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1.
火山侵蚀和塌陷——以侵入体为中心的矿床叠生的成因 总被引:1,自引:0,他引:1
叠生作用是早期深部斑岩型矿化与晚期浅部贵金属和贱金属低温热液型矿化并置和叠覆的过程,叠生作用被认为是由于火山机制在洪积条件下受到迅速侵蚀或扇形(及不太可能的在皮火山口)塌陷引起的火山古地表同热液剥蚀造成的,在热液系统1Ma的时间间隔内,古地表可下降1km,使所含各类矿床至少在7km的垂向范围内密集,由同矿化侵入作用造成的火山膨胀可以引发扇形塌陷,而火山机构的水热活动减弱使塌陷更容易。扇形塌陷引起大 相似文献
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火山-深成带金银矿床划分出5种成因类型:次火山的,火山-深成的(深-火山的)、酸性-硫质喷气的(近地表的),再生的和火山成因-沉积的,每一种类型都以其特殊的成矿控制构造,岩石的其他含矿物质,热液-交代改造的火山建造组合为特征,提出的方法扩大了预测火山-深成带矿床的可能性。 相似文献
3.
银山多金属矿床是一个特大型火山—潜火山热液矿床,具有复杂的多期多阶段的成矿作用和有序的成矿分带。成矿作用主要为火山—潜火山热液作用,但在此之前,还经历了一期由韧脆性剪切带形成而引起的动力变质热液作用。根据矿体与3个旋回潜火山岩体的时空关系,火山—潜火山热液成矿作用又可分为两个成矿期和5个成矿阶段。矿床地质地球化学研究表明成矿作用在空间上具有定向迁移的特点,结合流体动力学计算机数值模拟认为定向迁移的根本原因是构造岩浆脉动和隐伏岩体形态产状。笔者认为,矿区深部可能有隐伏岩体,但对隐伏的斑岩铜矿床不应抱很大希望 相似文献
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綦占胜 《吉林大学学报(地球科学版)》1988,(3)
吉林省中生代火山活动受北东向岩石圈深大断裂构造的控制。火山—次火山的热液成矿作用与它的物质成分和岩相有关,受火山构造的控制。区内多数矿床、矿点产于中生代火山岩盆地的边缘,构成以火山岩盆地为中心的矿化集中区。吉林省南部和北部地区一样,是寻找中生代陆相火山一次火山热液金、铜等矿产的有利地区。 相似文献
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民乐铜矿产于中三叠统钙碱性、碱性系列火山碎屑岩、熔岩、次火山岩(英安斑岩)中。矿床形成与陆相火山活动及其后的火山热液、英安斑岩体侵入有关,明显受火山岩岩性、岩相、层位及构造控制。成因上与火山喷发、英安斑岩体侵入作用有关,具有斑岩铜矿的一些特征。矿床受后期火山热液,次生富集叠加改造明显。 相似文献
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新疆东天山斑岩铜矿带的新进展 总被引:48,自引:9,他引:48
新疆东天山发现超大型斑岩铜矿床及矿带,预计3-5年内铜金属资源量有望超过千万吨,将形成一个远景巨大的铜矿带,该矿带的成矿地质背景为泥盆纪火山岛弧(390Ma左右),岩浆-热液演化是高氧化(fo2=10^-20-10^-8)控制之下的,高位斑岩体形成时代为360Ma,辉钼矿形成时代为322Ma,闪长玢岩经研究后属于一套从钙套性-碱性的玄武质过渡到英安质的火山杂岩,成矿9兴度推测达4-6km,大约与多宝山相当,故大部分矿化体产于围岩中,土屋,延东和灵龙等矿床类型属于斑岩型的地质证据占优,这些矿床也有后期叠加的热液蚀变和矿化。 相似文献
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通过区域地质调查,认为丰宁满族自治县双井子南西一带的晚侏罗世张家口期火山-侵入活动、同熔型岩浆作用、火山通道及火山断裂与银、铅(锌)矿化关系密切。在整体的火山-侵入活动过程中,先期的火山活动可使成矿物质初步富集,后期的岩浆侵入作用封闭性好,热量充足,可使成矿物质进一步叠加富集成矿。同熔型岩浆作用形成的石英正长斑岩是成矿物质的主要提供者,岩石中Ag、Pb、Zn等成矿元素的丰度值普遍较高,约为世界同类岩石平均值的4~10倍,呈强富集状态。火山通道深达上地幔,有利于岩浆向上运移及深部含矿热液的上升环流,是良好的导岩导矿构造。火山周边断裂规模相对较大,其内多形成构造角砾岩带,是成矿物质沉淀、富集的理想场所和最有利的容矿构造。放射状断裂是沟通火山通道和火山周边断裂并使含矿热液从火山通道向火山周边断裂运移的重要渠道,起到配矿构造的作用。 相似文献
10.
