黑云母的红外光谱研究

关于云母族矿物的红外光谱研究,国内外一些学者曾做过不少工作。笔者就近年来所收集到的一些产自宁芜地区、南岭地区花岗岩类岩石中27个黑云母样品,进行了红外光谱测定,确定了某些特征吸收峰的偏移及其与化学组分之间的关系,并探讨了黑云母矿物中主要金属阳离子的相互置换和晶体结构的关系。 黑云母属三八面体型的2∶1层状结构硅酸盐矿物。结构中上下四面体片(T)以尖顶相对,中间夹氢氧镁石型[Mg—O_4(OH)_2]八面体片(O),构成T—O—T型结构层。占有四面体晶位的阳离子主要为Si,约有1/4的Si可被R~(3+)(主要为Al~(3+)、次为Fe~(3+))取代。占有八面体晶位的阳离子主要为Mg~(2+)或Fe~(2+),次为Fe~(3+)、Al~(3+)、Mn~(2+)等。由T—O—T所组成的结构层则通过层间大阳离子K~+(少量的Na~+、Ca~(2+)等)彼此相连接。结构     

基于地物光谱特征的成像光谱遥感矿物识别方法

成像光谱技术是遥感技术发展的前沿技术之一 ,它是在可见光、近红外及短波红外上 ,集图像、光谱于一体的具有高光谱分辨率的纳米遥感技术。文中从岩矿光谱特性的研究入手 ,通过光谱特征识别准则 ,利用机载的可见光、近红外及短波红外成像光谱 (HyMap)数据 ,开展成像光谱遥感矿物识别的试验研究。试验识别的矿物有绿泥石、绿帘石、橄榄石、绢云母、滑石、石膏及黑云母等。试验结果表明 ,通过矿物光谱特征分析与其识别原则进行成像光谱遥感矿物识别获得了很好的效果。因此 ,基于地物光谱特征进行成像光谱矿物直接识别确实可行 ,有利于矿产资源评价中成矿物源和矿化蚀变信息分析。     

赣南钨矿床中黑钨矿和白钨矿的红外光谱

赣南钨矿产于燕山早期黑云母花岗岩体内外接触带,主要属气成—高温热液成因,为含钨石英大脉型及细脉带型矿床。前人对本区主要工业矿物黑钨矿和白钨矿进行过大量的工作,但红外光谱的研究较少。本文仅对上述矿物的红外光谱特征及其影响因素作初步探讨。     

吉林省小西南岔含银金矿床石英脉含矿性的红外光谱评价

石英是原生金银矿物的主要载体矿物。利用红外光谱方法测定石英包裹体中H_2O和CO_2的相对光密度D_1和D_2,统计分析Au、Ag与D_1、D_2之间的相关性,从而得出Au、Ag含量的红外光谱定量评价指标,可作为该地区进一步找矿的红外光谱标志。     

赣南钨矿床中黑钨矿和白钨矿的红外光谱探讨

赣南钨矿主要属气成一高温热液成因,为含钨石英大脉型及细脉带型矿床,产于燕山早期黑云母花岗岩体内外接触带。前人对本区主要工业矿物黑钨矿和白钨矿已进行过大量而系统的工作。而这些矿物的红外光谱还未见报导,笔者曾对江西漂圹、西华山、荡萍等点钨矿中的黑钨矿、白钨矿等进行过野外观察采样及室内测试研究。现仅将上述矿物的红外光谱特征、谱带归属及影响因素作初步探讨于下。     

计算机差谱技术在矿物红外光谱研究中的应用

在矿物红外光谱研究中运用差谱技术可消除其它矿物相谱带的覆盖,鉴定混合相中微量矿物成分,并得到单矿物谱图。 本文通过两个实例,介绍计算机差谱技术的特点、操作要点。云南腾冲热泉地区的粘土样品,用Perkin-Elmer983型红外分光光度计和3600数据站配合,应用视屏差减程序(Screen Diffe-rence)剥离掉主要组成矿物玉髓的红外光谱后,清晰显示出微量矿物明矾石的单矿物谱。西藏羊应乡热泉地区的岩心经处理后得到的粘粒,用计算机差谱技术进行多次剥离,得到一系列差减光谱,经确定,其矿物相为高岭石、蒙脱石、伊利石、石英、钠长石和微斜长石。     

