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1.
Graphitization in a high-pressure,low-temperature metamorphic gradient: a Raman microspectroscopy and HRTEM study 总被引：6，自引：0，他引：6
Olivier Beyssac Jean-Noël Rouzaud Bruno Goffé Fabrice Brunet Christian Chopin 《Contributions to Mineralogy and Petrology》2002,143(1):19-31
The graphitization of carbonaceous material (CM) in a high-pressure metamorphic gradient is characterized along a cross section in the Schistes Lustrés formation, Western Alps. Along this 25-km cross section, both the CM precursor and the host-rock lithology are homogeneous, and the prograde evolution of the pressure-temperature metamorphic conditions from the lower blueschist-facies (13 kbar, 330 °C) to the eclogite-facies (20 kbar, 500 °C) is tightly constrained by literature data. Raman microspectroscopy shows that at the micrometre scale, this process is progressive and continuous with increasing metamorphic grade, and that the structure of CM is very sensitive to temperature variations. At the nanometre scale (HRTEM), the CM is composed of a mixture of a microporous phase and an onion-ring like phase, both known as non-graphitizing under the effect of temperature at ambient pressure. The HP-LT graphitization produces structurally and microtexturally heterogeneous CM. With increasing metamorphic grade, the graphitization of the two types of CM proceeds up to the triperiodic graphite stage because of microtextural and structural changes that are specific to each type of CM. The microporous material is progressively transformed into graphite through a macroporous transitional stage. In this case, graphitization mainly occurs on the pore walls as a result of pore growth. In the case of concentric onion-ring like material, graphitization occurs in the regions with the largest radius of curvature, i.e. on the outer part of the ring. In comparison with 1-bar experiments, pressure seems to induce microtextural changes, which allows the subsequent structural modifications of the starting material. 相似文献
2.
含金毒砂中晶格金的确定及其形成机理研究 总被引：7，自引：0，他引：7
利用电子探针(EPMA)和高分辨透射电子图像(HRTEM)分析技术,对湖南黄金洞金矿含金毒砂进行了背散射电子图像、X-射线面扫描、定量微区分析、线分析以及高分辨晶体结构观测等综合研究。结果表明,含金毒砂中没有发现纳米级乃至更小粒级的超显微包体金,毒砂晶格完整,无任何“异构体”,Au散布于整个毒砂颗粒中,以晶格金形式存在。此外,金含量在不同的生长环带中有显著变化,表明Au是在毒砂形成过程中进入其晶格的。金的加入导致毒砂晶体结构中(100)面网间距局部变宽,晶胞参数也发生了微弱变化,a轴变长。详细分析认为,Au主要是以Au~(3+)替代Fe~(3+)进入AsS~(3-)八面体空位中的,Eh值变化可能是控制毒砂中晶格金形成的主要因素。 相似文献
3.
Previous cryogenic Raman spectroscopic analysis of H2O-NaCl-CaCl2 solutions has identified the Raman peaks of various hydrates of NaCl and CaCl2,and established a linear relationship between Raman band intensity of the hydrates and the composition of the solution(NaCl/（NaCl+CaCl2） molar ratio,or XNaC1) using synthetic fluids,which created the opportunity to quantitatively determine the solute composition of aqueous fluid inclusions with cryogenic Raman spectroscopy.This paper aims to test the feasibility of this newly established method with natural fluid inclusions.Twenty-five fluid inclusions in quartz from various occurrences which show a high degree of freezing during the cooling processes were carefully chosen for cryogenic Raman analysis.XNaCl was calculated using their spectra and an equation established in a previous study.These inclusions were then analyzed with the thermal decrepitation-SEM-EDS method.The XNaCl values estimated from the two methods show a 1:1 correlation,indicating that the new,non-destructive cryogenic Raman spectroscopic analysis method can indeed be used for fluid inclusion compositional study. 相似文献
4.
