CO_2 Density-Raman Shift Relation Derived from Synthetic Inclusions in Fused Silica Capillaries and Its Application

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.     

应用显微激光拉曼光谱分析单个流体包裹体同位素

单个流体包裹体同位素是研究特定成岩成矿（藏）阶段古流体成因和来源最有效的方法之一,在矿床、油气、地质流体和大地构造演化动力学等多个领域具有十分重要的用途。但是,目前还没有成熟的分析单个流体包裹体同位素的方法。文中在对目前国内外流体包裹体分析技术总结分析基础上,认为激光拉曼光谱是一项可以分析单个流体包裹体同位素的最有效方法,国外在该领域已经开展了许多创新性的研究工作,并取得了一些重要进展。对激光拉曼光谱分析单个流体包裹体同位素的原理和可行性进行了分析论证,提出通过对已知比值的同位素标准物质拉曼光谱测试和研究,在确定稳定同位素分子的拉曼参数和实验条件等基础上,可以建立起单个流体包裹体稳定同位素激光拉曼测试方法,从而改变目前只能依靠分析群体包裹体同位素来示踪古流体成因和来源的局限性和不确定性。     

赣中良山钼矿床流体包裹体特征及其地质意义

良山钼矿是近年来赣中地区新发现的钼矿,浅部矿体主要赋存于南华系浅变质岩系的构造裂隙中,矿石类型以含辉钼矿石英脉为主。流体包裹体岩相学和显微测温结果表明：含辉钼矿石英脉中的流体包裹体主要呈星散状随机或成群分布,其形态多样,大小集中在2~15 μm,包裹体的类型主要有纯液相包裹体、富气相两相包裹体、富液相两相包裹体和含液体CO₂三相包裹体4类,其中以富液相两相包裹体最为发育;包裹体的均一温度为136~298 ℃,盐度为1.22%~10.11%NaCleqv,密度为0.78~0.99 g/cm3,成矿流体属中-低温、低盐度、较低密度流体;成矿压力估算为13~70 MPa,形成深度为0.5~2.6 km。流体包裹体激光拉曼光谱分析表明：包裹体中气液相成分以H₂O为主,气相中还有少量的CO₂和CO。H、O、S同位素组成显示：成矿流体的δD值介于-61‰~-57.9‰,δ¹⁸OH₂O值介于-3.32‰~-0.52‰,具有岩浆水和大气降水混合的特征;成矿热液中的δ³⁴S值介于-1.8‰~+1.9‰,具有岩浆硫的特征。综合成矿地质特征及相关分析,认为成矿流体可能与燕山期的岩浆活动有关,属于岩浆热液流体,混合作用及钾化作用是促进金属富集沉淀成矿的主要因素,推测矿床属于岩浆热液充填石英脉型钼矿。     

Determining Pressure with Daughter Minerals in Fluid Inclusion by Raman Spectroscopy: Sphalerite as an Example

Abstract: Raman frequency of some materials, including minerals, molecules and ions, shifts systematically with changing pressure and temperature. This property is often used as a pressure gauge in high pressure experiments with the hydrothermal diamond anvil cell (HDAC). Since the system of fluid inclusion is similar to that of HDAC, it can also be used to determine the internal pressure of fluid inclusions. Sphalerite is a common daughter mineral. In this study, the frequency shift of the 350 cm?1 peak of sphalerite has been studied from 296 to 523 K and from 0.07 to 2.00 GPa using the HDAC. The global slope of the isotherms (?n350/?p)T is 0.0048 in the studied pressure range. No significant variation of the slopes with temperature has been observed. The correlation between the frequency shift of the 350 cm?1 peak of sphalerite and pressure and temperature is constrained as P=208.33(?np)350+3.13T?943.75. This relationship may be used to estimate the internal pressure of the sphalerite-bearing fluid inclusions.     

Metamorphic history of the South Tibetan Detachment System,Mt. Everest region,revealed by RSCM thermometry and phase equilibria modelling

This study combines microstructural observations with Raman spectroscopy on carbonaceous material (RSCM), phase equilibria modelling and U–Pb dating of titanite to delineate the metamorphic history of a well‐exposed section through the South Tibetan Detachment System (STDS) in the Dzakaa Chu valley of Southern Tibet. In the hanging wall of the STDS, undeformed Tibetan Sedimentary Series rocks consistently record peak metamorphic temperatures of ～340 °C. Temperatures increase down‐section, reaching ～650 °C at the base of the shear zone, defining an apparent metamorphic field gradient of ～310 °C km^?1 across the entire structure. U–Th–Pb geochronological data indicate that metamorphism and deformation at high temperatures occurred over a protracted period from at least 20 to 13 Ma. Deformation within this 1‐km‐thick zone of distributed top‐down‐to‐the‐northeast ductile shear included a strong component of vertical shortening and was responsible for significant condensing of palaeo‐isotherms along the upper margin of the Greater Himalayan Series (GHS). We interpret the preservation of such a high metamorphic gradient to be the result of a progressive up‐section migration in the locus of deformation within the zone. This segment of the STDS provides a detailed thermal and kinematic record of the exhumation of footwall GHS rocks from beneath the southern margin of the Tibetan plateau.     