江苏凹凸棒石,高岭石的红外吸收光谱法定量分析研究

利用红外光谱法进行矿物成份定量分析,是近年发展起来的一种新的矿物定量分析方法,这种方法快速简便,有一定精度,有推广价值。我们应用红外分光光度计,进行了江苏盱眙龙王山,拥小山地区凹凸棒石粘土中凹凸棒石含量和江宁地区祖堂山高岭石矿中高岭石含量的红外光谱定量分析试验,取得了较好的效果。粘土矿物的定量分析目前手段较少,一直是矿物研究中的薄弱     

花岗岩中黑云母风化的矿物变化机制

对采自广东阳江花岗岩风化剖面的黑云母及其风化产物进行了Ｘ射线衍射,扫描电子显微镜及能谱,高分辨率透射电子显微镜等分析,并探讨了黑云母风化过程中成分的变化及矿物的转化机制。研究结果表明：阳江地区花岗岩中黑云母的风化系列为黑云母→蛭石,绿泥石→伊利石／绿泥石,高岭石,黑云母风化初期的蛭石和绿泥石是独立的矿物相,而不是通常认为的水黑云母,而混层矿物伊利石／绿泥石的出现则表明了以黑云母风化程度为指标的深度     

热红外高光谱技术在地质找矿中的应用综述

热红外高光谱技术（6~14μm）是一种新兴的绿色地质找矿技术,它通过分析矿物热红外光谱特征,开展矿物信息提取及填图应用研究,进而指导找矿勘查。比起发展相对成熟的短波红外（1.1~2.5μm）高光谱技术,它对于短波红外波段无法识别的石英、长石、石榴子石、橄榄石、辉石、碳酸盐矿物、黑云母、角闪石、磷灰石等矿物具有更加敏感的探测能力。目前,热红外在地质找矿中的研究尚处于初级阶段,很多科学问题尚待解决。矿物化学成分的变化是引起热红外波谱特征变化的最重要因素,这也是开展矿物识别与提取的理论基础,本文首次系统分析了不同波谱库及文献中的热红外波谱,总结了上述典型矿物的热红外波谱特征,揭示了矿物的诊断性波段与识别标志。而后将热红外高光谱技术分为地面热红外光谱数据分析技术与空中热红外图像处理技术两大方向,其中地面热红外技术主要基于岩芯或地表样品的波谱特征,开展矿物精细填图研究,建立矿床的找矿勘查模型;空中热红外技术基于图像处理与分析,提取区域矿物分布信息,为找矿指明方向。最后本文指出了未来热红外高光谱技术在地质找矿中的技术难点及热点,即高精度热红外高光谱仪器的研发、矿物热红外光谱的快速识别技术、热红外图像信息提取算法的优化。     

盐矿物的红外吸收光谱

红外吸收光谱是各种化合物的最重要的特征。根据化合物的红外吸收光谱,研究各种物质的结构和成分,已是重要的现代方法之一。随着仪器的不断改进和样品制备技术的日益完善,红外光谱在矿物学研究的应用上日趋广泛。不同的矿物有着不同的红外吸收光谱。单个矿物红外光谱的唯一性是鉴定矿物的主要依据。在光谱的红外区域被矿物吸收的射线的波长与晶体中分子或原子间的振动有关。     

碳酸岩岩浆演化的指示性矿物—环带金云母——以山东西部雪野碳酸岩为例

山东西部莱芜－淄博地区的中生代雪野碳酸岩中发育有大量罕见的反环带云母，云母的电子探针分析表明，云母斑晶的核心为黑云母，过渡带和边缘是金云母，基质中云母为金云母，核心黑云母与过渡带的金云母界限清晰，成分突变以及核心黑云母的溶蚀结构表明，核心黑云母和过渡带与边缘带金云母不是同一岩浆体系结晶的产物，核心黑云母可能是碳酸岩岩浆捕获的外来黑云母，过渡带与边缘带金云母同基质中金云母具有相似的化学成分，从过渡带到边缘带，金云母的Mg(Mg Fe)逐渐降低，反映了碳酸岩岩浆的不断结晶演化过程，TiO2的不断降低，一方面是由于岩浆的分异结晶，另一方面则是岩浆上升期间去气作用导致岩浆内CO2／H2O值降低所致。云母斑晶从过渡带向边缘带Al2O3含量逐渐减少，表明碳酸岩浆自过渡带云母结晶后没有富Al的圈岩物质加入。     