M. AOYA Y. KOUKETSU S. ENDO H. SHIMIZU T. MIZUKAMI D. NAKAMURA S. WALLIS 《Journal of Metamorphic Geology》2010,28(9):895-914
The degree of graphitization of carbonaceous material (CM) has been widely used as an indicator of metamorphic grade. Previous work has demonstrated that peak metamorphic temperature (T) of regional metamorphic rocks can be estimated by an area ratio (R2) of peaks recognized in Raman spectra of CM. The applicability of this method to low‐pressure (<3 kbar) contact metamorphism was tested using Raman spectroscopic analyses of samples from two contact‐metamorphic aureoles in Japan (Daimonji and Kasuga areas). A suitable measurement procedure allows the dependence of the geothermometer on sample type (thin section, chip) and incident angle of laser beam relative to the c‐axes of CM to be tested. Two important general results are: (i) in addition to standard thin sections, chips are also suitable for spectral analysis; and (ii) the incident angle of the laser beam does not significantly affect the temperature estimation, i.e. spectral measurements for the geothermometer can be carried out irrespective of the crystallographic orientation. A laser wavelength of 532 nm was used in this study compared with 514.5 nm in an independent previous study. A comparison shows that the use of a 532‐nm laser results in a slightly, but systematically larger R2 ratio than that of a 514.5‐nm laser. Taking this effect into account, our results show that there is a slight but distinct difference between the R2–T correlations shown by contact and regional metamorphic rocks: the former are slightly better‐crystallized (have slightly lower R2 values) than the latter at the same temperature. This difference is interpreted as due to the degree of associated deformation. Despite the slight difference, the results of this study coincide within the estimated errors of ±50 °C with those of the previously proposed Raman CM geothermometer, thus demonstrating the applicability of this method to contact metamorphism. To facilitate more precise temperature estimates in regions of contact metamorphism, a new calibration for analyses using a 532‐nm laser is derived. Another important observation is that the R2 ratio of metamorphosed CM in pelitic and psammitic rocks is highly heterogeneous with respect to a single sample. To obtain a reliable temperature estimate, the average R2 value must be determined by using a substantial number of measurements (usually N > 50) that adequately reflects the range of sample heterogeneity. Using this procedure (with 532‐nm laser) and adapting our new calibration, the errors of the Raman CM geothermometer for contact metamorphic rocks decrease to ～±30 °C. 相似文献
5.
泗滨砭石的岩石矿物研究Ⅱ:矿物组成特征与红外发射功能的关系 总被引：2，自引：0，他引：2
为进一步查明泗滨砭石的矿物组成特征与砭石良好的红外发射功能间的关系,用激光喇曼光谱和高分辨透射电镜对砭石样品进行了研究.喇曼光谱研究除证实样品含有微米晶黄铁矿、石墨和锐钛矿外,还发现方解石、黄铁矿和锐钛矿的谱图上均有石墨的两个谱峰.TEM和HRTEM观察发现方解石全由纳米品组成,并普遍有石墨纳米粒子产出.纳米晶石墨多分布于方解石晶界间.4种矿物中纳米晶方解石含量最高,热容也最大,是泗滨砭石具有良好热辐射性质最重要的矿物学背景条件.纳米晶石墨的普遍存在提高了岩石整体导热和储热性能,其优良的热红外发射性能也是造成泗滨砭石在远红外波段具有很高发射率的一个重要原因.黄铁矿具有良好的热电性,而锐钛矿的红外线吸收和反射能力都较强、光电转换效率也高,它们也是泗滨砭石具有良好的热发射性能的一个辅助原因.上述4种矿物良好物理性质的共同作用,使加热后的泗滨砭石具有疏通经络、活血化淤、调理气血等重要的理疗功效,中医砭术在医疗保健上所利用的也正是砭石能辐射对人体有益的远红外线功能. 相似文献
6.
7.
