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湖南瑶岗仙钨矿床的陡倾黑钨矿石英脉沿燕山早期花岗岩顶部接触带两侧发育,石英脉在岩体中延深1000m,岩体外延深500 m。岩体上部的沉积岩包括寒武纪变质细砂岩、泥盆纪砂岩以及三叠纪含炭泥砂岩。毒砂黄玉层发育于三叠系与泥盆系角度不整合接触面上方的砂岩中,顺层分布,下方为陡倾含钨石英脉(宽0.3 m)。地质地球化学研究显示,毒砂黄玉层主要为一套由石英砂岩遭受强烈硅化,伴随毒砂、黄玉、白云母等蚀变形成的交代岩。蚀变岩中迁入的组分与含矿石英脉的成分一致,富Si、F、B及成矿元素W、Mo、Bi等,蚀变的流体与形成石英脉的成矿流体相同。瑶岗仙钨矿的垂向分带不同于"五层楼",顶部不发育细脉带和线脉带,而是以缓倾斜顺层分布的毒砂黄玉层直接发育于陡倾的石英中脉带之上,构成脉型钨矿床另一种成矿形式,即"上层下脉"的双层结构。这种模型的认识对脉型钨矿找矿有一定意义,即在富含毒砂-黄玉-白云母等强烈硅化的顺层状蚀变岩层下方,应重视寻找陡倾斜黑钨矿石英脉。 相似文献
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乐红铅锌矿床是扬子地块西南缘滇东北铅锌(银)多金属矿集区中的典型代表之一。通过对该矿床不同成矿阶段闪锌矿、石英、重晶石和方解石中流体包裹体岩相学、显微测温学和显微激光拉曼探针等测试,阐述了该矿床成矿流体性质和演化特征,并探讨了其成矿过程。研究发现,该矿床流体包裹体主要包括4类:Ⅰ类气相、Ⅱ类水溶液相(由Ⅱa型-富液相气液两相、Ⅱb型-富气相气液两相、Ⅱc型纯液相组成)、Ⅲ类含CO_2三相(V_(CO_2)+L_(CO)+L_(HO))及Ⅳ类含子矿物(L+V+S)包裹体。结果显示,重晶石阶段的均一温度为240.3~319.3℃,w(NaCl_(eq))为2.24~2%~1~20.73%,表现出中高温-中低盐度流体性质;白云石-黄铁矿-石英阶段具有中-高温(219.8~310.1℃),中盐度(w(NaCl_(eq))为7.02%~17.61%)特征;闪锌矿-方铅矿-黄铁矿阶段,包括S1闪锌矿具有中温(217.8~292.2℃)-中盐度(w(NaCl_(eq))为8.81%~16.71%)性质;S2闪锌矿具有中低温(180.2~241.3℃)-中盐度(w(NaCl_(eq))为7.73%~18.47%)性质;S3闪锌矿具有中低温(140.4~227.4℃)-中低等盐度(w(NaCl_(eq))为0.35%~19.21%)的流体性质,通过该阶段中含CO_2三相包裹体测试,估算成矿压力和成矿深度分别为45~74.9 MPa(平均58.2 MPa)、1.7~2.8 km。方解石阶段均一温度为165.3℃,中等盐度,w(NaCl_(eq))为11.28%,表现出低温-中等盐度的特征。不同成矿阶段的包裹体温度大致反映了该矿床成矿流体从早阶段至晚阶段,呈现中高温、中低盐度→中温、中等盐度→中低温、中低盐度的演化过程;早期高温-低盐度深部流体在热动力和构造应力驱动下大规模运移,受断裂构造影响发生减压沸腾作用,同时与大气降水发生混合,成矿流体物化性质陡变引起铅锌硫化物等的沉淀,并最终形成矿床。该研究为揭示矿床流体性质、演化及矿床成因提供了证据,深化了"构造-流体‘贯入’成矿"模型,亦对深化矿床成矿机制与指导找矿预测具有重要意义。 相似文献
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The Tianqiao Pb–Zn deposit in the western Yangtze Block, southwest China, is part of the Sichuan–Yunnan–Guizhou (SYG) Pb–Zn metallogenic province. Ore bodies are hosted in Devonian and Carboniferous carbonate rocks, structurally controlled by a thrust fault and anticline, and carried about 0.38 million tons Pb and Zn metals grading > 15% Pb + Zn. Both massive and disseminated Pb–Zn ores occur either as veinlets or disseminations in dolomitic rocks. They are composed of ore minerals, pyrite, sphalerite and galena, and gangue minerals, calcite and dolomite. δ34S values of sulfide minerals range from + 8.4 to + 14.4‰ and display a decreasing trend from pyrite, sphalerite to galena (δ34Spyrite > δ34Ssphalerite > δ34Sgalena). We interpret that reduced sulfur derived from sedimentary sulfate (gypsum and barite) of the host Devonian to Carboniferous carbonate rocks by thermal–chemical sulfate reduction (TSR). δ13CPDB and δ18OSMOW values of hydrothermal calcite range from –5.3 