Raman spectroscopy for fluid inclusion analysis

Journal of Geochemical Exploration 112 (2012) 1–20

Contents lists available at SciVerse ScienceDirect

Journal of Geochemical Exploration journal homepage: www.elsevier.com/locate/jgeoexp

Raman spectroscopy for fluid inclusion analysis Maria Luce Frezzotti a, b,⁎, Francesca Tecce b, Alessio Casagli a a b

Dipartimento Scienze della Terra, Università di Siena, Via Laterina 8, 53100 Siena, Italy Istituto Geologia Ambientale e Geoingegneria - CNR, c/o Dipartimento Scienze della Terra, Università “La Sapienza”, P.le Aldo Moro 5, 00185 Roma, Italy

a r t i c l e

i n f o

Article history: Received 7 June 2011 Accepted 18 September 2011 Available online 25 September 2011 Keywords: Raman spectroscopy Fluid inclusions Geological fluids Raman spectra database

a b s t r a c t Raman spectroscopy is a versatile non-destructive technique for fluid inclusion analysis, with a wide field of applications ranging from qualitative detection of solid, liquid and gaseous components to identification of polyatomic ions in solution. Raman technique is commonly used to calculate the density of CO2 fluids, the chemistry of aqueous fluids, and the molar proportions of gaseous mixtures present as inclusions. Raman spectroscopy has been applied to measure the pH range and oxidation state of fluids. The main advantages of this technique are the minimal sample preparation and the high versatility. Present review summarizes the recent developments of Raman spectroscopy in fluid inclusions research to provide support for laboratory analyses. © 2011 Elsevier B.V. All rights reserved.

Contents 1. 2. 3. 4.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods of analysis . . . . . . . . . . . . . . . . . . . . . . . . Gaseous fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. CO2 fluids . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Gaseous mixtures . . . . . . . . . . . . . . . . . . . . . . 5. Aqueous fluids . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1. Analyses of solutes: monoatomic ions . . . . . . . . . . . . 5.2. Analyses of solutes: polyatomic ions and molecules . . . . . . 6. Identification of mineral phases: a catalog of reference Raman spectra 6.1. Native elements, halides, oxides and sulfides (Table 2) . . . . . 6.2. Carbonates (Table 3). . . . . . . . . . . . . . . . . . . . . 6.3. Sulfates, phosphates, and borates (Tables 4 and 5) . . . . . . 6.4. Silicates (Tables 6 and 7) . . . . . . . . . . . . . . . . . . 7. Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Introduction Fluid inclusions (Fig. 1) represent the only first-hand information on fluids in the Earth's interior (e.g., Roedder, 1984; Wilkinson, 2001). They are acknowledged in an enormous range of lithologies (e.g., hydrothermal ore deposits, metamorphic rocks, igneous rocks, and geothermal systems), and pressure and temperature conditions. ⁎ Corresponding author. Tel.: + 39 0577 233929; fax: + 39 0577 233938. E-mail addresses: [email protected] (M.L. Frezzotti), [email protected] (F. Tecce), [email protected] (A. Casagli). 0375-6742/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.gexplo.2011.09.009

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

1 3 4 6 6 7 8 8 12 15 15 15 16 16 17 17 17

Fluid inclusions are generally small closed volumes (i.e., b50 μm in diameter; Fig. 1), in which pressure and temperature are interdependent variables. Both are related by the equation of state of the enclosed fluid, resulting in a nearly linear relation in the P–T space (isochore). Therefore, a key requirement for research and applications is the ability to characterize fluid composition and density. These two properties are usually obtained by petrographic and microthermometric methods (Poty et al., 1976). Raman spectroscopy is the non-destructive technique which better characterizes liquid and gaseous compounds, solid phases, and solute species in fluid inclusions. One of the main advantages is that

2

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Fig. 1. Photomicrographs of fluid inclusions: a) primary H2O fluid inclusions aligned following chevron halite bands, evaporite from Vitravo diapir, Crotone, Italy. b) Primary H2O fluid inclusions in anhydrite from a geothermal well (2410 m depth), Sabatini Volcanic District, Italy. c) Plane of liquid-rich and vapor-rich H2O fluid inclusions in sanidine from syenite, Sabatini Volcanic District, Italy. d) H2O fluid inclusion containing calcite and anhydrite daughter minerals (same provenance as in c). e) Tri-phase H2O–CO2 (L1 + L2 + G) fluid inclusions from an Alpine quartz vein, Binn, Switzerland. f) CO2 fluid inclusions in orthopyroxene, peridotite from Italy.

it allows the chemical and structural characterization of samples as small as 1 μm in diameter, a resolution not possible by conventional petrography, microthermometry, and other spectroscopic methods (e.g., infrared spectroscopy). Raman spectroscopy has become a conventional method in fluid inclusion research starting from the 70's (Burke and Lustenhouwer, 1987; Dhamelincourt et al., 1979; Dubessy et al., 1982, 1989; Guilhaumou, 1982; Pasteris et al. 1986, 1988; Rosasco et al., 1975; Seitz et al., 1987). The continuing interest and

Fig. 2. Energy level scheme for elastic (Rayleigh) and inelastic (Raman) scattering at the frequency of the light source (νl), and Raman and Rayleigh spectra. The molecular vibration of the analyzed sample is of frequency νm.

Fig. 3. Schematic diagram of a Raman spectrometer.

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

the importance of this technique is demonstrated by the number of publications and of review papers in this research field (e.g., Burke, 1994, 2001; Burruss, 2003; McMillan et al., 1996; Nasdala et al., 2004). Present review gives an introduction to Raman spectroscopy for the analysis of geological fluids trapped as inclusions. Our approach is instructional and we focus on selected examples from the literature and from our laboratory experience, but only as far as concerning the routine analysis. The theoretical and experimental treatment of this spectroscopy is on a basic level, and more advanced approaches, such as high-pressure and/or temperature and cryoscopic Raman measurements of fluid inclusions are not discussed in detail. As a first step toward the use of Raman spectroscopy for the study of geological fluids, we provide a catalog of reference spectra for main phases that can be present in fluid inclusions.

2. Fundamentals Raman spectroscopy is based on inelastic scattering of light by matter in its solid, liquid, or gas state. Monochromatic light scattered by matter contains radiations with frequencies different from the exciting light. This effect, predicted by Smekal (1923), was demonstrated by Raman (1928), and named after him. The discovery of a new optical scattering phenomenon won him the Nobel prize in physics in 1930. In several liquids Raman observed scattered light, which had energy greater than the incoming light (Raman antiStokes, see below). The observation of an increase in energy convinced him that he was in presence of a new light-scattering effect, since energy decreasing light-scattering, such as fluorescence, was already known at that time (Raman and Krishnan, 1928). Landsherg and Mandelstam (1928a,b) also found this effect independently and almost simultaneously in Moscow.

3

A straightforward way to explain the Raman scattering of light is by quantum mechanical model, which considers the interaction of photons with molecules in terms of energy-transfer mechanisms (cf., Colthup et al., 1975; Karr, 1975, and references therein). A molecule has different vibrational energy levels, the ground state n = 0, and the excited states n = 1, n = 2, n = 3 etc., which are separated by a quantum of energy ΔE = hνm, where h is the Plank's constant and νm is the frequency of the molecular vibration. The incident visible light (λ = 400–750 nm) with energy νl induces transitions to virtual vibrational energy levels in molecules. A virtual level is not an actual energy level of the molecule and it is generated when light photons interact with the molecule, raising its energy. This virtual level is unstable, and light is instantaneously released as scattered radiation. Returning to the initial state occurs by emitting light of frequency νl, νl − νm, and νl + νm. The concept is illustrated in Fig. 2. The Rayleigh or elastic scattering occurs when the transition starts and finishes at the same vibrational energy level without loss of energy (i.e., no frequency change; νl). Inelastic scattering (Raman effect) induces a change to lower (νl − νm) and higher (νl + νm) frequencies in scattered light, which are known as Stokes and anti-Stokes lines, with νm representing a fundamental rotational, vibrational or lattice frequency of the molecule. Rayleigh scattering can account for the wide majority of light scattered by molecules, being the Raman effect extremely weak – in the order of some 10 − 6–10 − 8 of incident photons – and variable, as the intensity of the Raman scattering is proportional to the fourth power of the frequency of the incident light. Raman spectroscopy is the measurement of the photons arising from inelastic (Raman) scattering of light. A Raman spectrum is the plot of light intensity expressed as arbitrary units, or counts, versus the frequency of scattered light (i.e., Raman vibrational modes) in frequency units (wavenumbers ˜ν = νc = λ1 in cm − 1, where c is the

Cc Dmd

Rt

C

I

C Rt

4000

300

a

c

600

900

1200

1500

-1

cm1800

b

Diamond

d

Rutile

e

Calcite

Fig. 4. Raman spectral images of daughter mineral distribution in an aqueous fluid inclusion. a) Optical microphotograph of analyzed fluid inclusion in garnet from ultra-high pressure metamorphic rocks, western Italian Alps, reporting the grid of single point measurements. b) Single point Raman spectrum showing the selected wavenumber intervals for daughter mineral mapping [diamond (red), rutile (blue), and calcite (green)]. c, d, and e) Spectral images of diamond, rutile, and calcite distribution in the fluid inclusion. The color intensity of the mineral phases (from black to white) reflects the increase in the intensity of the Raman band. The aqueous fluid in the inclusion has no significant Raman signal in the investigated region, and thus does not interfere with the measurement; modified from Frezzotti et al. (2011).

4

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Table 1 Main Raman vibrations (cm− 1) of major gaseous species and of solutes in aqueous fluids. Gasses

Main vibrations

Ref.

COS SO2

857 s 1151 w 524 s 1285 vs 1388 w 1370 1555 2143 2331 2611 2890 vs 2917 w 3020 2954 3336 vs 4156 w 4126 w 4143 w 4161 w 1032 w 586 w 354 vs 3657–3756 w 1595

1 2

CO2 Fermi doublet 13

CO2 O2 CO N2 H2S C3H8 CH4 C2H6 NH3 H2

H2O vapor

3

1 1 4 1 1 5 1 1 6

7

Solutes

Main vibrations

Ref.

Si(OH)40 Si2O(OH)60 ClO4−

750–800 590–680 vs 928 w 645 w 460 vs 980 w 620 w 450 vs 1049 w 690 w 1355 vs 1050 w 890 vs 1017 m 1360 vs 1064 w 684 m 1380 vs 1384 m 1276 2570–2590 vs 3040 sh 2870 vs 877 w 495 vs 2750–3900* w 1630

8, 9 8, 9 10

SO42−

NO3−

HSO4− HCO3− CO32−

CO2 in solution −

HS and H2S NH4+ B(OH)30 H2O liquid

10

A spectrum comprises one or more bands which reflect the vibrational energies of the molecules within the analyzed sample; these in turn are related to the nature of the bonding. Main molecular vibrations include stretching and bending modes, stretching frequencies being generally higher than bending frequencies. In order for a normal mode of vibration to be Raman active, it should produce a change in the polarizability of the molecule. The “selection rules” for Raman scattering depend on: 1) the creation of an induced dipole in the molecule (polarization); 2) the modification of the dipole by a molecular vibration; 3) the successive scattering of a photon from the modified dipole (McMillan and Hess, 1988, and references therein). As a thumbnail rule, those molecules which are not easily polarized are poor Raman scatterers. One example is H2O which has a strong dipole moment but electrons are not easily polarized and Raman scattering is weak. 3. Methods of analysis The basic instrumental set up requires a monochromatic light source, generally a laser, focused on a sample (solid, liquid, or gaseous); the light is scattered, collected at a 90° or 180° angle, and analyzed by a detector (Fig. 3). The first dispersive Raman spectrometers had the sun or a mercury lamp as the exciting source, a prism monochromator as the light disperser, and a photographic film as detector (Colthup et al., 1975; Kohlrausch, 1943). In modern commercial instruments, polarized laser light sources in the UV, visible, and IR are used to excite molecular samples, because of the high intensity and narrow bandwidth of wavelengths that are emitted (monochromaticity), and multi-channel charge-coupled devices (CCD) are generally used as detectors. Their combination, together with notch holographic filters to eliminate the Rayleigh line, results in more intense Raman scatter, with considerably reduced measuring time in obtaining high

10

11 12 12

12 11 13 14 15 a,b

vs = very strong; m = medium; w = weak; sh = shoulder; * Broad bands of several hundreds of cm− 1; 1 Burke, 2001; 2 Herzberg, 1945; 3 Rosso and Bodnar, 1995; 4 Herzberg, 1950; 5 Brunsgaard-Hansen et al., 2002; 6 Dubessy et al., 1988; 7 Fraley et al., 1969; 8 Zotov and Keppler, 2000; 9 Hunt et al., 2011; 10 Ross, 1972; 11 Dubessy et al., 1992; 12 Davis and Oliver, 1972; 13 Schmidt and Watenphul, 2010; 14 Schmidt et al., 2005; 15 a,b Walrafen, 1964, 1967. Ref. = References. Underlined vibrations indicate most intense Raman modes.

velocity of light; Fig. 2). Typically, only Stokes Raman scattered frequencies are presented since they have the same energy but are about 10 times more frequent than their anti-Stokes counterparts. The Rayleigh scattered frequency (i.e., light-source wavenumber) lies at 0 cm − 1 and Raman frequencies are expressed as relative wavenumbers, or Raman shifts. On this scale, frequencies correspond to the energy levels of different molecular vibrations and are independent from the wavelength of the light source: a mode at 464 cm − 1 will occur whether the light source wavelength is 514.5 or 632.8 nm.

Fig. 5. Raman spectra and relative wavenumbers of most common gaseous fluid species in fluid inclusions. Note that the hypothetical CO2 Raman band at 1340 cm− 1 is really two bands at 1285 and 1388 cm− 1, see text.

