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1.
花岗伟晶岩结构结晶动力学的研究进展 总被引：1，自引：0，他引：1
在地质流体演化方面,花岗伟晶岩位于花岗岩与热液石英脉的过渡位置,对其结构的实验研究对理解火成岩结构具有重要意义。长期以来,花岗伟晶岩被认为是花岗岩浆平衡结晶、缓慢冷却的结果,但近年来的一系列结晶动力学计算和实验发现伟晶岩在过冷却状态下快速生长,其结构主要受到结晶动力学参数的制约,F、B、P等助熔剂和H2O是影响这些参数的主要因素,富助溶剂的硅酸盐水溶液可作为伟晶岩的结晶介质。但由于快速淬火式实验设备的弊端,这些实验只能由淬火后的实验产物估算各类结晶动力学参数,只能以易淬火成玻璃的含水硅酸盐熔体作为结晶介质,只能静态地研究某一过冷却度下的结晶动力学状态。近年来,最新式热液金刚石压腔已经定型,可以模拟包括富助溶剂硅酸盐水溶液在内的各类伟晶岩结晶介质,能够在控制冷却速率的同时原位观测和微束分析晶体生长的动态特征,是模拟伟晶岩结构的理想工具,具有广阔的应用前景。 相似文献
2.
李建康 《吉林大学学报(地球科学版)》2014,44(2):518-526
花岗岩浆液态不混溶作用和饱和H2O花岗岩浆的热液出溶作用是花岗岩类矿床成矿流体形成的重要机制。利用最新式热液金刚石压腔,开展了成矿流体形成机制的原位观测实验。在岩浆热液出溶过程的实验中,初始样品为各类硅酸盐和纯H2O或LiCl水溶液,在H2O饱和状态中,硅酸盐熔体珠不断分异出富H2O的流体。花岗岩浆液态不混溶实验的初始样品为NaAlSi3O8-LiAlSiO4-SiO2-LiCl-H2O。在硅酸盐完全重熔后的降温过程中,硅酸盐熔体珠分离出富H2O熔体相和贫H2O熔体相,压力的突然降低促进了相分离的发生。研究表明：岩浆热液的出溶作用发生在H2O饱和的条件下,是岩浆的“第二次”沸腾作用,对花岗岩型稀有金属矿床的形成具有重要意义;花岗岩浆液态不混溶产生的富H2O熔体易于结晶出粗大晶体,暗示岩浆液态不混溶作用可能是一些花岗伟晶岩形成的主要机制。两类成矿流体形成机制实验条件的差异表明,Li是花岗岩浆发生不混溶作用的重要因素。在今后的研究中,应把热液金刚石压腔的原位观测与微束分析技术结合,在高温高压状态下分析成矿元素的迁移和富集规律。 相似文献
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本文从下述六个方面对岩浆包裹体的研究状况及意义进行评述:1.岩浆包裹体的形成机制和分类;2.岩浆包裹体的测温研究;3.岩浆包裹体的测压研究;4.岩浆包裹体的化学成分;5.利用岩浆包裹体进行实验岩石-矿物学研究:6.岩浆包裹体可做为矿化作用指示剂。虽然有几类异常岩浆包裹体(特别是在月岩样品中)还无法加以解释,但是。岩浆包裹体可以提供大量有关岩浆结晶演化、岩浆不混溶作用、岩浆混合作用、火成侵位时挥发组分的含量、性状及演化、玄武岩浆起源、以及岩浆岩体的潜在含矿标志等重要情报。其中有些资料,从其它来源无法获得。岩浆包裹体研究已经成为现代火成岩石学的一个不可缺少的独立分支,其前景十分广阔。 相似文献
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硅酸盐熔体包裹体的研究,和以模拟实验为主的实验岩石学,实验矿物学一样,已经成为现代岩浆岩石学,尤其是理论岩浆岩石学研究的一个必不可少的组成部分。均匀化测温研究,是硅酸盐熔体包裹体研究的一个重要组成部分。其方法是对于呈封闭系统的硅酸盐熔体包裹体进行加热,在反方向上,再造这些包裹体从结晶到熔融的所有阶段,直至其完全均匀化,也就是恢复到它们被生长着的矿物包含、捕获时的状态,借以测量矿物近液相线或固相线的结晶温度。 相似文献
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Homogenization has proved its effectiveness as a method of upscaling for linear problems, as they occur in single-phase porous media flow for arbitrary heterogeneous rocks. Here we extend the classical homogenization approach to nonlinear problems by considering incompressible, immiscible two-phase porous media flow. The extensions have been based on the principle of preservation of form, stating that the mathematical form of the fine-scale equations should be preserved as much as possible on the coarse scale. This principle leads to the required extensions, while making the physics underlying homogenization transparent. The method is process-independent in a way that coarse-scale results obtained for a particular reservoir can be used in any simulation, irrespective of the scenario that is simulated. Homogenization is based on steady-state flow equations with periodic boundary conditions for the capillary pressure. The resulting equations are solved numerically by two complementary finite element methods. This makes it possible to assess a posteriori error bounds. 相似文献
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Kenji Mibe Masami Kanzaki Kyoko N. Matsukage Shigeaki Ono 《Geochimica et cosmochimica acta》2004,68(24):5189-5195
