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1.
川南普格杏仁状玄武岩中普遍产出沥青和铜矿物。沥青主要产于玄武岩气孔、晶洞和裂隙中,少量产于水晶晶体的锥状体部位。铜矿物主要有自然铜、赤铜矿、黑铜矿、硅孔雀石和孔雀石等。自然铜可形成完整晶体,分布于水晶菱面体的锥体顶部,也可呈它形粒状或片状,分布于杏仁体、脉状体沥青的裂隙中和铜球粒核部;赤铜矿主要与板状自然铜一起分布于石英或玉髓脉的裂隙中;黑铜矿常与自然铜一起产出于裂隙或铜球粒中;硅孔雀石呈脉状、浸染状、网状分布在沥青中及其裂隙中,部分硅孔雀石呈皮壳状赋存在自然铜、水晶晶体表面和铜球粒表面;而孔雀石主要分布于铜球粒的最外圈。沥青与铜矿物形成次序为:沥青→自然铜→赤铜矿→黑铜矿→硅孔雀石→孔雀石。沥青和自然铜形成于水晶结晶作用晚期,自然铜形成于沥青之后。碳同位素研究显示沥青为生物成因,可能来源于下二叠统(P13)的碳酸盐岩中的生油层;沥青的红外光谱及螺旋生长纹与气孔构造也证实沥青是由成矿热液中的原油受热裂解为固相;成矿溶液中的有机质成熟度越髙,成矿溶液析出的自然铜越多;铜矿物的演化(Cu→Cu2+)与含有机质的成矿溶液的氧化还原条件及成分变化密切相关。 相似文献
2.
川南普格玄武岩顶部发育了一系列杏仁体，沥青、绿泥石、石英、自然铜等矿物以各种产状出现在杏仁体中。系统的矿物学研究表明：杏仁体中的绿泥石为辉绿泥石，形成于中—高温富有机质成矿热液环境；沥青属于石油沥青，有机质来源于下伏地层的中二叠统阳新组（P2 y）生物碎屑灰岩；绿泥石、沥青、石英及自然铜等矿物是玄武岩成岩后的构造应力与晚期基性火山活动共同作用形成的含有机质成矿热液演化的结果，其形成过程为：玄武质岩浆末期（基性岩浆作用末期）→含铜的火山热液(火山热液作用）→构造应力→含有机质的成矿热液→绿泥石→第一世代沥青→乳白色石英→烟灰色石英、第二世代沥青、自然铜→辉铜矿→葡萄石。玄武岩中含沥青的杏仁体、晶洞以及构造破碎带可以作为该地区的铜矿化的重要找矿标志。 相似文献
3.
滇黔交界地区峨眉山玄武岩铜矿化蚀变特征 总被引：15，自引：0，他引：15
滇黔交界地区蛾眉山玄武岩铜矿化具层控特征,主要发育于上二叠统蛾眉山玄武岩组第四岩性段下部。矿化主岩为玄武岩流顶部的淬碎玄武质角砾岩和玄武岩流之间的含炭沉积岩;矿石矿物主要为自然铜及其表生氧化产物黑铜矿、赤铜矿、孔雀石等;脉石矿物主要有沥青、炭质物、石英、沸石、方解石、绿帘石等,此外还有少量绿泥石、钠长石、铁阳起石、榍石、辉铜矿、硅孔雀石、铜蓝、褐铁矿等。以玄武岩为主岩的铜矿石典型矿物组合为自然铜 沥青 石英及不含沥青等有机质的自然铜 石英 绿帘石,以含炭沉积岩为主岩的铜矿石典型矿物组合为自然铜 炭质物 沸石 石英( 辉铜矿);原生铜矿化有2个期次：早期铜矿化发生于有机质流体贯人之前,晚期铜矿化发生于有机质流体贯人之后。该类铜矿化的同生火山热液特征不明显,以后生热液矿化为主。淬碎玄武质角砾岩不仅是有机流体的良好储层,也为成矿流体提供了就位空间,是铜矿化层控特征的主要控制因素。有机流体及含碳沉积岩中碳质为成矿物质以自然铜形式沉淀提供了还原条件。 相似文献
4.
