安徽铜陵冬瓜山大型铜矿:海底喷流-沉积与矽卡岩化叠加复合成矿过程

冬瓜山铜矿是长江中下游成矿带铜陵矿集区内的一个大型铜矿。该矿床被惯称为矽卡岩型矿床,但具明显的层控特征。主矿体呈层状、似层状,赋存于上石炭统碳酸盐建造与下伏上泥盆统砂岩建造的接触带附近,主要由一系列层控块状含铜硫化物透镜体、含铜矽卡岩透镜体、磁铁矿矿囊以及层状含铜黄铁矿-蛇纹石矿席组成。主矿体的底部为根植于上泥盆统砂岩建造内的层控脉状-网脉状矿,下部为层状含铜黄铁矿+蛇纹石矿席,主体为块状含铜硫化物透镜体与上覆硬石膏层构成的三个硫化物-硫酸盐韵律单元。该双层结构特征总体类似于VMS和SEDEX型矿床,但矿石结构构造表明,这些硫化物-硫酸盐沉积均不同程度地遭受了后期热液-变质作用叠加改造。层控含铜矽卡岩通常发育于块状含铜硫化物透镜体之上,小型磁铁矿矿体或矿囊通常围绕陡倾的闪长岩株零星分布。这两类矿化均与燕山期岩浆活动(约137Ma)和石英二长闪长岩株侵位密切相关。矿区可见两种蚀变作用:石英-绢云母蚀变与矽卡岩蚀变。前者在下盘砂岩中形成似整合蚀变带,包裹层控网脉状矿,其成因可解释为晚石炭世热液流体在海底之下砂岩透水层内发生侧向迁移、弥散排泄及金属卸载;后者由燕山期石英二长闪长岩侵位引起,形成两类矽卡岩,其中,镁质...     

华南燕山期大规模铜成矿作用的成矿模式及找矿方向

华南地区是中国最重要的金属矿产资源聚集区,其燕山期大规模成矿作用尤其引人注目。文章围绕华南燕山期大规模铜成矿作用,系统收集了该区内30余个主要矿床的地质和同位素年代学资料,初步总结了华南燕山期铜矿床的主要类型和时空分布特征。统计结果表明,斑岩型和浅成低温热液型矿床是华南燕山期最重要的铜成矿类型。对此,文章结合华南地区近年来铜及相关金、钼等金属的最新找矿勘查进展和矿床成因机制研究成果,分别以德兴矿集区、德化矿集区、紫金山矿集区和治岭头矿集区为例,提出了华南燕山期斑岩-浅成低温热液铜多金属成矿系统的几种成矿模式和找矿方向。     

阿尔泰南缘麦兹火山-沉积盆地东部萨吾斯铅锌矿床成因探讨

萨吾斯铅锌矿床位于阿尔泰南缘麦兹火山-沉积盆地东部,本研究首次阐述了该矿床的地质地球化学特征及其成因。该矿床赋存于下泥盆统康布铁堡组上亚组,以层状黑云石榴铁闪石矽卡岩、变流纹质晶屑凝灰岩、流纹斑岩、少量不纯大理岩为主要赋矿岩石;矿化与两类矽卡岩密切相关;表现出矽卡岩矿床与火山喷流沉积矿床的双重特征。野外地质考察、岩石薄片观察以及大量的矿物化学成分分析等表明,矽卡岩主要由锰铝榴石、铁铝榴石、铁闪石、黑云母和少量铁锰钙质碳酸盐矿物组成,其原岩为凝灰岩及其所夹的铁锰钙质碳酸盐条带;二者相互渗透交代的尺度局限于几厘米,与接触交代成因矽卡岩形成鲜明对比。综合上述,萨吾斯铅锌矿床不属接触交代矽卡岩型,而与火山喷流-沉积作用密切相关。与金属硫化物共生的石英脉氧同位素及其包裹体碳、氢同位素组成表明,成矿流体由岩浆水与表层流体混合而成。因此,萨吾斯铅锌硫化物矿床为火山喷流成因,这为阿尔泰南缘块状硫化物矿床的成因研究和找矿勘探部署提供重要理论依据。     

Geology, Ar-Ar Age and Mineral Assemblage of Eocene Skarn Cu-Au±Mo Deposits in the Southeastern Gangdese Arc, Southern Tibet: Implications for Deep Exploration

