨锡多金属成矿区。确定早期似层状矿体和晚期脉状矿体的流体性质、来源和演化过程, 并对其流体地球化学和同位素进行约束, 可以有效探讨洒西钨铍矿床成矿机制, 为老君山矿集区下一步找矿工作提供理论思考。洒西钨铍矿床脉状矿体的形成经历了硅酸盐阶段、氧化物-硫化物阶段和碳酸盐-萤石阶段, 白钨矿和绿柱石主要形成于前两阶段。对洒西钨铍矿床脉状矿体不同阶段石英中的流体包裹体进行了岩相学特征、显微测温、激光拉曼光谱分析等研究, 并对早期似层状矿体和晚期脉状矿体矿石中石英的氢-氧同位素组成进行了测试。结果表明: 该矿床内脉状矿体的流体包裹体主要有富液相包裹体、富气相包裹体和含子矿物多相包裹体3种类型。流体包裹体的气相成分以H2O主, 含少量还原性气体如C2H2等, 液相成分也以H2O为主。从硅酸盐阶段到碳酸盐-萤石阶段, 包裹体的均一温度和盐度(NaCleq)峰值范围分别为240~360℃、2.35%~13.81%;220~310℃、4.03%~9.86%和190~270℃、2.41%~6.88%。从硅酸盐阶段到碳酸盐-萤石阶段, 成矿流体的温度呈现降低趋势, 盐度也呈降低趋势。成矿流体总体上属中-高温度、低盐度、贫CO2、含部分还原性气体的NaCl-H2O流体体系。早期似层状矿体石英样品δ DV-SMOW值变化范围小, 为-102.8‰~-99.0‰, δ 18OV-SMOW值为11.7‰~13.0‰, δ 18OH2O值为3.16‰~6.46‰; 晚期脉状矿体氧化物-硫化物阶段石英样品δ DV-SMOW值变化范围较大, 为-99.6‰~-69.5‰, δ 18OV-SMOW值为11.2‰~14.1‰, δ 18OH2O值为3.08‰~6.73‰。综合表明成矿流体主要是岩浆水, 混合有少量大气降水或有机水, 流体可能发生了沸腾作用, 加之温度的降低, 导致晚期脉状矿体氧化物-硫化物阶段主要成矿物质的沉淀。洒西钨铍矿床属于中高温热液矿床。 相似文献