沥青、自然铜常常与石英出露于杏仁状玄武岩暗色团块的矿物颗粒间或间隙中。自然铜的晶出是在成矿热液中的有机质几乎裂解为沥青和天然气之后。自然铜与沥青的产出互为负相关关系,即暗色团块中的沥青或沥青与石英越发育,沥青中的自然铜含量越低,其附近或周围的自然铜与石英也越发育,但这两者晶出的时间与空间间隔极短,它们之间形成的先后关系依次为：石英→沥青→自然铜。沥青的碳同位素、化学组成及红外光谱测试表明,暗色团块及裂隙石英脉中玄武岩捕虏体中的沥青是生物成因的石油沥青。包裹体测温与拉曼分析给出,成矿热液中的有机质需在较高温度下（>350℃）才能裂解为沥青与天然气（CH4）,成矿热液温度越高,有机质成熟度就越高,沥青中的有机碳含量也越高,残存在沥青中的自然铜含量就越低。 相似文献
5.
《矿物学报》2017,(6)
峨眉山玄武岩铜矿与基韦诺超大型铜矿相似,杏仁状玄武岩中的自然铜矿石就是该类型铜矿床中的主要组成部分之一,本文称其为"杏仁体式"自然铜矿床。通过矿石矿物标型特征、矿物组合特征以及固溶体分离结构特征等分析研究,认为川南滇北"杏仁体式"自然铜矿为火山热液矿床,形成于低温还原环境,成矿作用发生在岩浆作用结束期及间歇期热液阶段,成矿经历过热液蚀变改造。铜矿物生成顺序为:自然铜→斑铜矿、辉铜矿、黄铜矿→赤铜矿、黑铜矿、孔雀石等。玄武岩中广泛分布的沥青与自然铜同时形成,并为自然铜及铜的硫化物的形成提供了强还原环境。沥青形成温度和斑铜矿-辉铜矿的固溶体分解温度将自然铜形成温度区间限定为290~225℃。 相似文献
6.
球粒状铁绿纤石(?)产出于云南昭通玄武岩晶洞中,与其共生的矿物有绿帘石、硅铁灰石、水晶、葡萄石及方解石等矿物.扫描电镜(SEM)下,该矿物呈扁平长柱状,沿柱体方向呈不同程度的弯曲,并绕球粒中的包裹体聚合生长成不同形状的球粒,聚合生长的方式取决于包裹体在球体中的位置与距离,越近球粒表面,越趋于平行排列.水晶的流体包裹体测温及拉曼光谱分析表明,铁绿纤石(?)属低温(148～169℃)热液产物,热液的盐度为 11%～12%,富含H2O及微量CH4,铁绿纤石(?)的形成可能与有机质(CH4)有关. 相似文献
7.
峨眉山玄武岩铜矿的三种成矿流体 总被引：2，自引：0，他引：2
峨眉山玄武岩铜矿化有3个原生矿化期次.第一期次表现为自然铜及少量硅孔雀石与石英、沸石、绿帘石、绿泥石、钠长石、榍石、铁阳起石等共生,产于玄武岩的气孔中;第二期次表现为自然铜与石英、方解石一起呈网脉状穿插于玄武岩中沥青的裂纹中,或自然铜与沸石一起穿插于含碳沉积岩中炭质的裂纹中,或自然铜与沥青、石英呈浸染状共生;第三期次表现为自然铜与石英一起呈细脉状穿插于石英绿帘石化玄武岩中,没有共生的有机质,有时有方解石脉. 相似文献
8.