To determine the second critical end point in silicate-H2O systems, a new method for the direct observations of immiscible fluids has been developed using a synchrotron X-ray radiography technique. High-pressure and high-temperature experiments were carried out with a Kawai-type, double-stage, multi-anvil high-pressure apparatus (SPEED-1500) installed at BL04B1, SPring-8, Japan. The Sr-plagioclase (SrAl2Si2O8)-H2O system was used as an illustrative example. A new sample container composed of a metal (Pt) tube with a pair of lids, made of single crystal diamonds, was used under pressures between 3.0 and 4.3 GPa, and temperatures up to ∼1600°C. The sample in the container could be directly observed through the diamond lids with X-ray radiography. At around 980 to 1060°C and pressures between 3.0 and 4.0 GPa, light gray spherical bubbles moving upward through the dark gray matrix were observed. The light gray spheres that absorb less X-rays represent an aqueous fluid, whereas the dark gray matrix represents a silicate melt. These two immiscible phases (aqueous fluid and silicate melt) were observed up to 4.0 GPa. At 4.3 GPa, no bubbles were observed. These observations suggest that the second critical end point in the Sr-plagioclase-H2O system occurs at around 4.2 ± 0.2 GPa and 1020 ± 50°C. Our new technique can be applied to the direct observations of various systems with two coexisting fluids under deep mantle conditions. 相似文献
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岩浆包裹体化学成分研究 总被引：8，自引：1，他引：8
岩浆包裹体化学成分研究难度较大,为了获得可信的数据,应当注意:1.非演化型岩浆包裹体的化学成分可以代表其初始成分。演化型岩浆包裹体应先均一、淬火后再行测定。2.均一演化型岩浆包裹体应严格遵守加热规则,否则过热作用会使包裹体壁部分熔化,造成淬火后所测包裹体成分与其真正的初始成分并不相当。3.实测资料证明,“边界层效应”对于岩浆包裹体化学成分影响微不足道。4.岩浆包裹体的化学成分只能代表其主矿物结晶时周围岩浆的成分,即仅相当于岩浆液相线上的一个点。5。把显微冷热台测温、激光喇曼探针和电子探针分析技术结合使用,对查明单个包裹体中挥发组分的性状和浓度具有很大的潜力和前途。 相似文献
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ABSTRACT Silicate melt inclusions (SMIs) are small droplets of magma that become trapped in minerals during crystal growth. SMIs in olivine crystals can provide critical information on the range of melt compositions and processes that occur during melt generation, evolution, transport, and eruption. The Pliocene–Quaternary volcanic rocks in the Qorveh–Bijar volcanic belt of western Iran show porphyritic and microlithic textures, with olivine and clinopyroxene being the dominant minerals. Magnesian olivines in these volcanic rocks contain primary SMIs. The composition and characteristic of olivine-hosted SMI of these rocks are investigated to constrain the source lithology for mafic volcanism. Bulk compositions of the SMIs overlap those of their host rocks and extend to higher CaO/Al2O3 values. The estimated entrapment pressures and temperatures of the studied SMIs are 9.1–10.3 kbar and 1220–1355°C. The calculated mafic parental melt contains 42.36 wt.% SiO2, low total alkalis (3.22 wt.%), and high MgO (16.1 wt.%). Exploratory calculations using pMELTS show that this parental composition underwent variable degrees of fractional crystallization, as reflected by the variable compositions of the SMIs. Several lines of evidence including pyroxene xenocrysts and high FeO/MnO, FC3MS (FeO/CaO – 3*MgO/SiO2), and Zn/Fe ratios (14–21), suggest that a metasomatized pyroxenitic source contributed to the genesis of the parental melt. Amphibole in the SMIs indicates a high volatile content in the parental melt, which we conclude was generated from a metasomatized lithospheric mantle source. The pyroxenite source also contained garnet. Our geochemical results lead us to propose a new petrogenetic model. Specifically, we infer that a dense and unstable portion of the lithosphere underwent localized laminar detachment and downward flow, i.e. lithospheric drip. This drip underwent volatile-enhanced partial melting during descent through the underlying hot asthenosphere and generated the studied volcanic rocks. 相似文献
10.