Raman spectrum of carbonaceous material: a possible metamorphic grade indicator for low-grade metamorphic rocks 总被引：7，自引：0，他引：7
Raman spectral analyses of carbonaceous material (CM) extracted from pelitic samples along two sections traversing the metamorphic belt of Taiwan were carried out in the present study. The results show similar spectral variations of CM with metamorphic grade as those documented in the literature. However, continuous sampling from zeolite facies through prehnite–pumpellyite facies to greenschist facies metamorphic rocks in the present study does reveal some interesting features on the Raman spectra of CM that were not noted before. Both the Raman D (disordered-)/O (ordered-) peak area (i.e. integrated intensity) ratio and the D/O peak width (i.e. full width at half maximum, FWHM) ratio of the CM decrease with progressive metamorphism, but the most prominent change in the D/O peak area ratio occurs in samples of lower greenschist facies metamorphic grade, while the most significant decrease in the D/O peak width ratio occurs in samples near the boundary of prehnite–pumpellyite facies and greenschist facies. This phenomenon is interpreted as a result of the decoupling of the changing rates of in-plane crystallite size and degree of defects of CM with progressive metamorphism. It is postulated that the Raman spectrum of CM can serve as a metamorphic grade indicator to distinguish samples of prehnite–pumpellyite facies metamorphic grade from those of greenschist facies metamorphic grade. 相似文献
8.
The present study deals with the direct determination of colloidal forms of iron in river-borne solids from main rivers of the Amazon Basin. The contribution of different forms of colloidal iron have been assessed using ultrafiltration associated with various techniques including electron paramagnetic resonance spectroscopy (EPR), high resolution transmission electron microscopy (HRTEM), and micro proton-induced X ray emission analysis (μPIXE). EPR shows the presence of Fe3+ bound to organic matter (Fe3+-OM) and colloidal iron oxides. Quantitative estimate of Fe3+-OM content in colloidal matter ranges from 0.1 to 1.6 weight % of dried solids and decreases as the pH of the river increases in the range 4 to 6.8. The modeling of the field data with the Equilibrium Calculation of Speciation and Transport (ECOSAT) code demonstrates that this trend is indicative of a geochemical control resulting from the solubility equilibrium of Fe oxyhydroxide phase and Fe binding to organic matter. Combining EPR and μPIXE data quantitatively confirms the presence of colloidal iron phase (min. 35 to 65% of iron content), assuming no divalent Fe is present. In the Rio Negro, HRTEM specifies the nature of colloidal iron phase mainly as ferrihydrite particles of circa 20 to 50 Å associated with organic matter. The geochemical forms of colloidal iron differentiate the pedoclimatic regions drained by the different rivers, corresponding to different major weathering/erosion processes. Modeling allows the calculation of the speciation of iron as mineral, organic and dissolved phases in the studied rivers. 相似文献
9.
10.
水钠锰矿为自然界中常见的锰氧化物矿物,其离子交换作用及结构转变理解尚不深刻,矿物表征手段较为局限.为探究水钠锰矿的离子交换特性以及结构转变在拉曼光谱上的反映,利用MnSO4和NaOH合成了三斜晶系的Na型水钠锰矿,进行了NH4+、K+、Mg2+、Ca2+、Ba2+、Co2+、Zn2+的离子交换实验,使用ICP-OES、XRD、拉曼光谱等手段对离子交换水钠锰矿进行表征.拉曼光谱分析表明,570~585 cm-1与640~655 cm-1两个锰氧八面体伸缩振动模式的相对强度及570~585 cm-1附近拉曼峰峰位指示水钠锰矿的结构对称型;570~585 cm-1拉曼峰强度大、振动频率高指示三斜对称型.280 cm-1与500 cm-1附近的拉曼峰是层间离子种类的识别标志.水钠锰矿层间若为Na+、K+、Mg2+、Ca2+、Ba2+等碱金属、碱土金属离子,则在280 cm-1附近存在1个峰值,500 cm-1存在2个分立的峰值;其他种类的层间离子仅500 cm-1处有1个孤峰,指示层间离子排列无序. 相似文献
11.