黔西北威宁地区香炉山铜矿床位于二叠系峨眉山玄武岩组第3段(P3β3)顶部与宣威组(P3x)底部之间,属于玄武岩型铜矿床。针对其含矿地层宏观地质特征与赋矿主岩矿物岩石学组构,本文以野外地质为基础,系统开展岩矿鉴定、扫描电镜与电子探针分析等研究,结果表明,本矿床赋矿主岩为岩屑粉砂岩的矿石矿物为辉铜矿、斑铜矿、黝铜矿和孔雀石,脉石矿物为长石、石英、绿泥石和碳质物等;赋矿主岩为火山角砾岩的矿石矿物为自然铜、斑铜矿、黄铜矿、辉铜矿、黝铜矿和孔雀石,其脉石矿物为石英、绿泥石、白云石和粘土矿物等,按其主要矿物含量,原生矿石可分为自然铜+辉铜矿+赤铁矿矿石、自然铜+黄铜矿+黝铜矿矿石、黄铜矿+斑铜矿+赤铁矿矿石3种自然类型。根据矿物共生组合与相互穿插关系,本矿床成矿作用可分为热液期和表生期,其中,热液期矿石矿物的形成顺序为斑铜矿→黄铜矿—黝铜矿—自然铜→辉铜矿,表生期形成孔雀石、赤铜矿、赤铁矿、钛铁矿、褐铁矿等矿物。 相似文献
9.
瓦西乡产出的南红玉中的红色点状及火焰纹典型包裹体分别是石英中的红色球粒与红色管状包裹体。鏡下及扫描电镜(SEM)研究,红色球粒分布在"三色"层水晶的菱面体单形晶面的间歇层面中,由红色核、黑色壳和红色表层组成;火焰纹管状包裹体主要出现在条带水晶中,管的方向垂直水晶的菱面体晶面,管的内壁呈黑色,外壳为红色。其球粒表层或管外壳的颜色、厚度及透光性则直接影响南红的颜色质量与润泽性。研究表明,球粒状和火焰状包裹体主要由片状、鳞片状或板片状赤铁矿组成;球粒圈层中的赤铁矿晶体c轴取向呈规律变化,可能与其V2O5含量有关。据水晶晶体中的球粒、管及共生矿物绿帘石、黄铜矿包裹体的红外光谱(IR)及流体包裹体均一法测温与激光拉曼(LRS)分析,球或管的赤铁矿属含有机质的低温热液(约160℃)成因,成矿溶液中的有机质也是促使铁氧化物凝聚形成具不同圈层结构的红色球粒与管的主要原因。有机质可能来自下二叠统茅口组碳酸盐。 相似文献
10.
MVT型铅锌矿床中矿物组成一般较简单,铜矿物非常少见。云南富乐铅锌矿床是川滇黔MVT型铅锌成矿域中代表性
大型铅锌矿床,其赋矿层位为该区最新地层-中二叠统阳新组白云岩,矿体距上覆峨眉山玄武岩不到160 m。通过矿相、
扫描电镜及能谱等分析测试,本研究在该矿床中发现了大量铜矿物,主要包括以下四类,即黄铜矿、锌砷黝铜矿、黝铜矿
和孔雀石,这些铜的独立矿物常交代闪锌矿和黄铁矿等矿物,形状多为环带状、脉状及不规则状等,部分黄铜矿呈乳滴状
分布于闪锌矿颗粒内部或呈他形交代闪锌矿,可能与闪锌矿同时形成,锌砷黝铜矿和黝铜矿呈他形细脉状穿插于闪锌矿或
分布于闪锌矿边缘及孔洞中,暗示这些铜矿物形成略晚于铅锌成矿。上述铜矿物常见于中低温热液铅锌矿床,其中锌砷黝
铜矿是硫盐矿物中较罕见的矿物,黝铜矿和锌砷黝铜矿的出现指示相对氧化的成矿环境,而孔雀石是在铜矿物的氧化过程
中形成的次生矿物。研究表明,本矿床矿石矿物的生成顺序为：黄铁矿→闪锌矿（乳滴状黄铜矿） →方铅矿→黄铜矿→锌
砷黝铜矿→黝铜矿→孔雀石,结合矿床产出的地质地球化学特征,云南富乐铅锌矿床中铜可能有两个来源：早期的乳滴状
黄铜矿与铅锌矿同期且均来自基底地层--昆阳群;后生铜矿物（黄铜矿、黝铜矿和锌砷黝铜） 主要来源于上覆峨眉山玄
武岩,这与铅锌主要来源于昆阳群等基底地层有所差异,研究成果为认识川滇黔地区铅锌成矿作用与峨眉山玄武岩关系提
供了新的地球化学依据。 相似文献
11.