Precambrian fossils from the Hamersley range,Western Australia,and their use in stratigraphic correlation

The palaeontology, correlation and sedimentation of the Proterozoic sequence in the Hamersley Range, Western Australia, are discussed. Fossil calcareous algal growths, such as stromatolites and onkolites are described, as well as possible medusoid impressions. These indicate shallow water accumulation of the sediments and provide evidence of the extensive existence of plant and animal life in the Late Precambrian of Western Australia.

Distinctive stromatolites are shown to characterize various levels in the Proterozoic succession. A descending sequence of stromatolite assemblages is proposed denoted by:

• Collenia frequens—Conophyton cf. inclinatum

• Collenia australasica—C. undosa

• C. cf. kona—C. brockmani

• C. sp. aff. multiflabella.

Emphasis is placed on the possible significance of these calcareous algae for correlation and age subdivision of the Proterozoic of Western Australia and its relation to other Precambrian successions.     

The orientation and vibrational states of H2O in synthetic alkali-free beryl

 The polarized single-crystal Raman spectra of synthetic H₂O-containing alkali-free beryl were recorded at room and low temperatures, and the polarized single-crystal IR spectra at room temperature. The H₂O molecule in the channel cavities is characterized by a Raman-active symmetric stretching vibration (ν₁) at 3607 cm⁻¹ and an IR-active asymmetric stretch (ν₃) at 3700 cm⁻¹ at room temperature. At low temperatures this ν₃ mode is observed in the Raman. Weak ν₁ and ν₃ modes of a second type of H₂O are also observed in the Raman spectra but only at 5 K. The H⋯&middot;H vector of the most abundant type of H₂O is parallel to the channel axis of beryl along [0 0 0 1]. The components of the polarizability tensor of the ν₁ mode of H₂O are similar to, but not exactly the same as, those of a free H₂O molecule. The Raman measurements indicate that the H₂O molecule is rotationally disordered around [0 0 0 1]. External translation and librational modes of H₂O could be observed as overtones with the internal H₂O-stretching modes. In the case of the librational motions, normal modes could also be observed directly in the Raman spectra at ∼200 cm⁻¹. The energies of the translational modes can be determined from an analysis of the overtones and are about 9 cm⁻¹ in energy (i.e., T_z). The energies of the librational modes are about 210 cm⁻¹ for R_x and 190 cm⁻¹ for R_y. Received: 8 April 1999 / Accepted: 5 April 2000     

辽宁岫岩玉的岩相结构和无损分析研究

利用外束质子激发X荧光技术（PIXE）、X射线衍射（XRD）、激光Raman光谱（Raman）以及扫描电子显微镜（SEM）等技术对辽宁岫岩玉进行岩石矿物学分析。实验结果表明岫岩玉矿相以叶蛇纹石为主,各种微量元素含量很低。岫岩玉Raman光谱的主要特征峰位于231、378、684、1048、1368和1397cm^-1处。PIXE、XRD和Raman光谱技术作为无损分析方法为鉴定岫岩玉提供了一种快速有效的方法,为研究贵重的古玉器提供了技术支持。     

新疆阿尔泰库威伟晶岩中绿柱石形成的物理化学条件

本文利用包裹体研究探讨了新疆阿尔泰库威伟晶岩中绿柱石形成时的物理化学条件。绿柱石中包裹体类型主要有二类：含硅酸盐子晶流体包裹体和不含硅酸盐子晶气液流体包裹体。含硅酸盐子晶流体包裹体代表岩浆－热液过渡阶段时的一种超临界流体相。结合显微镜观察和含硅酸盐子晶流体包裹体喇曼探针成分测定，得出绿柱石形成时体系中二氧化碳密度较高，ρｃｏ２＝０．６８￣０－．９６ｇ／ｃｍ＾３；盐度很低，ＮａＣｌ（ｗｔ％）＝３．２     

实验研究不同盐离子对水分子拉曼效应的影响

对流体包裹体中常见的几种盐水溶液进行了拉曼光谱分析.采用了频移参数描述水分子拉曼峰的形变强度,并讨论了频移参数与盐度之间的关系.实验分析结果表明,盐度越大,频移参数越大,水分子拉曼峰形变越大.对频移参数曲线斜率分析显示,盐类对水分子拉曼峰偏移程度影响的强弱顺序为NaCl＞Na2SO4＞NaHCO3＞Na2CO3.讨论了不同阳离子和阴离子对水伸缩振动拉曼峰的影响,结果表明,高价阳离子的影响明显高于低价阳离子;而阴离子对水拉曼峰影响的强弱顺序初步确定为Cl-≈SO2-4-＞HCO-3＞CO2-3≈NO-3.