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Fig. 6. Raman spectroscopy applied to CO2 density measurement. a) Main spectral features of CO2 fluids, which consist of the two bands of the Fermi doublet, bounded by the hot bands. The distance between the Fermi doublet (Δ) depends on fluid density. b) Superdense CO2 fluid inclusions (d N1.178 g/cm3) spectral features, including: i) increased Δ (≥106 cm− 1), ii) shifting of bands to lower wavenumbers, iii) increased band intensity ratio, iv) broadened band bases, and v) flattened hot bands (van den Kerkhof and Olsen, 1990); analyzed fluid inclusions are in pyroxenes from peridotite xenoliths, Hawaii; modified from Frezzotti and Peccerillo (2007). c) CO2 density as a function of Δ (cm− 1), as derived from the equations of: 1) Rosso and Bodnar (1995), 2) Kawakami et al. (2003), 3) Yamamoto and Kagi (2006), 4) Song et al. (2009), 5) Fall et al. (2011), and 6) Wang et al. (2011). The inset shows that the maximum difference in CO2 densities derived from the different equations is about 0.1 g/cm3; redrawn and modified from Wang et al. (2011).

signal to noise spectra (i.e., tens of seconds), and low detection limits. A detailed description of the different instrumental set up can be found in scientific Journals (e.g., Vibrational Spectroscopy, Elsevier; and Journal of Raman Spectroscopy, Wiley) and in the web at the pages of single manufacturing companies. Fluid inclusion analysis is based on the same fundamental principle: the laser excites the molecules to generate scattering. Raman

5

microspectrometers are the common analytical set up, where the excitation of the sample and collection of the scattered light at a 180° angle (backscattering) are achieved using a ordinary optical microscope focused within single fluid inclusions by means of high-magnification objectives (50× or 100×). Instruments offer perfect visualization of the subsurface of samples and of the laser spot, which makes easy the choice of the appropriate inclusion to be analyzed. The volume of the analyzed sample (spot size) depends mostly on the numerical aperture (N.A.) of the objective, and on the excitation wavelength. As an example, for a 514.5 nm excitation source and a 100× magnification objective with N.A.= 0.9, the spot size is 1 × 1 × 5 μm3. Thick double-polished sections are easily studied and require no special preparation. Fluid inclusions can be studied down to 1 μm diameter in situ, where microstructures are preserved and the different populations of fluid inclusions can be discriminated. This is possible because of the confocal arrangement of the optical pathway which allows a good spatial resolution perpendicular to the optical axis, as well as along the optical axis of the microscope (depth) (see, Nasdala et al., 1996, 2004). However, the depth resolution degrades with increasing optical penetration depth, therefore it is better to analyze fluid inclusions not deeper than 30 μm within a sample. The choice of laser wavelength influences the performance of the spectrometer. The characteristics of each laser are different, so that no laser may be ideal for every fluid inclusion analysis. In general, the optical power of the laser line and the efficiency of Raman CCD detectors tend to increase with decreasing wavelength. However, the cost of the laser, the likelihood of fluorescence (see below), and the risk of sample heating increase as well. The most popular choices are: (1) the green light Ar ion (λ = 514.5 nm) water- or air-cooled; (2) the blue light Ar ion (λ = 488 nm) air-cooled; and (3) the red light He\Ne (λ = 632.8 nm). Raman microspectrometers can be equipped with a programmable x–y microscope stage which allows sample areas to be mapped in the same way as with EDS and WDS microprobes. Single spot spectra are collected by multiple steps within a grid pattern, as illustrated in Fig. 4a. Each analyzed point contains the information of a whole spectrum (Fig. 4b). Generated Raman maps are chemical or structural images where integrated areas of single bands or band ratios, characteristics for the presence of a certain chemical species in a composite sample, are illustrated (Figs. 4c, d, e). The x–y resolution in a map depends on the distance between the single measuring points, while the depth resolution along z is determined by the confocal instrument settings (see above). The best resolution is achieved by setting the distance between two measuring points smaller than the laser spot size (“oversampling”). By increasing the distance between two spots, the spatial resolution decreases, but larger areas can be analyzed in a shorter time. Spatially resolved Raman spectra can be used to identify the distribution of fluid or mineral species within single fluid inclusions (Frezzotti et al., 2011; Korsakov et al., 2011). Fluorescence and the presence of overlapping bands from host mineral are possible competing effects during analysis, since they often overpower and conceal the weak Raman features from the fluid inclusions. Fluorescence generally appears as a very broad background, often much more intense than the Raman scattering. This effect may commonly arise from epoxy used to embed or polish the rock sections and can be easily eliminated using non-fluorescent epoxies and/or cleaning the sample. However, fluorescence can also be emitted by fluids contained in inclusions (e.g., hydrocarbons) or by the surrounding host mineral (e.g., Fe-bearing minerals). These last cases are much more difficult to cope with. Increasing the wavelength of the light source is a way of overcoming fluorescence: red or nearinfrared lower lasers (λ = 630–1060 nm) should not, in principle, give rise to fluorescence (Carey, 1999). Another practical method to mitigate a fluorescent background consists in repeating spectral accumulations for several times in order to bleach out this effect by protracted exposure to laser light (photo-bleaching).

6

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Fig. 7. Quantitative Raman analysis of H2 and CH4 contained in the gas bubble of an aqueous fluid inclusion in vesuvianite from rodingites, western Italian Alps (Ferrando et al., 2010). Relative mole% of H2 and CH4 in the gas bubble is calculated with Eq. (1) based on band area integration, and considering the relative Raman cross sections (σ) and the instrumental efficiency (ζ) at the wavenumbers of H2 and CH4. (σ of CH4 is 3.5 times higher than of H2; Burke, 2001).

Interpretation of spectra of crystalline phases is often complicated, due to the fact that Raman scattering intensity depends upon lattice orientation. Consequently, variations of band intensity ratios should be taken into account in the analysis of most minerals. Knowledge of the orientation of main crystallographic axes, and/or repetition of analysis after 90° rotation to get random orientations is helpful in mineral identification (Nasdala et al., 2004). In addition, due to lattice geometries, some minerals are very weak Raman scatterers. Unfortunately, among these there are major chloride species (e.g., NaCl, KCl, and CaCl2), which represent relevant constituents of aqueous fluid inclusions. The intensity of the Raman scattering can vary by many order of magnitudes depending on the nature of the molecules. Detection limits for single components within a single fluid inclusion depend on several contributing factors, including fluid inclusions size and geometry (i.e., number of molecules of the analyzed constituent), nature of the other constituents in fluid inclusions, and analytical conditions (e.g., intensity of the laser light, depth of the inclusion in the analyzed sample, etc.). Several approaches can be used, and they will be discussed in the following sections. 4. Gaseous fluids A custom application of Raman spectroscopy to fluid inclusion analysis is the qualitative identification of major gaseous fluid components. The characterizing Raman bands for most important geological fluids are reported in Table 1 and Fig. 5. Most gasses show a single symmetric stretching strong band, whose wavenumber is traditionally reported at ambient P–T conditions, since a progressive slight wavenumber downshift is known to occur with increasing fluid density (Burke, 2001; van den Kerkhof, 1988b). Early work on fluid inclusions allowed to recognize CO2, CH4, and N2 as relevant geological fluids (e.g., Dubessy et al., 1989; Frezzotti et al., 1992; Touret, 2001; van den Kerkhof, 1988a,b, 1990). H2S,

COS, SO2, CO, H2, NH3 and O2 have also been detected in appreciable amounts in some fluids (Bény et al., 1982; Ferrando et al., 2010; Frezzotti et al., 2002; Giuliani et al., 2003; Grishina et al., 1992; Peretti et al., 1992; Siemann and Ellendorff, 2001; Tsunogae and Dubessy, 2009). Identification of hydrocarbons heavier than CH4 is also possible (e.g., Guilhaumou, 1982; Hrstka et al. 2011; Makhoukhi et al., 2003; Munz, 2001; Orange et al., 1996; Pironon, 1993; Pironon and Barrès, 1990; Potter et al., 2004; Rossetti and Tecce, 2008; Schubert et al., 2007; Wesełucha-Birczyńska et al., 2010), although fluorescence often does not allow conventional analysis (see e.g., Pironon et al., 1998).

4.1. CO2 fluids The Raman spectrum of molecular CO2 shows two strong bands at 1285 and 1388 cm − 1, and two symmetrical weak bands below 1285 and above 1388 cm − 1, the so-called hot bands (Colthup et al., 1975; Dhamelincourt et al., 1979; Dubessy et al., 1999; Rosasco et al., 1975; Rosso and Bodnar, 1995; van den Kerkhof and Olsen, 1990). The two sharp bands appear because of a resonance effect, proposed by Fermi (1931) in order to explain the doublet structure in the region of CO2 symmetric stretching vibration. A small peak at 1370 cm − 1 is the 13CO2. Fig. 6a and b shows examples of spectra of CO2 fluid inclusions having different densities. The distance between the Fermi doublet (Δ, in cm − 1) is proportional to fluid density (Garrabos et al., 1980; van den Kerkhof, 1988b; Wang and Wright, 1973). Several equations (e.g., Fall et al., 2011; Kawakami et al., 2003; Rosso and Bodnar, 1995; Song et al., 2009; Wang et al., 2011; Yamamoto and Kagi, 2006) have been proposed to calculate the density (d) of pure CO2 fluid inclusions based on the distance between the Fermi doublet Δ (Fig. 6c). CO2 density can be determined in the range from 0.1 to 1.24 g/cm 3 with an accuracy better than 5% (Wang et al., 2011).

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

7

band intensities on fluid density. Nevertheless, Raman mass-spectroscopy remains a particularly attractive prospective since it could permit to analyze samples several order of magnitude smaller than generally used by mass-spectrometry. 4.2. Gaseous mixtures When fluid inclusions consist of mixtures of two or more gas species, the relative molar fractions of the end-members can be calculated. The prerequisite to quantitative Raman analysis is the knowledge of two essential parameters (cf., Burke, 2001): (1) the Raman scattering cross-section, which indicates the activity of a certain gas component in a mixture (Schrötter and Klöckner, 1979); and (2) the variation of the instrumental efficiency at the different wavenumbers for a specific excitation wavelength. The first parameter is dependent on the laser excitation wavelength. A list of major gas species crosssections for the 632.8 nm red light (e.g., He\Ne laser source), the 514.5 nm green light (Ar-ion laser source), and the 488 nm blue light (Ar-ion laser source) is reported in Burke (2001). The second parameter requires an empirical calibration for each Raman microspectrometer, by measuring synthetic or natural gas-mixture standards of known composition and density (Beeskow et al., 2005; Chou et al., 1990; van den Kerkhof, 1988b). The molar fraction (X) of end-member components in a gas mixture can be obtained using the following equation (Beeskow et al., 2005; Burke, 2001; Dubessy et al., 1989; Morizet et al., 2009; Nasdala et al., 2004; Wopenka and Pasteris, 1986, 1987):

Xa ¼

Fig. 8. Raman spectra of water contained in fluid inclusions, presenting examples for: a) low-salinity (b 1 NaCl wt.%) liquid water, b) high-salinity (20 NaCl wt.%) liquid water, and c) optically-hidden water in a CO2-rich fluid inclusion, peridotite from Ethiopia.

We observe a very good agreement between density data derived from Raman spectroscopy and from microthermometry, also for CO2 fluids containing minor amounts of other gaseous species (i.e., b5 mol% CH4 or N2; Frezzotti and Peccerillo, 2007). These two methods are complementary for the characterization of fluid inclusion composition and densities. Although the precision of microthermometric measurements is higher, the Raman densimeter permits to analyze very small fluid inclusions (b5 μm in diameter), and/or low density fluids. The relative intensities of the 13CO2 and the associated 12CO2 band (Fig. 6a) have been used to calculate the carbon isotope ratios in single fluid inclusions. The development of Raman as a massspectroscopy, however, is still at a very early stage of development; reported δ 13C determinations have uncertainties ≥ 20‰ (Arakawa et al., 2007; Dhamelincourt et al., 1979), and consent only to discriminate between inorganic and organic CO2 at best. This is due to the difficulty in controlling all parameters influencing intensity of scattering, probably including a dependence of 13CO2 and 12CO2

Aa σa ζa ∑ σAiζ i i

ð1Þ

where Xa, Aa, σa and ζa, are the molar fraction, the band area, the Raman cross-section and the instrumental efficiency for gas a, respectively, while ΣAi, σi, and ζi represents the sum of values for all gas species in the fluid inclusion. In order to get reliable quantitative analyses, no change in the analytical conditions should be made during measurements (i.e., laser intensity, focus, number of accumulations, and accumulation time). Accuracy of analyses is reported better than 5% (Pasteris et al., 1988; van den Kerkhof, 1988b). Note that when CO2 fluids are involved, the sum of the two bands forming the Fermi doublet should be used (Dubessy et al., 1989). In Fig. 7 is reported for example an aqueous fluid inclusion contained in vesuvianite from vein in rodingite from Bellecombe, Italian Western Alps (Ferrando et al., 2010). In the gas bubble, bands of CH4 and H2 have been obtained using an Ar-ion laser (λ = 514.5 nm) as the excitation source. The integrated measurements of the single gas Raman band area (A) are reported along with the relative cross-sections (σ) of H2 and CH4 and the instrumental efficiency (ζ) of the Raman spectrometer at 2917 and at 4156 cm − 1. Using Eq. (1), the resulting composition of the gas phase in the Alpine inclusion is equal to 82 mol% H2 and 18 mol% CH4. In more complex gaseous–aqueous fluid mixtures, the quantitative analysis of the different components is much more difficult and often requires measurements at high temperatures. Empirical equations for (semi)quantitative analyses of H2O-CH4 ± NaCl and H2O-CO2 ± NaCl systems have been proposed based on relative band areas in spectra (e.g., Azbej et al., 2007; Guillaume et al., 2003; Lu et al., 2007). In these complex fluid mixtures, analysis should include detection of gasses dissolved in water (e.g., CO2 or CH4), and the characterization of clathrate hydrates (ice-like compounds formed from CO2, CH4, or N2 and water under low-T and high-P conditions; Azbej et al., 2007; Dubessy et al., 2001; Fall et al., 2011; Orange et al., 1996; Pironon et al., 1991) .

8

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Fig. 9. Raman spectroscopy applied to solute analysis in aqueous fluids. a) Band of SO42− ions in a fluid inclusion in feldspar from syenite, Sabatini volcanic district, Italy. b) Bands of native sulfur in a fluid inclusion in orthopyroxene from peridotite, Italy. c) Bands of CO32− and HCO3− ions in a fluid inclusion from ultra-high pressure metamorphic rocks, western Italian Alps. d) Bands of Si(OH)40, and deprotonated H4-nSiO4n− monomers in a fluid inclusion from metamorphic rocks from western Italian Alps. The Raman modes of anhydrite (Anh), quartz (Qtz), and Mg-calcite (MgCc) daughter minerals are also shown. Raman bands of host minerals are marked with asterisks. c and d: modified from Frezzotti et al., 2011.