近年来在矿物标本市场上出现了许多与水晶、葡萄石、硅灰石等紧密共生树枝状金属铜晶簇标本,甚为新奇、美观,销售者称这些标本是产于云南昭通地区的天然产物,一些矿物标本爱好者及博物馆以单件数万元,数十万元进行购买.作者通过对这标本进行了矿物学,矿物共生组合及矿山地质背景实地考察,可以肯定类似这些在水晶、葡萄石、硅灰石标本上精美的“自然铜晶簇”并非天然形成,而是人工再生. 相似文献
12.
Kent Brooks 《Geology Today》2018,34(3):109-112
Zeolites are a diverse group of calcium and sodium aluminosilicate minerals. They are tectosilicates (3‐D arrays of SiO4 tetrahedra), but vary in chemistry and crystal symmetry. Some readily exchange sodium for calcium and are used as water softeners. They also find applications as molecular sieves in petroleum refining, although the bulk of zeolites used industrially today are synthetic. These minerals form at low temperatures under well‐defined conditions and can be used as indicators of palaeotemperatures. In the same environment, but at higher temperatures, other minerals form including quartz, calcite, prehnite and even native copper. The Inuit of East Greenland, a Stone Age people, may have utilized native copper from this environment as did the Copper Inuit of the central Canadian Arctic. 相似文献
13.
方涛 《中国地球化学学报》1997,16(2):178-182
Tenorite is an oxide of cupper which has been well documented on its structure,force constants and spectrum.Based on the isotopic shifts of its spectrum calculated from the force constants of tenorite,its reduced partition function ratios were calculated,from which an oxygen isotopic fractionation curve between tenorite and water was obtained:10^3lnα=2.51X^2-14.87X 6.31(X=10^3/T)Oxygen isotopic fractionation of tenorite was also calculated with the modified increment method of Zheng(1991),and another equation was obtained:10^3lnα=2.89X^2-13.10X 3.92(X=10^3/T) Calculated results of the two different models were fitted and possible deviation involved in the calcuation was also discussed. 相似文献
14.
High-temperature 'clockwise'P-T paths and melting in the development of regional migmatites: an example from southern Brittany, France 总被引：1，自引：0，他引：1
The Southern Brittany Migmatite Belt (SBMB), which evolved through the metamorphic peak between c. 400 Ma and c. . 370 Ma ago, consists of a heterogeneous suite of high-grade gneisses and anatectic migmatites, both metatexites and diatexites. Rare garnet-cordierite gneiss layers record evidence of an early prograde P-T path. In these rocks, growth-zoned garnet cores and a sequence of included mineral assemblages in garnet, from core to rim, of Qtz + Ilm + Ky, Pl + Ky + St + Rt + Bt and Pl + Sil + St + Rt + Bt constrain a prograde evolution during which the reactions Ilm + Ky + Qtz→ Aim + Rt, Ms + Chl→ St + Bt + Qtz + V and St + Qtz→ Grt + Sil + V were crossed. Parts of this prograde evolution are preserved as inclusion assemblages in garnet in all other rock types. In all rock types, garnet has reverse zoned rims, and garnet replacement by cordierite and/or biotite and plagioclase suggests the following reactions have occurred: Grt + Sil + Qtz→ Crd → Hc ± Ilm, Bt + Sil + Qtz → Crd ± Hc → Ilm → Kfs + V and (Na + Ca + K + Ti) + Grt → Bt + Pl + Qtz. Microstructural analysis of reaction textures in conjunction with a petrogenetic grid has enabled the construction of a tightly constrained 'clockwise' P–T path for the SBMB. The high-temperature part of the path has a steep dT/dP slope characteristic of near isothermal decompression. It is proposed that the P-T path followed by the SBMB is the result of the inversion, by overthrusting, of a back-arc basin and that such a tectonic setting may be applicable to other high-temperature migmatite terranes. The near isothermal decompression is at least partly driven by the upward (diapiric) movement of the diatexite/anatectic granite core of the SBMB. 相似文献
15.
