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91.
根据秦岭地区金矿床中黄铁矿特征,总结出典型的微细浸染型和含金石英脉型两种类型矿床特征。黄铁矿与金矿关系密切,含金黄铁矿多产于成矿的富集地段。通过对该区黄铁矿标型特征(晶形、粒级与热电性和微量元素)的系统研究,认为黄铁矿标型特征的研究,对深部找金矿与远景评价具有指导意义。 相似文献
92.
红岩黄铁矿床是产于广东英德盆地中泥盆统东岗岭碳酸盐地层中的一个层控矿床。作者经详细研究之后,认为在含矿地层沉积时就存在着一个古水下隆起,由于古水下隆起控制了古地形,因而表现出不同的沉积作用。在矿区的中部东岗岭组较薄,主要为潮坪一泻湖相,而矿区的东、西部东岗岭组沉积较厚,表现为礁滩相。黄铁矿在东岗岭组沉积期和成岩早期沉积并再富集。 在东岗岭组成岩的晚期发生白云岩化作用。来自下伏地层砂岩、泥岩的富含Mg、Fe的水与孔隙水以及地下淡水发生混合引起了灰岩的白云岩化,以及矿源层中成矿元素的活化,并与来自砂岩和泥岩中的成矿物质叠加在一起。在白云岩中,特别是在古水下隆起之上经白云岩化之后,含矿溶液经过充填和交代作用而形成红岩矿床。显微镜研究,微量元素分析,硫、铅、氧、碳同位素研究的结果都支持这一成岩成矿模式。 相似文献
93.
川南煤系硫铁矿矿山地质环境现状分析 总被引:1,自引:0,他引:1
着重分析当前川南煤系硫铁矿的矿山地质环境现状,以及硫铁矿山普遍存在的一些地质环境问题,旨在引起社会各方面对矿山地质环境保护的重视。 相似文献
94.
宁芜云台山黄铁矿矿床中黄铁矿矿物以自形晶为主 ,次为他形粒状 ;黄铁矿晶胞参数为 5 .415 2 3~ 5 .41843× 10 -10 m ,晶体化学式为 (Fe0 .9968Co0 .0 0 0 6Ni0 .0 0 2 6) 1.0 0 0 0 S2 .0 597;黄铁矿红外吸收光谱主吸收峰值为 34 8cm-1,最小透过率为 30 .0 0 %~ 48.80 % ,透过率极差为 31.13~ 47.5 1;黄铁矿中Fe平均含量为 45 .44 % ,S平均含量 5 3.91% ,具有富S特征 ;Co/Ni平均值为 0 .2 1;稀土元素总量平均为2 1.84× 10 -6,具有明显负铈异常 (δCe :0 .76~ 0 .93)和负铕异常 (δEu :0 .72~ 0 .90 ) ;硫同位素组成δ3 4S为 7.0 0‰~ 2 3.0 0‰ ,黄铁矿是含矿热液以堆积、充填和交代方式形成 ,黄铁矿床为火山热水沉积矿床。 相似文献
95.
