黔西南卡林型金矿研究现状及展望

黔西南卡林型金矿集区作为滇黔桂"金三角"重要组成部分,自发现以来,一直是地质科研工作研究的热点,取得了丰硕的成果。但迄今在金矿床的成矿时代、成矿物质来源及矿床成因等方面仍存在争议。本文在黔西南卡林型金矿研究现状的基础上,提出了今后重点研究方向。     

富碲化物型金矿形成的物理化学条件——以水泉沟金矿田为例

通过对冀北水泉沟金矿田与偏碱性岩有关的富碲化物型金矿和不含碲化物金矿床的地质特征、黄铁矿的标型特征以及流体包裹体成分的对比分析，揭示了富碲化物型金矿的某些共同特征及其所指示的物理化学条件。同时利用热力学分析，从理论上阐明了这些现象的内在原因，并提出其形成需要三个条件：①高碲的地球化学背景场；②有利于碲活化和迁移的物理化学条件（酸性）；③有利于碲化物沉淀的物理化学条件：低温、高ｆＴｅ２值和高的ｆＴｅ２／ｆＳ２比值     

卡林型金矿床中自然砷的特征与成矿物理化学条件示踪

在"滇黔桂"、"川甘陕"两个金三角密集区内的某些卡林型金矿床中,自然砷矿物的存在并非个别现象。自然砷呈致密块状、致密凝胶体状(肾状)、脉状或微细脉状产出。自然砷呈他形粒状,颗粒大小变化较大,一般为0.05～0.50mm,最大可达2mm。反光显微镜下为白色,显微硬度为114.21～150.60kg/mm2,相当于摩氏硬度3.27～3.59。矿物主要化学成分As的质量分数为92.74%～99.74%,并含有S0.18%～5.25%,Sb0.04%～3.65%。矿物为三方晶系,晶胞参数值a=0.3759nm,c=1.0527nm。利用矿床中含砷矿物的共生组合特点及热力学资料,探讨了卡林型金矿床形成的温度、成矿流体的f(O2)、f(S2)变化范围及金以金砷络合物形式迁移的可能性。     

黔西南低温成矿域中不同层位不同类型金矿的内在统一成矿机制探讨

黔西南地区是扬子地台西南缘重要且极有远景的低温成矿域,以发育金矿为主。其低温是因为该区岩浆岩露头极少,相对远离直接的岩浆作用。矿体均赋存于地层中,具多时代多层位赋矿特征,成矿温度低于300℃,矿体受深大断裂控制明显,矿床类型以卡林型金矿为主,次有凝灰岩型金矿。但是,两类矿床的原生矿石性质一致,而且成矿时代是基本一致的,二者只是赋矿层位不同而已。据此研究表明,该区不同层位、不同类型金矿是受深大断裂和深源流体统一制约,并伴随深源流体改造地壳岩石而发生多期多源叠加成矿的产物。     

卡林型金矿自然重砂特征及其找矿意义——以黔西南地区为例

黔西南地区是中国西南低温成矿域中卡林型金矿最重要的矿化集中区,由于该地区金的粒径极小,难以构成自然重砂异常,故不能直接运用自然金矿物来指示寻找黔西南的卡林型金矿。在贵州省矿产资源潜力评价项目的工作过程中,对黔西南地区的自然重砂矿物特征进行了较为系统的研究,发现采用细粒黄铁矿(载金矿物)、砷矿物(伴生矿物)、锑矿物和汞矿物的自然重砂组(综)合异常对寻找黔西南地区的卡林型金矿具有一定的指导作用和找矿意义。     

