“勉略宁三角区”碧口岩群地质特征及金矿成矿规律浅析   总被引：1，自引：0，他引：1  

王鹏 《陕西地质》2013,(2):21-26

碧口岩群是“勉略宁三角区”分布最为广泛的一套浅变质海相火山沉积岩系,属岛弧火山沉积岩建造,各地质体之间均为构造带接触.碧口岩群中Au为富集、强分异、强叠加型,具有明显的分段富集、成带分布的规律性.碧口岩群是区内最重要的金矿矿源层,断裂构造带控制金矿体分布.  相似文献   

矿液致裂作用对苗儿山矿田花岗岩型脉状铀矿床多期成矿的制约     

方适宜 《国外铀金地质》2012,(1):9-15,56

运用矿液致裂理论与多种测试技术,详细研究了桂北苗儿山矿田花岗岩型脉状铀矿床矿脉的形态与内部结构,获知成矿时矿液的压力大于围岩的静压力,矿脉由矿液压裂作用形成。在此基础上讨论了矿液致裂对花岗岩型脉状铀矿床多期成矿的控制。  相似文献   

矿田地质学的研究和发展问题     

吕古贤  李秀章  张迎春  郭涛  陈柏林  朱裕生 《地质与勘探》2012,48(6):1143-1150

矿田系矿床密集分布、成矿作用集中发育的地质单元或区域,相当于成矿区划Ⅴ级成矿单元。研究近期提出"矿田地质学为矿田构造学、矿田建造学和矿田成矿学所构成的学科研究领域"的新概念;重点分析矿田地质找矿的基本思路-构造岩相界面是地质找矿的基础,构造地球化学界面是找矿预测的信息,构造物理化学界面是成矿规律的本质。本文近期提出"整装勘查区就是包含一个或几个矿田的成矿地质区段"的论证,为地质找矿突破探讨了新的思路。  相似文献   

西藏甲玛铜多金属矿二长花岗斑岩岩浆-热液过渡特征及成矿意义   总被引：1，自引：0，他引：1  

秦志鹏  多吉  汪雄武  刘鸿飞  周云  彭惠娟 《地球学报》2012,33(4):501-509

以原始地质资料为基础,结合电子探针数据和岩石地球化学分析,从岩石学、岩相学和地球化学的角度分析了甲玛矿区二长花岗斑岩岩浆-热液过渡的特征及成矿作用。甲玛二长花岗斑岩岩浆热液过渡以电气石-钠/钙硅酸盐化、似伟晶细晶岩壳(脉)和具"冰长石"结构特征的钾长石、蠕状石及显微晶洞(或空腔)构造为特征;地球化学上表现为Na、K的反消长和挥发分含量的涨落,并伴随着Cu、Mo、Au等成矿物质从晚期岩浆的逃逸。甲玛二长花岗斑岩的岩浆热液过渡过程可划分为以超临界流体为代表的液相不混溶阶段和超临界流体逃逸为特征的气液分馏阶段。其中前者决定了岩浆晚期的矿质分馏程度,而后者控制了含矿蒸汽和成矿热液流体的形成,进而分别形成浸染状矿化和脉状矿化。  相似文献   

安徽沿江江南晚中生代岩浆-成矿年代学格架   总被引：23，自引：4，他引：23  

陈江峰  喻钢  杨刚  杨胜洪 《安徽地质》2005,15(3):161-169

根据新的较为可靠的同位素地质年代学数据,长江中下游金属成矿带中段（安徽段）的中生代岩浆-成矿作用可大致分为3期：135到145 Ma一期包括铜陵、月山以及江南广大地区的侵入岩和与之有关矿床,也包括江北的属于A型花岗岩带的大龙山石英正长岩.庐枞和宁芜盆地的火山岩形成于127到131 Ma,但赋存于火山岩中的铁矿床中钠长石给出的40Ar-39A,年龄却在122到126 Ma.最年轻的一组年龄为约126到120Ma,包括江南广大地区的花岗岩和宁芜地区的辉长质小侵入体.晚侏罗世以来的突发性岩石圈去根作用以及太平洋板块向西俯冲导致扬子与华北间的岩石圈边界的南北向拉张,都可能引发地幔上涌,并进一步导致地壳熔融和大规模的复杂的岩浆和成矿作用.  相似文献   

论动力热液成矿作用     

宫同伦 《地球科学与环境学报》1989,(4)

