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1.
对贵州遵义黄家湾下寒武统牛蹄塘组镍-钼富集层进行电子探针研究,发现镍主要赋存于黄铁矿、针镍矿、辉砷镍矿、铁辉砷镍矿、紫硫镍矿、赫硫镍矿;钼主要以"碳硫钼矿"的形式存在。镍钼硫化物多与黄铁矿、白铁矿交代共生,反映矿物经历了不同的成矿阶段。岩石中不仅富集Ni、Mo元素,而且Se元素存在超常富集,可以视为热液作用或生物作用的结果。遵义黄家湾下寒武统Ni-Mo富集层应为海底热液沉积和生物沉积混合成因,其物源较为复杂。  相似文献   

2.
刘建东  孙伟 《矿物学报》2014,(2):267-271
对张家界杆子坪黑色岩系型镍钼矿进行矿物学分析和扫描电镜研究,发现镍主要赋存于铁-方硫镍矿[(Ni,Fe)S2]、针镍矿(NiS)、方硫镍矿(NiS2)、硫镍矿(NiNi2S4)、辉砷镍矿(NiAsS)、紫硫镍矿(FeNi2S4)、镍黄铁矿[(Fe,Ni)9S8]等;钼主要以"胶硫钼矿"的形式存在。镍钼矿物多与黄铁矿、脉石矿物交代共生,反映出矿物嵌布关系的复杂性。镍钼矿物嵌布粒度不均匀且细小,给选矿带来很大的难度。  相似文献   

3.
喷流沉积型矿床是矿床地质学研究的前沿课题,查明矿石中重要组分(镍和钼)的赋存状态是该类矿床地质学研究的重要内容。湘黔地区天鹅山-黄家湾、大坪-大浒镍钼矿带是典型的海底喷流沉积矿床,本文采集该矿区的样品,应用化学和光谱定量分析、偏光显微镜和X射线衍射、扫描电镜、电子探针等大型现代仪器相结合的分析手段,研究了矿石中镍和钼的赋存状态。化学和光谱分析确定矿石中镍含量为3.76%,钼含量为4.99%;偏光显微镜下观察发现金属矿物零星分布,颗粒细小,结晶程度差,光学特征极不明显,晶体形貌特征难以观察,初步推断矿石矿物以胶状形式存在,但在光学显微镜下很难为这些矿物定名和描述;X射线衍射分析验证了偏光显微镜鉴定结果,印证了样品中存在很多非晶质矿物,仅有钨钼钙矿和镍黄铁矿两种矿物含有镍钼,且矿物含量很低(分别为0.4%和0.8%),对比化学分析结果,可推断样品还存在其他富含镍钼元素的矿物。进一步对富集镍钼元素的区域进行电子探针分析,最终确定了镍除了赋存于辉砷镍矿、方硫镍矿中,在胶状黄铁矿和磁黄铁矿边缘呈蠕虫状花边的镍黄铁矿中也有富集;钼主要赋存于碳硫钼矿中。矿石中的镍钼主要赋存于由胶态向结晶态过渡的金属矿物中,研究成果为该类矿床的矿石矿物学研究、选矿、冶炼及矿石综合利用提供重要的信息和依据。  相似文献   

4.
湖南张家界三岔和贵州遵义黄家湾在下寒武统黑色岩系中发育有镍钼多金属矿床,这是华南乃至全球这类矿床的2个典型实例。通过对其进行系统的矿相显微镜、电子探针以及扫描电子显微镜观测分析,分析了成矿岩系的矿物学特征,并进一步根据矿物结构、组成与共生关系,结合地质背景,讨论了矿床成因。结果显示,非矿层中的金属矿物类型较为单一,主要是黄铁矿;而矿层中发现的矿物种类丰富,主要包括"碳硫钼矿"、针镍矿、黄铁矿、胶磷矿等,其中"碳硫钼矿"和针镍矿分别是钼与镍的主要赋存形式。认为钼主要来自于海水,镍主要来自于热水(液)流体,矿床为海水-热水(液)-生物复合成因。这些研究结果为此类矿床研究提供了新的矿物学基础研究资料,并且有助于加深对矿床成因的认识。  相似文献   