5. Aqueous fluids The Raman modes of water consist of two main O\H stretching modes at 3657 and 3756 cm − 1 and one very weak H\O\H bending mode at 1595 cm − 1 (Carey and Korenowski, 1998; Fraley et al., 1969). However, the Raman spectrum of liquid H2O consists of several large overlapping bands in the OH stretching region from 2750 to 3900 cm − 1 (Fig. 8a and b), and of a weak bending mode at ~ 1630 cm − 1 (Walrafen, 1964, 1967). Reduced to minimum terms, such spectral complexity results from the strong interactions of a single water molecule with the neighboring molecules, forming intermolecular O\H\O bridging networks (Hare and Sorensen 1992; Sun, 2009). The characteristics of the Raman spectrum of water have been used to prove the presence of H2O in small CO2 fluid inclusions (b5–10 μm in size; Frezzotti and Peccerillo, 2007; Frezzotti et al., 2010; Hidas et al., 2010). Here, a water film of a thickness of 0.2 μm wrapping the CO2 fluid cannot be identified with optical techniques, although it may correspond to as much as 10–20 mol% of H2O. A detailed description of the method can be found in Dubessy et al. (1992) and in McMillan et al. (1996). One example is illustrated in Fig. 8c from CO2 fluid inclusions in peridotites from Ethiopia. The dominant spectral features of optically unnoticed water are the vibrational bands at 3658 and 3750 cm − 1 characteristic of OH − stretching vibrations for isolated molecules of H2O (i.e., lack of significant H intermolecular bonding). Raman spectroscopy allows determination of the appropriate water content of melt inclusion glass in minerals of granites and pegmatites (e.g., Behrens et al., 2006; Chabiron et al., 2004; Di Muro et al.,

2006; Severs et al. 2006; Thomas, 2000; Thomas and Davidson, 2006; Thomas et al., 2008b; Zajacz et al., 2005). Note that, during cooling of a natural water-rich melt inclusions, often SiO2 is deposited on the inclusion wall and makes an apparent aqueous fluid inclusion from what was primary a melt inclusion (Thomas et al. 2011a). 5.1. Analyses of solutes: monoatomic ions Qualitative and (semi)quantitative Raman analysis of water-rich fluid inclusions typically focuses on determination of solutes. Monoatomic charged cations, such as Na +, K +, Ca 2+, and Mg 2+ have too weak Raman spectra to be analyzed in fluid inclusions. A way to obtain spectra is by nucleation of salt-hydrates at low temperatures, but this requires the combination of the Raman microspectrometer with a fluid inclusion cooling stage. Spectra are reported for all major salt-hydrates, such as NaCl·2H2O, FeCl3·6H2O, CaCl2·6H2O, MgCl2·12H2O, KCl·MgCl2·6H2O, FeCl2·6H2O, LiCl·5H2O (Bakker, 2004; Baumgartner and Bakker, 2009, 2010; Derome et al., 2007; Dubessy et al., 1982, 1992; Samson and Walker, 2000; Schiffries, 1990). Chlorine ions have the power of breaking certain hydrogen bonds in aqueous solutions. The variation of OH stretching bands induced by different Cl concentrations in aqueous fluid inclusions (Fig. 8a and b) has been intensively investigated with different approaches. Semiquantitative estimation of the salt content in aqueous fluid inclusions requires development of a specific calibration for each spectrometer and it is complementary to measurements of phase transitions at low temperatures by microthermometry (e.g., eutectic and final melting temperatures).

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

9

Table 2 Main Raman vibrations (cm− 1) of selected native elements, halides, sulfides, oxides and hydroxides. Native elements, halides and sulfides Diamond C Graphite C Sulfur S8 Arsenic As

Main vibrations

Ref. 1332 1355

mw 157 w 187

Halite NaCl Sylvite KCl Fluorite CaF2 Cryolite Na3(AlF6) Elpasolite K2NaAlF6 Pyrite FeS2 Marcasite FeS2 Chalcopyrite CuFeS2

m 220 w 246 mw 220 w 225 vs 253

[1] 1580

s 462 w 437

3 4

358

[1]

vw 291 vw 213

[1] m 322 vw 485

135

vs 293

Covellite CuS Blende ZnS

326 387 w 342 s 377 vs 324 s 387 w 322 w 352 w 378

vw 263 w 218 w 274

Galena PbS Oxides and hydroxides

Main vibrations

Rutile TiO2 Anatase TiO2 Brookite TiO2 Spinel MgAl2O4 Magnetite Fe2+Fe23+O4 Hematite Fe2O3 Ilmenite FeTiO3 Gibbsite Al(OH)3 Diaspore AlO(OH) Corundum Al2O3 Goethite α-FeO(OH)

w 139 vs 143 vw 195 s 127 vs 150

2

m 555

vw 641

[1]

mw 620

5

559

1009

6

vs 428

7 7 7

vs 471 w 300 w 310 vs 349

7

w 419

vs 136

m 270

m 238

vs 444

w 639 w 669

[1]

[1]

Ref.

w 395 s 247

w 193

s 318 w 366 w 313

w 514 w 412

mw 645

vs 408

mw 666

w 306 s 223 vs 290 w 232 mw 242 m 255

w 242 mw 299

s 538 vs 409 w 498

w 920

9 w 768 10 11 vs 1313

vs 685

m 322 vs 380 w 331

vs 538 vs 569 vs 448

mw 378

vs 417

[1] 8

vs 668 m 609

mw 373

vs 389

vs 609 m 696 mw 638

12 13

w 979

14 3

m 644 m 547

mw 681

w 750

15 12

vs = very strong; s = strong; m = medium; mw = medium weak; w = weak; vw = very weak; [1] = Raman Spectra Database, Siena Geofluids Lab (http://www.dst.unisi.it/geofluids/ raman/spectrum_frame.htm); 2 Wopenka and Pasteris, 1993; 3 Giuliani et al., 2003; 4 Thomas and Davidson, 2010; 5 Nazmutdinov et al., 2010; 6 R. Thomas, pers. comm.; 7 Mernagh and Trudu, 1993; 8 Clark et al., 2007; 9 Yanqing et al., 2000; 10 Slotznick and Shim, 2008; 11 Shebanova and Lazor, 2003; 12 Kuebler et al., 2006; 13 Rull et al., 2007; 14 Ruan et al., 2001; 15 Xu et al., 1995; Ref. = References.

Mernagh and Wilde (1989) proposed a formula to calculate NaCl wt.%, with a relative error of 15%: 0

1

2ðY−X Þ B X=Y C NaClwt:% ¼ α @2− I 3400 cm−1 A−β ð Þ XþY Ið3200 cm−1 Þ

ð2Þ

where X is equal to the integral of the OH− band from 2800 to 3300 cm− 1, Y is equal to the integral from 3300 to 3800 cm− 1, I is the intensity at the specified wavenumbers, and α and β are regression parameter specific for each spectrometer (cf., McMillan et al., 1996). The idea behind Eq. (2) was to link the shape of the two halves forming the OH stretching band to the amount of Cl− in solution. More recently, calibration curves were expanded also to LiCl, KCl, MgCl2, CaCl2, and to

10

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Table 3 Main Raman vibrations (cm− 1) of selected carbonates. Carbonates

Calcite CaCO3 Aragonite CaCO3 Vaterite CaCO3 Mg-Calcite (Ca,Mg)CO3 Magnesite MgCO3 Dolomite CaMg(CO3)2 Natrite Na2CO3 K-Carbonate K2CO3 Zabuyelite Li2CO3 Siderite (Fe,Mg)CO3 Rhodochrosite MnCO3 Strontianite SrCO3 Witherite BaCO3 Cerussite PbCO3 Smithsonite ZnCO3 Nahcolite NaHCO3 Kalicinite KHCO3 Hydrated carbonates

Malachite Cu2(OH)2(CO3)

Azurite Cu3(OH)2(CO3)2

Artinite Mg2(OH)2(CO3)·3H2O Hydromagnesite Mg5(CO3)4(OH)2·4H2O Dypingite Mg5[(OH)(CO3)2]2·5H2O

Dawsonite NaAl(CO3)(OH)2 Thermonatrite Na2(CO3)·H2O Trona Na3H(CO3)2·2H2O Gaylussite Na2Ca(CO3)2·5H2O

CO32− vibrations

Ref. ν1

ν3

vs 1085

vw 1435

[1]

vs 1085

vw 1463

[1]

w 740 w 750 mw 714

vs 1090 s 1074 vs 1087

vw 1465

2

vw 1438

[1]

w 738

vs 1094

w 1444

3

w 725

vs 1097

vw 1443

[1]

w 698

vs 1078

w 1428

4

m 697

m 1405

5

w 712

vs 1064 sh 1043 vs 1091

w 1459

4

sh 738

vs 1090

vw 1442

[1]

mw 718

vs 1087

vw 1416

[1]

w 700

vs 1073 vw 1057

vw 1450

[1]

w 692

vs 1059

w 1420

[1]

vs 1056

s 1378

[1]

w 731

vs 1093

mw 1408

[1]

mw 688

vs 1048 m 1271 vs 1028 mw 1277

w 1432

[1]

T

ν4

s 284 mw 156 s 154 mw 206 m 301 sh 118 s 281 mw 155 s 329 mw 212 s 299 ms 176

mw 711

s 141 m 192 mw 96 m 301 w 194 s 289 mw 185 mw 149 mw 183 sh 250 s 136 m 152 w 227 s 150 mw 180 sh 215 m 303 mw 196

w 704

m 682

ν2

vw 854

m-w 839

w 635 w 673 CO32− vibrations

4

OH−

Ref.

T

ν4

ν1

ν3

vs 154 vs 178 vs 434 ms 272 ms 537 s 397 m 246 mw 170 mw 279 s 147 s 173 w 472 m 184 m 202 m 232 mw 203 mw 249 w 311 w 434 ms 189 m 260 mw 587 s 156 m 185 w 230 mw 140 mw 185 w 225 s 164 sh 265

w 721

sh 1098

vs 1492

vs 3468 mw 3386

[1]; 6

vs 1095

vw 1457

vs 3453 sh 937

[1]; 6

vs 3593 s 3229 s 3030 n.a.

7 8

w 704

w 727

w 723

vs 1094

vs 1119

sh 1487

vs 1122 mw 1092

mw 1447

vs 3648 m 3421 mw 3515

8

vs 1091 w 1065

mw 1505

vs 3282 m 3250

9

vs 1062

sh 1432

n.a.

[1]

vs 1060

w 1430

n.a.

[1]

vs 2944 s 3334

[1]; 10

vs 1071

7

ν1 = Symmetric stretching vibration; ν2 = Out-of-plane bending vibration; ν3 = Antisymmetric stretching vibration; ν4 = In-plane bending vibration; T = Translational lattice modes; OH− = OH stretching vibrations; vs = very strong; s = strong; ms = medium strong; m = medium; mw = medium weak; w = weak; vw = very weak; sh = shoulder; [1] = Raman Spectra Database, Siena Geofluids Lab (http://www.dst.unisi.it/geofluids/raman/spectrum_frame.htm). 2 Carteret et al., 2009; 3 Gillet, 1993; 4 Thomas et al., 2011a,b; 5 Koura et al., 1996; 6 Frost et al., 2002; 7 Edwards et al., 2005; 8 Frost et al., 2008; 9 Frost and Bouzaid, 2007; 10 Frost and Dickfos, 2007; n.a. = not analyzed; Ref. = References.

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

11

Table 4 Main Raman vibrations (cm− 1) of selected sulfates. SO42− vibrations

Sulfates

Ref.

ν2

ν4

ν1

ν3

Anhydrite CaSO4

mw 430 mw 500

vs 1018

mw 1131

2

Mg-sulfate MgSO4

ms 451 ms 475 ms 499 w 452 w 469 w 485

vs 1023 s 1053

ms 1136 w 1220 vw 1256 w 1103 w 1153 m 1106 m 1140

3

vs 1002

m 1125

[1]

w 1093 w 1109 w 1145 m 1104 mw 1093 ms 1156 mw 1190 w 1143

5

w 1160 vw 1068

[1]

Sulfohalite Na6(F,Cl)(SO4)2 Arcanite K2SO4

m 471

w 611 w 629 w 676 s 608 vw 681 vw 697 w 621 w 632 m 618 m 644 mw 620 mw 633 mw 644 m 634

mw 457

mw 622

vs 983

Aphthitalite (K, Na)3Na(SO4)2 Celestine SrSO4 Barite BaSO4 Anglesite PbSO4

m 457 mw 447 m 452

s 619

vs 984 vs 1000

s 461

ms 656 vw 627 w 617

mw 438 mw 450

w 608 vw 641

vs 978

Thenardite Na2SO4 Glauberite Na2Ca(SO4)2 Burkeite Na6(CO3)(SO4)2

Hydrated sulfates

mw 451 w 474

vs 994 vs 1002 vs 994 m 1065*

SO42− vibrations ν2

ν4

ν1

ν3

Gypsum CaSO4·2H2O Epsomite MgSO4·7H2O

s 494 m 414 mw 447

w 621

vs 1008

w 1142

vw 612

vs 984

Exahydrite MgSO4·6H2O Pentahydrite MgSO4·5H2O

w 445 w 466 m 447 vw 371

vw 610

vs 984

vw 602

vs 1005

vw 1061 vw 1095 vw 1134 w 1146 vw 1085 vw 1106 vw 1159

Starkeyite MgSO4·4H2O

vw 401 vw 462

vw 565 vw 616 vw 664

vs 1000

Sanderite MgSO4·2H2O Kieserite MgSO4·H2O K-Alum KAl(SO4)2·12H2O Alunite KAl3[(OH)3(SO4)]2 Syngenite K2Ca(SO4)2·H2O Görgeyite K2Ca5(SO4)6·H2O

m 447 w 492 m 436 w 481 mw 455 w 442 mw 509 w 485 mw 474 w 494 m 480 w 433 w 440 w 457 m 458

w 597 w 630 m 629

vs 1034

mw 614

vs 989 s 974 vs 1026

w 642 w 662 m 631 w 595 w 602 w 654 mw 627

vs 983 s 1007 vs 1013 vs 1005 w 1085

mw 1117 w 1215 mw 1130 w 1104 mw 1190 w 1079 w 1142 w 1168 w 1108 w 1115 w 1162

vs 989

w 1129

vs 448 mw 474

vs 626 mw 647

vs 1004

sh 1104

Mirabilite Na2SO4·10H20 Cesanite Na3Ca2(OH)(SO4)3

mw 654

[1] 4

vs 988

vs 1046

[1]

w 1156 vw 1086 vw 1116 vw 1186 m 1164

[1] [1] [1]

OH−

Ref.

vs 3405 mw 3491 vs 3303 s 3425

[1]; 6 3

vs 3428 m 3258 vs 3391 vs 3343 m 3553 m 3494 m 3289 vs 3427 s 3481 m 3558 m 3331 vs 3446 m 3539 vs 3297

3

vs 3396 m 3072 vs 3509 vs 3482 vs 3301 s 3378 vs 3525 m 3580

7

vs 3506 m 3340 n.a.