本文提出动力热液成矿作用的概念、特点、形成机制和热液矿床的新分类。动力热液作用极为常见,它所形成的矿床具有与其他热液矿床极不相同的特点,突出地表现在:成矿物质均系来自围岩,就地成矿;矿脉形态复杂多样、大小不等,且不生根,其分布仅局限于构造破碎带(形变带)之中,同期的矿脉和脉石脉在断裂带的不同构造岩分带中,其形成温度常不相同;不显围岩蚀变。笔者认为,层控矿床主要是通过各种成因的热液对矿源层或贫矿层的改造而成,对矿源层的改造动力热液是起着主要的作用。  相似文献   

新疆开合构造与成矿特征的有关问题   总被引：16，自引：2，他引：14  

陈哲夫 《地质通报》2004,23(3):214-221

根据新疆的构造与成矿特征,提出新疆开合构造与成矿论观点。即在大地构造上是“开合构造运动论”,在区域成矿上是“开合构造成矿论”。开合构造与成矿是紧密联系、彼此结合、相互渗透、解释互补的统一整体。在总结新疆矿产特征和成矿规律的基础上,对新疆矿产,特别是金(锑)、铜、镍、铅、锌今后寻找大型矿床的主攻类型和主攻地区进行了科学预测,为地质勘查提供了依据。  相似文献   

Sedimentary manganese metallogenesis in response to the evolution of the Earth system   总被引：5，自引：0，他引：5  

Supriya Roy 《Earth》2006,77(4):273-305

The concentration of manganese in solution and its precipitation in inorganic systems are primarily redox-controlled, guided by several Earth processes most of which were tectonically induced. The Early Archean atmosphere-hydrosphere system was extremely O₂-deficient. Thus, the very high mantle heat flux producing superplumes, severe outgassing and high-temperature hydrothermal activity introduced substantial Mn²⁺ in anoxic oceans but prevented its precipitation. During the Late Archean, centered at ca. 2.75 Ga, the introduction of Photosystem II and decrease of the oxygen sinks led to a limited buildup of surface O₂-content locally, initiating modest deposition of manganese in shallow basin-margin oxygenated niches (e.g., deposits in India and Brazil). Rapid burial of organic matter, decline of reduced gases from a progressively oxygenated mantle and a net increase in photosynthetic oxygen marked the Archean-Proterozoic transition. Concurrently, a massive drawdown of atmospheric CO₂ owing to increased weathering rates on the tectonically expanded freeboard of the assembled supercontinents caused Paleoproterozoic glaciations (2.45-2.22 Ga). The spectacular sedimentary manganese deposits (at ca. 2.4 Ga) of Transvaal Supergroup, South Africa, were formed by oxidation of hydrothermally derived Mn²⁺ transferred from a stratified ocean to the continental shelf by transgression. Episodes of increased burial rate of organic matter during ca. 2.4 and 2.06 Ga are correlatable to ocean stratification and further rise of oxygen in the atmosphere. Black shale-hosted Mn carbonate deposits in the Birimian sequence (ca. 2.3-2.0 Ga), West Africa, its equivalents in South America and those in the Francevillian sequence (ca. 2.2-2.1 Ga), Gabon are correlatable to this period. Tectonically forced doming-up, attenuation and substantial increase in freeboard areas prompted increased silicate weathering and atmospheric CO₂ drawdown causing glaciation on the Neoproterozoic Rodinia supercontinent. Tectonic rifting and mantle outgassing led to deglaciation. Dissolved Mn²⁺ and Fe²⁺ concentrated earlier in highly saline stagnant seawater below the ice cover were exported to shallow shelves by transgression during deglaciation. During the Sturtian glacial-interglacial event (ca. 750-700 Ma), interstratified Mn oxide and BIF deposits of Damara sequence, Namibia, was formed. The Varangian (≡ Marinoan; ca. 600 Ma) cryogenic event produced Mn oxide and BIF deposits at Urucum, Jacadigo Group, Brazil. The Datangpo interglacial sequence, South China (Liantuo-Nantuo ≡ Varangian event) contains black shale-hosted Mn carbonate deposits. The Early Paleozoic witnessed several glacioeustatic sea level changes producing small Mn carbonate deposits of Tiantaishan (Early Cambrian) and Taojiang (Mid-Ordovician) in black shale sequences, China, and the major Mn oxide-carbonate deposits of Karadzhal-type, Central Kazakhstan (Late Devonian). The Mesozoic period of intense plate movements and volcanism produced greenhouse climate and stratified oceans. During the Early Jurassic OAE, organic-rich sediments host many Mn carbonate deposits in Europe (e.g., Úrkút, Hungary) in black shale sequences. The Late Jurassic giant Mn Carbonate deposit at Molango, Mexico, was also genetically related to sea level change. Mn carbonates were always derived from Mn oxyhydroxides during early diagenesis. Large Mn oxide deposits of Cretaceous age at Groote Eylandt, Australia and Imini-Tasdremt, Morocco, were also formed during transgression-regression in greenhouse climate. The Early Oligocene giant Mn oxide-carbonate deposit of Chiatura (Georgia) and Nikopol (Ukraine) were developed in a similar situation. Thereafter, manganese sedimentation was entirely shifted to the deep seafloor and since ca. 15 Ma B.P. was climatically controlled (glaciation-deglaciation) assisted by oxygenated polar bottom currents (AABW, NADW). The changes in climate and the sea level were mainly tectonically forced.  相似文献   