黔西南紫木凼金矿床三维地质建模与成矿分析

为实现黔西南紫木凼金矿床矿体的空间展布并分析成矿过程,利用3DMine建模软件对紫木凼金矿床三维地质模型进行了可视化构建。基于大量剖面和钻孔资料,结合矿床地层、岩性、构造等地质特征及已有成矿物质来源、流体来源等研究结果,通过矿床地质、构造、矿体展布之间的关系,建立了金矿床的空间展布模型,并分析了紫木凼金矿床成矿过程。结果表明：① Au的富集展布和规模受地层与构造影响明显,表现为上部矿体主要沿F₁断层蚀变带产出,品位沿断层蚀变中心向周围递减,下部矿体主要赋存于龙潭组（P₂l）层间破碎带中,背斜轴部矿体品位较高;② Au的富集成矿过程为：含Au热液沿深大断裂上升至龙潭组（₂l）层间破碎带时,因温度、压力等因素导致热液中部分Au顺层沉淀。残余热液继续上升至F₁断层处与其他流体混合并与围岩反应,因流体压力降低、pH值显著增高等因素使Au沿F₁断层蚀变带沉淀;③基于紫木凼金矿床三维地质模型的构建和Au的富集成矿过程分析,归纳为紫木凼金矿床“热液运移-流体混合-断层沉淀”的成矿模式,对探究中国卡林型金矿床成因及成矿预测提供一定参考。     

西秦岭地区金矿类型及其成矿作用

西秦岭地区是中国最重要的金矿矿集区之一,除产出少数夕卡岩型金矿床外,几乎所有的其他金矿床都可归并为造山型、卡林型和类卡林型3种类型。研究表明,西秦岭地区中生代花岗岩主要形成于中晚三叠世,而金矿成矿主要集中在晚三叠世,它们都是华北板块与华南板块碰撞导致的秦岭造山作用的产物。西秦岭地区造山型金矿床主要赋存在泥盆系和石炭系一套复杂的构造变形和区域变质的绿片岩相岩中,主要受北西西向脆韧性剪切带控制,成矿元素组合主要为Au-Ag。矿石中含有大量显微自然金、银金矿,明金可见。成矿流体主要为变质流体。由造山作用引起的强烈构造运动为成矿流体提供了运移通道,为矿质沉淀提供了有利的场所。虽然一些造山型金矿床与中酸性岩体相邻,但矿化与岩浆活动不具直接的成因关系。西秦岭地区卡林型金矿床主要产于轻微变质的寒武系至三叠系沉积岩中,明显受地层、岩性和构造控制。金矿床中的金以超显微金和存在于含砷黄铁矿与毒砂晶格中的固溶体金为主。成矿元素组合为Au-As-Hg-Sb-Ba。成矿流体由早期形成的地层水被后期大气降水补给活化形成,也有部分岩浆水或变质水的加入。在伸展背景下大气降水通过循环演化形成了较浅层次的流体系统,导致Au等成矿元素发生沉淀而形成浸染状矿石。西秦岭地区类卡林型金矿床主要产于浅变质沉积岩建造中,受脆韧性剪切带的控制,并形成于花岗岩岩体附近。与造山型、卡林型金矿床最大的不同之处在于,类卡林型金矿床的形成与同时期的岩浆活动有密切的成因关系。矿石中存在显微自然金,载金矿物主要为黄铁矿、含砷黄铁矿和碲化物。成矿热液主要是岩浆水与变质水、建造水的混合流体。与造山型金矿床类似,流体不混溶导致类卡林型金矿床的形成。     

贵州簸箕田金矿单矿物稀土元素和同位素地球化学特征

簸箕田金矿位于灰家堡背斜东头倾覆端,是灰家堡卡林型金矿田重要的组成部分。金矿床具有低温成矿特征,出现硅化、白云石化、黄铁矿化等围岩蚀变和特征的Au-As-Hg元素组合。成矿期方解石具有MREE富集和正Eu异常特点,显示矿热液是一种MREE相对富集以及具有正Eu异常的还原性流体,来源于深部或至少经历过对富含斜长石源区的水-岩反应。成矿期方解石的δ~(13)C为-6‰～-0.1‰,成矿期后方解石的δ~(13)C为0.2‰～3.2‰,显示成矿期碳来源于地幔碳和地层碳的混合,成矿期后碳主要来自于地层。矿床硫同位素变化于0.73‰～5.86‰,组成均一化较高,具有接近幔源硫的特征,反映了成矿物质可能主要来自于深源岩浆。总之我们推测成矿物质主要来源于深部,在燕山期区域构造作用下沿深大断裂上涌,当成矿流体运移至背斜核部时,由于成矿条件的聚变,金被快速富集沉淀,形成簸箕田金矿床。     

贵州省贞丰县水银洞金矿床地质研究

水银洞金矿作为滇黔桂"金三角"地区发现的全隐伏超大型金矿床,累计查明金资源量260.45 t,矿体埋深在150~1400 m之间,矿床金资源开发利用已有十余年历史,目前矿区仍处于外围和深部勘查阶段.通过对近年来矿床勘查、开发利用和综合研究成果进行总结,系统阐释了矿床地质特征、成矿流体性质、成矿物质来源、矿床成因及控矿因素、成矿机制及成矿模式、找矿标志及找矿模型,丰富了以层控型全隐伏水银洞金矿为代表的黔西南卡林型金矿成矿理论,为实现区内金矿找矿突破提供理论支撑.     

