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1.
冀东高级变质岩石的流体包裹体研究 总被引：5，自引：5，他引：5
冀东高级变质的石榴石斜长片麻岩、含或不含石榴石的角闪二辉斜长片麻岩、紫苏花岗岩、斜长角门岩等岩石中的流体包裹体主要有４类，按形成的先后顺序依次为：（１）Ｈ２Ｏ和ＣＯ２两液相包裹体，ＣＯ２的部分均一温度是－１２℃，密度１．０４ｇ／ｃｍ３，Ｈ２Ｏ含量２１％～３９％（ｍｏｌｅ％），ＣＯ２含量５０％～７１％（ｍｏｌｅ％）；（２）ＣＯ２液相包裹体，冰点温度－５６℃～－６１℃，均一温度－７．４℃～－３５．１℃，ＣＯ２密度约为１．０５ｇ／ｃｍ３，ＣＯ２含量８２．１％～９８．４％（ｍｏｌｅ％），还有少量的ＣＨ４、Ｎ２和Ｈ２等组分；（３）Ｈ２Ｏ和ＣＯ２多相包裹体，ＣＯ２的部分均一温度７℃～２８℃，ＣＯ２密度为０．６４～０．９３ｇ／ｃｍ３，气相组分以ＣＯ２、ＣＨ４和ＣＯ为主，液相成分主要是Ｈ２Ｏ和ＣＯ２；（４）多世代盐水溶液包裹体，冰点温度－０．５℃～－２０℃，盐度０．８７％～２２．８％（ｗｔ％），盐水密度０．７～１．０５ｇ／ｃｍ３，均一温度在１５０℃～２００℃和约３００℃，存在两个峰值。不同世代的流体包裹体记录了等密度降温的Ｐ－Ｔ路径。包裹体反映的变质作用早期降温过程流体的Ｈ２Ｏ／Ｈ２Ｏ＋ＣＯ２（ｍｏｌｅ）比值降低，晚期升高 相似文献
2.
胶东金矿区两种花岗岩之间熔融再生关系的实验研究 总被引：5，自引：0，他引：5
以玲珑片麻状花岗岩为初始物,采用纯水和Ｈ２Ｏ－ＣＯ２混合物（ｘ（Ｈ２Ｏ）＝０．７０）两种实验介质,在１．５×１０２ＭＰａ和不同温度下（７４０℃,７７０℃,８１０℃,８５０℃）进行部分熔融实验,验证了胶东金矿区与金矿密切相关的栾家河中粗粒花岗岩与玲珑片麻状花岗岩之间的熔融再生关系．结果表明,栾家河岩体是由玲珑岩体在８１０℃,１．５×１０２ＭＰａ,水不饱和（ｘ（Ｈ２Ｏ）＝０．７０）条件下经１８％的熔融形成的．实验结果与岩体中大量发育ＣＯ２包裹体的地质事实相符合,从熔体分离机制上阐明了两岩体之间的生成关系． 相似文献
3.
建平烧锅营子金矿流体包裹体特征研究 总被引：2，自引：0，他引：2
对烧锅营子金矿石英流体包裹体进行了详细研究。流体包裹体均一温度为２８０℃～３２０℃、爆裂温度为２４０℃～２９０℃。成矿流体富含Ｎａ＋、Ｋ＋、Ａｕ＋、Ｃｌ－、Ｈ２Ｏ和ＣＯ２。金以ＡｕＣｌ－形式存在于成矿流体中。ＣＯ２含量与金矿化强度呈正相关。成矿流体ｐＨ值为５．３１～５．５３。成矿流体呈弱酸性、低盐度、低密度、相对氧化环境。 相似文献
4.
川西北马脑壳金矿床流体包裹体研究与热液成矿机理探计 总被引：2，自引：0，他引：2
系统的流体包裹体研究表明,马脑壳金矿床物石英中发育有液相,纯液相,含ＣＯ３三相,纯ＣＯ２相及含有机质等五种主要类开型的原生流体包裹体,其均一温度为１２０～３００℃,热液盐度为０．５～１１．０ｗｔ％ＮａＣｌ,密度为０．７８～０．９５ｇ／ｃｍ＾３,成矿压力为３２．８７～１１３．６１５ＭＰａ,主矿化阶段成矿认发生过明星的流体混合及相分离作用,由此导致含矿热液体纱Ｔ、ｐＨ、ｆｏ２及ｆｓ２等物化条件参数的降 相似文献
5.