Wen-Yong Duan Xu-Ping Li Ze-Li Wang Shuang Chen Guang-Ming Sun Ling-Quan Zhao 《地学前缘(英文版)》2021,12(3):101125
The analysis of early stage rodingite from the ultramafic rocks of the Xialu Massif in the Xigaze Ophiolite, Tibet, in China shows that the rodingitization involved continuous changes in fluid composition during different stages of subduction. The early stage prehnite-bearing rodingite was produced at low pressures and temperatures along extensional fractures. Samples of rodingite were collected along a profile from the center to the margin of a rodingitized intrusive igneous rock (~10 m × 30 m), and they record wide variations in bulk composition, mineralogy, and texture. The mineral assemblages, from center to margin, vary from (1) relics of primary clinopyroxene (Cpxr) and primary amphibole (Ampr) + newly formed late amphibole (Act) + primary plagioclase (Plr) + clinozoisite + prehnite + albite + chlorite + titanite + ilmenite (R1 rodingite), through (2) relics of primary clinopyroxene (Cpxr) + newly formed late clinopyroxene (Cpxn) + primary and late amphiboles (Ampr + Act) + clinozoisite + prehnite + albite + chlorite + titanite (R2 rodingite), to (3) newly formed late clinopyroxene (Cpxn) and amphibole (Act) + clinozoisite + prehnite + albite + chlorite + titanite (R3 rodingite). As a result of the metasomatic process of rodingitization, the content of CaO in the whole rock chemical composition from R1 to R3 increases, SiO2 decreases, and Na2O + K2O is almost completely removed. Mass-balance diagrams show enrichments in large ion lithophile elements such as Rb, Cs, Ba, and Pb as well as Ni during rodingitization. The central part of the rodingitized intrusion (R1 rodingite) was only slightly affected by metasomatism. On the other hand, the contents of the rare earth elements (REEs), high field strength elements (HFSEs; e.g. Zr, Nb, Ta, Hf, and Y), and some highly compatible elements such as Cr and Sc decreased slightly during rodingitization. Thermodynamic modeling based on equilibrium mineral assemblages indicates that the rodingite of the Xialu Massif formed in an H2O-saturated, CO2-rich environment. The estimated conditions of metamorphism were ~281–323 °C and 0.4–3.9 kbar, representing the subgreenschist facies. In this environment, REEs and HFSEs were soluble in the fluids and partly removed. Moreover, these prehnite rodingites formed in a progressively reducing and less alkaline environment, as indicated by decreases in f(O2) and bulk-rock Fe3+/Fe2+ ratios, and the records of fluid ΔpH from the center to the margin of the studied rodingitized intrusion. 相似文献
16.
该矽卡岩型铜金矿床位于阿尔泰萨拉寇克申花岗杂岩体与下寡武统火山沉积岩之接触带上，热液型金矿化（360-130℃）多叠加于早期矽卡岩（ > 400℃）之上。金矿化多分布于石榴万一硅灰石矽卡岩中。在氧化作用过程中导致次生成化物富集、自然金的成色降低，原因是金的活动性比银更强。与之同时，在氧化作用过程中自然金有部分银去除，故其成色与内生矿石中自然金相近。因此，在氧化带中自然金的成色具有广阔的离散性特点。为此，在评价深部矿石过程中应充分地加以考虑。 相似文献
17.