5.
滇西南墨江金厂金镍矿床金、镍赋存状态及成矿过程探讨   总被引:5,自引:5,他引:0  
墨江金厂金镍矿床位于滇西南哀牢山造山带中段,是西南三江地区一个独特的金镍共生矿床。笔者通过野外地矿物主要为针镍矿、辉砷镍矿、锑硫镍矿、黄铁矿等。依据矿(化)脉切割关系、矿石结构构造及矿物共生组合,墨江金厂金镍矿床成岩-成矿期共发育4个世代黄铁矿。沉积变质期以草莓状黄铁矿和胶状黄铁矿为主,热液成矿期可划分为:早阶段石英-针镍矿-辉砷镍矿-锑硫镍矿-黄铁矿;主阶段石英-黄铁矿-毒砂-硫锑铜银矿-自然金;晚阶段方解石-石英-黄铁矿。对矿区赋金镍贯通性矿物黄铁矿进行详细的电子探针分析,结果显示4个世代黄铁矿微量元素有所差异。其中热液主阶段黄铁矿中含有Au、As、Sb、Pb、Zn、Cu、Co、Ni和Te,显示其流体成分复杂。不同阶段黄铁矿Ni含量不同,沉积变质期黄铁矿中Ni含量较低,为0.00%~0.82%,平均0.26%;热液早阶段黄铁矿中Ni含量最高,为0.43%~3.15%,平均1.38%;热液主阶段黄铁矿中Ni含量降低,为0.00%~0.99%,平均0.22%;热液晚阶段黄铁矿中Ni含量最低,为0.00%~0.09%,平均0.03%。研究结果表明墨江金厂金镍矿床中主要含金矿物和含镍矿物形成于热液期,含金矿物形成晚于含镍矿物。Ni在热液流体中的迁移能力与流体温度正相关,温度越高,Ni进入黄铁矿晶格的能力越强。基于上述金、镍成矿过程研究成果,并对比国内外热液镍矿床的地质-地球化学特征,推断墨江金厂金镍矿床是一个受岩浆热液改造的中-低温热液金镍矿床。  相似文献   

6.
位于芬兰北部中拉普兰绿岩带的克维特斯塔(Kevitsa)镍-铜-铂族元素矿床是世界上主要的岩浆镍-铜硫化物矿床之一。该矿床储量大,含丰富的镍-铜硫化物和铂族元素。对矿床产出环境、地质特征、矿床成因等进行了总结,结果表明:矿体主要赋存于克维特斯塔基性—超基性层状侵入体的超基性单元中。主要矿石类型为普通型和镍-铂族元素型2种,其中镍-铂族元素型矿石内橄榄石具极高的Ni含量。主要矿石矿物为磁黄铁矿、镍黄铁矿、黄铜矿、黄铁矿、针硫镍矿、红砷镍矿、砷镍矿、辉砷镍矿等,绝大部分铂族矿物包含在硅酸盐中和附着在硫化物颗粒边界。Re-Os、Sm-Nd、Sr及S同位素特征显示成矿岩浆为幔源,但受到地壳物质的混染作用。Pb同位素年代学结果表明克维特斯塔侵入体形成于古元古代。  相似文献   

7.
贵州省遵义松林地区下寒武统牛蹄塘组镍钼多金属层富集U、Mo、Ni、Re、Tl等元素.本文以松林地区镍钼多金属层磷块岩为主要研究对象,在松林系统取样的基础上,开展化学分析、径迹蚀刻、扫描电镜、能谱面扫描、浸出实验等工作.结果表明下寒武统牛蹄塘组镍钼多金属层中Ni、Mo显著富集,达到工业品位,U、Re、Tl明显富集.径迹蚀刻实验揭示铀主要富集于磷块岩碎屑边缘有机碳外带,为进一步确定铀的赋存形式圈定重点观察区.该区镍钼多金属层中铀呈晶质铀矿形式赋存于溶蚀重结晶磷块岩的溶蚀孔洞、微裂隙或微孔隙中,并与中高温热液矿物针镍矿、辉砷镍矿、闪锌矿、方铅矿、磷灰石共生.浸出实验采用去离子水、H2 SO4、NaHCO3+MnO2三种介质浸出样品中水溶态、酸可溶态、氧化可溶态的铀.80℃,48 h条件下浸出实验结果显示多金属磷块岩由黑色褪色为浅灰色、灰色,碳质页岩实验前后颜色均为黑色.遵义地区镍钼多金属层及碳质页岩中铀主要以吸附状态或独立矿物形式存在,以类质同象形式存在的难溶铀占比较小.研究认为,该区镍钼多金属层磷块岩中铀以独立矿物形式存在并与中高温热液矿物共生,为揭示扬子陆块东缘陆源裂陷环境下发生海底喷流和热水沉积作用提供新的微观证据.  相似文献   

