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中国矽卡岩矿床基本地质特征 总被引：8，自引：1，他引：8
中国是世界上矽卡岩矿床最发育的国家之一,矿种包括Fe、Cu、Pb、Zn、W、Sn、Mo、Bi、Au、U、TR、稀有元素和非金属等。矿床常成群成带分布,主要产于地台活化区和褶皱带的拗陷区,成矿时代以燕山期为主。 与侵入体有成因联系的矿床具有明显的岩浆岩和交代岩成矿专属性。矽卡岩矿床的形成大多经历了接触变质作用(部分矿床有岩浆期镁矽卡岩阶段)、岩浆期后矽卡岩阶段和酸性淋滤作用,分别形成各类矽卡岩和交代岩,矿化主要形成于矽卡岩晚期和酸性淋滤阶段,各类含矿交代岩常围绕侵入体呈带状分布,但互有成因联系,在一定地区组成一定的交代系列。在矿床形成过程中碱质和挥发分起着十分重要的作用。 相似文献
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文章通过对沂南县铜井铜金矿床深部地质特征的论述,阐明了深部矿体的赋存特征;通过同位素测定,分析了矿床的物质来源、形成温度、形成时间和矿床成因。认为铜井铜金矿是由铜井杂岩体,尤其是闪长玢岩、二长花岗斑岩沿层理或层间滑脱带侵入,与灰岩接触交代形成的夕卡岩型矿床。根据成矿地质特征建立了矿床的成矿模式。 相似文献
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环山菱镁矿床为富含镁质岩石经区域变质和混合岩化作用形成的沉积变质热液交代矿床。含矿岩系为下元古界兴东群建党组变质岩。矿体具有一定规模,氧化镁品位高。矿床开发条件好,经济效益显著。 相似文献
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325、326矿床钠交代与铀成矿的关系 总被引：4，自引：0，他引：4
325、326矿床是典型的钠交代型铀矿床。该矿与钠交代有着十分密切的关系,矿体几乎都在钠交代岩内。钠交代增大了花岗岩有效孔隙度,降低了抗压强度,成为同步构造活动的薄弱环节。钠交代形成的“海绵体”为铀的沉淀富集提供了极其有利的空间。钠交代促使原岩中铀的赋存状态发生改变,使铀发生活化转移。钠交代还为铀成矿提供了物质基础。 相似文献
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杨柳坪铜-镍-铂族元素矿床的矿化类型及意义 总被引：8，自引：1，他引：7
铜镍硫化物及铂族元素矿床一般属于岩浆结晶分异成因,很少有热液交代成因产出。Hulbert指出,世界范围内热液型矿床对于铂族元素的贡献甚微。在我国开采的铜镍硫化物矿床中也很少有独立的热液交代型矿体,只在一些矽卡岩型矿床(主要是铜矿)中伴生有Ni和PGE。但在四川杨柳坪矿区,新近发现的独立的、完全由热液形成的铜-镍-铂族元素矿体提供了新的热液成矿实例,该矿体赋存在基性超基性岩体之外的灰岩-片岩中,与基性-超基性岩没有直接关系,矿石品位很高。 相似文献
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The paper presents a comparative mineralogical-geochemical characterization of amphibolites and basic metasomatic rocks in the Belomorian belt. The metasomatites are spread much more locally than the amphibolites. The metasomatic rocks compose bodies of very diverse morphology, some of which are similar to the morphologies of amphibolite bodies (podiform and tabular bodies and lenses). The metasomatites are characterized by a great diversity of their petrographic varieties, whereas the usual assemblage of the amphibolites is amphibole ± garnet + plagioclase + quartz. Although one of the varieties of both rock types contains the same assemblage (garnet-hornblende), the metasomatites contain no quartz, have different quantitative proportions of their minerals, their compositions, and different overall contents of amphibole and garnet. The metasomatites are more mafic and contain 85–100% mafic minerals, whereas the amphibolites contain only 60–65% mafic minerals. The rocks have different concentrations of most major and some trace elements, including REE. The basic metasomatites are poorer than the amphibolites in SiO2, Al2O3, Na2O, K2O, LREE, and HREE but richer in MgO and Cr2O3. The Cr concentrations in some of the metasomatites are higher than the clarkes of this element in crustal ultrabasic rocks. The main Cr concentrator in the rocks was determined to be amphibole: some grains of this mineral contain as much as 6800 ppm Cr. The element is unevenly distributed even within single grains. Amphiboles of the amphibolites do not contain Cr at all. Another difference of amphiboles from the metasomatic rocks and amphibolites is the depletion of this mineral in the former rocks in Al and Fe, the absence of K, but high concentrations of MgO and 1.5–2.0 times higher. A remarkable feature of the compared rocks is their geneses. The amphibolites of the Belomorian belt are metamorphosed mafic Archean rocks, whereas the basic metasomatites were produced by Fe-Mg-Ca metasomatism (basification) closely related to the granitization of various rocks, first of all, amphibolites. It is important to distinguish between these rocks of various genesis and age, particularly when geological survey is conducted. 相似文献
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我国个旧锡矿是闻名中外最大的锡矿床之一,矿床中除含锡外,还伴生铜、钴、锌、钨、铋、铍及稀有元素。矿化主要产于燕山期花岗岩接触带及其附近的三叠纪碳酸盐围岩中的交代岩。本文着重讨论含锡花岗岩接触带交代岩的类型。矿物组合、分带性、岩石化学特征及其与矿化的关系,把各类含矿交代建造作为一个有成团联系的统一体——交代系列来考虑。 相似文献
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《International Geology Review》2012,54(10):1208-1214
An attempt at energy (heat) analysis of greisenization is made on the basis of determining the solution and specific heat of the original rocks and their metasomatites. A great amount of heat is released in greisenization; metasomatic zones are formed with the energy level lower than in the original rocks. -- Author. 相似文献
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《Russian Geology and Geophysics》2007,48(11):901-912