北京房山岩体黑云母矿物化学特征及其对岩石成因的指示意义

房山岩体位于华北克拉通燕山构造带内,在平面上为不对称环状分布的复式侵入体.其主要由多期侵入的花岗闪长质岩石组成,被划分为中央相、过渡相和边缘相3个岩相带,岩体内部分布大量的暗色镁铁质微粒包体.黑云母作为中酸性火成岩中重要的镁铁质矿物,其矿物化学特征可以记录岩浆属性以及岩石形成时的物理化学条件.本研究对房山花岗岩体和暗色镁铁质微粒包体中的黑云母进行了系统的岩相学观察,并通过电子探针分析对黑云母的化学组成进行了详细研究,从而探讨房山花岗岩体的岩浆来源以及岩浆混合作用过程.结果表明,花岗岩体和暗色镁铁质微粒包体中的黑云母具有相似的矿物化学成分.花岗岩体中的黑云母富Mg,贫Fe,属于镁质黑云母.从外向内3个相带的花岗岩中黑云母的含铁系数[（Fe3++Fe2+）/（Fe3++Fe2++Mg2+）]分别为0.42~0.47,0.45~0.47,0.41~0.46.FeOT/MgO均接近0.60.MF值[2×Mg/（Fe2++Mg+Mn）]分别为1.05~1.21,1.06~1.15,1.12~1.23,指示3个相带的花岗岩的物质来源均发生了壳幔混染.从外向内3个相带中的暗色镁铁质微粒包体中的黑云母富Mg,贫Fe,属于镁质黑云母,含铁系数[（Fe3++Fe2+）/（Fe3++Fe2++Mg2+）]分别为0.44~0.48,0.45~0.50,0.44~0.52.FeOT/MgO均接近0.60.MF值[2×Mg/（Fe2++Mg+Mn）]分别为1.00~1.16,1.03~1.15,1.10~1.18,说明包体的岩浆受到了中酸性岩浆的影响,发生了岩浆混合.花岗岩体与暗色镁铁质微粒包体中的黑云母矿物化学特征相似,但不同岩相带之间存在差异,推测该区域发生了一个多阶段的岩浆相互作用过程,可能为幔源基性岩浆注入壳源酸性岩浆,在岩浆房内以不同程度进行了岩浆混合.      

Chemical mineralogy of some cordierite-bearing rocks near Yellowknife,Northwest Territories,Canada

Meta-graywacke and meta-argillite of Archean age near Yellowknife contain biotite, cordierite, gedrite and sillimanite isograds towards the Sparrow Lake granite pluton. The chemistry of biotite, cordierite, gedrite and garnet in rocks that up-grade from the cordierite isograd indicate a small range of chemical composition, particularly with reference to Mg, Fe and Mn. The analyses show further that among the coexisting ferromagnesian minerals Fe/Fe+ Mg ratio decreases in the sequence: garnet, gedrite, biotite, cordierite while Mn/Fe+Mg+Mn ratio decreases in the sequence garnet, gedrite, cordierite, biotite. The same order is also observed in the distribution diagrams. The regular distribution of Mg, Fe and Mn among the coexisting phases demonstrate that chemical equilibrium was attained and preserved in these Archean rocks. Mg-Fe distribution between cordierite and biotite appears to be dependent on the temperature of crystallization or metamorphic grade.     

A field and theoretical analysis of garnet+chlorite+chloritoid+biotite assemblages from the tri-state (MA,CT, NY) area,USA

The prograde evolution of minerals in metapelites of a Barrovian sequence from the tri-state area (Massachusetts, Connecticut, New York) of the Taconic Range involves assemblages with garnet (Ga), chlorite (Ch), chloritoid (Ct), biotite (Bi) and staurolite (St). Detailed petrologic observations, mineral compositions and chemical zoning in garnet show: (1) garnet high in Mn and Fe but low in Mg is stable with chlorite at grades below those where chloritoid+biotite is found; (2) early formed garnet reacted partially to form Ct+Bi at intermediate grades; (3) at higher grades garnet (with low Mn)+chlorite is again produced, at the expense of chloritoid+biotite, suggesting a reversal in the continuous reaction involving the phases Ga, Ch, Ct and Bi. Thermodynamic modeling of the assemblage Ga+Ch+Ct+Bi±St in the MnKFMASH system reveals: (1) in the MnKFASH system the prograde reaction is Ga+Ch=Ct+Bi whereas in the KFMASH system the prograde reaction is the opposite: Ct+Bi=Ga+Ch; (2) the Ga–Ch–Ct–Bi–St invariant point in the KFMASH system occurs twice, at approximately 6.5 kbar, 545° C and 14.8 kbar, 580° C (although one of them may be metastable in a complex phase system); the appearance of the petrogenetic grid is markedly different from that of Albee, but similar to that of Spear and Cheney; (3) as a consequence, in the KFMASH system, chloritoid+biotite are stable over a wide range of P-T conditions whereas garnet+chlorite assemblages are restricted to a narrow band of P-T conditions; (4) MnO increases the stability field of Ga+Ch relative to both Ct+Bi at low temperatures, and St+Bi at high temperatures; (5) in natural samples the occurrence of Ct+Bi is controlled more by bulk Mg–Fe(-Mn) composition than P-T conditions. Specifically, Ct+Bi is restricted to bulk compositions with Fe/(Mg+Fe+Mn)>0.6. Rocks with Fe/(Mg+Fe+Mn)<0.5 are likely to display only chlorite+biotite at low grade. These observations are consistent with Wang and Spear and Spear and Cheney.     