中国贵州与美国内华达卡林型金矿对比及对找矿勘查的指示作用

文章从区域地质及矿床地质等方面对内华达和贵州卡林型金矿进行详细的总结和对比,结果表明两地金矿有很多相似,也有很多差异。主要的相似性包括:两地构造背景演化均经历了早期拉张裂陷、沉积一套被动大陆边缘海相沉积地层、之后造山挤压和晚期拉张;矿体主要受富铁地层和构造控制;与金矿化相关的蚀变作用均有硫化、去碳酸盐岩化、硅化和泥化;金主要以不可见金赋存于含砷黄铁矿中;晚期雄黄、雌黄、辉锑矿、方解石等矿物以脉状充填在开放空间。重要差别体现在:矿床区域分布控制因素;绝大部分贵州金矿矿床范围内未见岩浆岩;贵州金矿特有的白云石化以及相对较弱的去碳酸盐化、硅化(似碧玉岩)和泥化;载金黄铁矿的形貌和微量元素含量;部分贵州金矿含成矿期-成矿晚期毒砂;贵州有大量晚期石英-(方解石)脉;贵州成矿流体更富集CO_2,且具有更高的温度、压力和pH值。相似性和差异性的鉴定对于卡林型金矿(尤其是贵州卡林型金矿)找矿勘查具有重要指示作用。斜坡相地层是卡林型金矿最好的赋矿层位,卡林型金矿勘查中需要多关注斜坡相地层,尤其是富铁斜坡相地层。近期在贵州玄武岩分布区的区域不整合面(又称"构造蚀变体",即SBT)中,金矿勘查取得重大突破,玄武岩富含铁,是一种潜在的卡林型金矿赋矿岩性。在贵州地区,识别茅口组和龙潭组(或峨眉山玄武岩)之间的SBT及SBT上部的构造高点对于台地相区的区域金矿勘查至关重要。识别切割泥盆纪碳酸盐岩台地的区域同沉积断裂,对于调查矿床的区域分布(尤其是盆地相中金矿的区域分布)非常关键。大量似碧玉岩露头或者石英-方解石脉表明该区发生了大量的水-岩反应,预示周围可能有大规模成矿作用发生。辉锑矿、雄黄、雌黄等成矿晚期矿物多以脉状充填在矿体周围的开放空间,比矿体的分布范围更广,对矿体有很好的指示意义。     

秦岭卡林型金矿床金、砷地球化学探讨

讨论了秦岭卡林型金矿床中Ａｕ 、Ａｓ 的元素地球化学、矿物学特征。在含矿岩系中获得的Ａｕ、Ａｓ 等成矿元素初始含量较高,且主要集中在成岩黄铁矿中。在矿石样品中对含砷硫化物矿物的研究表明,Ａｕ 、Ａｓ 在矿物显微结构中具有强的正相关性。在大量金进入到硫化物结构之前,就已有［ＡｓＳ］３ － 的存在。在含砷硫化物矿物中,金多半以一种带电类型（Ａｕ３ ＋） 存在, 它很可能替代铁位置上的过剩砷, 以固溶体方式沉淀于硫化物矿物中。此时, 黄铁矿构成（Ａｕ３ ＋ ,Ｆｅ２ ＋）（［ＡｓＳ］３ － ［Ｓ２］２ － ）,毒砂构成（Ａｕ３ ＋ ,Ｆｅ２ ＋）（［ＡｓＳ］３ － ［ＡｓＳ］３ －） 。通过电子探针（ＥＭＰ） 和透射电镜（ＴＥＭ） 对秦岭卡林型金矿含砷硫化物矿物中金的赋存状态的研究表明,在金的成矿作用早期阶段, 金主要以固溶体形式优先富集于含砷黄铁矿和毒砂及砷黝铜矿之中,并且认为是以金的氧化和砷的还原的共沉淀方式发生的。在此之后的金成矿作用晚期阶段,由于热液蚀变和结晶作用程度的增高,寄主矿物耐熔性质相对降低,加之金本身的聚集能力,和因过量砷加入而造成的含砷硫化物矿物的晶格缺陷,致使已形成的固溶体金以“出溶”形式发生再分布,赋存于硫化物矿物晶粒     