3

3

3 3

[1]; 8 [1]; 9 10

11 [1]

ν1 = Symmetric stretching vibration; ν2 = Out-of-plane bending vibration; ν3 = Anti-symmetric stretching vibration; ν4 = In-plane bending vibration; * = Symmetric stretching vibration of CO3 group. Peak intensities as in Table 3. [1] = Raman Spectra Database, Siena Geofluids Lab (http://www.dst.unisi.it/geofluids/raman/spectrum_frame.htm); 2 Thompson et al., 2005; 3 Wang et al., 2006; 4 Korsakov et al., 2009; 5 Montero and Schmolz, 1974; 6 Kloprogge and Frost, 2000; 7 Barashkov et al., 2004; 8 Frost et al., 2006; 9 Kloprogge et al., 2002; 10 Kloprogge et al., 2004; 11 Hamilton and Menzies, 2010; n.a. = not analyzed; Ref. = References.

12

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Table 5 Main Raman vibrations (cm− 1) of selected phosphates and borates. PO43− vibrations

Phosphates

Ref.

ν2

ν4

ν1

ν3

Apatite Ca5(PO4)3(OH,F,Cl) Fluorapatite Ca5(PO4)3F

w 428 w 446 mw 432 w 449

vs 960

w 430

983

425

584 595 610

w 1026 w 1040 m 1053 mw 1081 w 1042 mw 1039 w 1127 1005

[1]

Chlorapatite Ca5(PO4)3Cl Herderite CaBePO4 (F,OH) Triplite (Mn,Fe,Mg,Ca)2(PO4)(F,OH) Berlinite AlPO4 Amblygonite LiAl(PO4)F Lacroixite NaAl(PO4)F Na-phosphate Na3PO4

w 578 w 588 m 592 w 608 mw 581 w 581

980

1034

1111

1229

1011

4; 5 4; 5 4

1001

4

910 942 993 1059

5

601 644 609 623 524 544

391 482 344

Xenotime (Y,Yb)PO4 Monazite (La,Ce,Nd,Th)PO4

485

611 630 741 642

m 466

m 620

998 1056 vs 987

2

3 4

1100 1136

5

1394

5

mw 1054

6

Main vibrations

Ref. 428 475 401 415 475

Metaboric acid HBO2 (monoclinic) Metaboric acid HBO2 (orthorhombic) Li-metaborate LiBO2 Sassolite H3BO3 Hambergite Be2BO3(OH,F) Na-tetraborate Na2B4O7·10H2O Li-tetraborate Li2B4O7·5H2O

vs 963

437 461

Lazulite (Mg,Fe)Al2(PO4)2(OH)2

Borates

vs 965

782

518 533 595

5 809

5

713 w 500

1419 vs 880

vs 153

Borax Na2B4O5(OH)4·8H2O Ca–Mg-hexaborates CaB6O10, MgB6O10 with 4 to 7.5 H2O Hydroboracite CaMgB6O11·6H2O

181 257

Cs-Ramanite CsB5O8·4H2O Rb-Ramanite RbB5O8·4H2O

m 98 mw 293 mw 101

7 w 992

385

461

576

756

852

391

446 493

543

772

845 896

344

405 463

571

776

322 383 398

524 548 564 vs 548 w 508 vs 554

634 638 641 606

753

852 855 861 837 876

4

948

943 997 953 964

7 1036

5

1028 1097 1352

5

5 4

5

m 768

m 907

8

w 765

w 914

8

ν1 = Symmetric stretching vibration; ν2 = In-plane bending vibration; ν3 = Antisymmetric stretching vibration; ν4 = Out-of-plane bending vibration. Peak intensities as in Table 3. [1] = Raman Spectra Database, Siena Geofluids Lab (http://www.dst.unisi.it/geofluids/raman/spectrum_frame.htm); 2 Penel et al., 1997; 3 Kuebler et al., 2006; 4 Rickers et al., 2006; 5 R.Thomas, pers. comm.; 6 Silva et al., 2006; 7 Thomas and Davidson, 2010; 8 Thomas et al., 2008a,b; Ref. = References.

other more complex salt systems (Dubessy et al., 2002; Sun et al., 2010). The methods described above are all similar, they only differ in the selected bands of water in the OH-stretching region taken as standards. 5.2. Analyses of solutes: polyatomic ions and molecules Polyatomic charged anions have Raman spectra characterized by the presence of one or more bands (Table 1). Band area and

intensity, although proportional to the solute concentration, cannot be linearly transformed into absolute concentrations, since these are considerably influenced also by measurement conditions (e.g., laser power, optical arrangement, etc.; McMillan et al., 1996; Nasdala et al., 2004). Semi-quantitative analysis of polyatomic solutes in fluid inclusions has been in some cases possible based on relative band-intensity ratios, using selected bands of water as standard. The application of intensity ratios eliminates the influence of measurement conditions. Note that during analyses high laser power

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

13

Table 6 Main Raman vibrations (cm− 1) of selected orthosilicates and tectosilicates. Orthosilicates

Main vibrations

Ref.

Forsterite (Mg0.9,Fe0.1)2SiO4

227

303

Pyrope Mg3Al2Si3O12 Almandine Fe32+Al2Si3O12

211 170

216

Spessartine Mn3Al2Si3O12 Grossular Ca3Al2Si3O12

175

221

181

247 280

Uvarovite Ca3Cr2Si3O12

176

242 272

370

Andradite Ca3(Fe3+, Ti)2Si3O12

174

236

Kyanite Al2SiO5

142

Sillimanite Al2SiO5 Andalusite Al2SiO5 Zircon ZrSiO4

235 293 202 225

Tectosilicates

Main vibrations

Orthoclase KAlSi3O8

157 177 197 159 178 199 163

Microcline KAlSi3O8 Sanidine KAlSi3O8 Albite NaAlSi3O8 Quartz SiO2 Coesite SiO2 Cristobalite SiO2

183 128

116 151 176 114

423

548

608

364

563

650

323 342 370 321 350 373

500 556

1038

3

849 879 827 848 880 828 894

905

1029

3

1007

3

816 842 874

995

3

952

4

325 370

452 494

509 526 590 516 574

302 325 360 386 310

405 419 437 486 456

562

597

708

874

323 361 356

453

553

719

834

669

438

3

907 964 920 992 974

1127

[2]

1065 1111 1008

[2] [2]

Ref. 514 583

263 267 286 284

455 475

514

462 475 457 480 402 464 485 427 466

230 273 286

3

420

458 477

204 269

[1]

1066

863 897 630

921 964 902 928 916

500 552 550

284

210 292 206 265

824 856 882 871

356

326 355

751

814

749

813

514

767

813

508

764

816

520

521

420

651

608 698 785

792

967

1035 1062

1137

[1]

1007

1128 1142

[1]

1123

[1]

807

1032 1098 1066

1161

[2]; 5 6

815 837

1036 1065

1144 1164

977

1075

6

[2]

[1] = Raman Spectra Database, Siena Geofluids Lab (http://www.dst.unisi.it/geofluids/raman/spectrum_frame.htm); [2] = Raman Spectra Database Lyon (http://www.ens-lyon.fr/ LST/Raman). 3 Kolesov and Geiger, 1998; 4 Mernagh and Liu, 1991; 5 Sendova et al., 2005; 6 Palmeri et al., 2009. Ref. = References.

could result in heating the inclusion fluid with consequent possible changes in the speciation of ions. The study of the speciation of sulfur in aqueous solution to determine the redox potential (H2S/SO42−) and pH range (SO42−/HSO4−; HS−/H2S) of geological fluids represents one of the first applications of Raman microspectroscopy to fluid inclusion research (Boiron et al. 1999; Dubessy et al., 1983, 1992, 2002; Rosasco and Roedder, 1979). Sulfate ions give rise to a main S\O stretching band at ~980 cm− 1 (Fig. 9a) and to two additional weak bands around 620, and 450 cm− 1 (Table 1; Ross, 1972; Schmidt, 2009). Only the 980 cm− 1 band is generally strong enough to be observed in fluid inclusions, and has very low detection limits (0.01–0.05 mol/kg; Dubessy et al. 1982, 1983; Rosasco and Roedder, 1979). Bisulfate ions (HSO4−) can be identified by their main S\O and S\OH stretching modes at ~1050 and 890 cm− 1, respectively (Table 1). Hydrogen sulfide (H2S0 and HS−) is characterized by S\H stretching modes in the 2570– 2590 cm− 1 range.

The carbonate ion CO32− fundamental stretching mode is expected at 1064 cm − 1. Other less intense bands at ~1380, and 684 cm − 1 may be observed in concentrated solutions. HCO3− has a very strong C\OH stretching mode at ~1017 cm − 1, and a less intense C\O stretching mode at ~ 1360 cm − 1 (Table 1). Raman studies of carbonates and bicarbonates in solution were initiated by Davis and Oliver (1972) and Dubessy et al. (1982), although these ions were not detected in fluid inclusions at that time. Absence was attributed mainly to their low Raman scattering compared, for example, to that of sulfate ions, and to their relatively low solubility in geological fluids (cf., Burke, 2001; Dubessy et al., 1982; McMillan et al., 1996). More recently, there has been increasing Raman evidence for significant HCO3−(aq) and CO32−(aq) in fluid inclusions (Fig. 9c) mainly from pegmatites, ore deposits, and high pressure metamorphic rocks (Frezzotti et al., 2011; Hrstka et al., 2011; Thomas et al., 2006, 2009a,b, 2011a; Xie et al., 2009). CO32−(aq) concentrations as low as 0.36 wt.% can be measured using a modified technique by Sun and Qin (2011) (R. Thomas,

14

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Table 7 Main Raman vibrations (cm− 1) of selected phyllosilicates and inosilicates, both single and double chains. Phyllosilicates

Main vibrations

Biotite K2(Mg,Fe2+)6-4(Fe3+,Al,Ti)0-2(Si6-5Al2-3O20)(OH,F)4 Muscovite KAl4(Si6Al2O20)(OH,F)4 Phlogopite K2(Mg,Fe2+)6(Si6Al2O20)(OH,F)4 Paragonite Na2Al4(Si6Al2O20)(OH)4

178

Talc Mg6(Si8O20)(OH)4 Clinochlore (Mg, Fe2+)5Al(OH)8(AlSi3O10)

113 196 104 198

178 197 192

549 216 261 279 203 218 272 295

385

407

639

331 372

335 366 358

Chrysotile Mg3Si2O5(OH)4

231

345 389

Antigorite (Mg,Fe2+)3(OH)4Si2O5

230

375

Lizardite Mg3(OH)4Si2O5

233

679

680

717 767 702 754 792

413 465

647

708 756

434

678

786 793

548

914 957

1117 1038 1096 1062

Ref.

3658 3680 3627

2

3673

1018 1055

679

OH−

3477

[1] 3715

[1]

3631

[1]

3677

3

3605 3647 3679 3657

4

620 692

1105

520

683

1044

350 388

510

630 690

1096

343 382 320 389

414

664 684 662

1011

[1]

1009

7

224

667

1040

[1]

229

665

1017

8

Inosilicates

Main vibrations

Enstatite MgSiO3 Diopside CaMgSi2O6 Hornblende (Na,K)0-1Ca2(Mg, Fe2+,Fe3+,Al)5(Si6-7Al2-1O22)(OH,F)2 Pargasite NaCa2Mg4Al3Si6O22(OH)2

237

3658 3687

3703 3718 3745 3709 3729 3774 3708 3723

5; 6 5; 6 5; 6 Ref.

OH− = OH stretching vibrations; [1] Raman Spectra Database, Siena (http://www.dst.unisi.it/geofluids/raman/ spectrum_frame.htm); 2 Kuebler et al., 2006; 3 Fumagalli et al., 2001; 4 Kleppe et al., 2003; 5 Rinaudo et al., 2003; 6 Auzende et al., 2004; 7 Thompson et al., 2005; 8 Downs, 2006. Ref. = References.

pers. comm.). Higher carbonate concentrations can be determined easily. These results are of particular interest since they suggest that alkaline aqueous solutions may represent relevant geological fluids. Raman spectroscopy is a powerful technique to study the speciation of silica in aqueous fluids at different P–T and pH conditions (e.g., Hunt et al., 2011; Newton and Manning, 2003, 2008; Zotov and Keppler, 2000, 2002). In neutral solutions, SiO2 dissolves predominantly as neutral monomers (Si(OH)40) and dimers (Si2O(OH)60) under most crustal and upper mantle P–T conditions. Si(OH)40(aq) can be identified by a

Raman band in the 750–800 cm− 1 region (Table 1). In alkaline fluids, increasing dissociation of monomers and dimers in deprotonated species (e.g., SiO(OH)3−, Si2O2(OH)5−) yields additional Raman bands in the 950–1100 cm− 1 region, as shown in Fig. 9d. B(OH)30 is the predominant boron species in aqueous fluids over a wide range of P–T–pH conditions. The Raman spectrum of B(OH)30(aq) shows a strong band at 877 cm − 1 and an additional weaker band at 495 cm − 1 (Table 1; Janda and Heller, 1979; Schmidt et al., 2005). A method of determining the B(OH)30(aq) concentration in fluid

Fig. 10. Raman spectra of carbon phases in fluid inclusions; a) Diamond in a CO2 fluid inclusion from peridotites, Hawaii; modified from Frezzotti and Peccerillo (2007). b) Graphite in a CO2 fluid inclusion from peridotites, Italy. Excitation light source: Ar ion laser (λ = 514.5 nm). G_G-band, or order band; D_D-band, or disorder band. Note that the Raman wavenumber of the D-band decreases with increasing wavelength of the excitation light source: for example using a He–Ne laser light (λ = 632.8 nm), the graphite D-band is expected at about 1330 cm− 1.