位于奥地利Ｐｅｎｎｉｎｅ推覆体内意大利北部地区晚阿尔卑斯脆性构造中充填有含金石英脉，这些含金脉形成于阿尔卑斯隆起后期。奥地利Ｂｏｃｋｓｔｅｉｎ金矿和意大利ＶａｌｌｅＡｎｚａｓｃａ金矿流体包裹体的组成复杂，可由卤水（５ｗｔ％ＮａＣｌ等当量）变为含ＣＯ＿２５０ｍｏｌ％的溶液。室温下随ＣＯ＿２含量）曾加，包裹体从两相水包体变成ＣＯ＿２均一成气体的三相包裹体。再变成ＣＯ＿２均一成液体的三相包裹体。包裹体组分变化范围很大，被解释成是流体不混溶的证据，其组分是不混溶流体随机混合的结果。流体包裹体均一温度为２００～２８０℃，由此可估算出含金石英脉的形成温度。Ｂｏｃｋｓｔｅｉｎ和ＶａｌｌｅＡｎｚａｓｃａ石英脉形成时流体压力为０．１ＧＰａ，并且前者形成压力小于后者。流体不混溶性对ＶａｌｌｅＡｎｚａｓｃａ和Ｂｏｃｋｓｔｅｉｎ乃至许多与阿尔卑斯隆起有关的金矿中的金沉淀具有重要意义。 相似文献
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7.
五台山区太古宙铁建造型金矿成矿流体性质和成因 总被引：1，自引：1，他引：0
五台山区铁建造金矿经历初生成矿作用和叠加成矿作用。初生成矿作用形成于变质峰期一,与区域变质作用有关。矿石富含水溶液包裹２体。包裹体均一温度１７１～２５５℃,压力０．１２～０．３１ＧＰａ。流体成分模式Ａｕ－Ｈ２Ｓ＋ＮａＣｌ－ＣＯ２－Ｈ２Ｏ。氢氧同位素具变质水和雨水双重笥,本主要来源于变质热液,受雨水混合。叠加成矿作用可能受岩浆活动影响,矿石富含ＣＯ２包裹体,均一温度３０６～３８５℃,压力０．６～１０ 相似文献
8.
粤西河台金矿床的流体包裹体及成矿流体 总被引：10，自引：0，他引：10
河台金矿床存在三种类型流体包裹体：低盐度（约１．５￣６ｗｔ％ＮａＣｌ）Ｈ２Ｏ－ＣＯ２包裹体、中等盐度（约６￣１４ｗｔ％ＮａＣｌ）水溶液包裹体、富ＣＯ２包裹体。它们的均一化温度范围在１３０℃至３１０℃之间，捕获时的围压大约为５０￣１７０ＭＰａ。初始的成矿流体是一个低盐度的以Ｈ２Ｏ－ＮａＣｌ－ＣＯ２为主的化学体系，主要源于大气水与变质建造水的混合。在演化过程中，成矿热液流体发生了ＣＯ２发泡和气液两相不 相似文献
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10.
新疆乔尕山和粤西河台韧性剪切带金矿床中熔融包裹体的发现及矿床成因 总被引：6，自引：0，他引：6
乔尕山和河台金矿床属典型韧性剪切带金矿床，分别产于志留－泥盆系及震旦系云开群地层中。在2个矿床含金石英脉及糜棱岩中首次发现了熔融包裹体及流体－熔融包裹体，对解决此类型矿床成因具重大意义。乔尕山金矿床包裹体均一温度：熔融包裹体为900－1100℃，液相包裹体为285－390℃；河台金矿包裹体均一温度，熔融包裹体为870℃，不混熔液相包裹体为530℃，液相包裹体为180－350℃。前者流体性质属Na^ -K^ -Ca2 -SO4^2-HCO3^--Cl^-体系；后者流体性质属K^ -Ca^2 -Mg^2 -Na^ -SO4^2--HCO^3--Cl^-体系。运用电子显微镜能谱对熔融包裹体子矿物进行分析，鉴定出石英，钾长石、硅灰石及铝硅酸盐等9种子矿物，它们分别组成不同矿物组合，为熔融包裹体在矿脉中存在提供了重要的实验依据。在变质溶熔作用及强烈 动力变质作用下，沉积变质岩可以形成铝硅酸盐熔融体，具熔体－流体性质，成矿与多阶段铝硅酸盐熔体及流体作用相关。 相似文献
11.