Recalibration of mutually consistent garnet–biotite and garnet–cordierite geothermometers

Garnet–biotite and garnet–cordierite geothermometers have been consistently calibrated, using the results of Fe²⁺–Mg cation exchange experiments and utilizing recently evaluated nonideal mixing properties of garnet. Nonideal mixing parameters of biotite (including Fe, Mg, Al^VI, and Ti) and of cordierite (involving Fe and Mg) are evaluated in terms of iterative multiple least-square regressions of the experimental results. Assuming the presence of ferric Fe in biotite in relation to the coexisting Fe-oxide phases (Case A), and assuming the absence of ferric Fe in biotite (Case B), two formulae of garnet–biotite thermometer have been derived. The garnet–cordierite geothermometer was constructed using Margules parameters of garnet adopted in the garnet–biotite geothermometers. The newly calibrated garnet–biotite and garnet–cordierite thermometers clearly show improved conformity in the calculated temperatures. The thermometers give temperatures that are consistent with each other using natural garnet–biotite–cordierite assemblages within ±50 °C. The effects of ferric Fe in biotite on garnet–biotite thermometry have been evaluated comparing the two calibrations of the thermometer. The effects are significant; it is clarified that taking ferric Fe content in biotite into account leads to less dispersion of thermometric results.     

Pressure, temperature and cooling rates of granulite facies migmatitic pelites from the southern Adirondack Highlands, New York

Detailed petrographic analysis was performed on samples from five localities within the southern Adirondacks. Textures and zoning patterns in garnet from all samples provide evidence for dehydration melting of biotite. Zoning of grossular in garnet – providing a record of prograde growth – shows both increasing and decreasing trends in garnet from the same sample. However, Ca concentrations at the garnet rims of most samples are identical (grossular = 3.4%). These observations have been interpreted as evidence for the differential timing of garnet nucleation and growth. All Fe/(Fe + Mg) and some spessartine distributions are consistent between samples, displaying diffusive profiles established largely upon cooling. Only one sample, in which retrogression was minimal, contains garnet with flat Fe/(Fe + Mg) profiles. A general pelitic pseudosection constructed in the system MnNCKFMASH reveals a maximum for Ca in garnet where the plagioclase‐out isopleth intersects the solidus (muscovite = 0). The pseudosection predicts bell‐shaped core‐to‐rim profiles of grossular during anatexis, similar to those observed in the rocks. Garnet–biotite thermometry and GASP barometry indicate peak temperatures of at least 790 °C at about 7–9 kbar, similar to conditions determined for the central Adirondacks. Cooling rates determined from finite difference modelling of spessartine and Fe/(Fe + Mg) diffusional profiles indicate a multi‐stage cooling history in which some period of rapid cooling (>200 °C Myr^?1) is required.     

Garnet-bearing granite from the Třebíč pluton, Bohemian Massif (Czech Republic)

Summary Garnet occurs as a significant mineral constituent of felsic garnet-biotite granite in the southern edge of the Třebíč pluton. Two textural groups of garnet were recognized on the basis of their shape and relationship to biotite. Group I garnets are 1.5–2.5 mm, euhedral grains which have no reaction relationship with biotite. They are zoned having high X_Mn at the rims and are considered as magmatic. Group II garnets form grain aggregates up to 2.5 cm in size, with anhedral shape of individual grains. The individual garnet II grains are usually rimmed by biotite and have no compositional zoning. The core of group I garnets and group II garnets contains 67–80 mol% of almandine, 5–19 mol% of pyrope, 7–17 mol% of spessartine and 2–4 mol% of grossular. Biotite occurs in two generations; both are magnesian siderophyllites with Fe/(Fe + Mg) = 0.50–0.69. The matrix biotite in granites (biotite I) has high Ti content (0.09–0.31 apfu) and Fe/(Fe + Mg) ratio between 0.50 and 0.59. Biotite II forms reaction rims around garnet, is poor in Ti (0.00–0.06 apfu) and has a Fe/(Fe + Mg) ratio between 0.61 and 0.69. The textural relationship between biotite and garnet indicates that garnet reacted with granitic melt to form Ti-poor biotite and a new granitic melt, depleted in Ti and Mg and enriched in Fe and Al. In contrast to the host durbachites (hornblende-biotite melagranites), which originated by mixing of crustal melts and upper mantle melts, the origin of garnet-bearing granites is related to partial melting of the aluminium-rich metamorphic series of the Moldanubian Zone.     