江西银山金铜多金属矿床构造动力热液与火山岩浆热液双重藕合成矿作用 总被引:1,自引:0,他引:1
该文根据江西银山金铜多金属矿床特征及与邻区矿床的对比,论证了构造动力热液成矿作用在银山矿床形成过程中的意义;提出了矿区火山岩浆热液成矿作用的新认识,即:火山岩浆热液成矿与石英斑岩岩浆演化阶段关系更为密切,矿化与深部大斑岩体有关,形成内带斑岩型Au、Cu矿,外带脉型Au,Cu,Pb,Zn,Ag矿的成矿系列。根据两种成矿作用之间相互时空关系,作者认为银山矿床是构造动力热液与火山乐热液双重藕合成矿的产物 相似文献
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The magma–ore deposit relationship of most low-sulfidation epithermal ore deposits is still unclear, partly because many stable isotopic studies of such deposits have indicated the predominance of meteoric waters within hydrothermal fluids. However, it is certainly true that hydrothermal systems are ultimately driven by magmatic intrusions, and epithermal gold deposits might therefore be produced by magmatic activity even in deposits having has no obvious links to a magma. We re-examine the genesis of two typical low-sulfidation epithermal gold deposits, the Kushikino and Hishikari deposits, using structural simulations and isotope data.Many epithermal gold deposits including the Kushikino and Hishikari deposits have been discovered in Kyushu, southwestern Japan. The Kushikino deposit comprises fissure-filling veins within Neogene andesitic volcanics that overlie unconformably Cretaceous sedimentary basement. The veins consist of gold- and silver-bearing quartz and calcite with minor amounts of adularia, sericite and sulfides. Although carbon and oxygen isotopic data for the veins indicate a meteoric origin of the ore fluid, finite element simulations suggest that the vein system might have formed in direct response to magma intrusion. In particular, geophysical data suggest that intruding magma has uplifted the basement rocks, thereby producing fractures and veins and a positive Bouguer anomaly, and providing the heat necessary to drive an ore-forming hydrothermal system.The second component of this study has been to investigate the nature and evolution of the Kushikino and Hishikari epithermal systems. Isotope data document the geochemical evolution of the hydrothermal fluids. We conclude that the existence of sedimentary basement rocks at depth might have affected the strontium and carbon isotopic ratios of the Kushikino and Hishikari ore fluids. The 87Sr/86Sr ratios and δ13C–δ18O trend reveal that major ore veins in the Hishikari deposit can be distinguished from shallow barren veins. It was suggested isotopically that fluids responsible for the barren veins in nearby shallow and barren circulation systems were only controlled by the shallow host rocks. Such multi-isotope systematics provide a powerful tool with which to determine the center of hydrothermal activity and thereby document the evolution of hydrothermal fluids. 相似文献
13.