Sanjiang Tethyan metallogenesis in S.W. China: Tectonic setting, metallogenic epochs and deposit types   总被引：21，自引：6，他引：21  

Zengqian Hou  Khin Zaw  Guitang Pan  Xuanxue Mo  Qiang Xu  Yunzhong Hu  Xingzhen Li 《Ore Geology Reviews》2007,31(1-4):48-87

Tectonically, the Sanjiang Tethyan Metallogenic Domain (STMD) is located within the eastern Himalayan–Tibetan Orogen in the Sanjiang Tethys, southwestern China. Although this metallogenic domain was initiated in the Early Palaeozoic, extensive metallogenesis occurred in the Late Palaeozoic, Late Triassic and Himalayan (Tertiary) epochs. Corresponding tectonic settings and environments in the domain are: an arc-basin system related to the subduction of the Palaeo-Tethyan oceanic slabs; a post-collision crustal extension setting caused by the lithospheric delamination or slab breakoff underneath the Sanjiang Tethys during the Late Triassic; large-scale strike-slip faulting and thrusting systems due to the Indo-Asian continent collision since the Palaeocene. In this metallogenic domain important gold, copper, base metals, rare metals and tin ore belts, incorporating a large number of giant deposits, were developed. The main types of deposits include: (1) porphyry copper deposits, controlled by a large-scale strike-slip fault system, (2) VHMS deposits, mainly occurring in intra-arc rift basins and post-collision crustal extensional basins, (3) shear-zone type gold deposits in the ophiolitic mélange zone along the thrusting–shearing system, (4) hydrothermal silver-polymetallic deposits in the Triassic intra-continental rift basins and Tertiary strike-slip pull-apart basins, and (5) Himalayan granite-related greisen-type tin and rare-metallic deposits. Within the metallogenic epochs of the Late Palaeozoic to Cenozoic, the styles and types of the ore deposits changed from VHMS types in the Late Palaeozoic through exhalative-sedimentary type deposits in the Late Triassic, to porphyry-type copper deposits, shear-zone type gold deposits, hydrothermal vein-type silver-polymetallic deposits, greisen-type tin and rare-metal deposits in the Cenozoic. Correspondingly, ore-forming metals also changed from a Pb–Zn–Cu–Ag association through Ag–Cu–Pb–Zn, Fe–Ag–Pb and Ag–Au–Hg associations, to Ag–Cu–Pb–Zn, Cu–Mo, Au, Sn, and Li–Rb–Cs–Nb–Zr–Hf–Y–Ce–Sc associations.  相似文献   

新疆准噶尔盆地哈图金矿成矿流体的某些物理化学特征及与成矿关系   总被引：5，自引：0，他引：5  

王莉娟  王玉往 《地质与勘探》2005,41(6):21-26

哈图金矿是位于准噶尔盆地西缘的大型石英脉型金矿床.石英及黄铁矿矿物及矿物包裹体稀土元素、微量元素及爆裂温度等研究表明,哈图金矿的主要矿化类型-石英脉型矿体与蚀变岩型矿体是不同来源的流体叠加成矿,而不是同一种成矿流体在不同温度下矿质沉淀产物.石英脉型矿体主要与花岗岩浆热液关系密切,蚀变岩型矿体主要与深源流体有关,在矿体浅部它们强烈的挤压复合部位形成明金富矿体石英脉.石英脉型矿体石英的爆裂曲线出现α-β转变峰,这种转变峰的强度从上向下增强, 反映了流体初始温度较高,应与侵入岩浆热液有关,向矿体浅部,由于大量的循环天水的加入及远离了岩浆源,使成矿流体温度降低,石英的爆裂曲线没有α-β转变峰.大量天水的加入,使流体温度降低的同时,金也大量析出、富集形成含明金富矿体.蚀变岩型矿体石英爆裂曲线不出现α-β转变峰,反映其形成温度低于石英转变峰的温度,应与侵入岩浆无明显密切关系.  相似文献