8.
贵州遵义镍-钼富集层中独居石的发现及成因意义   总被引:1,自引:0,他引:1  
对贵州遵义天鹅山-黄家湾镍-钼富集层中镍-钼矿石进行了电子探针研究,在镍-钼矿石中发现了稀土独立矿物——独居石,呈不规则的细粒、蠕虫状分布于矿石中,并与镍、钼的独立矿物共生;独居石La和Ce的含量高(La2O3含量变化范围为25.70%~30.52%,Ce2O3含量变化范围为22.96%~27.68%),贫Sm、Th(Sm2O3含量的变化范围为0.49%~0.80%,ThO2含量的变化范围为0%~0.19%),具有热液成因独居石的化学成分特征。镍-钼矿石中稀土矿物独居石的发现为镍-钼矿层的热液成因提供了直接的矿物学证据。  相似文献   

9.
我国早古生代煤主要蕴藏在煤炭资源贫乏的南方各省,因坚硬似岩石又称之为石煤,储量极为丰富,仅浙江至广西就分布有长约1 600 km的石煤矿,石煤中含有或富集了多种金属元素,目前已发现的伴生元素达60多种,如钒、钼、磷、钡、镍、铀、金、银等,局部可形成工业矿床而作为某种矿物资源单独开采,是我国有待系统开发的潜在的多矿产资源。研究表明:石煤形成于以菌藻类为主的生物堆积和浅表海或古陆边缘的海相还原环境,含有大量的菌藻类(如蓝绿藻和褐藻)、古孢子、海绵骨针及一些分类尚不明确的原始动、植物等生物化石,具有低碳、高灰、高硫的特点,海相沉积环境和藻类对硫的机械富集与捕集是造成含石煤岩系中硫含量高的主要因素。石煤中富集的金属元素绝大多数是亲硫元素,早期聚煤作用过程是石煤中伴生元素富集的重要阶段,多金属硫化物是石煤中金属元素最重要的赋存形式,主要有硫磺、黄铁矿、黄铜矿、闪锌矿、方硫镍矿、辉镍矿、辉砷镍矿、针镍矿、含镍黄铁矿和硫钼矿等,大量实验及同位素研究资料揭示了细菌还原硫酸盐作用是导致大规模金属硫化物矿化最可能的生物营力,也是石煤和金属硫化物矿床主要的成煤和成矿机制,硫的生物地球化学行为直接影响了金属元素的富集与赋存状态,但早...  相似文献   

10.
新疆萨尔托海铬铁矿中的Fe-Ni-As-S矿物研究   总被引:2,自引:1,他引:1  
谭娟娟  朱永峰 《岩石学报》2010,26(8):2264-2274
新疆萨尔托海铬铁矿是一个典型的与蛇绿岩有关的高铝型豆荚状铬铁矿,其中矿石铬尖晶石发生了明显的热液蚀变,发育了富Cr的蚀变环边,形成高铁铬铁矿,Cr#在蚀变后升高,发生了Cr元素的次生富集。在矿石颗粒间隙中的Fe-Ni-As-S矿物组合主要为镍黄铁矿-赫硫镍矿-针镍矿-砷镍矿。围岩纯橄岩普遍发育强烈的蛇纹石化,其中的Fe-Ni-As-S矿物组合为赫硫镍矿-镍黄铁矿-砷镍矿,还有少量的针镍矿和铜矿物。通过对硫化物的成分对比分析,认为矿石中的镍黄铁矿和赫硫镍矿都属于岩浆演化的产物(600℃),与赫硫镍矿和针镍矿一样,均从贫S的母岩浆中通过岩浆熔离过程形成。围岩和矿石中的含砷矿物以及围岩中的镍黄铁矿都是晚期热液活动的结果,其中砷镍矿具有特殊的蠕虫状-乳滴状结构,与围岩中的赫硫镍矿和镍黄铁矿共生。围岩和矿石中Fe-Ni-As-S矿物组合的形态和成分差异,说明金属矿物的整体演化从岩浆期到热液期经历了从贫S到富As的环境变化,最终形成了现在所观察到的复杂Fe-Ni-As-S矿物组合。  相似文献   