Epithermal Gold Mineralization in Chinese Tianshan Province 总被引:1,自引:0,他引:1
Xiao Long Wang Fangzheng Department of Science Technology China University of Geosciences Wuhan 《中国地质大学学报(英文版)》2000,11(4)
INTRODUCTIONTheTianshanrange ,locatedwithintheXinjiangUygurAutonomousRegionofNorthwestChina ,extendsforabout2 5 0 0kminanE Wdirectionandhasawidthof 5 0 0km .AsoneofthemajorPaleozoicorogensintheworld ,Tianshanhasagreatpotentialforgoldmineralizationwithmineralizi… 相似文献
14.
论新疆东准噶尔陆相火山成矿作用 总被引:6,自引:0,他引:6
刘家远 《大地构造与成矿学》2001,25(4):434-438
早石炭世晚期至早二叠世时期,东准噶尔地区陆相火山作用广为发育。近年来的研究证明,这一时期的陆相火山作用形成了两套重要的成矿岩浆建造,即安山-英安质喷溢、喷发岩建造和中性-中酸性潜火山杂岩建造,它们具有同一的成矿专属性,与金、铜、铁成矿密切相关。前者主要形成特征的浅成低温热液陆相火山岩型金矿。后者与金、铜成矿关系极为密切,其突出特征表现为受同-成矿岩浆作用的制约,在不同的外部条件下,形成不同类型的多种矿床,分别构成自成体系的金矿床系列和铜矿床系列,充分揭示了东准噶尔与陆相火山作用有关金、铜成矿的广阔前景和深远意义。 相似文献
15.
从"景"、"场"、"相"、"床"4个等级体制观点出发,阐述了该金属成矿省成矿内部组成,观点新颖。金矿赋存于中新世-更新世马林丹群火山岩中,该群火山岩呈零星岛状散布于斯丹岗-哥塔巴托-大姑玛线性构造活动带(SCDL)的东部,并受到后期安山玢岩的侵入。安山玢岩具有埃达克岩性质,它的侵入对于后期的围岩蚀变和成矿作用起到重要的控制作用。拉拉布矿床的安山岩具有明显的热液蚀变,属于冰长石-绢云母型金矿化,认为金是在PH值近中性的浅表环境中由于热液沸腾并伴随流体的混合沉淀而成,通常富集于标高30~200m之间。围岩蚀变强度大,并有明显的分带规律,制约着金矿的形成。金的富集与下列地质事件相关:(1)形成角砾岩之前的围岩蚀变作用;(2)热液角砾岩的形成;(3)形成角砾岩后的围岩蚀变作用;(4)金矿形成。 相似文献
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Mineral assemblages formed during hydrothermal alteration reflect the geochemical composition
of ore-forming fluids. Gold is mainly transported in solution as AueCl and AueS complexes. The
change of physicochemical conditions such as temperature, pressure, oxygen fugacity, and sulfur fugacity
are effective mechanisms for gold precipitation. Gold tends to be concentrated in the vapor phase of fluids
at high temperatures and pressures. AueAs and AueSb associations are common in gold deposit. Native
antimony and/or arsenic e native gold assemblages may precipitate from hydrothermal fluids with low
sulfur fugacity. Hydrothermal fluids forming epithermal gold deposits are Au-saturated in most cases,
whereas fluids of Carlin-type are Au-undersaturated. Quasi-steady As-bearing pyrite extracts solid solution
Au from hydrothermal fluids through absorption. The capability of As-bearing pyrite to absorb Au
from under-saturated fluid is the key to the formation of large-scale Carlin-type deposits. With increasing
new data, studies on the geochemistry of gold deposits can be used to trace the origin of ore-forming
fluids, the source of gold, and the transporting form of Au and other ore-forming elements, such as Si,
S, F, Cl, As and Ag. 相似文献
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浅成低温热液型金矿床研究最新进展 总被引:23,自引:0,他引:23
浅成低温热液型金矿床是目前世界上最为重要的金矿床类型之一 ,也是当前国际矿床学界研究的热点之一。近年来对该类型矿床的深入研究 ,包括对该类矿床的进一步分类、流体形成演化、成矿时代、与碱性岩之间的关系 ,以及与斑岩型及其他类型矿床之间的内在联系等方面均取得了重要进展。研究表明 ,高硫化型与低硫化型金矿床不仅在矿物组合上具有显著差别 ,而且在形成的构造背景、成矿机理等方面也明显不同。高硫化型矿床主要形成于挤压应力场环境和流体混合导致成矿物质沉淀 ,而低硫化型矿床主要产于张性或中性环境下由于流体的沸腾使得矿体形成。浅成低温热液型金矿床的形成时间受其所处大地构造环境演化的控制。与浅成低温热液型金矿床有关的碱性岩通常具有相似的地球化学特征 ,即碱性岩具有异常高的氧逸度和富含挥发份。由于发现大量的浅成低温热液型金矿床与斑岩型矿床之间密切伴生 ,它们之间的内在关系正在引起越来越多矿床学家的重视 ,对其形成机理的研究还有待于进一步深入 相似文献