Room-temperature-polarized single-crystal Raman spectra have been measured for both GdAlO3 and YAlO3. Both aluminates crystallize in the orthorhombic (Pbnm) perovskite structure. Of the 24 possible Raman modes in 4 symmetries,
20 and 17 modes were observed for gadolinium and yttrium aluminates, respectively. Comparisons of the Raman spectra of these
two aluminates to those of 28 other orthorhombic ABO3 perovskites revealed remarkably similar spectral patterns, regardless of chemistry or valency of the cations. Closer examination
of the effect of mass, valencies, and size of the cations on the Raman spectra versus composition revealed that for the observed
modes, the A cation plays the dominant role in determining the Raman shift. In particular, the one to two lowest energy modes
in each symmetry are determined by cation mass and valency no matter what the chemistry. For some perovskites with common
A cations, higher energy modes were also strikingly similar. In particular, the calcium perovskites had almost all Ag modes at the same energies despite the greatly varying B cations. The second to the lowest mode in Ag and B1g depended only on A cation mass for all perovskites. The volume plays a minor role throughout but is hard to separate from
mass effects because the most massive cations are also the largest. However, if the B-cation is common, for example, aluminates
or ferrites, the volume has a minor effect on the higher energy modes. These trends were not observed for all perovskites.
Notable exceptions were found if a perovskite is near a phase transition or metastable, as found for three manganites. The
effect of increased valency of the A cation from 2–4 to 3–3 perovskites expresses itself as relatively larger Raman shifts
for the lowest energy modes. Analog studies of MgSiO3 perovskites should be undertaken with only 2–4 perovskites. The increased understanding for the mode distributions of perovskites
allows for better estimates of their thermodynamic properties through vibrational modeling. 相似文献
12.
变质沉积岩普遍含有碳质物,其源自沉积母岩中有机质。在变质过程中这些有机质逐渐转变为碳质物或石墨,且碳质物结晶程度可以作为变质等级的可靠指示标志。拉曼光谱是表征碳质物结晶度的有效工具,Beyssac et al.(2002a)基于碳质物拉曼光谱参数(R1=D1/G,D1和G为碳质物拉曼光谱峰强;R2=D1/(G+D1+D2),G、D1和D2为碳质物拉曼光谱峰面积)与寄主岩变质温度之间的线性关系构建了碳质物拉曼光谱温度计:T(℃)=-445(R2)+641,其简单且实用,并被应用到阿尔卑斯和喜马拉雅造山带热结构与折返机制研究中;随后,Rahl et al.(2005)对该变质温度计进行修订,修订后温度估算表达式为:T(℃)=737.3+320.9R1-1067R2-80.638R12,并将变质温度估算范围扩展为100~700℃。本文对碳质物拉曼光谱变质温度计的基本原理、方法、应用条件及其在造山带热结构重建与演化方面的研究进展进行了综述,并对碳质物拉曼光谱温度计与传统温度计估算的变质温度进行了系统的对比分析,结果表明碳质物拉曼光谱温度计代表峰期变质温度,不会受后期退变质影响,当传统温度计结果代表峰期变质温度时,二者计算结果一致。碳质物拉曼光谱温度计已被用于造山带热结构重建、折返过程的热演化,以及高应变带、流体相关热异常等研究。尽管变质过程的压力、变质持续时间、碳质物前体类型等因素对于碳质物拉曼光谱温度计的影响尚待研究,但与传统矿物组合温压计相结合,该方法可以有效评价峰期变质条件和造山多期热演化。 相似文献
13.
一种潜在的地质压力计：流体包裹体子矿物的激光拉曼光谱测压法 总被引：8，自引：0，他引：8
高温高压下矿物的拉曼原位测量表明，某些拉曼活性的物质其拉曼位移与压力之间具有良好的线性关系。这一特性使我们能够通过测量矿物包裹体中含有这些子矿物的拉曼位移以确定矿物的形成压力。与目前常采用的共存矿物对压力计以及流体包裹体的CO2等容线法等压力测定方法相比，该方法具有快速、方便和准确的特点。由于包裹体中可以存在各种不同的子矿物以及不同的溶液物质，因此系统研究包裹体中一切可能存在的矿物或物质的拉曼位移与温度和压力之间的关系将可以提供一种方便、准确的地质压力测量手段。 相似文献
14.