Phase equilibria modelling of residual migmatites and granulites: An evaluation of the melt‐reintegration approach 
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下载免费PDF全文 Omar Bartoli 《Journal of Metamorphic Geology》2017,35(8):919-942
Suprasolidus continental crust is prone to loss and redistribution of anatectic melt to shallow crustal levels. These processes ultimately lead to differentiation of the continental crust. The majority of granulite facies rocks worldwide has experienced melt loss and the reintegration of melt is becoming an increasingly popular approach to reconstruct the prograde history of melt‐depleted rocks by means of phase equilibria modelling. It involves the stepwise down‐temperature reintegration of a certain amount of melt into the residual bulk composition along an inferred P–T path, and various ways of calculating and reintegrating melt compositions have been developed and applied. Here different melt‐reintegration approaches are tested using El Hoyazo granulitic enclaves (SE Spain), and Mt. Stafford residual migmatites (central Australia). Various sets of P–T pseudosections were constructed progressing step by step, to lower temperatures along the inferred P–T paths. Melt‐reintegration was done following one‐step and multi‐step procedures proposed in the literature. For El Hoyazo granulites, modelling was also performed reintegrating the measured melt inclusions and matrix glass compositions and considering the melt amounts inferred by mass–balance calculations. The overall topology of phase diagrams is pretty similar, suggesting that, in spite of the different methods adopted, reintegrating a certain amount of melt can be sufficient to reconstruct a plausible prograde history (i.e. melting conditions and reactions, and melt productivity) of residual migmatites and granulites. However, significant underestimations of melt productivity may occur and have to be taken into account when a melt‐reintegration approach is applied to highly residual (SiO2 <55 wt%) rocks, or to rocks for which H2O retention from subsolidus conditions is high (such as in the case of rapid crustal melting triggered by mafic magma underplating). 相似文献
12.
Melt segregation in the continental crust: distribution and movement of melt in anatectic rocks 总被引：31，自引：3，他引：31
E. W. Sawyer 《Journal of Metamorphic Geology》2001,19(3):291-309
The grain‐ and outcrop‐scale distribution of melt has been mapped in anatectic rocks from regional and contact metamorphic environments and used to infer melt movement paths. At the grain scale, anatectic melt is pervasively distributed in the grain boundaries and in small pools; consequently, most melt is located parallel to the principal fabric in the rock, typically a foliation. Short, branched arrays of linked, melt‐bearing grain boundaries connect melt‐depleted parts of the matrix to diffuse zones of melt accumulation (protoleucosomes), where magmatic flow and alignment of euhedral crystals grown from the melt developed. The distribution of melt (leucosome) and residual rocks (normally melanocratic) in outcrop provides different, but complementary, information. The residual rocks show where the melt came from, and the leucosomes preserve some of the channels through which the melt moved, or sites where it pooled. Different stages of the melt segregation process are recorded in the leucosome–melanosome arrays. Regions where melting and segregation had just begun when crystallization occurred are characterized by short arrays of thin, branching leucosomes with little melanosome. A more advanced stage of melting and segregation is marked by the development of residual rocks around extensive, branched leucosome arrays, generally oriented along the foliation or melting layer. Places where melting had stopped, or slowed down, before crystallization began are marked by a high ratio of melanosome to leucosome; because most of the melt has drained away, very few leucosomes remain to mark the melt escape path — this is common in melt‐depleted granulite terranes. Many migmatites contain abundant leucosomes oriented parallel to the foliation; mostly, these represent places where foliation planes dilated and melt drained from the matrix via the branched grain boundary and larger branched melt channel (leucosome) arrays collected. Melt collected in the foliation planes was partially, or fully, expelled later, when discordant leucosomes formed. Leucosomes (or veins) oriented at high angles to the foliation/layering formed last and commonly lack melanocratic borders; hence they were not involved in draining the matrix of the melting layer. Discordant leucosomes represent the channels through which melt flowed out of the melting layer. 相似文献
13.