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

15

A catalog of about 140 spectra of minerals which are of interest in fluid inclusion research is presented in Tables 2–7, as a supplement to the web Raman mineral library available at: http://www.dst.unisi.it/ geofluids/raman/spectrum_frame.htm. Each table reports mineral name and formula, a list of the main Raman modes observed, and references. Main vibrations are reported using the ν notation in scattering geometries, where the symmetric stretching vibration (ν1) represents the strongest Raman mode. Reference spectra catalog also includes selected gas and solute species that were discussed above and listed in Table 1. All measured spectra correspond well to spectra reported in literature. Relatively pure phases and/or phases contained within fluid inclusions were measured on a Horiba (Jobin Yvon) Labram spectrometer at the University of Siena, using a water-cooled Ar ion laser (λ = 514.5 nm) as the excitation source. Present catalog intends to provide a first library dedicated to fluid inclusion research. 6.1. Native elements, halides, oxides and sulfides (Table 2)

Fig. 11. Comparison of the Raman spectra of calcite, dolomite, and magnesite in the interval 0–1600 cm− 1. Main CO32− group vibrations are illustrated. ν1 = Symmetric stretching vibration; ν3 = Antisymmetric stretching vibration; ν4 = In-plane bending vibration; T = Translational lattice modes. Calcite, skarn from Vulsini volcanic district, Italy. Dolomite, eclogite from Sulu, China. Magnesite, peridotite from Baldissero, southern Italian Alps.

inclusions has been presented by Thomas (2002), with a minimum detection limit of 0.050 wt.%. Nitrate and phosphate ions have not yet been reported in fluid inclusions, while NaOH(aq) and LiOH(aq) can be present in some ore-forming fluids (Thomas et al., 2011b) 6. Identification of mineral phases: a catalog of reference Raman spectra

Carbon is by far the strongest Raman scatterer and the most studied phase by Raman spectroscopy. In C\O ± H fluid mixtures, precipitation of C (graphite, or diamond at higher pressures) reflects a decrease in fO2 buffer conditions in the fluid–rock system (e.g., redox reactions), often induced by a change in P and/or T. The process has been studied and modeled in natural and synthetic fluid inclusions by various authors (e.g., Frezzotti et al., 1994; Huizenga, 2001; Luque et al., 1998, 2009; Sterner and Bodnar 1984; van den Kerkhof et al., 1991). Fig. 10 reports the spectra of diamond and graphite detected within fluid inclusions. Diamond is characterized by a very strong mode at 1332 cm − 1 (sp 3 bonds; Table 2). Well-crystallized graphite shows one intense bands at 1580 cm − 1 (sp 2 bonds; socalled G-band or order band). In microcrystalline graphite and disordered carbon, presence of defects gives rise to an additional band at 1350 cm − 1 (D-band or disorder band; excitation light source at 514 nm), which increases in intensity with increasing disorder, and to an upshift to 1600 cm − 1 of the G-band (e.g., Wopenka and Pasteris, 1993 and references therein). The area ratio of the order–disorder bands has been proved to represent a reliable geothermometer in natural graphite (i.e., increasing disorder at decreasing temperature; Beyssac et al., 2002; Wopenka and Pasteris, 1993). However, caution should be used in applying the order–disorder geothermometer to graphite contained within fluid inclusions. The crystallinity of graphite precipitated from fluids does not show large variations and it is generally rather high – even at moderate temperatures – unlike what observed in natural graphite (Cesare and Maineri, 1999; Luque et al. 1998, 2009). The solubility of uncharged molecules of S in water is appreciable, and S80 in fluid inclusions (Fig. 9b) has been recognized by the dominant broad bands at 462 (S\S stretching) and 220 cm − 1 (S\S\S bending). Additional minor bands may occur at 153, 187, 246, and 437 cm − 1 (Giuliani et al., 2003). Spectra of chlorides (e.g., halite and sylvite) have not been reported from fluid inclusions. The problem with halides is that they are extremely weak Raman scatterers: one exception is represented by fluorides (Table 2; Burruss et al., 1992; Rickers et al., 2006). Raman bands of most common oxide and hydroxide minerals are listed in Table 2. The three polymorphs of TiO2 are also reported, although only rutile has been observed in fluid inclusions (Frezzotti et al., 2007). 6.2. Carbonates (Table 3)

Fluid inclusions may contain mineral phases, which form by different processes, including direct fluid precipitation (daughter minerals) and reaction of fluid contained within inclusions with the host mineral (step-daughter minerals) (Fig. 1; Roedder, 1984). Minerals including or included within fluid inclusions can be readily identified by comparison of their spectral fingerprints with reference spectra.

Carbonates are common phases in fluid inclusions, and a recent example of Raman identification of multiple carbonates in fluid inclusions in pegmatites is reported in Thomas et al. (2011a). Raman vibrational modes are dependent on the main carbonate groups, modified by the interactions with the bonded mineral lattice. CO32− exhibits three main distinct internal vibrational modes over the

16

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Fig. 12. Raman vibrational mode regions for major silicate classes. Main vibrational regions of borates, phosphates, sulfates, and carbonates are reported for comparison.

range 400–1400 cm − 1. Generally, strong Raman modes appear around 1050–1100 cm − 1 due to the symmetric stretching vibration (ν1) of the carbonate group, while weaker (around 20 time less intense) Raman bands near 700 cm − 1 and 1400 cm − 1 are due to the in-plane bending mode (ν4) and the antisymmetric stretch (ν3) of CO3, respectively. Lattice modes show Raman shifts below 400 cm − 1. As shown in Fig. 11, close similarities exist in the Raman modes of the CO3 group between different carbonate minerals. However, significant differences are evident in the positions of their respective lattice modes over the range 100–350 cm− 1 (T in Fig. 11 and Table 3): for example bands of CaCO3 (156 and 284 cm− 1), CaMg(CO3)2 (176, 299 cm− 1), and MgCO3 (212 and 329 cm− 1) are distinct and identifiable without difficulty. Raman spectroscopy is well suited to distinguish among the polymorphs calcite, aragonite and vaterite (Table 3). Calcite has main Raman modes at 1085 (ν1), 1450 (ν3), and 712 cm − 1 (ν4). Aragonite has the main vibrational mode at 1085 cm (ν1), and weak vibrations at 1463 (ν3) and 704 cm− 1 (ν4), and an additional very weak band at 854 cm− 1 (ν2). In vaterite, the main vibration mode (ν1) forms a doublet at 1074 and 1090 cm− 1. A doublet is also present at 740 and 750 cm− 1 (ν4). The most intense lattice Raman modes are at 284, 206, and 301 cm− 1 for calcite, aragonite and vaterite, respectively. Mg-calcite shows a slight upshift of the main stretching band to 1087 cm− 1 and has a broader band base than pure calcite (Burke, 2001). In hydrated (i.e., hydrous and OH-bearing) carbonates, the OH stretching vibrations give rise to additional broad Raman bands located between 3000 and 3700 cm− 1 (Table 3). 6.3. Sulfates, phosphates, and borates (Tables 4 and 5) Sulfates and phosphates are strong Raman scatterers. The Raman bands of these minerals are due to the vibrations within SO4 and PO4 tetrahedra. Differences among spectra listed in Tables 4 and 5 result from the nature of metals within the main molecular unit, from the bond strength between the main molecular units and neighboring atoms, and from the different degrees of distortion of the main molecular unit in the mineral lattice (cf., Nasdala et al., 2004, and references therein). In sulfates, the strongest Raman band due to the symmetric stretching vibration (ν1), of SO4 tetrahedra is at about 1000 cm − 1, at lower wavenumbers than that of CO3 groups: 1018 cm − 1 for anhydrite, 994 cm − 1 for thenardite, and 1008 cm − 1 for gypsum (Table 4). Additional weaker bands over the ranges 400–500 cm − 1,

600–700 cm − 1, and 1100–1200 cm − 1 are due to the in-plane (ν2) and the out-of-plane (ν4) bending modes, and to the asymmetric stretching of SO4 tetrahedra. The Raman bands of hydrated sulfates are closely related to those of the sulfate ion in aqueous solution (i.e., 980, 620, and 450 cm − 1; Table 1), and show a progressive shift toward higher wavenumbers with decreasing of the hydration state (cf., hydrous magnesium sulfate list in Table 4; Wang et al., 2006). In borates, the distribution of the main Raman bands is mainly dependent on the mineral structure and on the type of borate ion (i.e., boron–oxygen ratio, charge, and hydroxyl groups present); vibrational modes are observed in the regions: 490–670, 690–800, 820–910, and 950–1040 cm − 1 (Table 5). Borates in fluid inclusions have been investigated by Williams and Taylor (1996), Peretyazhko et al. (2000), Thomas (2002), and Rickers et al. (2006). 6.4. Silicates (Tables 6 and 7) Silicate minerals are critically important to fluid inclusion research: quartz, olivine, pyroxenes and garnet represent very common host phases for fluid inclusions, and their Raman bands should be fully characterized before analyzing fluid inclusions. In addition, they can be found as daughter mineral phases in fluid inclusions, because of high silica solubility in aqueous fluids at most crustal and upper mantle P–T conditions (e.g., Manning, 2004). Compared to carbonates and sulfates, silicate minerals are weaker Raman scatterers, due to the low polarizability of the Si\O bonds. Silicates having different chemical composition or/and structure are discriminated from their spectral features. Fig. 12 compares main vibration regions for the different classes of silicates. In orthosilicates, Raman bands are determined by the vibration modes of the isolated SiO4 tetrahedra, similarly to what observed in sulfates and phosphates. Olivine and garnet show the main stretching modes of SiO4 group in the 800–1050 cm − 1 region (Table 6). A very good correlation has been shown between the wavenumbers of the SiO4 main bands and cation substitution (e.g., Mg/Fe + Mg in olivine) which permits the determination of the chemical composition of these minerals (e.g., Guyot et al. 1986). In inosilicates and phyllosilicates, where tetrahedra are to some extent connected, bands generated by the vibration modes of the Si\Ob\Si bonds (Ob = bridging oxygen) dominate the spectra. Spectra of pyroxenes show main Si\O bending and stretching modes over the 600–700 and the 900–1050 cm − 1 regions, respectively (Fig. 12; Wang et al., 2000). Clinopyroxene (diopside-

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

hedembergite series) and orthopyroxene (enstatite–ferrosilite series) can be easily distinguished by the number of bands in the 600–700 cm − 1 region: orthopyroxene has two bands, while clinopyroxene has only a single band (cf., Table 7). Most amphiboles and phyllosilicates are very weak Raman scatterers and reconnaissance within fluid inclusion is often difficult. As shown in Fig. 13, however, the position and the shape of the more intense OH stretching band(s) can be used to distinguish among minerals containing hydroxyl groups. Tectosilicate spectra are dominated by vibrations of Si and O atoms within the framework structures of fully linked tetrahedra (McMillan and Hess, 1990). Main bands, which occur over the range 380–530 cm − 1 (Fig. 12), are due Si\O\Si symmetric stretching and bending modes. The Raman frequencies of main modes show a relationship with the size of rings made by tetrahedra (Sharma et al., 1983): four-membered ring structures, such as feldspars and coesite, have main modes above 500 cm − 1, whereas structures with

17

six-membered rings, such as quartz, tridymite, cristobalite, and nepheline have main modes in the 380–480 cm − 1 region (Table 6). 7. Concluding remarks Raman analysis of fluid inclusions permits to qualitatively detect or identify gaseous and liquid phases, as well as enclosed (or enclosing) minerals. In some cases, quantitative analyses are possible (e.g., relative mole% in gas mixtures, and solute concentration in aqueous fluids). Major advantages of Raman spectroscopy are the minimal sample preparation, and the excellent volume resolution: fluid inclusions as small as the laser spot size (1–2 μm) can be precisely located and analyzed within double polished thick sections. In addition, Raman is a non-destructive technique, meaning that there is no need to decrepitate fluid inclusions. Fluorescence, that can cover the Raman spectrum, represents the most significant disadvantage during analysis, and the risk of fluorescence must be always considered when selecting fluid samples to analyze (e.g., hydrocarbons). Another significant disadvantage is the absence of adequate libraries of reference spectra. This last inconvenience is in part remedied by the compilation of a small spectral library dedicated to fluid inclusion research, presented in our review paper. Raman spectroscopy has been used to successfully analyze fluid inclusions with an increasing number of publications through the years. No other technique can analyze liquid, gas and solid constituents in fluid inclusions. Incorporating this exclusive method with evolving new technologies (e.g., spectral imaging) provides a bright future for this “old” technique in the analysis of geological fluids. Acknowledgments Present research was in part supported by the PRIN 2008-BYTF98. We acknowledge helpful reviews by R. Thomas and an anonymous reviewer of an earlier version of the manuscript. We are grateful to the Museo di Mineralogia of the University of Rome “La Sapienza” and to the Museo di Mineralogia of the University of Siena for providing several mineral samples for Raman analysis. Raman facilities in Siena were provided by PNRA, the Italian research program for Antarctica. References

Fig. 13. Comparison of O\H stretching modes for selected phyllosilicates analyzed in fluid inclusions. Phlogopite, peridotite from Italy. Muscovite, quartzite from Sulu, China. Paragonite, quartzite from Sulu, China. Talc, peridotite from Italy. Clinochlore, peridotite from Ethiopia. In clinochlore OH spectrum, the additional vibration at 3565 cm− 1 indicates excess of Al, or presence of a humite phase (Frost et al., 2007).