Alfons M. van den Kerkhof Geoffrey H. Grantham 《Contributions to Mineralogy and Petrology》1999,137(1-2):115-132
In the Port Edward area of southern Kwa-Zulu Natal, South Africa, charnockitic aureoles up to 10 m in width in the normally
garnetiferous Nicholson's Point Granite, are developed adjacent to intrusive contacts with the Port Edward Enderbite and anhydrous
pegmatitic veins. Mineralogical differences between the country rock and charnockitic aureole suggest that the dehydration
reaction Bt + Qtz → Opx + Kfs + H2O and the reaction of Grt + Qtz → Opx + Pl were responsible for the charnockitization. The compositions of fluid inclusions
show systematic variation with: (1) the Port Edward Enderbite being dominated by CO2 and N2 fluid inclusions; (2) the non-charnockitized granite by saline aqueous inclusions with 18–23 EqWt% NaCl; (3) the charnockitic
aureoles by low-salinity and pure water inclusions (<7 EqWt% NaCl); (4) the pegmatites by aqueous inclusions of various salinity
with minor CO2. As a result of the thermal event the homogenization temperatures of the inclusions in charnockite show a much larger range
(up to 390 °C) compared to the fluid inclusions in granite (mostly <250 °C). Contrary to fluid-controlled charnockitization
(brines, CO2) which may have taken place along shear zones away from the intrusive body, the present “proximal” charnockitized granite
formed directly at the contact with enderbite. The inclusions indicate contact metamorphism induced by the intrusion of “dry”
enderbitic magma into “wet” granite resulting in local dehydration. This was confirmed by cathodoluminescence microscopy showing
textures indicative for the local reduction of structural water in the charnockite quartz. Two-pyroxene thermometry on the
Port Edward Enderbite suggests intrusion at temperatures of ∼1000–1050 °C into country rock with temperature of <700 °C. The
temperature of aureole formation must have been between ∼700 °C (breakdown of pyrite to form pyrrhotite) and ∼1000 °C. Charnockitization
was probably controlled largely by heat related to anhydrous intrusions causing dehydration reactions and resulting in the
release and subsequent trapping of dehydration fluids. The salinity of the metamorphic fluid in the contact zones is supposed
to have been higher at an early stage of contact metamorphism, but it has lost its salt content by K-metasomatic reactions
and/or the preferential migration of the saline fluids out of the contact zones towards the enderbite. The low water activity
inhibited the localized melting of the granite. Mineral thermobarometry suggests that after charnockite aureole genesis, an
isobaric cooling path was followed during which reequilibration of most of the aqueous inclusions occurred.
Received: 8 November 1998 / Accepted: 21 June 1999 相似文献
96.
97.
Spheroidal weathering of granite porphyry with well‐developed columnar joints by oxidation,iron precipitation,and rindlet exfoliation 下载免费PDF全文
Spheroidal weathering, one of the important rock weathering styles, has been attributed to chemical weathering by the water from joint surfaces, and mechanical aspects of the weathering have not been well addressed. We made an investigation on spheroidal weathering of Miocene granite porphyry with well‐developed columnar joints and found that this spheroidal weathering proceeds through chemical processes and accompanying mechanical processes. The investigation of the textures, physical properties, mineralogy, and chemistry of the porphyry revealed the presence of a brown band on the surface margins of corestones, representing the oxidation of pyrite and chlorite, and the precipitation of iron hydroxides, and the consequent generation of micro‐cracks within the band. During weathering, oxidation progresses inwards from joints that surround the rindlets, including both high‐angle columnar and low‐angle planar joints, and causes rounding of the unweathered interior portion of the rock. Microscopic observations of the brown band embedded with fluorescent resin show that pores are first filled with iron hydroxides, and that micro‐cracks then form parallel to the oxidation front in the outer portion of the brown band. Iron hydroxide precipitation increases the P‐wave velocity in the brown band, while micro‐crack formation decreases the tensile strength of the rock. Where the brown band has thickened to ~6 cm, the micro‐cracks are connected to one another to create continuous cracks, which separate the rindlets from the corestone. Micro‐crack formation parallel to the corestone surface may be attributed to compressive stresses generated by small amounts of volumetric expansion due to the precipitation of iron hydroxides in the brown band. Earth surface is under oxidizing environments so that precipitation of iron hydroxides commonly occurs; the spheroidal weathering in this paper is a typical example of the combination of chemical and mechanical processes under such environments. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
98.