S. FERRERO O. BARTOLI B. CESARE E. SALVIOLI‐MARIANI A. ACOSTA‐VIGIL A. CAVALLO C. GROPPO S. BATTISTON 《Journal of Metamorphic Geology》2012,30(3):303-322
The occurrence of crystallized and glassy melt inclusions (MI) in high‐grade, partially melted metapelites and metagraywackes has opened up new possibilities to investigate anatectic processes. The present study focuses on three case studies: khondalites from the Kerala Khondalite Belt (India), the Ronda migmatites (Spain), and the Barun Gneiss (Nepal Himalaya). The results of a detailed microstructural investigation are reported, along with some new microchemical data on the bulk composition of MI. These inclusions were trapped within peritectic garnet and ilmenite during crystal growth and are therefore primary inclusions. They are generally isometric and very small in size, mostly ≤15 μm, and only rarely reaching 30 μm; they occur in clusters. In most cases inclusions are crystallized (‘nanogranites’) and contain a granitic phase assemblage with quartz, feldspar and one or two mica depending on the particular case study, commonly with accessory phases (mainly zircon, apatite, rutile). In many cases the polycrystalline aggregates that make up the nanogranites show igneous microstructures, e.g. granophyric intergrowths, micrographic quartz in K‐feldspar and cuneiform rods of quartz in plagioclase. Further evidence for the former presence of melt within the investigated inclusions consists of melt pseudomorphs, similar to those recognized at larger scale in the host migmatites. Moreover, partially crystallized inclusions are locally abundant and together with very small (≤8 μm) glassy inclusions may occur in the same clusters. Both crystallized and partially crystallized inclusions often display a diffuse nanoporosity, which may contain fluids, depending on the case study. After entrapment, inclusions underwent limited microstructural modifications, such as shape maturation, local necking down processes, and decrepitation (mainly in the Barun Gneiss), which did not influence their bulk composition. Re‐homogenized nanogranites and glassy inclusions show a leucogranitic and peraluminous composition, consistent with the results of partial melting experiments on metapelites and metagraywackes. Anatectic MI should therefore be considered as a new and important opportunity to understand the partial melting processes. 相似文献
14.
Catherine A. Stuart Sandra Piazolo Nathan R. Daczko 《Journal of Metamorphic Geology》2018,36(8):1049-1069
High‐strain zones are potential pathways of melt migration through the crust. However, the identification of melt‐present high‐strain deformation is commonly limited to cases where the interpreted volume of melt “frozen” within the high‐strain zone is high (>10%). In this contribution, we examine high‐strain zones in the Pembroke Granulite, an otherwise low‐strain outcrop of volcanic arc lower crust exposed in Fiordland, New Zealand. These high‐strain zones display compositional layering, flaser‐shaped mineral grains, and closely spaced foliation planes indicative of high‐strain deformation. Asymmetric leucosome surrounding peritectic garnet grains suggest deformation was synchronous with minor amounts of in situ partial melting. High‐strain zones lack typical mylonite microstructures and instead display typical equilibrium microstructures, such as straight grain boundaries, 120° triple junctions, and subhedral grain shapes. We identify five key microstructures indicative of the former presence of melt within the high‐strain zones: (a) small dihedral angles of interstitial phases; (b) elongate interstitial grains; (c) small aggregates of quartz grains with xenomorphic plagioclase grains connected in three dimensions; (d) fine‐grained, K‐feldspar bearing, multiphase aggregates with or without augite rims; and (e) mm‐ to cm‐scale felsic dykelets. Preservation of key microstructures indicates that deformation ceased as conditions crossed the solidus, breaking the positive feedback loop between deformation and the presence of melt. We propose that microstructures indicative of the former presence of melt, such as the five identified above, may be used as a tool for recognising rocks formed during melt‐present high‐strain deformation where low (<5%) volumes of leucosome are “frozen” within the high‐strain zone. 相似文献
15.
对花岗闪长质熔体在500MPa～2000MPa,650℃～750℃和一定水含量条件下结晶作用实验的结果表明,斜长石在500MPa和水饱和条件下的结晶温度为675℃,斜长石的结晶及其成分明显受温度、压力和熔体水含量影响。花岗闪长质熔体有斜长石结晶时残余熔体的SiO2含量高于无斜长石结晶的情况。花岗闪长质熔体发生角闪石、黑云母和斜长石结晶后的残余熔体在主量元素组成上与典型的A型花岗岩基本一致,也与初始物产地的A型花岗岩接近。因此,实验研究初步从主量元素上证明,东准噶尔A型花岗岩浆可以来源于花岗闪长质岩浆的分异结晶作用。 相似文献
16.