Abstract. Medium‐ and large‐scaled skarn Cu‐Au±Mo deposits, e.g. Kelu, Liebu, Chongmuda and Chenba among others, are distributed in Shannan area of the Gangdese Cu‐Au metallogenic belt. Intrusions‐related skarn copper mineralization belongs to high K and calc‐alkaline rock series, located in late collision volcano‐magmatic arc and formed between 20 to 30 Ma. Copper mineralization occurs at exocontact zone of the lower Cretaceous Bima Group carbonate and other calcareous‐bearing sedimentary rocks with intrusions. At present, three main mineralization types are identified, including skarn type, hydrothermal vein type and porphyry type. Mineralizing associations are Cu‐Mo, Cu‐Au and Cu. In ore districts, those mineralization types form an entire porphyry‐skarn Cu‐Au±Mo ore‐forming system. Alterations of the exocontact are mainly skarnization and hornfelsization, while the alterations of the endocontact are mainly sericitization, silicification, and chloritization of intrusion. In the study area, the endoskarn is not well developed. Copper mineralization occurs mainly in the exocontact in the form of stratoid, lenticular and pockety ore body. Veined mineralization can be seen in marblized and hornfelsed siltstone, being away from the contact zone. In the endocontact, the mineralization is mainly veinlet‐like and disseminated. In Shannan area, skarnization can be divided into early skarnization stage and late hydrous silicate stage. The early skarnization stage is featured by mainly andradite and grossular skarn, containing minor diopside, hedenbergite, magnetite and some copper minerals; and the late hydrous silicate stage is of replacement of garnet skarn by chlorite, epidote, quartz and calcite together with sulfides precipitation. The latter is the main stage of copper mineralization. Bornite is the dominant ore mineral associated with minor chalcopyrite and pyrite; and gold as well as silver are distributed in bornite and wittichenite. Results of microthermometry study of fluid inclusions in quartz of late hydrous silicate stage from different deposits show intermediate temperature and low to intermediate‐salinity features for all samples. The dominant inclusion type is composed of two phases, being about 4 to 15 % vapor and 85 to 96 % liquid at room temperature. Homogenization temperatures range from 232 to 335d?C. Salinities have been recorded between 4.2 and 15.5 wt% NaCl equivalent. Boiling fluid inclusions are not identified and it indicates that metal deposition mainly resulted from water‐rock reactions. The results of sulfur isotope analysis indicate that the sulfur isotope values (δ³⁴S 1.29–1.68 %o) of the samples collected from skarns are similar with that from the endocontact (δ³⁴S 1–1.75 %o). Both of them have very close sulfur isotope values (near δ³⁴S 0 %o), which indicate the sulfur of both the skarn type and the porphyry type mineralization was from deep sources. Ages determined on biotite from ore‐bearing intermediate porphyries by Ar‐Ar methods range from 23.77±0.29 to 29.88±0.56 Ma, showing that skarn copper mineralization in the study area evidently is older than the porphyry Cu(‐Mo) mineralization in Gangdese, and likely representing another metallogenic event. The Cu‐Au skarn deposits in the Kelu‐Liebu‐Chongmuda belt are interpreted as the shallow level, skarn‐related deposits in a porphyry‐skarn mineralization. Appearance of porphyry copper mineralization in some skarn deposits implies that skarn copper mineralization of the study area resemble to those in northern sub‐metallogenic belt, having uniform porphyry‐skarn ore‐forming system. Therefore, it is presumed there should be potential to find deep level porphyry‐type Cu‐Au mineralization targets.     

青海省格尔木市那陵郭勒河西地区铁多金属矿工艺矿物学研究

青海省格尔木市那陵郭勒河西地区铁多金属矿规模大,具有铁铜金等多金属矿化,属于接触交代型铁多金属矿床。本文采用工艺矿物学研究方法,查明了矿石工艺矿物学特性。研究结果表明,矿石的组成矿物种类较为简单,金属硫化物主要是黄铜矿、磁黄铁矿、黄铁矿、闪锌矿;铁矿物主要是磁铁矿、赤铁矿。脉石矿物主要是石英、方解石、透闪石、透辉石;其次为石榴子石、白云母、蛇纹石。矿石中铁、铜锌矿物均具均匀细粒—微细粒嵌布特征;通过选矿可获得铜精矿、锌精矿、铁精矿。     