to –3.4‰ and + 14.9 to + 19.6‰, respectively, and fall in the field between mantle and marine carbonate rocks. They display a negative correlation, suggesting that CO2 in the hydrothermal fluid was a mixture origin of mantle, marine carbonate rocks and sedimentary organic matter. Sulfide minerals have homogeneous and low radiogenic Pb isotope compositions (206Pb/204Pb = 18.378 to 18.601, 207Pb/204Pb = 15.519 to 15.811 and 208Pb/204Pb = 38.666 to 39.571) that are plotted in the upper crust Pb evolution curve and overlap with that of Devonian to Carboniferous carbonate rocks and Proterozoic basement rocks in the SYG province. Pb isotope compositions suggest derivation of Pb metal from mixed sources. Sulfide minerals have 87Sr/86Sr ratios ranging from 0.7125 to 0.7167, higher than Sinian to Permian sedimentary rocks and Permian Emeishan flood basalts, but lower than basement rocks. Again, Sr isotope compositions are supportive of a mixture origin of Sr. They have an Rb–Sr isotopic age of 191.9 ± 6.9Ma, possibly reflecting the timing of Pb–Zn mineralization. C–O–S–Pb–Sr isotope compositions of the Tianqiao Pb–Zn deposit indicate a mixed origin of ore-forming fluids, which have Pb–Sr isotope homogenized before the mineralization. The Permian flood basalts acted as an impermeable layer for the Pb–Zn mineralization hosted in the Devonian–Carboniferous carbonate rocks. 相似文献
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大洋洲地区大地构造格架与优势矿产资源 总被引：1，自引：0，他引：1
大洋洲横跨印澳板块、太平洋板块和欧亚板块三大板块,区内从太古宙至今经历了漫长的构造演化历史。根据区域地质特征,该区可划分为3个一级构造单元,即澳大利亚中西部前寒武纪克拉通、澳大利亚东部古生代造山带和环太平洋中新生代岛弧区,12个二级构造单元和40个三级构造单元。3个一级构造单元由于经历了不同的构造演化过程,各自发育了不同的岩石组合和矿化作用。在研究区域构造演化与成矿作用耦合关系的基础上,总结出3个构造单元的成矿特征：澳大利亚中西部前寒武纪克拉通成矿过程与克拉通的生长有关,成矿时代主要为太古宙和元古宙,优势矿种为金、铜、镍、锰、铁、铀、稀土、铅锌、铝土等;东部古生代造山带成矿多和古太平洋与古冈瓦纳板块的相互作用有关,成矿时代为古生代,优势矿种为铜、金、铅锌和钨锡;环太平洋中新生代岛弧区的成矿作用多与印澳板块、欧亚板块与太平洋板块的相互作用有关,成矿时代多集中在中一更新世,优势矿种为铜、金、镍、钴等。对大洋洲地区矿产资源潜力进行了评估,认为大洋洲地区的铁、锰、铜、铝、镍、金、铀、稀土等矿产资源均具有较好的潜力。 相似文献
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南台钼多金属矿床是北秦岭典型的斑岩-矽卡岩型矿床,矿区内出露的岩浆岩主要有花岗斑岩、石英斑岩脉和爆破角砾岩,花岗斑岩内及接触带发育斑岩型和矽卡岩型钼多金属矿化。锆石LA-ICPMS定年测得花岗斑岩的U-Pb年龄为(151±1)Ma(N=12,MSWD=0.32),矿区内6件辉钼矿的Re-Os同位素模式年龄介于(146±2)～(151±2)Ma,其加权平均年龄为(148.8±1.7)Ma(N=6,MSWD=0.84)。成岩年龄与成矿年龄在误差范围内基本一致,表明南台钼多金属矿床形成于晚侏罗世,与其以北的华北克拉通南缘的主要斑岩型钼矿床大规模成矿时间一致。该花岗斑岩的锆石Hf同位素组成显示:176Hf/177Hf初始比值介于0.281 864～0.282 454,εHf(t)=-28.8～-7.9,两阶段模式年龄TDM2为2 654～1 506 Ma,均变化于一个较宽的范围,表明花岗斑岩的源区物质具有多源的特征,其中以壳源组分为主,可能有少量幔源组分的混入,暗示了成矿物质也可能主要来源于地壳,但地幔组分对成矿也有贡献。 相似文献