采用半导体脉冲激光光源和时间分辨探测技术, 对Ab -An -Di相图同结线附近处于玄武岩成分区的2个硅酸盐样品进行了升温过程的Raman光谱研究.研究了该成分区域中玻璃-晶体-熔体高温下的相转变、升温过程及其熔体的特征光谱的变化特点.发现高温熔体结构与低温玻璃结构存在明显区别, 晶体对熔体结构有继承性.同时观察到了Ab12 An3 6Di52在熔态时的分相作用, 可能反映了该组分液态不混溶的发生.通过对高频区的解谱, 初步探索了体系中各结构单元的种类及含量与温度的关系. 相似文献
17.
Grain-scale melt distribution in two contact aureole rocks: implications for controls on melt localization and deformation 总被引：2，自引：1，他引：2
The grain‐scale spatial arrangement of melt in layer‐parallel leucosomes in two anatectic rocks from two different contact aureoles located in central Maine, USA, is documented and used to constrain the controls on grain‐scale melt localization. The spatial distribution of grain‐scale melt is inferred from microstructural criteria for recognition of mineral pseudomorphs after melt and mineral grains of the solid matrix that hosted the melt. In both rocks, feldspar mimics the grain‐scale distribution of melt, and quartz is the major constituent of the solid matrix. The feldspar pockets consist of individual feldspar grains or aggregates of feldspar grains that show cuspate outlines. They have low average width/length ratios (0.54 and 0.55, respectively), and are interstitial between more rounded and equant (width/length ratios 0.65 for both samples) quartz grains. In two dimensions, the feldspar pockets extend over distances equivalent to multiple quartz grain diameters, possibly forming a connected three‐dimensional intergranular network. Both samples show similar mesoscopic structural elements and in both samples the feldspar pockets have a shape‐preferred orientation. In one sample, feldspar inferred to replace melt is aligned subparallel to the shape‐preferred orientation of quartz, indicating that pre‐ or syn‐anatectic strain controlled the grain‐scale distribution of melt. In the other sample, the preferred orientation of feldspar inferred to replace melt is different from the orientations of all other mesoscopic or microscopic structures in the rock, indicating that differential stress controlled grain‐scale melt localization. This is probably facilitated by conditions of higher differential stress, which may have promoted microfracturing. Grain‐scale melt distribution and inferred melt localization controls give insight into possible grain‐scale deformation mechanisms in melt‐bearing rocks. Application of these results to the interpretation of deep crustal anatectic rocks suggests that grain‐scale melt distribution should be controlled primarily by pre‐ or syn‐anatectic deformation. Feedback relations between melt localization and deformation are to be expected, with important implications for deformation and tectonic evolution of melt‐bearing rocks. 相似文献
18.
An experimental study of grain scale melt segregation mechanisms in two common crustal rock types 总被引：3，自引：0，他引：3
Creation of pathways for melt to migrate from its source is the necessary first step for transport of magma to the upper crust. To test the role of different dehydration‐melting reactions in the development of permeability during partial melting and deformation in the crust, we experimentally deformed two common crustal rock types. A muscovite‐biotite metapelite and a biotite gneiss were deformed at conditions below, at and above their fluid‐absent solidus. For the metapelite, temperatures ranged between 650 and 800 °C at Pc=700 MPa to investigate the muscovite‐dehydration melting reaction. For the biotite gneiss, temperatures ranged between 850 and 950 °C at Pc=1000 MPa to explore biotite dehydration‐melting under lower crustal conditions. Deformation for both sets of experiments was performed at the same strain rate (ε.) 1.37×10?5 s?1. In the presence of deformation, the positive ΔV and associated high dilational strain of the muscovite dehydration‐melting reaction produces an increase in melt pore pressure with partial melting of the metapelite. In contrast, the biotite dehydration‐melting reaction is not associated with a large dilational strain and during deformation and partial melting of the biotite gneiss melt pore pressure builds more gradually. Due to the different rates in pore pressure increase, melt‐enhanced deformation microstructures reflect the different dehydration melting reactions themselves. Permeability development in the two rocks differs because grain boundaries control melt distribution to a greater extent in the gneiss. Muscovite‐dehydration melting may develop melt pathways at low melt fractions due to a larger volume of melt, in comparison with biotite‐dehydration melting, generated at the solidus. This may be a viable physical mechanism in which rapid melt segregation from a metapelitic source rock can occur. Alternatively, the results from the gneiss experiments suggest continual draining of biotite‐derived magma from the lower crust with melt migration paths controlled by structural anisotropies in the protolith. 相似文献
19.