Layered gabbros at Nordre Aputit?q and Kruuse Fjord were emplacedduring extensional tectonism that led to the formation of theNorth Atlantic basin in the Early Tertiary. Sub-solidus reactionsbetween the gabbros and hydrothermal fluids formed superimposedalteration assemblages in fractures, cavities, and the adjacentgabbros. The earliest secondary minerals are Ca-Al amphibole+ clinopyroxene + biotite ? plagioclase that form thin veinsor porous pegmatitic masses. These minerals are crosscut, overgrownor partially replaced by one or more generations of prehniteand epidote bearing assemblages associated with filling of thefractures and cavities, and with extensive wall rock albitization. Wide variations in the partitioning of Fe3+ and Al between coexistingprehnite and epidote solid solutions occur in these alteredgabbros. The partitioning data define distinct clusters in termsof associated mineralogy and paragenetic relations. This, togetherwith prehnite and epidote compositions from active geothermalsystems, are used to evaluate the thermodynamic properties ofthe intercrystalline exchange reaction:When compared to thecompositions of prehnite and epidote in the Nordre Aputit?qand Kruuse Fjord intrusions, it is concluded that the latestand lowest temperature generations of prehnite and epidote displaydisequilibrium partitioning of Fe3+ and Al, manifested by theoccurrence of prehnite that is relatively enriched in Fe3+ Thermodynamic analysis of phase relations in the system Na2O-CaO-Al2O3-Fe2O3-FeO-SiO2-H2O-HClis used to determine local equilibrium constraints on Fe3+-Alsubstitution in prehnite and epidote. It appears that parageneticand compositional relations of prehnite and epidote are sensitiveindicators of local fluctuations in fluid composition and temperature.The complex magmatic and structural history of the gabbros atNordre Aputit?q relative to Kruuse Fjord is considered to beresponsible for the differences in mineral paragenesis and compositionsof prehnite and epidote within these intrusions. 相似文献
18.
The Emeishan continental flood basalt, which is widespread in Yunnan, Guizhou and Sichuan provinces of Southwest China, is the volcanic product of a Permian mantle plume, and native copper-chalcocite mineralization associated with the basalt is very common in the border area of Yunnan and Guizhou provinces. The mineralization occurred in the tuff intercalation and terrestrial sedimentary rock intercalation which were formed during the main period of basalt eruption. The orebodies are controlled by the stratigraphic position and faults. Metal ore minerals in the ores are mainly native copper, chalcocite and tenorite, with small amounts of chalcopyrite, bomite, pyrite and malachite, and sometimes with large amounts of bitumen, carbon and plant debris. Several decades of ore deposits are distributed in the neighboring areas of the two provinces, while most of them are small-scale deposits or only ore occurrences. By comparing the lead isotopic composition of the ores with that of the wall-rocks, cover and basement rocks of various periods, the source of copper in this type of ore deposits was studied in this paper. The results showed that: (1) The Pb isotopic composition of the ores from ten deposits is absolutely different from that of sili-ceous-argillaceus rocks of the Upper Permian Xuanwei Formation, limestones of the Lower Permian Series and Carboniferous, Cambrian sandstone-shale and recta-sedimentary rock and dolomite from the upper part of the Meso-Proterozoic Kunyang Group, This indicates that ore lead was derived neither from the cover rock nor from the basement rocks; (2) Although the Neo-Proterozoic Siman dolomite and silicalite, and dolomite in the lower part of the Kunyang Group are similar in Pb isotopic composition to the ores, lead and copper contents in these rocks are very low and they have not made great contributions to copper mineralization; (3) The ores have the same Pb iso-topic composition as the basalt, the latter being enriched in copper. These facts indicate that lead and copper were derived from the basalt. According to the regional geological data and the geological-geochemical characteristics of the ore deposits, it is suggested that ore-forming materials were leached out from the basalt. The thickness and buried depth of the basalt and regional tectonic dynamics can affect the formation of large-scale copper deposits. Therefore, exploration for this type of ore deposits should be conducted in the areas from western Yunnan to western Sichuan, where there are developed basalts of great thickness, with extensive tectonic movement and magmatic activity. 相似文献