黔西南泥堡金矿床大型隐伏金矿体地质特征研究

泥堡金矿区Ⅲ号金矿体是近年来发现的受断裂控制的大型隐伏矿体,是泥堡金矿区找矿勘探工作的重大突破。该矿体受F1断层控制,其容矿岩石为蚀变沉凝灰岩。蚀变沉凝灰岩普遍发育粘土化、碳酸盐化,而与金矿化密切关联的蚀变类型为黄铁矿化、硅化,次为毒砂化。对泥堡金矿床产出特征进行分析发现,Ⅲ号矿体明显受构造（F1断层）、地层（P3l2）和岩性（蚀变沉凝灰岩）控制。结合矿床赋矿岩石、矿物组合和控矿因素分析,认为泥堡金矿的形成与晚二叠世沉积火山凝灰质密切相关,F1断层活动及燕山期热水（液）作用是Ⅲ号金矿体成矿的关键。通过对比分析,认为区域上车榔—泥堡—三道沟—潘家庄一线是寻找类似金矿体（断控型）的重要区域,龙潭组二段及蚀变沉凝灰岩是重要的找矿标志。     

A study on the genetic relations between Permian Longtan Formation coal series strata and Carlin-type gold deposits,southwestern Guizhou Province,China

A large number of the Carlin-type gold deposits occur in the Longtan Formation in southwestern Guizhou Province. The Longtan Formation contains abundant basalt, tuff and siliceous rocks. All rocks of the Long-tan Formation are enriched in gold, which were deposited in a limited platform environment in the transition zone from marine to continental. The process of sedimentation was accompanied by the eruption of Emeishan basalt and hydrothermal deposition controlled by co-sedimentary submarine deep faults in the west, which led to the formation of a peculiar gold-bearing formation with coal series strata. This formation controlled the occurrence of the Carlin-type gold deposits in southwestern Guizhou Province. In response to the remobilization of the Emei mantle plume during the Yanshanian period, As, Au and other ore-forming materials were continuously extracted by deeply circulating waters from the Emeishan basalt and coal seams, thereafter forming ore-forming hydrothermal solutions. When these elements were transported in the coal seams, large amounts of As, Au and other elements were enriched in pyrite within the coal seams, thus forming high-As coal and Carlin-type gold deposits in the Longtan Formation coal series strata.     

中国金矿床时空分布及成矿背景

中国金矿床的时空分布不均一,金矿主要产于稳定陆块边缘或稳定陆块内的活动带,形成了金的矿集区,成矿时代主要以中生代为主,其次为晚古生代及新生代,而早古生代和前寒武纪金矿床则处于相对次要地.从地质构造演化的角度探讨金矿形成的大地构造背景,认为金矿的形成及分布受控于壳幔相互作用及岩石圈不连续。     

南美洲圭亚那地盾北部绿岩带地质特征、典型金矿床及金成矿作用

圭亚那地盾位于南美洲亚马孙克拉通的北部,其北部广泛发育太古宙典型的花岗岩-绿岩带,主要岩石组成为花岗岩、片麻岩和英云闪长岩,古元古代变质超基性-基性火山岩-侵入岩、其他变质火山岩等。由于独特的地质构造位置和复杂的构造演化历史,形成了良好的绿岩型金成矿地质背景,产生了大量的金矿床。通过总结圭亚那地盾北部绿岩带的岩石特征、成岩时代和构造演化历史,对委内瑞拉埃尔卡劳金矿、圭亚那欧迈金矿和苏里南罗瑟贝尔金矿进行典型矿床剖析,系统研究了该区绿岩带型金矿的成矿地质背景、成矿流体及成矿年代学特征,建立了区域绿岩带型金矿成矿模型,并在分析找矿要素的基础上,提出圭亚那地盾北部的金矿找矿方向。     