Origin of migmatites by deformation-enhanced melt infiltration of orthogneiss: a new model based on quantitative microstructural analysis 总被引：2，自引：1，他引：1
P. HASALOVÁ K. SCHULMANN O. LEXA P. &#;TÍPSKÁ F. HROUDA S. ULRICH J. HALODA P. TÝCOVÁ 《Journal of Metamorphic Geology》2008,26(1):29-53
A detailed field study reveals a gradual transition from high‐grade solid‐state banded orthogneiss via stromatic migmatite and schlieren migmatite to irregular, foliation‐parallel bodies of nebulitic migmatite within the eastern part of the Gföhl Unit (Moldanubian domain, Bohemian Massif). The orthogneiss to nebulitic migmatite sequence is characterized by progressive destruction of well‐equilibrated banded microstructure by crystallization of new interstitial phases (Kfs, Pl and Qtz) along feldspar boundaries and by resorption of relict feldspar and biotite. The grain size of all felsic phases decreases continuously, whereas the population density of new phases increases. The new phases preferentially nucleate along high‐energy like–like boundaries causing the development of a regular distribution of individual phases. This evolutionary trend is accompanied by a decrease in grain shape preferred orientation of all felsic phases. To explain these data, a new petrogenetic model is proposed for the origin of felsic migmatites by melt infiltration from an external source into banded orthogneiss during deformation. In this model, infiltrating melt passes pervasively along grain boundaries through the whole‐rock volume and changes completely its macro‐ and microscopic appearance. It is suggested that the individual migmatite types represent different degrees of equilibration between the host rock and migrating melt during exhumation. The melt topology mimicked by feldspar in banded orthogneiss forms elongate pockets oriented at a high angle to the compositional banding, indicating that the melt distribution was controlled by the deformation of the solid framework. The microstructure exhibits features compatible with a combination of dislocation creep and grain boundary sliding deformation mechanisms. The migmatite microstructures developed by granular flow accompanied by melt‐enhanced diffusion and/or melt flow. However, an AMS study and quartz microfabrics suggest that the amount of melt present did not exceed a critical threshold during the deformation to allow free movements of grains. 相似文献
20.
On the Initiation of Metamorphic Sulfide Anatexis 总被引：3，自引：0，他引：3
Mineral assemblages in common sulfide ore deposits are examinedtogether with phase relations to (1) investigate the pressure–temperatureconditions required for the onset of metamorphically inducedpartial melting involving economic minerals, and (2) place constraintson the amount of melt produced. Deposits that contain sulfosaltor telluride minerals may start to melt at conditions rangingfrom lowest greenschist facies to amphibolite facies. Depositslacking sulfosalt and/or telluride minerals may begin to meltonce P–T conditions reach the upper amphibolite facies,if galena is present, or well into the granulite facies if galenais absent. The result is two broad melting domains: a low- tomedium-temperature, low melt volume domain involving meltingof volumetrically minor sulfosalt and/or telluride minerals;and a high-temperature, potentially higher melt volume domaininvolving partial melting of the major sulfide minerals. Epithermalgold deposits, which are especially rich in sulfosalt minerals,are predicted to commence melting at the lowest temperaturesof all sulfide deposit types. Massive Pb–Zn (–Cu)deposits may start to melt in the lower to middle amphibolitefacies if pyrite and arsenopyrite coexist at these conditions,and in the upper amphibolite facies if they do not. Exceptingsulfosalt-bearing occurrences, massive Ni–Cu–PGE(platinum group element) deposits will show little to no meltingunder common crustal metamorphic conditions, whereas disseminatedCu deposits are typically incapable of generating melt untilthe granulite facies is reached, when partial melting commencesin bornite-bearing rocks. The volume of polymetallic melt thatcan be generated in most deposit types is therefore largelya function of the abundance of sulfosalt minerals. Even at granulite-faciesconditions, this volume is usually less than 0·5%. Theexception is massive Pb–Zn deposits, where melt volumessignificantly exceeding 0·5 vol. % may be segregatedinto sulfide magma dykes, allowing mobilization over large distances. KEY WORDS: sulfide melt; ore deposits; melt migration; metamorphism 相似文献