Wall-rock metasomatites of the Kara gold deposit, a high-temperature medium-depth pneumatolytic-hydrothermal formation, have been studied. Gold mineralization is associated with the intrusion of granitoids of the Kara-Chacha massif (J3) and dikes of alkaline rocks (J3-K1), which include hybrid porphyries, “grorudites”, etc. They are characterized by telescoping of ores, expressed best of all on joints of ore-bearing sites.The origin of the Kara-Chacha massif (Amudzhikan-Sretensk complex) is connected with pre-ore areal propylitization. The propylites demonstrate a zonal pattern relative to the massif and ore veins. A composite metasomatic column of propylitized rocks has been compiled.The thickness of intensely altered wall rocks does not exceed 1.5–2.0 m and the structure of these zones is very heterogeneous. Syn-ore metasomatites are found in propylitized rocks. The major factor of syn-ore alteration of host rocks is the active behavior of alkaline elements. Albitization, silicification (in separate sites), tourmaline and pyrite alteration occur at the early quartz-pyrite-tourmaline stage of mineralization. Sodium is supplied at this stage. During the next quartz-actinolite-magnetite stage sodium and potassium are active. The host rocks demonstrate albitization, feldspar alteration, silicification, actinolitization, biotite alteration, and magnetite impregnation. Aegirine in veins is accompanied by occurrence of aegirine, alkaline amphibole, green biotite and, locally, quartz in host rocks. Potassium becomes more significant later, reaching the maximum activity at the quartz-sulfide stage. The development of quartz-arsenopyrite assemblage was accompanied by K-feldspatization, sericitization of host rocks, formation of green and tan biotites, and arsenopyrite impregnation. The formation of K-feldspar, sericitization, silicification, and sulfide impregnation are associated with quartz-sulfide ore. The final quartz-carbonate-polymetallic stage is accompanied by silicification and carbonate alteration of host rocks. Potassium becomes increasingly more active from outer zones of metasomatic columns to inner ones. The gold contents tend to increase with the potassium contribution in zones of hydrothermal alterations.The propylite alteration and syn-ore changes become more intense veinward. It can indicate that hydrothermal solutions with dissolved minerals penetrated through the most reworked zones. However, hydrothermal solutions during propylite alteration and later syn-ore changes of host rocks not always penetrated through the same zones of weakness, such as tectonic dislocations, contacts of various rocks, etc. The rocks, comprising inner zones of the metasomatic column of propylites are quite often observed at a certain distance from veins and accompanied inner zones of metasomatic columns of later syn-ore metasomatites. They sometimes are not associated with ore veins. However, they are demonstrate later superimposed threads and separate impregnations of syn-ore minerals.Abundant telescoping of mineralization and inheritance of mineralization stages complicate the structure of zones with syn-ore metasomatites. In the sites with telescoped mineralization the metasomatites contain minerals intrinsic to all stages of mineralization found at the deposit. 相似文献
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It is shown that formation of high-temperature granulite-like rocks in the contact aureole of the Yurchik gabbronorite intrusion of the Ganal Ridge in East Kamchatka was caused by contact metamorphism, metasomatism, and local melting of the primary sedimentary-volcanogenic rocks of the Vakhtalkinskaya Sequence of the Ganal Group. The temperature in the inner part of the aureole reached 700–800°C and caused transformation of basic rocks into two-pyroxene-plagioclase, clinopyroxene-amphibole-plagioclase, and amphibole-plagioclase rocks, while sedimentary rocks were replaced by garnet-biotite and garnet-cordierite-biotite hornfelses. Locally, basic volcanic hornfelses were subjected to metasomatic alteration with the formation of bodies of biotite-orthopyroxene-plagioclase metasomatites. In the zones of the most intense fluid filtration, the metasomatites experienced local magmatic replacement resulting in the formation of biotite-orthopyroxene-plagioclase ± garnet migmatite veinlets and patches. Bodies of garnet enderbites were formed after sedimentary interlayers at temperatures of 700–800°C and a lithostatic pressure of 3.2–4.8 kbar. The comparison of the chemical composition of the Vakhtalkinskaya basic volcanics and the products of their transformation indicates that, in terms of chemistry, the metasomatic alterations and magmatic replacement correspond to siliceous-alkaline metasomatism (granitization) causing a subsequent and uneven influx of Si, Al, Na, K, Rb, Ba, Zr, Nb, and Cl and removal of Fe, Mg, Mn, Ca, and some trace elements (Cr, Co, Ti, Y, and S). The processes of metamorphism and metasomatism were presumably provoked by highly mineralized mantle fluids that were filtered through magmatic channels that served as pathways for gabbroid magma. 相似文献