长江中下游成矿带龙角山矽卡岩钨矿床成矿作用过程 ——来自白钨矿和石榴子石主微量元素的证据

白钨矿和石榴子石的原位微量元素特征能提供成矿流体的演化信息.长江中下游成矿带鄂东南矿集区龙角山矿床是近年发现的大型矽卡岩钨矿床,为区域找矿勘查和成科学研究提供了新的方向.龙角山矿床的流体演化和矿床成因亟待开展系统研究.文章在详细的野外工作和前人研究基础上,通过对矿床中矽卡岩阶段、退蚀变阶段和石英硫化物阶段的白钨矿和石榴...     

安徽龙桥铁矿床辉长闪长岩的发现及其岩石学和年代学研究

龙桥铁矿床是长江中下游成矿带内的大型铁矿床,主矿体呈似层状赋存于三叠系东马鞍山组泥灰岩、角砾状灰岩和泥质粉砂岩中,单个矿体铁矿石资源量大于1亿吨,具有鲜明的成矿特色。前人研究认为,矿区内正长岩类侵入岩与成矿关系密切,龙桥矿床是成矿带内唯一与正长岩有关的大型铁矿床。随着生产勘探,在矿床中部井下巷道中发现辉长闪长岩侵入体,为矿床成因以及成矿模式提供了新的线索。文章在详细的野外地质工作基础上,开展了辉长闪长岩的岩石学、地球化学和年代学研究。辉长闪长岩岩体呈岩株状产出,被正长岩体穿切破坏,靠近矿体部位发育透辉石矽卡岩化蚀变。辉长闪长岩主要由拉长石(60%)、钾长石(10%)、普通辉石(10%)和角闪石(5%)组成;与正长岩相比,辉长闪长岩明显具有低硅、低钾、高镁铁特征。锆石LA ICP-MS定年结果表明其成岩时代为(133.5±0.8)Ma。在前人对龙桥矿床研究的基础上,笔者认为龙桥铁矿床辉长闪长岩与铁成矿作用关系更为密切,成岩成矿作用几乎同时发生,而正长岩为成矿期后破矿岩体。通过与庐枞矿集区和长江中下游成矿带内铁矿床对比表明,庐枞矿集区内大型铁矿床与正长岩无成因联系,而闪长质侵入岩则是庐枞矿集区内重要的成矿母岩。龙桥铁矿床与长江中下游成矿带庐枞、宁芜矿集区内玢岩型铁矿床以及鄂东南矿集区内矽卡岩型铁矿床在成岩成矿时代方面相近,属长江中下游第二期成岩成矿作用的产物。闪长质侵入岩是成矿带内矽卡岩型及玢岩型铁矿成矿的必要条件,而正长岩类侵入岩的形成大多晚于闪长岩,与铁成矿作用无直接关系。     

黑龙江省翠宏山钨钼多金属矿床辉钼矿Re-Os同位素定年及其地质意义

翠宏山钨钼多金属矿床是小兴安岭-张广才岭成矿带内一个重要的矽卡岩型矿床,钨、钼、锌均达大型规模。为确定该矿床的形成时代,对取自岩体内接触带钨钼矿体的7件辉钼矿样品进行了Re-Os同位素测年研究。结果表明:辉钼矿中Re质量分数为（0.376 9～0.973 7）×10^-6,Os质量分数为（1.272～3.234）×10^-9;获得的模式年龄为(199.0±3.1)～(203.9±3.8) Ma,加权平均年龄为（201.6±1.4）Ma(MSWD=0.80),等时线年龄为（198.9±3.7）Ma(MSWD=0.83)。结合区域成矿作用分析认为:翠宏山多金属矿床的形成时代为早侏罗世,与成矿带内的霍吉河和鹿鸣等斑岩型（细网脉型）钼矿床同属燕山早期大规模构造-岩浆-成矿事件的产物。根据本次辉钼矿Re-Os定年结果,结合前人在矿区内所测多个花岗岩体的锆石U-Pb年龄认为:与翠宏山多金属矿床具成因联系的岩体应为二长花岗岩、碱长花岗岩,成岩成矿作用与古太平洋板块俯冲有关。辉钼矿中Re质量分数、成矿岩体的物质源区综合研究表明,翠宏山多金属矿床的成岩成矿物质具有壳幔混源特征。     