福建永定大坪铌钽矿化花岗斑岩体位于永定县城南部的大石凹-蓝地火山喷发盆地,对斑岩型铌钽矿床的产出具有重要的指示意义。本文通过岩相学、显微测温和激光拉曼等实验对大坪岩体ZK10001和ZK10401钻孔不同深度岩石样品中的流体和熔体包裹体进行了研究,试图揭示岩体的熔体-流体演化过程,分析铌钽等成矿元素的富集机制。观测结果表明,大坪岩体主要发育气液两相盐水溶液包裹体和硅酸盐熔体包裹体。流体包裹体均一温度集中在175～225℃,盐度集中在3%～7%NaCleq,密度集中在0.75～0.95g/cm~3,成矿流体主要为中低温、低盐度和低密度的流体,总体属于H_2O-NaCl体系。熔体包裹体主要分布于石英斑晶雪球结构的环带中,含有钠长石、石英和钽铁矿等子矿物。熔体包裹体完全均一温度较高,能够代表早期原始岩浆的组成。研究表明,大坪岩体的原始岩浆富铌钽等成矿元素和碱性组分,大坪岩体的铌钽矿化是岩浆高度分异的产物,铌钽的富集过程经历了斑晶阶段和基质阶段等两阶段结晶分异过程:在早期斑晶结晶阶段,少量铌钽矿物与斑晶一起结晶,并被斑晶包裹;岩浆演化晚期发生流体出溶现象,但未分异出大量流体,F等挥发分促进了铌钽在结晶残余熔体中富集,并在基质间隙中沉淀。大坪矿化岩体的存在指示出斑岩型铌钽矿床存在的可能性。 相似文献
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Homogenization temperature and salinity were determined for fluid inclusions in mostly quartz and partly sphalerite, cassiterite, and barite from the 28 tin-polymetallic ore deposits in Bolivia. Generally, the homogenization temperatures and salinities of these fluid inclusions are comparatively high for ore deposits formed by cassiterite mineralization, such as Morococala and Avicaya in the Oruro district, frequently indicating a temperature higher than 300°C and salinity higher than 20 equiv. wt% NaCl. Particularly, it is quite possible that tin deposits associated with the W-Bi and tourmaline mineralizations such as Viloco and Caracoles have been produced by such high-temperature hypersaline fluid ranging up to 500°C and 56 equiv. wt% NaCl, similar to the porphyry copper type. This feature reveals that the hydrothermal fluid related to the Sn-W-Bi mineralization may be of magmatic origin. Homogenization temperatures for the Pb-Zn deposits with no tin minerals are low, mostly ranging 170°–300°C. At the Avicaya-Bolivar mining area in the Oruro district as well as at the Tasna and Chocaya-Animas mining areas in the Quechisla district temperature gradients consistent with the zonal distributions of ore minerals were confirmed. 相似文献
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西藏甲玛铜多金属矿床成因研究——来自流体包裹体的证据 总被引：1，自引：0，他引：1