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V. A. Glebovitskii S. A. Bushmin B. V. Belyatsky E. S. Bogomolov A. P. Borozdin E. V. Savva Yu. M. Lebedeva 《Petrology》2014,22(2):184-204
Manifestations of the main types of metasomatites (beresite, propylite, listwaenite, aceite, and gumbeite) were identified in the shear zones of the Fenno-Karelian craton on the basis of the previously proposed systematics of metasomatic facies. These metasomatites were formed in shear stress environments, which determined their morphological features, in particular, finely banded texture. Comparatively low-temperature conditions of infiltration process and salting out effect (reduction of CO2 solubility with increasing salt content) lead to the heterogenization of fluid into two phases: aqueous salt solution and almost pure CO2. This results in more aggressive and mobile behavior of the fluid, and, correspondingly, more intense differentiation of the matter and contrast in metasomatic banding. Relations between metasomatic parageneses indicate an evolution trend of the processes from propylite, beresite and listwaenite to alkaline varieties and their repeated manifestation in the same shear zones. The results of Rb-Sr isochron dating of ore metasomatites from eight deposits and occurrences of the Fenno-Karelian craton (more than 100 samples of rocks and minerals) confirm previous assumptions. In general obtained data show that the shear zones controlling the distribution of the studied occurrences operated as fluid pathways during a long time period, up to 200 Ma, after the Svecofennian orogeny completion and did not show any correlation with Paleoproterozoic and Neoarchean magmatism. Rb-Sr isotope data on the metasomatites indicate three peaks of the post-Svecofennian metallogenic activity: 1700–1780, 1600–1650, and 1400–1500 Ma. Since the studied ore deposits were formed within tectonic structures, which evolved on the Archean crust and have a long prehistory, and fluid flows were subjected to intensive contamination by ancient crustal material, a relatively high initial Sr isotope ratios of formed ore-metasomatic systems were developed. High variablity of this value in the studied rocks ((87Sr/86Sr)0 from 0.706 to 0.750) is related to the heterogeneity of crustal protolith and to the relative storage and manifestation of the juvenile component of the fluid, which was responsible for the metasomatic transformation of the Archean and Paleoproterozoic rocks and ore-deposit formation. 相似文献
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Enstatite, anthophyllite, tremolite, and chlorite are developedin a zoned sequence as a vein cross cutting a peridotite bodylocated within the basal gneiss region of southern Norway. Theyare believed to have formed during the main regional metamorphicevent at temperatures around 700 °C and Ptotal in excessof 6 kb. It is thought that metasomatic reaction occurred by means of(and to a lesser extent directly involved) a pore fluid phaserich in alkali halides. The zonal sequence now found representsthe results of incomplete reaction of the peridotite body withpore fluids derived from the acid gneiss country rocks. Eachzone illustrates partial attainment of equilibrium one componentat a time. Local equilibrium was maintained between the fluidphase and the various silicates during reaction. Questions ofcomponent ‘mobility’ are considered. There appears to be no doubt that enstatite developed by metasomaticreaction on this small scale. This raises interesting possibilitiesof metasomatic development on a larger scale: enstatite occursas a major constituent of some ultrabasic bodies in this regionof southern Norway. 相似文献
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E. N. Terekhov 《Geochemistry International》2007,45(4):364-380