黄陵断穹核部石墨矿是我国鳞片(晶质)石墨矿的主要产区,对该区石墨矿的研究具有重要理论和实际意义。该区已有石墨矿研究成果多侧重于矿床地质方面,对矿床成因分析缺乏地球化学支撑。为此,本文从地球化学层面查明石墨矿原岩类型,碳质富集岩相、变质作用和晶质石墨的形成,为矿床成因和成矿作用提供地球化学依据。通过系统采集区内主要石墨矿样品,进行主量元素、微量元素、稀土元素和同位素分析,根据矿床地球化学原理和分析方法,阐明石墨矿的物质来源,成矿元素集散行为和矿床形成机制。根据主量元素含量和组合,推断石墨的原岩为碳质粉砂质泥岩。微量元素的双重性指示石墨矿的物质有两个来源:中太古代野马洞岩组和中太古代东冲河片麻杂岩。独特的稀土元素配分型式说明物源转化为原岩时存在着强烈的地球化学反应。石墨矿的碳同位素组成支持碳质来自有机物的观点。 相似文献
99.
南海北部西沙海槽S1站位的岩心柱沉积物中广泛发育自生矿物黄铁矿,其形态以管状为主,且具有内部中空的圈层结构。使用扫描电镜、电子探针、LA-ICP-MS、SIMS等测试方法研究了管状黄铁矿的形态及圈层结构,结果显示: (1)管状黄铁矿发育内部中空的圈层结构,其中内圈层(Ipy)由莓球状黄铁矿呈五角十二面体紧密堆积组成,外圈层(Opy)由晶形较好晶粒较大的八面体黄铁矿组成,并混有沉积碎屑及钙质生物壳体;(2)内圈层和外圈层分别呈现出贫S富Fe和富S贫Fe的特征,其成因是甲烷渗漏造成的局部还原环境使得As进入黄铁矿中导致晶格空缺或被扭曲,从而促进Ni、Co、Cu、Zn、Pb等微量元素的掺入;(3)内圈层、外圈层发生了明显的硫同位素分馏现象,内圈层中 δ34S 平均为-37.8‰,外圈层中 δ34S 平均为-29.3‰。研究认为,管状黄铁矿作为曾经甲烷渗漏的通道,其生长机制可分为3个阶段: (1)气水通道形成阶段: 向上运移的甲烷流体在沉积物孔隙中逐渐形成气水通道;(2)外圈层形成阶段: 当向上运移的甲烷与硫酸盐发生甲烷厌氧氧化时,逐渐形成晶体较大、晶形较好的八面体黄铁矿外圈层;(3)内圈层形成阶段: 随着甲烷浓度逐渐降低,在气水通道中的微生物作用下,剩余甲烷与向下运移的硫酸盐继续反应形成莓球状黄铁矿内圈层。因此,南海北部的泥岩中大量发育的管状黄铁矿常常与地层中甲烷水合物的存在有关。 相似文献
100.
狮吼山矿区是江西省内规模最大的矽卡岩型硫铁多金属矿床,伴生W、Cu、Au多种成矿元素,成矿作用与矿区出露的茶山迳复式花岗岩体有关。岩体主要包括茶山迳似斑状黑云母二长花岗岩和莲湖细粒二长花岗岩两期,为研究成矿岩体的侵位时代、岩石成因及与成矿的关系,本次工作进行了U-Pb锆石定年、岩相学和岩石地球化学等测试分析。结果表明:岩体具有高硅、高钾、富铝的特征,属高钾钙碱性系列花岗岩;轻重稀土元素分馏明显,均为右倾型,弱Eu负异常,以富集Cs、Rb、Th、U、Pb,亏损Ba、Nb、Sr、和Ti等元素为主要特征,属于低Ba-Sr壳源花岗岩类;锆石具较好晶形,具典型岩浆锆石特征,利用LA-ICP-MS进行U-Pb测年,获得谐和年龄为(162.4±0.6)Ma(MSWD=1.8),加权平均年龄为(162.4±1.4)Ma(MSWD=1.4),谐和年龄与加权平均年龄在误差范围内高度一致,表明茶山迳复式岩体侵位于燕山早期中侏罗世;综合考虑岩体矿物组合、主微量元素及高分异特征,认为其成因分类应属于S型花岗岩;对比中国花岗岩成矿元素平均含量,茶山迳两期花岗岩均具有较高的W、Mo、Bi、Pb等成矿元素含量,可同时为成矿作用提供热源、流体及物质。 相似文献