甲玛铜多金属矿床位于西藏冈底斯斑岩铜矿带东段,是近年来勘探发现的超大型斑岩-矽卡岩型铜多金属矿床。通过冷热台显微观察与测温、扫描电镜、激光拉曼探针测试,对甲玛矿床各成矿阶段典型矿物的流体包裹体研究表明,成矿流体富含挥发分,临界相均一的流体来自岩浆超临界流体出溶,主成矿阶段具有沸腾包裹体组合特征,有机质包裹体荧光效应显著。显微测温结果显示,岩浆-热液阶段斑岩中石英斑晶的流体包裹体均一温度范围为250～540℃,含石盐子晶高盐度包裹体盐度范围为35～61(wt%)NaCl.eq,中等盐度的临界均一的气液包裹体盐度范围为3～29(wt%)NaCl.eq,岩浆期后热液阶段斑岩、角岩中石英脉的流体包裹体均一温度范围为210～410℃,盐度范围为33～41(wt%)NaCl.eq,与其不混溶共生的中低盐度气液两相流体包裹体盐度范围为5～25(wt%)NaCl.eq。矽卡岩阶段矿物均一温度范围为130～360℃,盐度范围为3～41(wt%)NaCl.eq,从岩浆热液过渡阶段到石英-硫化物阶段均一温度与盐度呈阶梯式降低趋势。斑岩体石英的流体包裹体中含有较多黄铜矿子矿物,岩浆结晶分异过程中已经具成矿元素的富集。激光拉曼探针测试结果显示,成矿早期至主成矿期矿物流体包裹体气相成分主要为CO2、CH4和N2,各阶段矿物流体包裹体气相成分具有继承性。成矿流体为高温度高盐度,富含CO2、CH4的流体。成矿流体主要源于岩浆,后期混有大气降水。当岩浆热液上升时因压力的突然释放造成高温含矿热流体发生减压沸腾,CO2和CH4等气体大量逃逸,导致成矿物质快速沉淀。矿床在成因上与岩浆-热液成矿作用密切相关。 相似文献
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滇东南南秧田钨矿床位于老君山钨锡多金属成矿区内,大地构造位置位于扬子板块、华夏板块与三江褶皱系的结合部位。钨矿体主要呈似层状赋存于南秧田组,根据不同的矿物组合及穿插关系,可划分出三种矿石类型,即矽卡岩型矿石、石英脉型矿石和碳酸盐型矿石。对南秧田不同矿化类型白钨矿中流体包裹体的岩相学观察后发现该矿床主要发育4类流体包裹体:富液相两相包裹体(Ⅰ类)、富气相两相包裹体(Ⅱ类)、含子矿物三相包裹体(Ⅲ类)和纯气相包裹体(Ⅳ类)。矽卡岩型矿石白钨矿中流体包裹体的均一温度变化于176~311℃,盐度变化于0.2%~10.9%NaCleqv。石英脉型矿石白钨矿中流体包裹体的均一温度变化于200~395℃,盐度变化于0.4%~11.3%NaCleqv。碳酸盐型矿石白钨矿中流体包裹体的均一温度和盐度分别变化于201~395℃和2.6%~11.3%NaCleqv。显微测温结果表明成矿流体属中高温度、中低盐度流体。激光拉曼探针分析表明,白钨矿中流体包裹体组分主要为H2O,含少量的CH4。矽卡岩阶段成矿流体δD值范围为−80.2‰~−78.3‰,δ18O水值为6.8‰,石英脉阶段成矿流体的δD和δ18O水值分别为−93.7‰~−79‰和6.5‰~7.1‰,表明成矿流体主要来自于岩浆水,并可能经历了强烈的去气作用,或者存在不同程度地层有机质、大气降水和孔隙水的混入。流体包裹体均一温度和盐度呈正相关关系及H、O同位素特征综合分析,本研究认为岩浆水与大气降水混合是引起白钨矿沉淀的主要因素。 相似文献
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热液金刚石压腔在地质流体研究中的应用 总被引：6，自引：1，他引：6
热液金刚石压腔(HDAC)是专为模拟地壳温压条件下的地质作用而设计的，它尤其适用于观测水或其它流体与地质物质之间的相互作用。HDAC可时-190～1200℃，0～10GPa的热液体系进行实验，并可在实验的温压条件下．用各种先进的光学方法分析样品，更可以把实验的全程录像存档。充满流体的HDAC本身就可当做是一个人工合成的流体包裹体。因此它可以用来研究流体的状态方程和相关系。它又可时其它流体包裹体样品施加外压力，因此在热分析的过程中可免除包裹体的膨胀或爆破的困境。HDAC可应用到颇为宽广的温压范围，它已被广泛地用来观测各种化学体系的临界现象，包括在地质方面特别有用的含水硅酸盐体系。HDAC也可与同步辐射X光源相结合，而取得各种金属或稀土元素水溶液的x射线吸收精细结构(X-ray absorption fine structure；XAFS)光谱，因而时在热液里的金属或稀土元素络合物的组分和结构提供了最基本的资料。然而，X光的强度在透过金刚石时，因绕射和吸收而大大地减弱，因此应用一般的HDAC来获取那些吸收边在10keV以下的元素的XAFS光谱颇为困难。目前已有两种改良式的HDAC解除了这方面的困难，而时在元素周期表上的第一排过渡性金属元素和稀土元素的水溶液，提供清晰的XAFS光谱。这些资料可用来研究金属或稀土元素络合物在地质热液里的特性，及其在元素迁移和成矿作用方面的效应。而这些元素在地质应用方面特别重要。 相似文献
16.