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中国东部中生代浅成热液金矿的类型、特征及其地球动力学背景 总被引:35,自引:0,他引:35
中国东部中生代浅成热液金矿可以划分为与花岗岩和与碱性岩有关的两种类型;也可以分为高硫型和低硫型两大类,而且以后一种为主。这些金矿的形成和分布受区域构造制约,具体地说是受破火山口、火山角砾岩筒以及与火山机构有关的断裂控制。成矿围岩为火山岩类及同源花岗质岩石和周围地层。主要的蚀变组合为冰长石一玉髓一绢云母或明矾石一高岭石一石英(玉髓)。成矿年龄分布在180~188Ma,135~144Ma,127~115Ma和94~105Ma四个区间,前三组年龄分别响应于中生代华北板块与扬子克拉通的造山碰撞后陆内造山的伸展过程、构造体制大转折以及岩石圈大减薄,后一组为华南地区岩石圈再一次强烈伸展期间的产物。虽然这些矿床的形成时间有差异,但都是发育于大陆伸展环境中。 相似文献
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《International Geology Review》2012,54(3):287-310
The continental margin of Northeast China, an important part of the continental margin-related West Pacific metallogenic belt, hosts numerous types of gold-dominated mineral deposits. Based on ore deposit geology and isotopic dating, we have classified hydrothermal gold–copper ore deposits in this region into four distinct types: (1) gold-rich porphyry copper deposits, (2) gold-rich porphyry-like copper deposits, (3) medium-sulphidation epithermal copper–gold deposits, and (4) high-sulphidation epithermal gold deposits. These ore deposits formed during four distinct metallogenic stages or periods, at 123.6 ± 2.5 Ma, 110–104 Ma, 104–102 Ma, and 95.0 ± 2 Ma, corresponding to periods of Cretaceous intermediate–acid volcanism and late-stage emplacement of hypabyssal magmas along the northern margin of the North China platform. The earliest stage of mineralization (123.6 ± 2.5 Ma) corresponds to the formation of medium-sulphidation epithermal copper – gold deposits and was associated with a continental margin magmatic arc system linked to subduction of the Pacific Plate beneath the Eurasia. This metallogenesis is closely related to high-K calc-alkaline intermediate–acid granite and pyroxene – diorite porphyry magmatism. The second and third stages of mineralization in the study area (110–104 Ma and 104–102 Ma, respectively) correspond to the formation of gold-rich porphyry copper, porphyry-like copper, and high-sulphidation gold deposits, with metallogenesis closely related to sodic or adakitic magmatism. These magmas formed in a continental margin magmatic arc system related to oblique subduction of the Pacific Plate beneath the Eurasia, as well as mixing of crust-derived remelted granitic and mantle-derived adakitic magmas. During the final stage of mineralization (95.0 ± 2 Ma), metallogenesis was closely related to sodic or adakitic magmatism, with diagenesis and metallogenesis related to the disintegration or destruction of the Pacific Plate, which was subducted beneath the Eurasian Plate during the Mesozoic. 相似文献