黔西南卡林型金矿床与古油藏的成因联系:有机岩相学证据

黔西南卡林型金矿床中存在两种类型的有机质,一种为具较低反射率的原地藻类体,散布于金矿石和沉积围岩中,多呈层纹状或条带状平行于层理面产出;另一种为热解沥青/焦沥青,多呈微细粒状产于蚀变及矿化岩石中,尤其是高品位矿石中,与主阶段似碧玉状石英、含砷黄铁矿、毒砂紧密共生或伴生,或呈分散的粒状被主阶段和晚阶段的石英、方解石、雄黄等热液矿物包裹。沥青以含较高的与成矿密切相关的微量元素As(4.90%～7.88%)和S(大多为7.48%～15.24%)区别于原地有机质(不含As,S含量2.72%～7.18%)。金矿石热液矿物中常见气相CH4、气液两相CH4-H2O等烃类流体包裹体。古油藏沥青多见于二叠系生物礁碳酸盐岩的溶洞、孔隙、裂缝等开放空间中,或单独产出,或与热液方解石伴生,沥青多呈镶嵌结构,显示出高热演化程度的特点。岩相学证据显示,金矿床成矿流体是一种富含金属和碳氢化合物的油水不混溶的盆地流体,金与烃类有机质一起活化、迁移,并通过不同的沉淀和捕获机制成矿、成藏。     

Structural features and metallogenesis of the Carlin-type Jinfeng (Lannigou) gold deposit, Guizhou Province, China

Jinfeng, previously known as Lannigou, is the largest Carlin-type gold deposit in the Yunnan–Guizhou–Guangxi region in southwestern China. Gold mineralization in the Jinfeng deposit is almost entirely fault-hosted and structurally controlled, with very little disseminated ore occurring in the adjacent host rocks. The structural elements in the Jinfeng deposit can be subdivided into 3 groups comprising NS-, NW-, and NE-striking faults and folds, with NW-striking structures controlling the overall framework of the deposit. Four tectonic stages have been recorded in the Jinfeng area, i.e., rifting, orogenic compression, lateral transpression, and lithospheric extension. A series of contemporaneous normal faults, such as the N-striking and east-dipping F1 and F7 faults developed along the edges of a carbonate platform during basin rifting (D₂–T₂). These structures provided an initial framework for subsequent basin evolution, and also represent the principal hydrothermal conduits. A gradual change of the compression direction during the orogenic stage (T₃) from E→W to NE→SW, gave rise to the NW-striking structures, including large, tight to overturned folds such as the Huangchanggou synclinorium and associated thrusts such as the F3 fault. The development of these orogenic, predominantly NE-dipping structures, as well as accompanying NE-striking dextral shear and transform faults (such as the F2 fault) along the margin of the Laizishan Dome established the structural pattern of the deposit area. The NW-striking folds were refolded by NE-striking superimposed folds during post-collisional lateral transpression (J₁) and NW–SE directed compression. Oblique stress distribution gave rise to NS-trending compression and EW-trending extension, with dilational zones developing at the intersection of the F2 and the F3 faults east of the Laizishan dome. It is these dextral- and sinistral-normal dilational zones in which gold was precipitated during the main ore-forming event at Jinfeng. Following the main ore stage lithospheric extension occurred during the Yanshan stage (J₂–K) resulting in minor reverse faults that in places cut pre-existing structures. The above four main structural deformation stages mirror the evolution of the Youjiang Basin from inception to basin inversion and post-orogenic collapse and renewed extension. Significant gold metallogenesis at Jinfeng occurred during the transition from collisional compression to extensional tectonics in the early Jurassic, and is focussed into intersections of F2 and F3 and fault splays adjacent to F3. This structurally controlled gold metallogenic model is likely to be applicable to analogous settings elsewhere in the Yunnan–Guizhou–Guangxi triangle area, and has implications for the targeting of Carlin-type gold mineralization in this region.     