11.
华北克拉通在中奥陶世至晚石炭世期间一直出露地表,经历了长期的风化作用,形成大规模的铁-铝黏土矿,其成矿物源一直是研究的热点,尤其是本溪组底部铁矿和铁质黏土矿与上部铝黏土矿是否为同一来源尚未查清。本研究选取克拉通南缘大安铝黏土矿床作为研究对象,展开微区矿物及元素地球化学组成分析,进一步探讨铁-铝黏土矿物质来源。大安矿床内含矿岩系自下而上包括铁质黏土岩、铝土矿、铝质黏土矿;局部喀斯特高地缺失铝土矿,铝质黏土矿直接覆盖于铁质黏土岩之上。铁质黏土岩在洼地以菱铁矿、黄铁矿和伊利石为主,在隆起区以赤铁矿、伊利石和高岭石为主。铝土矿以硬水铝石、伊利石和锐钛矿为主;铝质黏土矿主要矿物为伊利石。矿物微区分析在黏土矿底部发现大量的碳化硅和少量自然硅、硅铁矿、铬铁矿;区域对比揭示北秦岭造山带内商丹缝合带和二郎坪群中的蛇绿岩为铝黏土矿形成提供了成矿物质。本溪组底部铁质黏土与上部铝黏土矿稳定元素比率(例如Zr/TiO2、Hf/TiO2、Nb/TiO2、Ta/TiO2)存在明显差异,揭示二者为不同来源: 底部铁质黏土岩和铁矿层为底板碳酸盐岩原地风化的产物;而上部铝黏土矿是异地搬运物,北秦岭造山带在晚石炭世的整体抬升为华北铝黏土矿形成提供了重要的成矿物质。  相似文献   

12.
During the Middle Ordovician to Late Carboniferous period,the North China Craton(NCC)was exposed and experienced prolonged weathering that resulted in the formation of large-scale iron,clay and bauxite deposits. The source of ore-forming material has always been a research focus,in particular,whether the sources of the iron ore and the Fe-bearing clay at the bottom of Benxi Formation are the same as the upper bauxite and clay deposit is still unclear. In this study,the Da'an bauxite and clay deposit at the southern margin of the NCC was chosen to carry out a detailed analysis of the micro-region mineral composition and elemental geochemical characteristics for further exploring the sources of iron,bauxite and clay deposits. The composition of the ore-bearing rocks in the Da'an bauxite deposit from the bottom to top includes Fe-bearing clay(locally iron ore),bauxite,and bauxitic clay;locally,in karstic uplift,bauxitic clay layer is directly overlying on the Fe-bearing clay. The Fe-bearing clay is dominated by siderite,pyrite,and illite in the karstic depression,and hematite,illite,and kaolinite in the uplift. Bauxite is mainly composed of diaspore,illite,and anatase,while bauxitic clay is mainly composed of illite. Mineral microanalysis revealed the development of large amounts of moissanite and small amounts of natural silica,silicalite,and chromite at the bottom of bauxitic clay layer. Regional comparison and correlation reveal that the ophiolite in the Shangdan suture zone and Erlangping Group in the North Qinling orogenic belt(NQOB)likely provides source materials for bauxite and clay deposits. The obvious differences in immobile element ratios (e.g., Zr/TiO2,Hf/TiO2,Nb/TiO2,Ta/TiO2)between the bottom Fe-bearing clay layer and the upper bauxite and clay layer in Da'an deposit,revealing that they are from different sources. The bottom Fe-bearing clay and iron ore layers are the products of in-situ weathering of underlying carbonates,while the top bauxite and clay are allochthonous. The regional uplift of the NQOB during the Late Carboniferous period provided important ore-forming materials for the formation of the NCC bauxite and clay deposits.  相似文献   

13.
湘西北黑色岩系中矿产资源的综合利用   总被引:11,自引:1,他引:11       下载免费PDF全文
矿物资源的综合利用具有极其重要意义,以湘西北黑色岩系中的镍,钼多矿矿庆层为例,探讨了如何合理综合利用本地镍,相金属资源,尤其是金,铂,钯等金融矿产以及磷等非金属资源,并结合经济,环境环境等多方面因素的考虑自行设计利用流程,指出了湘西北多矿种资源综合利用的广阔前景,同时提出了可行性建议。  相似文献   