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闪锌矿流体包裹体显微红外测温及其矿床成因意义——以云南会泽超大型富锗银铅锌矿床为例 总被引：2，自引：0，他引：2
显微红外测温是利用红外显微镜研究不透明半透明矿物的流体包裹体丰度和分布特征,并与冷热台相结合进行流体包裹体显微测温分析的一种有效的新技术。云南会泽超大型富锗银铅锌矿床是分布于川滇黔接壤区典型的会泽型(HZT)铅锌矿床。本文以该矿床的闪锌矿、方解石流体包裹体为例,应用显微红外测温技术发现闪锌矿中发育大量流体包裹体,按其相态可分为6类:纯气相(V)、富液相气液两相(L+V)、富气相气液两相(L+V)、纯液相(L)、含子矿物三相(L+V+S)、含CO2三相(LCO2+LH2O+VCO2)包裹体,而在热液方解石中仅发现富液相气液两相(L+V)、纯液相(L)包裹体。闪锌矿中的流体包裹体均一温度集中在2个区间:150~221℃和320~364℃;而盐度变化范围较大,主要集中于3个区间:12.0%~18.0%、5.0%~11.0%、1.1%~5.0%。不同世代闪锌矿流体包裹体均一温度大致反映成矿流体演化的全过程,而方解石流体包裹体均一温度主要反映成矿流体演化的中晚阶段,而且与脉石矿物(方解石)共生的闪锌矿流体包裹体均一温度也高于方解石包裹体均一温度;反映了闪锌矿流体包裹体较方解石更能反映成矿流体的信息,进一步揭示从早成矿阶段到晚成矿阶段,成矿流体大致经历了中高温-中盐度→中低温-中盐度→中低温-中低盐度的演化过程。通过压力校正后的流体包裹体捕获温度反映了早成矿阶段成矿流体呈中高温,进一步证实了该矿床并非低温矿床。通过矿床对比研究,不仅反映了该矿床明显不同于典型的MVT铅锌矿床,而且表明了显微红外测温技术为该类矿床成矿流体p-T-x条件及矿床成因的研究提供了新方法与途径,并将在金属矿床成矿流体的研究领域发挥重要作用。 相似文献
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The giant sediment-hosted Jinding zinc-lead deposit is located in the Lanping Basin, northwestern Yunnan Province, China. The genesis of the deposit has long been debated and the sources of the ore-forming fluids and metals are controversial. This study presents rare earth element (REE) and noble gas isotope data that constrain the origins of the ore fluids and the heat source driving the hydrothermal circulation. The early-stage sulfides are enriched in light REEs and have high ∑REE values (30.8–94.8 ppm) and weakly negative Eu (δEu 0.85–0.89) and Ce anomalies (δCe 0.84–0.95), suggesting that the fluids were likely derived from dissolution of Upper Triassic marine carbonates with input of REEs from aluminosilicate rocks in the basin. In contrast, the late-stage sulfides have irregular REE patterns, generally low ∑REE values (0.24–10.8 ppm) and positive Eu (δEu 1.22–10.9) and weakly negative Ce anomalies (δCe 0.53–0.90), which suggest that the ore-forming fluids interacted with evaporite minerals. The 3He/4He (0.01–0.04 Ra) and 40Ar/36Ar values (301–340) of the ore-forming fluids indicate crustal and atmospheric origins for these noble gases. These findings are in agreement with the published fluid inclusion microthermometry data and the results of H, O, C, S, Pb and Sr isotope studies. Our data, in combination with published results, support a two-stage hydrothermal mineralization model, involving early-stage basinal brines and late-stage meteoric water that acquired metals and heat from crustal sources. 相似文献
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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