四川软玉（透闪石玉）猫眼的矿物学研究 总被引：4，自引：0，他引：4
采用电子探针(EPMA)、X射线粉晶衍射(XRD)、Raman光谱、扫描电镜(SEM)和偏光显微镜等方法对四川软玉(透闪石玉)猫眼进行了研究。结果表明，四川软玉猫眼主要由微晶一隐晶质透闪石矿物集合体组成；透闪石主要呈近于平行定向排列的显微纤维状，显微纤维变晶结构是软玉猫眼的主要结构，具有此结构的软玉能表现出良好的猫眼效应；透闪石纤维较粗、相互聚集形成束状或捆状结构时，猫眼的眼线比较分散，猫眼效应较差；透闪石纤维局部相互穿插绞合是软玉猫眼表现出高韧性和较强抗断裂性能的主要因素。 相似文献
15.
Abstract: The densities of CO2 inclusions in minerals are commonly used to determine the crystallizing conditions of the host minerals. However, conventional microthermometry is difficult to apply for inclusions of small size (< 5–10 μm) or low density. Raman analysis is an alternative method for determining CO2 density, provided that the CO2 density–Raman shift relation is known. This study aims to establish this CO2 density–Raman shift relation by using CO2 inclusions synthesized in fused silica capillaries. By using this newly-developed synthetic technique, we formed pure CO2 inclusions, and their densities were determined by microthermometry. The Raman analysis showed that the relation between CO2 density (D in g/cm3) and the separations (Δ in cm?1) between the two main bands (i.e. Fermi diad bands) in CO2 Raman spectra can be represented by a cubic equation: D (g/cm3)=0.74203(?0.019Δ3+5.90332Δ2?610.79472Δ+21050.30165)?3.54278 (r2=0.99920). Our calculated D value for a given Δ is between those obtained from two previously-reported equations, which were derived from different experimental methods. An example was given in this study to demonstrate that the densities of natural CO2 inclusions that could not be derived from microthermometry could be determined by using our method. 相似文献
16.
We present a spectroscopic study of the iron \(\hbox{M}_{2/3}\)-edge for several minerals and compounds to reveal information about the oxidation state and the local coordination of iron. We describe a novel approach to probe the iron \(\hbox{M}_{2/3}\)-edge bulk sensitively using X-ray Raman scattering. Significant changes in the onset and shape of the Fe \(\hbox{M}_{2/3}\)-edge were observed on ferrous and ferric model compounds with Fe in octahedral and tetrahedral coordination. Simulation of the spectra is possible using an atomic multiplet code, which potentially allows determination of, e.g., crystal-field parameters in a quantitative manner. A protocol is discussed for determination of the Fe oxidation state in compounds by linear combination of spectra of ferric and ferrous end members. The presented results demonstrate the capabilities of Fe \(\hbox{M}_{2/3}\)-edge spectroscopy by X-ray Raman scattering to extract information on the ratio of trivalent to total iron \(\hbox{Fe}^{3+}/\sum \hbox{Fe}\) and local coordination. As X-ray Raman scattering is performed with hard X-rays, this approach is suitable for in situ experiments at high pressure and temperature. It thus may provide indispensable information on oxidation state, electronic structure and local structure of materials that are important for physical and chemical processes of the deep Earth. 相似文献
17.
Lutz Nasdala Ronald Miletich Katja Ruschel Tamás Váczi 《Physics and Chemistry of Minerals》2008,35(10):597-602
Pressure-induced changes of Raman band parameters of four natural, gem-quality zircon samples with different degrees of self-irradiation
damage, and synthetic ZrSiO4 without radiation damage, have been studied under hydrostatic compression in a diamond anvil cell up to ~10 GPa. Radiation-damaged
zircon shows similar up-shifts of internal SiO4 stretching modes at elevated pressures as non-damaged ZrSiO4. Only minor changes of band-widths were observed in all cases. This makes it possible to estimate the degree of radiation
damage from the width of the ν3(SiO4) band of zircon inclusions in situ, almost independent from potential “fossilized pressures” or compressive strain acting
on the inclusions. An application is the non-destructive analysis of gemstones such as corundum or spinel: broadened Raman
bands are a reliable indicator of self-irradiation damage in zircon inclusions, whose presence allows one to exclude artificial
color enhancement by high-temperature treatment of the specimen. 相似文献
18.