The paper reports data on the distribution of REE in metasomatic rocks, including those with corundum, that were formed during the exhumation of the rocks of the Belomorian Belt at 1.9–1.75 Ga. This process is thought to have occurred concurrently with the horizontal extension and tectonic denudation of the upper crust, which, in turn, induced the massive release of fluids. The latter formed two major groups of silicic metasomatic rocks. The deepest-sitting corundum-bearing and other mafic metasomatic rocks are enriched in REE, alkalis, and alumina compared to the host rocks. The coeval acid metasomatic rocks such as orthotectites are, conversely, depleted in REE (with positive Eu anomalies), mafic elements, and HFSE but are also enriched in alumina. These complimentary rocks are thought to have been produced early during the exhumation of deep rocks under the effect of reduced fluids whose genesis was related to decompression. The silicic metasomatic rocks of the second group (with muscovite) have elevated REE concentrations (with negative Eu anomalies) and were formed by already oxidized fluids at shallower depths. The fact that the corundum-bearing metasomatic rocks are enriched in REE (in spite of the ultrabasic composition of these rocks) suggests that they were generated in an extensional environment with the participation of deep fluids, which enriched the rocks in Al, Na, K, Ba, Sr, Zr, and LREE. 相似文献
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《International Geology Review》2012,54(10):1565-1572
A critical coordination of the often contradictory ideas on the relation of secondary quartzites to volcanism, granitoid intrusions, and deposition of endogenic ores, represents them essentially as products of postvolcanic hydrothermalism, as metasomatites, and as predecessors of the ores. Physicomechanical and chemical properties of secondary quartzites, and also their morphology and structural positions are particularly conducive to their functioning as barriers or screens in the deposition of ores. The very same properties, genetically inherent, usually disqualify secondary quartzites as potential host rocks of the imposed ores. 相似文献
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I. A. Tararin Z. G. Badredinov S. I. Dril’ N. S. Gerasimov G. P. Sandimirova T. A. Vladimirova 《Geochemistry International》2013,51(11):896-911
Geological and geochemical data indicate that the formation of the granulite-like rocks in the contact aureole of the Yurchik gabbronorite intrusion of the Ganal Range, Kamchatka, was caused by the contact metamorphism, metasomatism, and local melting of the initial volcanosedimentary rocks of the Vakhtalka Sequence of the Ganal Group. The temperature in the inner part of the aureole reached 700–800°C and caused the transformation of the basic volcanic rocks of the sequence into two pyroxene-plagioclase, clinopyroxene-amphibole-plagioclase, and amphibole-plagioclase hornfelses, while sedimentary rocks were converted into garnet-biotite ± cordierite hornfelses. The hornfelsed basic volcanic rocks were locally subjected to metasomatic alteration and magmatic replacement with formation of biotite-orthopyroxene-plagioclase metasomatic bodies containing biotite-orthopyroxene-plagioclase ± garnet veinlets and aggregates. During these processes, sedimentary interlayers were converted into garnet enderbites at 700–800°C and 3.2–4.8 kbar. The comparison of the chemical composition of basic volcanic rocks of the Vakhtalka Sequence and their transformation products indicates that the metasomatic alteration and magmatic replacement correspond to siliceous-alkaline metasomatism (granitization) and cause subsequent and uneven influx of SiO2, Al2O3, Na2O, K2O, Rb, Ba, Zr, Nb, and Cl and removal of Fe, Mg, Mn, Ca, Cr, Co, Ti, Y, and S. REE data on basic metavolcanic rocks, hornfelses, and metasomatites suggest that the processes of hornfelsation, metasomatism, and magmatic replacement of the initial volcanic rocks were accompanied by significant increase in LREE and slight decrease in HREE. The Sr and Nd isotope study of the rocks in the aureole showed that the initial basic volcanic rocks of the Vakhtalka Sequence are isotopically close to both mature island arc tholeiites and mid-ocean ridge basalts. The metasomatic alteration and magmatic replacement of volcanic rocks in the aureole lead to the decrease of 143Nd/144Nd and increase of 87Sr/86Sr approximately parallel to mantle array. Pb isotopic ratios in the studied rocks become more radiogenic from initial metavolcanic rocks to metasomatites. It is suggested that the processes of metamorphism, metasomatism, and magmatic replacement were caused by highly mineralized mantle fluids, which percolated along magmatic channels serving as pathways for gabbroid magma. 相似文献