Arakawa, M., Yamamoto, J., Kagi, H., 2007. Selected daughter mineral phases and their Raman spectral data. Developing micro-Raman mass spectrometry for measuring carbon isotopic composition of carbon dioxide. Applied Spectroscopy 61, 701–705. Auzende, A.L., Daniel, I., Reynard, B., Lemaire, C., Guyot, F., 2004. High-pressure behaviour of serpentine minerals: a Raman spectroscopic study. Physics and Chemistry of Minerals 31, 269–277. Azbej, T., Severs, M.J., Rusk, B.G., Bodnar, R.J., 2007. In situ quantitative analysis of individual H2O–CO2 fluid inclusions by laser Raman spectroscopy. Chemical Geology 237, 255–263. Bakker, R.J., 2004. Raman spectra of fluid and crystal mixtures in the system H2O, H2O– NaCl and H2O–MgCl2 at low temperatures: applications to fluid inclusion research. The Canadian Mineralogist 42, 1283–1314. Barashkov, M.V., Komyak, A.I., Shashkov, S.N., 2004. Vibrational spectra and structure of potassium alum KAl(SO4)2 ·12[(H2O)x(D2O)1-x]. Journal of Applied Spectroscopy 71, 328–333. Baumgartner, M., Bakker, R.J., 2009. Raman spectroscopy of pure H2O and NaCl–H2O containing synthetic fluid inclusions in quartz -a study of polarization effects. Mineralogy and Petrology 95, 1–15. Baumgartner, M., Bakker, R.J., 2010. Raman spectra of ice and salt hydrates in synthetic fluid inclusions. Chemical Geology 275, 58–66. Beeskow, B., Rankin, A.H., Murphy, P.J., Treloar, P.J., 2005. Mixed CH4–CO2 fluid inclusions in quartz from the South Wales Coalfield as suitable natural calibration standards for microthermometry and Raman spectroscopy. Chemical Geology 223, 3–15. Behrens, H., Roux, J., Neuville, D.R., Siemann, M., 2006. Quantification of dissolved H2O in silicate glasses using confocal microRaman spectroscopy. Chemical Geology 229, 96–112. Bény, C., Guilhaumou, N., Touray, J.C., 1982. Native-sulphur-bearing fluid inclusions in the CO2–H2S–H2O–S system – microthermometry and Raman microprobe (MOLE) analysis – thermochemical interpretations. Chemical Geology 37, 113–127.

18

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Beyssac, O., Rouzaud, J.N., Goffé, B., Brunet, F., Chopin, C., 2002. Graphitization in a highpressure, low-temperature metamorphic gradient: a Raman microspectroscopy and HRTEM study. Contributions to Mineralogy and Petrology 143, 19–31. Boiron, M.C., Moissette, A., Cathelineau, M., Banks, D., Monnin, C., Dubessy, J., 1999. Detailed determination of palaeofluid chemistry: an integrated study of sulphatevolatile rich brines and aquo-carbonic fluids in quartz veins from Ouro Fino (Brazil). Chemical Geology 154, 179–192. Brunsgaard-Hansen, S., Berg, R.W., Stenby, E.H., 2002. How to determine the pressure of a methane-containing gas mixture by means of two weak Raman bands, v3 and 2v2. Journal of Raman Spectroscopy 33, 160–164. Burke, E.A.J., 1994. Raman microspectrometry of fluid inclusions. In: De Vivo, B., Frezzotti, M.L. (Eds.), Fluid Inclusions in Minerals: Method and Applications. Short Course of Working Group (IMA) “Inclusions in Minerals”, Virginia Polytechnic Institute and State University, pp. 25–44. Burke, E.A.J., 2001. Raman microspectrometry of fluid inclusions. Lithos 55, 139–158. Burke, E.A.J., Lustenhouwer, W.J., 1987. The application of a multichannel laser Raman microprobe (Microdril-28) to the analysis of fluid inclusions. Chemical Geology 61, 11–17. Burruss, R.C., 2003. Raman spectroscopy of fluid inclusions. In: Samson, I., Anderson, A., Marshall, D. (Eds.), Fluid inclusions: analysis and interpretation: Mineralogical Association of Canada, short course series, 32, pp. 279–289. Burruss, R.C., Ging, T.G., Eppinger, R.G., Samson, I.M., 1992. Laser-excited fluorescence of rare-earth elements in fluorite: initial observations with a laser Raman microprobe. Geochimica et Cosmochimica Acta 56, 2713–2723. Carey, P.R., 1999. Raman spectroscopy, the sleeping giant in structural biology, awakes. Journal of Biological Chemistry 274, 26625–26628. Carey, D.M., Korenowski, G.M., 1998. Measurement of the Raman spectrum of liquid water. Journal of Chemical Physics 108, 2669–2675. Carteret, C., Dandeu, A., Moussaoui, S., Muhr, H., Humbert, B., Plasari, E., 2009. Polymorphism studied by lattice phonon Raman spectroscopy and statistical mixture analysis method. Application to calcium carbonate polymorphs during batch crystallization. Crystal Growth & Design 9, 807–812. Cesare, B., Maineri, C., 1999. Fluid-present anatexis of metapelites at El Joazo (SE Spain): constraints from Raman spectroscopy of graphite. Contributions to Mineralogy and Petrology 135, 41–52. Chabiron, A., Pironon, J., Massare, D., 2004. Characterization of water in synthetic rhyolitic glasses and natural melt inclusions by Raman spectroscopy. Contribution to Mineralogy and Petrology 146, 485–492. Chou, I.M., Pasteris, J.D., Seitz, J.C., 1990. High-density volatiles in the system C–O–H–N for the calibration of a laser Raman microprobe. Geochimica et Cosmochimica Acta 54, 535–543. Clark, R.J.H., Wang, Q., Correia, A., 2007. Can the Raman spectrum of anatase in artwork and archaeology be used for dating purposes? Identification by Raman microscopy of anatase in decorative coatings on Neolithic (Yangshao) pottery from Henan, China. Journal of Archaeological Science 34, 1787–1793. Colthup, N.B., Daly, L.H., Wiberly, S.E., 1975. Introduction to Infrared and Raman Spectroscopy, 2nd edition. Academic Press, New York. 523 pp. Davis, A.R., Oliver, B.G., 1972. A vibrational-spectroscopic study of the species present in the CO2–H2O system. Journal of Solution Chemistry 1, 329–339. Derome, D., Cathelineau, M., Fabre, C., Boiron, M.C., Banks, D., Lhomme, T., Cuney, M., 2007. Paleo-fluid composition determined from individual fluid inclusions by Raman and LIBS: application to mid-proterozoic evaporitic Na–Ca brines (Alligator Rivers Uranium Field, northern territories Australia). Chemical Geology 237, 240–254. Dhamelincourt, J.M., Beny, C., Dubessy, J., Poty, B., 1979. Analyse d'inclusions fluides à la microsonde MOLE à effet Raman. Bulletin de Minéralogie 102, 600–610. Di Muro, A., Giordano, D., Villemant, B., Montagnac, G., Scaillet, B., Romano, C., 2006. Influence of composition and thermal history of volcanic glasses on water content as determined by micro-Raman spectrometry. Applied Geochemistry 21, 802–812. Downs, R.T., 2006. The RUFF Project: an integrated study of the chemistry, crystallography, Raman and infrared spectroscopy of minerals. Program and Abstracts of the 19th General Meeting of the International Mineralogical Association in Kobe, Japan, O03-13. Dubessy, J., Audeoud, D., Wilkins, R., Kosztolanyi, C., 1982. The use of the Raman Microprobe Mole in the determination of the electrolytes dissolved in the aqueous phase of fluid inclusions. Chemical Geology 37, 137–150. Dubessy, J., Geisler, D., Kosztolany, C., Vernet, M., 1983. The determination of sulphate in fluid inclusions using the MOLE Raman microprobe. Application to a Keuper halite and geochemical consequences. Geochimica et Cosmochimica Acta 47, 1–10. Dubessy, J., Pagel, M., Bény, J.-M., Christensen, H., Hickel, B., Kosztolanyi, C., Poty, B., 1988. Radiolysis evidenced by H2–O2- and H2-bearing fluid inclusions in three uranium deposits. Geochimica Cosmochimica Acta 52, 1155–1167. Dubessy, J., Poty, B., Ramboz, C., 1989. Advances in C–O–H–N–S fluid geochemistry based on micro-Raman spectrometric analysis of fluid inclusions. European Journal of Mineralogy 1, 517–534. Dubessy, J., Boiron, M.C., Moissette, A., Monnin, C., Stretenskaya, N., 1992. Determination of water, hydrates and pH in fluid inclusions by micro-Raman spectrometry. European Journal of Mineralogy 4, 885–894. Dubessy, J., Moissette, A., Bakker, R.J., Frantz, J.D., Zhang, Y.G., 1999. High temperature Raman spectroscopic study of H2O–CO2–CH4 mixtures in synthetic fluid inclusions: first insights on molecular interactions and analytical implications. European Journal of Mineralogy 11, 23–32. Dubessy, J., Buschaert, S., Lamb, W., Pironon, J., Thiery, R., 2001. Methane-bearing aqueous fluid inclusions: Raman analysis, thermodynamic modeling and application to petroleum basins. Chemical Geology 173, 193–205.

Dubessy, J., L'Homme, T., Boiron, M.C., Rull, F., 2002. Determination of chlorinity in aqueous fluids using Raman spectroscopy of the stretching band of water at room temperature: application to fluid inclusions. Applied Spectroscopy 56, 99–106. Edwards, H.G.M., Jorge Villar, S.E., Jehlicka, J., Munshi, T., 2005. FT-Raman spectroscopic study of calcium-rich and magnesium-rich carbonate minerals. Spectrochimica Acta Part A 61, 2273–2280. Fall, A., Tattitch, B., Bodnar, R.J., 2011. Combined microthermometric and Raman spectroscopic technique to determine the salinity of H2O–CO2–NaCl fluid inclusions based on clathrate melting. Geochimica et Cosmochimica Acta 75, 951–964. Fermi, E., 1931. Über den Ramaneffekt des Kohlendioxyds. Zeitschrift für Physik 71, 250–259. Ferrando, S., Frezzotti, M.L., Orione, P., Conte, R.C., Compagnoni, R., 2010. Late-Alpine rodingitization in the Bellecombe meta-ophiolites (Aosta Valley, Italian Western Alps): evidence from mineral assemblages and serpentinization-derived H2-bearing brine. International Geology Review 52, 1220–1243. Fraley, P.E., Rao, K.N., Jones, L.H., 1969. High resolution infrared spectra of water vapor: ν1 and ν3 of H218O. Journal of Molecular Spectroscopy 29, 312–347. Frezzotti, M.L., Peccerillo, A., 2007. Diamond-bearing COHS fluids in the mantle beneath Hawaii. Earth and Planetary Science Letters 262, 273–283. Frezzotti, M.L., Burke, E.A.J., De Vivo, B., Stefanini, B., Villa, I.M., 1992. Mantle fluids in pyroxenite nodules from Salt Lake Crater (Oahu, Hawaii). European Journal of Mineralogy 4, 1137–1153. Frezzotti, M.L., Di Vincenzo, G., Ghezzo, C., Burke, E.A.J., 1994. Evidence of magmatic CO2rich fluids in peraluminous graphite-bearing leucogranites from Deep Freeze Range (northern Victoria Land, Antarctica). Contributions to Mineralogy and Petrology 117, 111–123. Frezzotti, M.L., Andersen, T., Neumann, E.R., Simonsen, S.L., 2002. Carbonatite melt-CO2 fluid inclusions in mantle xenoliths from Tenerife, Canary Islands: a story of trapping, immiscibility and fluid–rock interaction in the upper mantle. Lithos 64, 77–96. Frezzotti, M.L., Ferrando, S., Dallai, L., Compagnoni, R., 2007. Intermediate alkalialumino-silicate aqueous solutions released by deeply subducted continental crust: fluid evolution in UHP OH-rich Topaz-Kyanite Quartzites from Donghai (Sulu, China). Journal of Petrology 48, 1219–1241. Frezzotti, M.L., Ferrando, S., Peccerillo, A., Petrelli, M., Tecce, F., Perucchi, A., 2010. Chlorine-rich metasomatic H2O–CO2 fluids in amphibole-bearing peridotites from Injibara (Lake Tana region, Ethiopian plateau): nature and evolution of volatiles in the mantle of a region of continental flood basalts. Geochimica et Cosmochimica Acta 74, 3023–3039. Frezzotti, M.L., Selverstone, J., Sharp, Z.D., Compagnoni, R., 2011. Carbonate dissolution during subduction revealed by diamond-bearing rocks from the Alps. Nature Geoscience. doi:10.1038/NGEO1246. Frost, R.L., Bouzaid, J.M., 2007. Raman spectroscopy of Dawsonite NaAl(CO3)(OH)2. Journal of Raman Spectroscopy 38, 873–879. Frost, R.L., Dickfos, M., 2007. Hydrated double carbonates—a Raman and infrared spectroscopic study. Polyhedron 26, 4503–4508. Frost, R.L., Martens, W.N., Rintoul, L., Mahmutagic, E., Kloprogge, J.T., 2002. Raman spectroscopic study of azurite and malachite at 298 and 77 K. Journal of Raman Spectroscopy 33, 252–259. Frost, R.L., Wills, R.A., Weier, M.L., Martens, W., Kloprogge, J.T., 2006. A Raman spectroscopic study of alunites. Journal of Molecular Structure 785, 123–132. Frost, R.L., Palmer, S., Bouzaid, J., Reddy, J., 2007. A Raman spectroscopic study of humite minerals. Journal of Raman Spectroscopy 38, 68–77. Frost, R.L., Bahfenne, S., Graham, J., 2008. Raman spectroscopic study of the magnesium carbonate minerals artinite and dypingite. Journal of Raman Spectroscopy 40, 855–860. Fumagalli, P., Stixrude, L., Poli, S., Snyder, D., 2001. The 10 phase: a high-pressure expandable sheet silicate stable during subduction of hydrated lithosphere. Earth and Planetary Science Letters 186, 125–141. Garrabos, Y., Tufev, R., Le Neindre, B., Zalczer, G., Beysens, D., 1980. Rayleigh and Raman scattering near the critical point of carbon dioxide. Journal of Chemical Physics 72, 4637–4651. Gillet, P., 1993. Stability of Magnesite (MgCO3) at mantle pressure and temperature conditions: a Raman spectroscopic study. American Mineralogist 78, 1328–1331. Giuliani, G., Dubessy, J., Banks, D., Vinh, H.Q., Lhomme, T., Pironon, J., Garnier, V., Trinh, P.T., Van Long, P., Ohnenstetter, D., Schwarz, D., 2003. CO2-H2S-COS-S8-AlO(OH)-bearing fluid inclusions in ruby from marble-hosted deposits in Luc Yen area, North Vietnam. Chemical Geology 194, 167–185. Grishina, S., Dubessy, J., Kontorovich, A., Pironon, J., 1992. Inclusions in salt beds resulting from thermal metamorphism by dolerite sills (eastern Siberia, Russia). European Journal of Mineralogy 4, 1187–1202. Guilhaumou, N., 1982. Analyse ponctuelle des inclusions fluids par microsonde molèculaire à laser (MOLE) et microthermomètrie, Travaux du Laboratoire de Géologie, Ecole Normale Supérieure de Paris 14. 78 pp. Guillaume, D., Teinturier, S., Dubessy, J., Pironon, J., 2003. Calibration of methane analysis by Raman spectroscopy in H2O-NaCl-CH4 fluid inclusions. Chemical Geology 194, 41–49. Guyot, F., Boyer, H., Madon, M., Velde, B., Poirier, J.P., 1986. Comparison of the Raman microprobe spectra of (Mg,Fe)2SiO4 and Mg2GeO4 with olivine and spinel structures. Physics and Chemistry of Minerals 13, 91–95. Hamilton, A., Menzies, R.I., 2010. Raman spectra of Mirabilite, Na2SO4 10H2O and the rediscovered metastable heptahydrate, Na2SO4·7H2O. Journal of Raman Spectroscopy 41, 1014–1020. Hare, D.E., Sorensen, C.M., 1992. Interoscillator coupling effects on the OH stretching band of liquid water. Journal of Chemical Physics 96, 13–22. Herzberg, G., 1945. Infrared and Raman Spectra of Polyatomic Molecules. Van Nostrand, Princeton. 285 pp.