14.
Gersdorffite from two mineralization types (post-Variscan vein deposits, strata-bound mineralization) was investigated in the Niederberg area Rhenish Massif. In the ternary Ni–Co–Fe space gersdorffite from post-Variscan vein deposits displays a tight cluster with the highest Ni-contents ranging from 0.825 to 0.962 atoms per formula unit (a.p.f.u.). As/S ratios comprise a narrow range from 0.875 to 1.012. In contrast gersdorffite from the strata-bound mineralization displays a substitutional trend. Co and Fe substitute for Ni in a ± fixed ratio. Ni ranges between 0.494 and 0.836 a.p.f.u. As/S ratios (1.025–1.211) display a wider range and indicate higher As-contents relative to gersdorffite from post-Variscan vein deposits. Based on these results, two different hydrothermal fluid systems can be identified in the Niederberg area forming gersdorffite in both mineralization types. The hydrothermal fluids circulating in the post-Variscan vein deposits were homogeneous (high Ni-activities, lower As fugacities) and mixing occurred far away from the site of deposition whereas the fluids of the strata-bound mineralization were more heterogeneous (decreasing Ni-activities) with moderate elevated As fugacities. With respect to the post-Variscan vein deposits in the Niederberg area the results are compatible with earlier findings.Comparison with available gersdorffite analyses from adjacent areas (borehole Viersen, Ramsbeck deposit) reveal that gersdorffite compositions provide a reliable tool in distinguishing between different hydrothermal systems on a regional scale in the northern Rhenish Massif. However, gersdorffite compositions cannot be used to discriminate between Variscan and post-Variscan deposits with confidence.The country rocks in the Niederberg area are possible sources for Ni, Co and Fe during gersdorffite formation of the strata-bound mineralization. However, due to the remarkable homogeneity of gersdorffite compositions of the post-Variscan vein deposits irrespective of age and composition of the immediate adjacent host-rocks it is assumed that these host-rocks are not the source of the metals. Reduced Zechstein sulfate is assumed to be the source of sulfur. The As source remains unknown.Due to conflicting experimental data concerning the gersdorffite solid solution field it is not possible to derive reliable formation temperatures for the strata-bound mineralization. However, gersdorffite compositions of the post-Variscan vein deposits are compatible with low formation temperatures (<300 °C) in accordance with earlier findings.  相似文献   

15.
遵义牛蹄塘组发现的多水硫磷铝石   总被引:2,自引:0,他引:2  
遵义牛蹄塘组黑色岩系发现的多水硫磷铝石主要产出在Ni-Mo多金属层的微裂隙中,偶尔在多金属层下部的黑色粉砂岩中以脉体形式产出。该矿物结构不稳定,结构中一部分水分子很容易失去,在X射线衍射鉴定时其特征谱线变化较大;在自然条件下存放一定时间后,样品具有稳定的X射线衍射特征。此外,对这些样品进行了红外光谱、热重和差热分析、TEM观测、化学分析和晶胞参数计算,与纤磷铝石进行了对比和讨论。  相似文献   

16.
Summary The Ni-Mo Huangjiawan mine, Guizhou Province, People’s Republic of China, occurs in Lower Cambrian black shale (stone coal) in an area where other mines have recently extracted ore from the same horizon. Detailed electron microprobe (EMPA) and scanning electron microscope (SEM) analyses of representative thin sections have revealed a complex assemblage of sulfides and sulfarsenides. Early sulfidic and phosphatic nodules and host matrix have been lithified, somewhat fractured, and then mineralized with later-stage sulfides and sulfarsenides. Gersdorffite, millerite, polydymite, pyrite, sphalerite, chalcopyrite, galena, and clausthalite have been recognized. EMPA data are given for the major phases. Pyrite trace-element distributions and coeval Ni-, As-sulfides indicate that in the main ore layer, the last sulfide deposition was Ni-As-Co-rich. Mo and V deposition were early in the petrogenesis of these rocks. The assemblages gersdorffite-millerite-polydymite (pyrite) and millerite-gersdorffite (pyrite) and the composition of gersdorffite indicate a formation temperature of between 200° and 300 °C suggesting that the last solutions to infiltrate and mineralize the samples were related to hydrothermal processes. Environmentally sensitive elements such as As, Cd, and Se are hosted by sulfides and sulfarsenides and are the main source of these elements to residual soil. Crops grown on them are enriched in these elements, and they may be hazardous for animal and human consumption. Authors’ addresses: H. E. Belkin, U.S. Geological Survey, 956 National Center, Reston, VA 20192, USA; Kunli Luo, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun Road, Beijing 100101, People’s Republic of China  相似文献   