Geology of gold-bearing skarn deposits in the middle and lower Yangtze River Valley and adjacent regions

The middle and lower Yangtze River Valley and adjacent regions are the most important metallogenic belt of gold (and copper)-bearing skarn deposits in China. The total gold reserves in this belt have been estimated at more than 600 t. The gold-bearing skarns are mainly distributed in the southeastern Hubei, Tongling and northern Anhui regions. Favorable tectonic settings are depressions and fold zones of the platforms, i.e., mobile belts. These skarns are hosted by platformal limestone, dolomitic limestone and dolomite of the Triassic, Carboniferous-Permian and Middle to Lower Cambrian formations. The related intrusions are Yenshanian (180 to 113 Ma) calc-alkaline quartz monzodiorite, granodiorite, quartz monzonite, monzogabbro, and their hybabyssal facies. The intrusions have high Fe₂O₃/FeO (>0.5) and intermediate initial ⁸⁷Sr/⁸⁶Sr ratios (0.7046 to 0.7087). Their REE distribution patterns are LREE-enriched and exhibit smooth, right-dipping curves. These suggest that the source materials mainly came from upper mantle, with contamination by sialic crustal components. The auriferous skarns are both calcic and magnesian, but calcic skarns are most common. The constituent minerals of the calcic skarns are diopside, garnet, wollastonite, vesuvianite and scapolite, whereas magnesian skarns are dominated by forsterite, spinel, diopside, phlogopite, chondrodite and clinohumite, with abundant superimposed serpentine, clinochlore and brucite. The compositions of coexisting pyroxenes and garnets are diopside and andradite, indicating the high oxygen fugacity and low acidity conditions. Gold is closely associated with Cu (Pb, Zn) sulfides and exists mainly in the form of native gold and electrum. Arsenides, tellurides, bismuthides and selenides are present in many ore deposits. Therefore, Cu, As, Bi, Te, Ag, Pb, Zn, Se and Co are the major metals present in the deposits and are important geochemical ore-searching indicators. In some Au (Fe, Cu) magnesian skarns, magnesiomagnetite, magnesioferrite and ludwigite are locally abundant. The metasomatic zoning in many gold skarn deposits is very distinct consisting of an outward sequence of: Fe (Cu)→Cu (Mo)→Cu (Au)→Au (Cu)→Au (Pb, Zn). The geologic characteristics of Au (Cu) skarn deposits that formed in the mobile platformal setting of China have distinct differences compared to Au skarns formed in orogenic belts at convergent plate margins in British Columbia and the western USA.     

西藏甲玛铜多金属矿床铜山矿体为manto型矿体?

manto型矿化是指"沿层交代"并受地层控制,构造控矿,品位高,富含硫化物矿石。甲玛铜多金属矿床位于西藏冈底斯成矿带东段,在公益性与商业性勘查结合下,取得重大找矿突破的世界级超大型斑岩-矽卡岩型铜多金属矿床。铜山(南坑)矿体是继揭露甲玛深部斑岩矿体之后的又一找矿重大突破。铜山矿体规模达到大型,铜金属量70多万吨,钼金属量2万吨,铅+锌金属量120多万吨,伴生金金属量20多吨,伴生银金属量2 000多吨。铜山矿体距离斑岩体中心1 km,受铜山滑覆构造控制,滑覆体内部次级褶皱、裂隙发育,为热液流体运移、沉淀提供了良好的空间;赋存于林布宗组角岩、林布宗组角岩和多底沟组大理岩层间及多底沟组大理岩中,呈透镜体、脉状、囊状、豆荚状;富含硫化物,主要为黄铜矿、闪锌矿、方铅矿、斑铜矿、磁黄铁矿、黄铁矿、辉钼矿等;品位较高,铜平均品位0.99%,铅+锌平均品位2.88%。通过野外地质调查,并与世界上其他manto型矿体对比,甲玛铜山矿体属于斑岩成矿系统远端的manto型富矿体。甲玛manto型矿体的发现和确定在西藏冈底斯成矿带上尚属首例,对该成矿带其他斑岩、矽卡岩矿床寻找外围manto型富矿体具有极其重要的指导意义,其经济意义也十分巨大,目前已经建成日处理4万吨的露天采场。