Geochemical characteristics and metallogenesis of Carlin-type gold deposits in the Sandu-Danzhai metallogenic zone, Guizhou Province, China

Geochemical studies of the Paiting and Miaolong Carlin-type gold deposits in the Sandu-Danzhai metal-logenic zone,Guizhou Province,have shown that the mineralized-altered rocks show LREE-enrichment patterns,generally displaying negative Eu anomalies(δEu=0.51?0.97) and unobvious negative Ce anomalies(δCe=0.86?0.99).Calcite and fluorite in relation with metallogenesis show MREE-enrichment patterns,generally displaying rather weak negative Eu anomalies(δEu=0.74?0.93) and weak negative Ce(δCe=0.70?0.98) anomalies.The δ13CPDB values of carbon in calcite are-1.61‰?-5.82‰,the δ18OSMOW values of oxygen are 13.97‰?19.24‰,and the δ34SCDT values of sulfur in stibnite are 17.72‰?21.68‰.In regard to δD and δ18O,ore-forming fluids pos-sess the characteristics of metamorphic water.The process of metallogenesis of the Carlin-type gold deposits is con-trolled by the Yanshanian tectonic activities.The Yanshanian movement promoted the migration and mobilization of metamorphic fluids in the extensively developed medium-to high-grade metamorphic rocks in this region,carrying primarily enriched gold and associated elements such as Hg,As,and Sb in the Sinian metamorphosed black shales and Lower Cambrian black shales.The ore-forming fluids found their way into a suitable metallogenic environment along the fault zone,followed by gold precipitation to form gold deposits.     

Metallogenic model and prognosis of the Shuiyindong super-large strata-bound Carlin-type gold deposit,southwestern Guizhou Province,China

The Shuiyindong deposit is one of the largest (more than 100 tonnes of Au) and highest grade (more than 7×10-6-10×10-6), strata-bound Carlin-type gold deposits in southwestern Guizhou Province, China. The deposit is controlled by both structure and favorable lithology. It is situated near the axis of the striking Huijiabao anticline and is hosted in bioclastic limestone of the Permian Longtan Formation. Gold mineralization occurred under low temperature with Th of 220℃± and is closely associated with decarbonation, silicification, sulfidation and dolomitization. The deposit has a characteristic elemental assemblage of Au-As-Hg-Tl. Studies of geochemistry and isotope compositions indicated that the ore-bearing materials and fluids of the gold deposit mainly originated from a plutonic source, and possess a mixing feature with the strata matter during transportation from mantle to crust. Fluid inclusions in vein quartz from the gold deposit are rich in volatile flux, indicating that metallogenic fluid is an overpressured one. The activity and geothermal state of the Earth's crust in the long period of time are favorable for the formation of overpressured fluids in a large area, and extensive structures would drive the fluids into ore-forming system and make gold deposits formed. The complexity of structural movement in the upper crust of southwestern Guizhou Province resulted in complicated gold mineralization. Through metallogenic prognosis and exploration, the proven reserves of the deposit increased by tens of tonnes of Au and the deposit has become a super-large strata-bound Carlin-type gold deposit.     

黔西南泥堡金矿床构造解析及构造控矿作用

泥堡金矿床地处黔西南碳酸盐岩台地相区,赋矿围岩主要为玄武质火山碎屑岩,以断控型矿体为主、层控型矿体为辅,是滇黔桂"金三角"地区典型的卡林型金矿床之一。详细的野外填图和研究表明,构造是其最主要的控矿要素之一。泥堡金矿区构造类型以断层和褶皱为主,构造线以北东向为主,北西向为辅。矿床受区域性的北东东向潘家庄断裂控制,但矿体主要受次一级的断层和褶皱控制,其中枢纽北东东向二龙抢宝背斜与北西向背斜叠加形成的穹窿构造是层控型金矿体的主要构造控制因素;断控型金矿体主要受控于F_1逆断层,逆冲断层+上盘牵引背斜构造是泥堡金矿最典型的构造控矿组合样式。印支期造山挤压奠定了矿区北东东向的总体构造格架,燕山期叠加了北西向构造。F_1虽总体表现为逆断层性质,但在燕山晚期叠加了正滑运动,并形成了张性空间,有利于的成矿流体运移和金沉淀。根据矿床构造控矿规律分析,提出F_1北部的次级断层F_(1-1)及其上盘牵引背斜为金矿有利的找矿靶区,有待今后工程验证。