17.
The flotation response of gersdorffite has been determined in a series of batch flotation tests in which a sulphide sample containing about 76% gersdorffite was floated from mixtures with quartz.Using xanthate as collector, the arsenide floated strongly at pH 9, irrespective of whether lime, sodium hydroxide or sodium carbonate was used as pH modifier. When the pH was raised further to 10 or more using lime, the flotability decreased sharply.Changing the pulp potential at pH 9 also strongly affected the flotation response. Above about − 230 mV SHE, the mineral floated strongly, but below this potential it was essentially non-flotable. As far as it was tested (up to + 400 mV SHE), no upper limiting potential was found.Adding cyanide to the grinding mill brought about only a weak depressant effect on subsequent gersdorffite flotation at both pH 9 and 10. However, adding the same amount of cyanide to the flotation cell produced a strong depressant effect at the same pH values. At both pH 9 and pH 10, a threshold cyanide addition existed below which gersdorffite floated strongly, and above which it did not. For the conditions used in this study, this addition equates to about 100 g/t at pH 9 and about 80 g/t at pH 10. A hypothesis for the depression effect is presented which is consistent with both the available flotation data and a series of diagnostic analyses of grinding and flotation pulps completed during the test work.  相似文献   

18.
《Chemical Geology》2006,225(3-4):291-303
The Fe–Co–Ni–As–S system has been investigated by combining experimental data with data compiled from literature. The main focus is the phase relations and crystal chemistry of the monosulfide, pentlandite, gerdorffite–cobaltite, diarsenide, and skutterudite solid solutions.The phase relations along the Co(As, S)2–Ni(As, S)2 section has been constructed using literature data. There was reasonable agreement between the different data sets and it was possible to combine them into a unifying model showing the phase relations enveloping the gersdorffite–cobaltite solid solution.The compositional variations and the related changes in unit-cell parameters of these five Fe–Co–Ni-bearing solid solutions have been statistically analyzed. Comparison between the resulting coefficients and the effective ionic radius [Shannon, R.D., 1976. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta. Cryst. A32, 751–767.] of the substituting elements test assumptions made concerning valence, spin state, and metal–metal bonding.Monosulfide solid solution and pentlandite both behave in a way consistent with extensive metal–metal bonding. Fe causes significant relative unit-cell expansion; Co causes a large contraction of the unit cell and Ni a moderate contraction. This supports previously suggested bonding models arguing that 56 d electrons stabilize the pentlandite cube-cluster and one d electron from each metal atom participate in metal–metal bonding. Crystal chemical models explaining the variation in the metal/sulfur ratio in pentlandite by metal vacancies are challenged by the observation that excess sulfur increases the unit-cell size of pentlandite.In cobaltite–gersdorffite, diarsenide, and skutterudite, Co has less than half the structural impact than Ni, although both elements caused significant increases in some unit-cell parameters. This partly contradicts bonding models explaining the metal atoms to be in their divalent low-spin state in cobaltite–gersdorffite and the diarsenides, suggesting that the bonding situation is more complex than normally assumed. Substituting As with S causes an expected unit-cell increase in cobaltite–gersdorffite.  相似文献   

19.
The Laowangzhai gold deposit, located in the Ailaoshan gold belt (SW China), is hosted in various types of rocks, including in quartz porphyry, carbonaceous slate, meta‐sandstone, lamprophyre, and altered ultramafic rocks. In contrast to other wall rocks, the orebodies in altered ultramafic rocks are characterized by the occurrence of a large amount of Ni‐bearing minerals. The ore‐forming process of the orebodies hosted by altered ultramafic rocks can be divided into two stages: pyrite‐vaesite‐native gold and gersdorffite‐violarite stages. The contents of As and Sb increased during the evolution of ore‐forming fluid based on the mineral assemblages. Thermodynamic modeling of the Ni‐Cu‐As‐Fe‐S system using the SUPCRT92 software package with the updated database of slop16.dat indicates the fS2 in ore‐forming fluid decreases significantly from stage I to stage II. The decreases of fS2 due to crystallization of sulfides and fO2 due to fluid–rock reaction were responsible for ore formation in altered ultramafic rocks of the Laowangzhai gold deposit. Geological evidence, the in situ sulfur isotope values of pyrite, and the other published isotopic data suggest that the ore‐forming fluid for ultramafic rock ores was dominantly composed of evolved magmatic fluid with the important input of sediments.  相似文献   

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