维拉斯托铅锌矿床发育在大兴安岭南段西坡成矿带内。矿区出露的岩浆岩主要为石英闪长岩、花岗闪长岩以及碱性花岗岩等;矿体严格受断裂构造控制,属典型的热液脉型矿床。矿床的热液期可划分为3个阶段:Ⅰ石英-毒砂-黄铁矿阶段、Ⅱ多金属硫化物-石英阶段和Ⅲ石英-碳酸盐阶段。流体包裹体研究表明,维拉斯托矿床矿石主要发育气液两相、富CH_4以及含CH_4-CO_2的包裹体。Ⅰ阶段3种类型包裹体均发育,Ⅱ阶段以气液两相和含CH_4-CO_2的包裹体为主,Ⅲ阶段仅发育气液两相包裹体。Ⅰ阶段包裹体均一温度范围为243.1℃~398.5℃,盐度为4.8%~12%NaCleqv;Ⅱ阶段均一温度为190.0℃~331.1℃,盐度为3.5%~9.1%NaCleqv;Ⅲ阶段均一温度范围为180.0℃~240.0℃,盐度范围为3.7%~6.7%NaCleqv,显示成矿流体具有中温、低盐度和低密度的特点;激光拉曼光谱分析包裹体气相成分主要为CO_2、CH_4和H_2O。氢、氧同位素分析结果表明成矿流体具有岩浆水和大气降水的混合特征;硫同位素结果显示成矿物质具有深源的特点。综合分析认为,矿床的形成与燕山期中酸性岩浆活动密切相关,深部岩浆在上升过程中与下渗的大气降水发生混合,导致矿物质在近东西向的"S"型压扭性断裂中沉淀并富集成矿。 相似文献
17.
LA-ICPMS analyses of silicate melt inclusions in co-precipitated minerals: Quantification, data analysis and mineral/melt partitioning 总被引：6，自引：0，他引：6
We present a new approach to determine the composition of silicate melt inclusions (SMI) using LA-ICPMS. In this study, we take advantage of the occurrence of SMI in co-precipitated mineral phases to quantify their composition without depending on additional sources of information. Quantitative SMI analyses are obtained by assuming that the ratio of selected elements in SMI trapped in different phases are identical. In addition Fe/Mg exchange equilibrium between olivine and melt was successfully used to quantify LA-ICPMS analyses of SMI in olivine. Results show that compositions of SMI from the different host minerals are identical within their uncertainty. Thus (1) the quantification approach is valid; (2) analyses are not affected by the composition of the host phase; (3) the derived melt compositions are representative of the original melt, excluding significant syn- or postentrapment modification such as boundary layer effects or diffusive reequilibration with the host mineral. With this data we established a large dataset of mineral/melt partition coefficients for the investigated mineral phases in hydrous calc-alkaline basaltic-andesitic melts. The clinopyroxene/melt and plagioclase/melt partition coefficients are consistent with the lattice strain model of Blundy and Wood [Blundy, J., Wood B., 1994. Prediction of crystal-melt partition-coefficients from elastic-moduli. Nature372, 452-454]. 相似文献
18.