Mineral reactions participating in intragranular fracture propagation: implications for stress corrosion cracking

Two examples of mineral reactions accompanying intragranular fracturing of silicates are described from amphibolites at the Grenville front, Coniston, Ontario, and a granodiorite within the Miéville shear zone, Switzerland. At these localities coarse grained (> 1 mm) hornblende and biotite respectively have undergone initial deformation by intense transgranular fracturing. The ambient temperature of deformation is estimated at 400–500°C for the amphibolites, and 250–300°C for the granodiorite.Fracture intensity within hornblende increases with progressive deformation until fractures coalesce and grains lose cohesion. Fractures are occupied by hornblende in close optical continuity with the parent grain, and typically contain median sutures decorated by arrays of solid inclusions. Relative to the parent grain, hornblende in fractures is depleted in Ti, Al, plus K, and enriched in Mg. Given the preferential partitioning of Mg, Al^VI and Ti into the M2 site of calcic amphiboles, the decrease of Ti and Al^VI in the host-to-crack transition is consistent with the corresponding increase of the Mg/(Mg + Fe²⁺) ratio.Fractures within biotite are bounded by an envelope of paler brown biotite which corresponds to a decrease of Ti and increase of Fe + Mg relative to regions unaffected by cracking. Fractures are occupied by secondary ilmenite, low-Ti biotite and high-Ti muscovite. Ti and Al do not vary significantly as a function of Mg/(Fe + Mg) in the host-to-crack transition, as anticipated from the approximately equal partitioning of these two cations into the M1 and M2 octahedral cation sites. The direct relationship of the mineral reactions to the fractures is taken as evidence for the participation of the reactions in crack propagation. These features may thus represent examples of natural stress corrosion cracking.     

Phase equilibria and the pressure-temperature path of the highest-grade Ryoke metamorphic rocks in the Yanai district, SW Japan

The garnet-cordierite zone, the highest-grade zone of the Ryoke metamorphic rocks in the Yanai district, SW Japan, is defined by the coexistence of garnet and cordierite in pelitic rocks. Three assemblages in this zone are studied in detail, i.e. spinel + cordierite + biotite, garnet + cordierite + biotite and garnet + biotite, all of which contain quartz, K-feldspar and plagioclase. The Mg/(Fe + Mg) in the coexisting minerals decreases in the following order: cordierite, biotite, garnet and spinel. Two facts described below are inconsistent with the paragenetic relation in the K₂OFeOMgOAl₂O₃SiO₂H₂O (KFMASH) system in terms of an isophysical variation. First, garnet and biotite in the last assemblage have Mg/(Fe + Mg) higher than those in the second. Second, the first two assemblages are described by the reaction,

A petrogenetic grid for pelitic schists in the system SiO2-Al2O3-FeO-MgO-K2O-H2O

A quantitative petrogenetic grid for pelitic schists in the system KFMASH that includes the phases garnet, chlorite, biotite, chloritoid, cordierite, staurolite, talc, kyanite, andalusite, sillimanite, and pyrophyllite (with quartz, H₂O and muscovite or K-feldspar in excess) is presented. The grid is based on thermodynamic data of Berman et al. (1985) and Berman (1988) for endmember KFASH and KMASH equilibria and natural Fe-Mg partitioning for the KFMASH system. Calculation of P-T slopes and the change in Fe/(Fe+Mg) along reactions in the KFMASH system were made using the Gibbs method. In addition, the effect on the grid of MnO and CaO is evaluated quantitatively. The resulting grid is consistent with typical Buchan and Barrovian parageneses at medium to high grades. At low grades, the grid predicts an extensive stability field for the paragenesis chloritoid+biotite which arises because of the unusual facing of the reaction chloritoid+biotite + quartz+H₂O = garnet+chlorite+muscovite, which proceeds to the right with increasing T in the KFMASH system. However, the reaction proceeds to the left with increasing T in the MnKFASH system so the assemblage chloritoid + biotite is restricted to bulk compositions with high Fe/(Fe+Mg+Mn). Typical metapelites will therefore contain garnet+chlorite at low grades rather than chloritoid + biotite.