使用配备Linkam冷热台的显微激光拉曼光谱仪,采用融合二氧化硅毛细管样品,在-120～31℃温度区间,1 200～1 500cm-1光谱区间上,原位采集H2O-CO2体系流体包裹体的拉曼光谱,并针对CO2特征拉曼光谱展开分析。结果表明,融合二氧化硅毛细管样品中的流体具有代表性。通过对毛细管样品进行拉曼光谱采集,该实验获得了流体包裹体中CO2气相、CO2液相、CO2固相、CO2水合物相和CO2水溶液相的特征光谱。光谱分析结果显示,在实验温度区间上,CO2固相和CO2水合物相特征峰的稳定性,有助于鉴别拉曼光谱;同时,CO2气相、CO2液相和CO2水溶液相费米共振峰峰位因CO2压力或密度影响而发生变化。此外,该实验在温度变化过程中,鉴定了不同相的拉曼特征光谱。结果表明,激光拉曼光谱结合显微测温技术能够有效鉴别包裹体中不同的流体相,获得相变过程,确定相变温度。 相似文献
19.
Kilian Pollok Bjørn Jamtveit Andrew Putnis 《Contributions to Mineralogy and Petrology》2001,141(3):358-366
Oscillatory zoned grandite garnets from skarns of the Oslo rift region (southern Norway) have been studied using analytical transmission electron microscopy (ATEM). Our results show lamellae with a width varying from about 10 nm to more than 500 nm in both periodic and non-periodic sequences, which represent oscillatory zoning at a very fine scale. The compositions of adjacent lamellae alternate bimodally from Xand=0.55-0.75 to Xand=0.95-1.0. High resolution (HRTEM) images show that the compositional interfaces are sharp and coherent. Oscillatory zoning at the nm-scale puts constrains on the origin of oscillatory zoning in grandites and underlines the dynamic nature of the crystal growth process. The influence of growth rate is discussed against the background of local growth dynamics and external forcing at different length scales. This study emphasises the importance of adequate spatial resolution in analysing chemical variations in grandite garnets and shows that commonly applied methods (e.g. optical microscopy, backscattered electron imaging and electron or ion microprobe) are not sufficient to detect 'real' zonation patterns. Finally, proposed hypotheses on the origin of birefringence of grandite garnets with intermediate compositions are reviewed and discussed on the basis of the observed microstructure. 相似文献
20.
Kurt Leinenweber Andrzej Grzechnik Mary Voorhees Alexandra Navrotsky Nan Yao Paul F. McMillan 《Physics and Chemistry of Minerals》1997,24(7):528-534
High pressure perovskites in the system CaTiO3?CaSiO3 in the composition range from 0 to 50% CaSiO3 have been re-examined using powder x-ray diffraction, Raman spectroscopy, and transmission electron microscopy. In runs performed at 9 GPa and 1200 °C, a solid solution is obtained with compositions ranging from CaTiO3 to near Ca(Ti0.65Si0.35)O3, and with the orthorhombic distortion in the CaTiO3 end-member diminishing to pseudocubic for Ca(Ti0.65Si0.35)O3. Raman spectra show intensity changes and band broadening which are attributed to the reduction of orthorhombic character, but still indicate lower than cubic symmetry for the entire solid solution range. An ordered intermediate, Ca2TiSiO6, has been recovered from a run at 14 GPa at 1200 °C. The space group is Fm3m, with a=7.410(2)?Å, and the compound has the double perovskite structure. In this structure, Si-rich octahedral sites and Ti-rich octahedral sites alternate along the three principal axes. Transmission electron microscopy confirms the presence of the Fm3m ordered structure, and also documents the presence of lesser amounts of at least three other ordered perovskite structures which are not resolved in the x-ray data. These may account for extra features observed in the Raman spectrum which are inconsistent with mode assignments for the Fm3m phase. Non face-centered ordering schemes for these regions are suggested based on modeling of the HRTEM patterns. 相似文献