Halite precipitation with water and air temperature was observed in detail,and homogenization temperature of fluid inclusions in halite formed in ancient and modem Chaka Salt Lake was studied.Halite precipitates mainly in August every year and largely precipitates between 13 and 15pm at one day when water temperatures reach 20℃but can seldom reach 30℃.Homogenization temperatures of fluid inclusions in halite formed in Chaka Salt Lake range from 14℃to 38℃with an average of 23.7℃.The number of inclusions appears an obvious peak value at homogenization temperatures between 18～25℃,which probably represent the water temperature in which halite mainly precipitates when water temperatures reach 20℃.Therefore,homogenization temperatures of fluid inclusions in halite formed in Chaka Salt Lake can well reflect the water temperature. 相似文献
19.
The Zaldívar porphyry copper deposit, Northern Chile, consists of two major intrusions, the 290 Ma Zaldívar, and the more recent Miocene (38.7 Ma) Llamo porphyry. Five types of inclusions have been identified in quartz phenocrysts from Llamo porphyry, including melt inclusions (M), and four types of fluid inclusions, called MS (multi solids), B (brines), G (vapor-rich) and W (aqueous), respectively.Melt remnants, well preserved as M-inclusions, homogenize around 1000 °C. They show a rhyolitic composition, comparable to the most evolved acidic rhyolitic end member found elsewhere in the regional magmatism and to worldwide volcanic rhyolitic glass. High silica content in some inclusions can, however, be due to partial remelting of the quartz host during the heating run. Copper content in the same inclusions ranges between 0.03 and 0.57 wt.%, with an average concentration of 0.10 wt.%, suggesting a major magmatic source for the copper (orthomagmatic model).MS inclusions, which contain a number of solids at room temperature, mostly H2O-bearing phases (system NaCl–KCl–((Fe, Mg, Cu)Cl)–H2O, average salinity 70 wt.% NaCl equiv.), homogenize at magmatic temperatures (around 1000 °C). They represent the first fluids to have exsolved from the magma at depth, at a pressure of about 2 kbar. Their high homogenization temperature, comparable to values measured for melt inclusions (1000 to 1050 °C), may indicate trapping of MS and M inclusions in host phenocrysts from an immiscible mixture of silicate melt and highly saline fluids expelled from the magma during the early stage of quartz crystallization.The data indicate a magmatic origin for copper, as well as extremely high melt temperatures. These features are interpreted by magmatic differentiation of mantle-derived primitive melts, corresponding to major changes in the tectonic regime of the Andean margin, which occurred in Miocene times. 相似文献
20.
Rosario Esposito Rita Klebesz Omar Bartoli Yury I. Klyukin Daniel Moncada Angela L. Doherty Robert J. Bodnar 《Central European Journal of Geosciences》2012,4(2):208-218
Melt inclusions (MI) trapped in igneous phenocrysts provide one of the best tools available for characterizing magmatic processes. Some MI experience post-entrapment modifications, including crystallization of material on the walls, formation of a vapor bubble containing volatiles originally dissolved in the melt, or partial to complete crystallization of the melt. In these cases, laboratory heating may be necessary to return the MI to its original homogeneous melt state, followed by rapid quenching of the melt to produce a homogeneous glass phase, before microanalyses can be undertaken. Here we describe a series of heating experiments that have been performed on crystallized MI hosted in olivine, clinopyroxene and quartz phenocrysts, using the Linkam TS1400XY microscope heating stage. During the experiments, we have recorded the melting behaviors of the MI up to a maximum temperature of 1360°C. In most of the experiments, the MI were homogenized completely (without crystals or bubbles) and remained homogeneous during quenching to room temperature. The resulting single phase MI contained a homogeneous glass phase. These tests demonstrate the applicability of the Linkam TS1400XY microscope heating stage to homogenize and quench MI to produce homogeneous glasses that can be analyzed with various techniques such as Electron Microprobe (EMP), Secondary Ion Mass Spectrometry (SIMS), Laser ablation Inductively Coupled Plasma Mass Spectrometry (LA ICP-MS), Raman spectroscopy, FTIR spectroscopy, etc. During heating experiments, the optical quality varied greatly between samples and was a function of not only the temperature of observation, but also on the amount of matrix glass attached to the phenocryst, the presence of other MI in the sample which are connected to the outside of the crystal, and the existence of mineral inclusions in the host. 相似文献