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20 Herzberg, G., 1950. Molecular Spectra and Molecular Structure I. Spectra of Diatomic Molecules, Second edition. Van Nostrand, Princeton, NJ. 658 pp. Hidas, K., Guzmics, T., Szabò, C., Kovàcs, I., Bodnar, R.J., Zajacz, Z., Nédil, Z., Vaccari, L., Perucchi, A., 2010. Coexisting silicate melt inclusions and H2O-bearing, CO2-rich fluid inclusions in mantle peridotite xenoliths from the Carpatian–Pannonian region (central Hungary). Chemical Geology 274, 1–18. Hrstka, T., Dubessy, J., Zachariàš, J., 2011. Bicarbonate-rich fluid inclusions and hydrogen diffusion in quartz from the Libčice orogenic gold deposit, Bohemian Massif. Chemical Geology 281, 317–332. Huizenga, J.M., 2001. Thermodynamic modelling of C–O–H fluids. Lithos 55, 101–114. Hunt, J.D., Kavner, A., Schauble, E.A., Snyder, D., Manning, C.E., 2011. Polymerization of aqueous silica in H2O–K2O solutions at 25–200 °C and 1 bar to 20 kbar. Chemical Geology 283, 161–170. Janda, R., Heller, G., 1979. Ramanspektroskopische Untersuchungen an festen und in Wasser gelösten Polyboraten. Zeitschrift für Naturforschung 34b, 585–590. Karr, C., 1975. Infrared and Raman Spectroscopy of Lunar and Terrestrial Minerals. Academic Press, New York. 375 pp. Kawakami, Y., Yamamoto, J., Kagi, H., 2003. Micro-Raman densimeter for CO2 inclusions in mantle-derived minerals. Applied Spectroscopy 57, 1333–1339. Kleppe, A.K., Jephcoat, A.P., Welch, M.D., 2003. The effect of pressure upon hydrogen bonding in chlorite. A Raman spectroscopy study of clinochlore to 26.5 GPa. American Mineralogist 88, 567–573. Kloprogge, J.T., Frost, R.L., 2000. Raman microscopy at 77K of natural gypsum CaSO4·2H2O. Journal of Materials Science Letters 19, 229–231. Kloprogge, J.T., Schuiling, R.D., Ding, Z., Hickey, L., Wharton, D., Frost, R.L., 2002. Vibrational spectroscopic study of Syngenite formed during the treatment of liquid manure with sulphuric acid. Vibrational Spectroscopy 28, 209–221. Kloprogge, J.T., Hickey, L., Duong, L.V., Martens, W.N., Frost, R.L., 2004. Synthesis and characterization of K2Ca5(SO4)6·H2O, the equivalent of görgeyite, a rare evaporite mineral. American Mineralogist 89, 266–272. Kohlrausch, K.W.F., 1943. Ramanspektren. Leipzig. 469 pp. Kolesov, B.A., Geiger, C.A., 1998. Raman spectra of silicate garnets. Physics and Chemistry of Minerals 25, 142–151. Korsakov, A.V., Golovin, A.V., De Gussem, K., Sharygin, I.S., Vandenabeele, P., 2009. First finding of burkeite in melt inclusions in olivine from sheared lherzolite xenoliths. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 73, 424–427. Korsakov, A.V., Dieing, T., Golovin, A.V., Toporski, J., 2011. Raman imaging of fluid inclusions in garnet from UHPM rocks (Kokchetav massif, Northern Kazakhstan). Spectrochimica acta Part A Molecular and biomolecular spectroscopy 80, 88–95. Koura, N., Kohara, S., Takeuchi, K., Takahashi, S., Curtiss, L.A., Grimsditch, M., Saboungi, M.L., 1996. Alkali carbonates: Raman spectroscopy, ab initio calculations, and structure. Journal of Molecular Structure 382, 163–169. Kuebler, K., Wang, A., Freeman, J.J., Jolliff, B.L., 2006. Database of Raman mineral spectra for planetary surface exploration. Lunar and Planetary Science XXXVII, abs. 1907. Landsherg, G.S., Mandelstam, L.I., 1928a. New phenomenon in scattering of light (preliminary report). Journal of the Russian Physico-Chemical Society, Physics Section 60, 335. Landsherg, G.S., Mandelstam, L.I., 1928b. Eine neue Erscheinung bei der Lichtzertreuung. Naturwissenschaften 16, 557. Lu, W., Chou, I.M., Burruss, R.C., Song, Y., 2007. A unified equation for calculating methane vapor pressures in the CH4–H2O system with measured Raman shifts. Geochimica et Cosmochimica Acta 71, 3969–3978. Luque, F.J., Pasteris, J.D., Wopenka, B., Rodas, M., Barrenechea, J.F., 1998. Natural fluiddeposited graphite: mineralogical characteristics and mechanisms of formation. American Journal of Science 298, 471–498. Luque, F.J., Ortega, L., Barrenechea, J.F., Millward, D., Beyssac, O., Huizenga, J.M., 2009. Deposition of highly crystalline graphite from moderate-temperature fluids. Geology 37, 275–278. Makhoukhi, S., Marignac, C., Pironon, J., Schmitt, J.M., Marrakchi, C., Bouabdelli, M., Bastoul, A., 2003. Aqueous and hydrocarbon inclusions in dolomite from Touissit-Bou Berker district, Eastern Morocco: a Jurassic carbonate hosted Pb–Zn (Cu) deposit. Journal of Geochemical Exploration 78–79, 545–551. Manning, C.E., 2004. The chemistry of subduction fluids. Earth and Planetary Science Letters 223, 1–16. McMillan, P.F., Hess, A.C., 1988. Symmetry, group theory and quantum mechanics. In: Hawthorne, F.C. (Ed.), Spectroscopic methods in mineralogy and geology. Reviews in Mineralogy. Mineralogical Society of America, Washington, D.C., pp. 11–61. McMillan, P.F., Hess, A.C., 1990. Ab initio valence force field calculations for quartz. Physics and Chemistry of Minerals 17, 97–107. McMillan, P.F., Dubessy, J., Hemley, R., 1996. Applications in Earth, planetary and environmental sciences. In: Turrell, G., Corset, G. (Eds.), Raman Microscopy. Academic Press, pp. 289–351. Mernagh, T.P., Liu, L., 1991. Raman spectra from the Al2SiO5 polymorphs at high pressure and room temperature. Physics and Chemistry of Minerals 18, 126–130. Mernagh, T.P., Trudu, A.G., 1993. A laser Raman microprobe of some geologically important sulphide minerals. Chemical Geology 103, 113–127. Mernagh, T.P., Wilde, A.R., 1989. The use of the laser Raman microprobe for the determination of salinity in fluid inclusions. Geochimica et Cosmochimica Acta 53, 765–771. Montero, S., Schmolz, R., 1974. Raman spectra of orthorhombing sulfate single crystals I: K2SO4, Rb2SO4, Cs2SO4 and Tl2SO4. Journal of Raman Spectroscopy 2, 101–113. Morizet, Y., Paris, M., Gaillard, F., Scaillet, B., 2009. Raman quantification factor calibration for CO–CO2 gas mixture in synthetic fluid inclusions: application to oxygen fugacity calculation in magmatic systems. Chemical Geology 264, 58–70. Munz, I.A., 2001. Petroleum inclusions in sedimentary basins: systematic, analytical methods and applications. Lithos 55, 195–212.

19

Nasdala, L., Pidgeon, R.T., Wolf, D., 1996. Heterogeneous metamictization of zircon on microscale. Geochimica et Cosmochimica Acta 60, 1091–1097. Nasdala, L., Smith, D.C., Kaindl, R., Zieman, M.A., 2004. Raman spectroscopy: analytical perspectives in mineralogical research. In: Beran, A., Libowitzky, E. (Eds.), Spectroscopic methods in mineralogy: EMU Notes in Mineralogy, 6, pp. 281–343. Nazmutdinov, R.R., Zinkicheva, T.T., Vassiliey, S.Y., Glukhov, D.V., Tsirlina, G.A., Probst, M., 2010. A spectroscopic and computational study of Al(III) complexes in sodium cryolite melts: ionic composition in a wide range of cryolite ratios. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 75, 1244–1252. Newton, R.C., Manning, C.E., 2003. Activity coefficient and polymerization of aqueous silica at 800 °C, 12 kbar, from solubility measurements on SiO2-buffering mineral assemblages. Contributions to Mineralogy and Petrology 146, 135–143. Newton, R.C., Manning, C.E., 2008. Thermodynamics of SiO2–H2O fluid near the upper critical end point from quartz solubility measurements at 10 kbar. Earth Planetary Science Letters 274, 241–249. Orange, D., Knittle, E., Farber, D., Williams, Q., 1996. Raman spectroscopy of crude oils and hydrocarbon inclusions: a feasibility study. In: Dyar, M.D., McCammon, C., Scaefer, M.W. (Eds.), Mineral spectroscopy: a tribute to Roger G. Burns: Geochemical Society, Special Publications, volume 5, pp. 65–81. Palmeri, R., Frezzotti, M.L., Godard, G., Davies, R.J., 2009. Pressure-induced incipient amorphization of α-quartz and transition to coesite in an eclogite from Antarctica: a first record and some consequences. Journal of Metamorphic Geology 27, 685–705. Pasteris, J.D., Kuehn, C.A., Bodnar, R.J., 1986. Applications of the laser Raman microprobe RAMANOR U-1000 to hydrothermal ore deposits: Carlin as an example. Economic Geology 81, 915–930. Pasteris, J.D., Wopenka, B., Seitz, J.C., 1988. Practical aspects of quantitative laser Raman microprobe spectroscopy for the study of fluid inclusions. Geochimica et Cosmochimica Acta 52, 979–988. Penel, G., Leroy, G., Rey, C., Sombert, B., Huvenne, J.P., Bres, E., 1997. Infrared and Raman microspectrometry study of fluor-fluor-hydroxy and hydroxyl-apatite powders. Journal of Material Science: Materials in Medicine 8, 271–276. Peretti, A., Dubessy, J., Mullis, J., Frost, R., Trommsdorff, V., 1992. Highly reducing conditions during alpine metamorphism of the Maleno peridotite (Sondrio, Northern Italy) indicated by mineral paragenesis and H2 in fluid inclusions. Contributions to Mineralogy and Petrology 112, 329–340. Peretyazhko, I.S., Prokof'ev, V.Y., Zagorskii, V.E., Smirnov, S.Z., 2000. Role of boric acids in the formation of pegmatite and hydrothermal minerals: petrologic consequences of sassolite (H3BO3) discovery in fluid inclusions. Petrology 8, 214–237. Pironon, J., 1993. Estimation de la longueur de chaîne des hydrocarbures des inclusions fluides par spectrométrie Raman. Compte-Rendus de l'Académie des Sciences de Paris 316 Série II, pp. 1075–1082. Pironon, J., Barrès, O., 1990. Semi-quantitative FT-IR microanalysis limits: evidence from synthetic hydrocarbon fluid inclusions in sylvite. Geochimica et Cosmochimica Acta 54, 509–518. Pironon, J., Sawatzki, J., Dubessy, J., 1991. NIR FT-Raman microspectroscopy of fluid inclusions: comparisons with VIS Raman and FT-IR microspectroscopies. Geochimica et Cosmochimica Acta 55, 3885–3891. Pironon, J., Canals, M., Dubessy, J., Walgenwitz, F., Laplace-Biulhe, C., 1998. Volumetric reconstruction of individual oil inclusions by confocal scanning laser microscopy. European Journal of Mineralogy 10, 1143–1150. Potter, J., Rankin, A.H., Treloar, P.J., 2004. Abiogenic Fischer–Tropsch synthesis of hydrocarbons in alkaline igneous rocks; fluid inclusions, textural and isotopic evidence from the Lovozero complex, N.W. Russia. Lithos 75, 311–330. Poty, B., Leroy, J., Jachimowicz, L., 1976. Fluid inclusions studies in quartz from fissures of western and central Alps. Schweizer Mineralogische und Petrographische Mitteilungen 54, 717–752. Raman, C.V., 1928. A new radiation. Indian Journal of Physics 387. Raman, C.V., Krishnan, K.S., 1928. The optical analog of the Compton effect. Nature 121, 711. Rickers, K., Thomas, R., Heinrich, W., 2006. The behavior of trace elements during the chemical evolution of the H2O-, B-, and F-rich granite-pegmatite-hydrothermal system at Ehrenfriedersdorf, Germany: a SRF study of melt and fluid inclusions. Mineralium Deposita 41, 229–245. Rinaudo, C., Gastaldi, D., Belluso, E., 2003. Characterization of chrysotile, antigorite and lizardite by FT-Raman spectroscopy. The Canadian Mineralogist 41, 883–890. Roedder, E., 1984. Fluid inclusions. Reviews in Mineralogy 12, 644. Rosasco, G.J., Roedder, E., 1979. Application of a new Raman microprobe spectrometer to nondestructive analysis of sulfate and other ions in individual phases in fluid inclusions in minerals. Geochimica et Cosmochimica Acta 43, 1907–1915. Rosasco, G.J., Roedder, E., Simmons, J.H., 1975. Laser-excited Raman spectroscopy for nondestructive partial analysis of individual phases in fluid inclusions in minerals. Science 190, 557–560. Ross, S.D., 1972. Inorganic Infrared and Raman Spectra. McGraw-Hill Book Company, London. 140 p. Rossetti, F., Tecce, F., 2008. Composition and evolution of fluids during skarn development in the Monte Capanne thermal aureole, Elba island, central Italy. Geofluids 8, 167–180. Rosso, K.M., Bodnar, R.J., 1995. Microthermometric and Raman spectroscopic detection limits of CO2 in fluid inclusions and the Raman spectroscopic characterization of CO2. Geochimica et Cosmochimica Acta 59, 3961–3975. Ruan, H.D., Frost, R.L., Kloprogge, J.T., 2001. Comparison of Raman spectra in characterizing gibbsite, bayerite, diaspore and bohemite. Journal of Raman Spectroscopy 32, 745–750. Rull, F., Martinez-Frias, J., Rodriguez-Losada, J.A., 2007. Micro-Raman spectroscopic study of El Gasco pumice, western Spain. Journal of Raman Spectroscopy 38, 239–244. Samson, I.M., Walker, R.T., 2000. Cryogenic Raman spectroscopic studies in the system NaCl-CaCl2-H2O and implications for low-temperature phase behaviour in aqueous fluid inclusions. Canadian Mineralogist 38, 35–43.

20

M.L. Frezzotti et al. / Journal of Geochemical Exploration 112 (2012) 1–20

Schiffries, C.M., 1990. Liquid-absent aqueous fluid inclusions and phase equilibria in the system CaCl2–NaCl–H2O. Geochimica et Cosmochimica Acta 54, 611–619. Schmidt, C., 2009. Raman spectroscopic study of a H2O + Na2SO4 solution at 21–600 °C and 0.1 MPa to 1.1 GPa. Relative differential ν1-SO42−. Raman scattering cross sections and evidence of the liquid–liquid transition. Geochimica et Cosmochimica Acta 73, 425–437. Schmidt, C., Watenphul, A., 2010. Ammonium in aqueous fluids to 600 °C, 1.3 GPa: a spectroscopic study on the effects on fluid properties, silica solubility, and Kfeldspar to muscovite reactions. Geochimica et Cosmochimica Acta 74, 6852–6866. Schmidt, C., Thomas, R., Heinrich, W., 2005. Boron speciation in aqueous fluids at 22 to 600 °C and 0.1 MPa to 2 GPa. Geochimica et Cosmochimica Acta 69, 275–281. Schrötter, H.W., Klöckner, H.W., 1979. Raman scattering cross-sections in gases and liquids. In: Weber, A. (Ed.), Raman Spectroscopy of Gases and Liquids. Springer-Verlag, Berlin, pp. 123–166. Schubert, F., Diamond, L.W., Tòth, T.M., 2007. Fluid-inclusion evidence of petroleum migration through a buried metamorphic dome in the Pannonian Basin, Hungary. Chemical Geology 244, 357–381. Seitz, J.C., Pasteris, J.D., Wopenka, B., 1987. Characterization of CO2-CH4-H2O fluid inclusions by microthermometry and laser Raman microprobe spectroscopy: inferences for clathrate and fluid equilibria. Geochimica et Cosmochimica Acta 51, 1651–1664. Sendova, M., Zhelyaskov, V., Scalera, M., Ramsey, M., 2005. Micro-Raman spectroscopic study of pottery fragments from the Lapatsa Tomb, Cyprus, ca 2500 BC. Journal of Raman Spectroscopy 36, 829–833. Severs, M.J., Azbej, T., Thomas, J.B., Mandeville, C.W., Bodnar, R.J., 2006. Experimental determination of H2O loss from melt inclusions during laboratory heating. Chemical Geology 237, 358–371. Sharma, S.K., Simons, B., Yoder, H.S., 1983. Raman study of anorthite, calcium Tschermak’s pyroxene, and gehlenite in crystalline and glassy states. American Mineralogist 68, 1113–1125. Shebanova, O.N., Lazor, P., 2003. Raman spectroscopic study of magnetite (FeFe2O4): a new assignment for the vibrational spectrum. Journal of Solid State Chemistry 174, 424–430. Siemann, M.G., Ellendorff, B., 2001. The composition of gases in fluid inclusions of Late Permian (Zechstein) marine evaporates in Northern Germany. Chemical Geology 173, 31–44. Silva, E.N., Ayala, A.P., Guedes, I., Paschoal, C.W.A., Moreira, R.L., Loong, C.K., Boatner, L.A., 2006. Vibrational spectra of monazite-type rare-earth orthophosphates. Optical Materials 29, 224–230. Slotznick, S.P., Shim, S.H., 2008. In situ Raman spectroscopy measurements of MgAl2O4 spinel up to 1400 °C. American Mineralogist 93, 470–476. Smekal, A., 1923. The quantum theory of dispersion. Naturwissenschaften 11, 873–875. Song, Y., Chou, I.M., Hu, W., Burruss, R.C., Lu, W., 2009. CO2 density-Raman shift relation derived from synthetic inclusions in fused silica capillaries and its application. Acta Geologica Sinica 83, 932–938. Sterner, S.M., Bodnar, R.J., 1984. Synthetic fluid inclusions in natural quartz I. Compositional types synthesized and applications to experimental geochemistry. Geochimica et Cosmochimica Acta 48, 2659–2668. Sun, Q., 2009. The Raman OH\ stretching bands of liquid water. Vibrational Spectroscopy 51, 213–217. Sun, Q., Qin, C., 2011. Raman OH stretching band of water as an internal standard to determine carbonate concentrations. Chemical Geology 283, 274–278. Sun, Q., Zhao, L., Li, N., Liu, J., 2010. Raman spectroscopic study for the determination of Cl-concentration (molarity scale) in aqueous solutions: application to fluid inclusions. Chemical Geology 272, 55–61. Thomas, R., 2000. Determination of water contents of granite melt inclusions by confocal laser Raman microprobe spectroscopy. American Mineralogist 85, 868–872. Thomas, R., 2002. Determination of the H3BO3 concentration in fluid and melt inclusions in granite pegmatites by laser Raman microprobe spectroscopy. American Mineralogist 87, 56–68. Thomas, R., Davidson, P., 2006. Progress in the determination of water in glasses and melt inclusions with Raman spectroscopy: a short review. Zeitschrift für geologische Wissenschaften 34, 159–163. Thomas, R., Davidson, P., 2010. Hambergite-rich melt inclusions in morganite crystals from the Muiane pegmatite, Mozambique and some remarks on the paragenesis of hambergite. Mineralogy and Petrology 100, 227–239. Thomas, R., Schmidt, C., Veksler, I., Davidson, P., Beurlen, H., 2006. The formation of peralkaline pegmatitic melt fractions: evidence from melt and fluid inclusion studies. Anais da Academia Brasileira de Ciencias 16, 61–67. Thomas, R., Davidson, P., Hahn, A., 2008a. Ramanite-(Cs) and ramanite-(Rb): new cesium and rubidium pentaborate tetrahydrate minerals identified with Raman spectroscopy. American Mineralogist 93, 1034–1042. Thomas, S.-M., Thomas, R., Davidson, P., Reichart, P., Koch-Müller, M., Dollinger, G., 2008b. Application of Raman spectroscopy to quantify trace water concentrations in glasses and garnets. American Mineralogist 93, 1550–1557. Thomas, R., Davidson, P., Badanina, E., 2009a. A melt and fluid inclusion assemblage in beryl from pegmatite in the Orlovka amazonite granite, East Transbaikalia, Russia: implications for pegmatite-forming melt systems. Mineralogy and Petrology 96, 129–140. Thomas, R., Davidson, P., Rhede, D., Leh, M., 2009b. The miarolitic pegmatites from the Königshain: a contribution to understanding the genesis of pegmatites. Contributions to Mineralogy and Petrology 157, 505–523.

Thomas, R., Davidson, P., Schmidt, C., 2011a. Extreme alkali bicarbonate- and carbonaterich fluid inclusions in granite pegmatite from the Precambrian Rønne granite, Bornholm Island, Denmark. Contribution to Mineralogy and Petrology 161, 315–329. Thomas, R., Davidson, P., Beurlen, H., 2011b. Tantalite-(Mn) from the Borborema Pegmatite Province, northeastern Brazil: conditions of formation and melt- and fluid-inclusion constraints on experimental studies. Mineralium Deposita. doi:10.1007/s00126-0110344-9. Thompson, J., Wiens, R., Sharma, S., Lucey, P., Misra, A., 2005. Combined remote LIBS and Raman spectroscopy measurements. Lunar and Planetary Science XXXVI pdf.1517. Touret, J.L.R., 2001. Fluids in metamorphic rocks. Lithos 55, 1–25. Tsunogae, T., Dubessy, J., 2009. Ethane- and hydrogen-bearing carbonic fluid inclusions in a high-grade metamorphic rock. Journal of Mineralogical and Petrological Sciences 104, 324–329. van den Kerkhof, A.M., 1988a. Phase transitions and molar volumes of CO2–CH4–N2 inclusions. Bulletin de Minéralogie 111, 257–266. van den Kerkhof, A.M., 1988b. The system CO2–CH4–N2 in fluid inclusions: theoretical modeling and geological applications. Ph.D. Thesis, Vrije Universiteit Amsterdam, The Netherlands. 206 pp. van den Kerkhof, A.M., 1990. Isochoric phase diagrams in the system CO2–CH4 and CO2–N2: application to fluid inclusions. Geochimica et Cosmochimica Acta 54, 621–629. van den Kerkhof, A.M., Olsen, S.N., 1990. A natural example of superdense CO2 inclusions: microthermometry and Raman analysis. Geochimica et Cosmochimica Acta 55, 2533–2544. van den Kerkhof, A.M., Touret, J.L.R., Maijer, C., Jansen, J.B.H., 1991. Retrograde methanedominated fluid inclusions from high-temperature granulites of Rogaland, southwestern Norway. Geochimica et Cosmochimica Acta 55, 2533–2544. Walrafen, G.E., 1964. Raman spectral studies of water structure. Journal of Chemical Physics 40, 3249–3256. Walrafen, G.E., 1967. Raman spectral studies of effects of temperature on water structure. Journal of Chemical Physics 47, 114–126. Wang, C.H., Wright, R.B., 1973. Raman studies of the effect of density of the Fermi resonance in CO2. Chemical Physics Letters 23, 241–246. Wang, A., Haskin, L., Jolliff, B., Wdowiak, T., Agresti, D., Lane, A.L., 2000. The Athena Raman spectrometer. Workshop on Concepts and Approaches for Mars Exploration, July 18– 20, 2000, Houston, Texas. Lunar Planetary Institute, Houston. abstract no. 6030. Wang, A., Freeman, J.J., Jolliff, B.L., Ming-Chou, I., 2006. Sulfates on Mars: a systematic Raman spectroscopic study of hydration states of magnesium sulfates. Geochimica et Cosmochimica Acta 70, 6118–6135. Wang, X., Ming-Chou, I., Hu, W., Burruss, R.C., Sun, Q., Song, Y., 2011. Raman spectroscopic measurements of CO2 density: experimental calibration with high-pressure optical cell (HPOC) and fused silica capillary capsule (FSCC) with application to fluid inclusion observations. Geochimica et Cosmochimica Acta 75, 4080–4093. Wesełucha-Birczyńska, A., Słowakiewicz, M., Natkaniec-Nowak, L., Proniewicz, L.M., 2010. Raman microspectroscopy of organic inclusions in spodumenes from Nilaw (Nuristan, Afghanistan). Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. doi:10.1016/j.saa.2010.08.054. Wilkinson, J.J., 2001. Fluid inclusions in hydrothermal ore deposits. Lithos 55, 229–272. Williams, A.E., Taylor, M.C., 1996. Mass spectrometric identification of boric acid in fluid inclusions in pegmatite minerals. Geochimica et Cosmochimica Acta 60, 3435–3443. Wopenka, B., Pasteris, J.D., 1986. Limitations to quantitative analysis of fluid inclusions in geological samples by laser Raman microprobe spectroscopy. Applied Spectroscopy 40, 144–151. Wopenka, B., Pasteris, J.D., 1987. Raman intensities and detection limits of geochemically relevant gas mixtures for a laser Raman microprobe. Analytical Chemistry 59, 2165–2170. Wopenka, B., Pasteris, J.D., 1993. Structural characterization of kerogens to granulitefacies graphite: applicability of Raman microprobe spectroscopy. American Mineralogist 78, 533–557. Xie, J.C., Yang, X.Y., Sun, W.D., Du, J.G., Xu, W., Wu, L.B., Wang, K.Y., Du, X.W., 2009. Geochronological and geochemical constraints on formation of the Tongling metal deposits, middle Yangtze metallogenic belt, eastcentral China. International Geology Review 51, 388–421. Xu, J., Huang, E., Lin, J., Yunyi Xu, L., 1995. Raman study at high pressure and the thermodynamic properties of corundum: application of Kieffer's model. American Mineralogist 80, 1157–1165. Yamamoto, J., Kagi, H., 2006. Extended micro-Raman densimeter for CO2 applicable to mantle-originated fluid inclusions. Chemical Letter 35, 610–611. Yanqing, Z., Erwei, S., Suxian, C., Wenjun, L., Xingfang, H., 2000. Hydrothermal preparation and characterization of brookite-type TiO2 nanocrystallites. Journal of Materials Science Letters 19, 1445–1448. Zajacz, Z., Halter, W., Malfait, W.J., Bachmann, O., Bodnar, R.J., Hirschmann, M.M., Mandeville, C.W., Morizet, Y., Muntener, O., Ulmer, P., Webster, J.D., 2005. A compositionindependent quantitative determination of the water content in silicate glasses and silicate melt inclusions by confocal Raman spectroscopy. Contribution to Mineralogy and Petrology 150, 631–642. Zotov, N., Keppler, H., 2000. In-situ Raman spectra of dissolved silica species in aqueous fluids to 900 °C and 14 kbar. American Mineralogist 85, 600–604. Zotov, N., Keppler, H., 2002. Silica speciation in aqueous fluids at high pressures and high temperatures. Chemical Geology 184, 71–82.