Raman spectroscopy for fluid inclusion analysis

Raman microspectrometry of fluid inclusions

Fluid inclusion petrography

Chapter 1.INTRODUCTION TO OXYGEN FUGACITY AND ITS PETROLOGIC IMPORTANCE

Carbon and hydrogen isotopic reversals in deep basin gas: Evidence for limits to the stability of hydrocarbons

A localized dehydration zone, Sondrum stone quarry, Halmstad, SW Sweden, consists of a central, 1 m wide granitic pegmatoid dyke, on either side of which extends a 25-3 m wide dehydration zone (650-700 degrees C; 800 MPa; orthopyroxene-clinopyroxene-biotite-amphibole-garnet) overprinting a local migmatized granitic gneiss (amphibole-biotite-garnet) Whole-rock chemistry indicates that dehydration of the granitic gneiss was predominantly isochemical Exceptions include [Y + heavy rare earth elements (HREE)], Ba, Sr, and F, which are markedly depleted throughout the dehydration zone Systematic trends in the silicate and fluorapatite mineral chemistry across the dehydration zone include depletion in Fe, (Y + HREE), Na, K, F, and Cl, and enrichment in Mg, Mn, Ca, and Ti Fluid inclusion chemistry is similar in all three zones and indicates the presence of a fluid containing CO2, NaCl, and H2O components Water activities in the dehydration zone average 036, or XH2O = 025 All lines of evidence suggest that the formation of the dehydration zone was due to advective transport of a CO2-rich fluid with a minor NaCl brine component originating from a tectonic fracture Fluid infiltration resulted in the localized partial breakdown of biotite and amphiboles to pyroxenes releasing Ti and Ca, which were partitioned into the remaining biotite and amphibole, as well as uniform depletion in (Y + HREE), Ba, Sr, Cl, and F At some later stage, H2O-rich fluids (H2O activity > 08) gave rise to localized partial melting and the probable injection of a granitic melt into the tectonic fracture, which resulted in the biotite and amphibole recording a diffusion profile for F across the dehydration zone into the granitic gneiss as well as a diffusion profile in Fe, Mn, and Mg for all Fe-Mg silicate minerals within 100 cm of the pegmatoid dyke

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The Role of Advective Fluid Flow and Diffusion during Localized, Solid-State Dehydration: Sondrum Stenhuggeriet, Halmstad, SW Sweden

Retrograde methane-dominated fluid inclusions from high-temperature granulites of Rogaland, southwestern Norway

AssrRAcr The temperatures and pressures of diagenesis and very low-grade metamorphism of the Palaeozoic formations of the Valley-and-Ridge province in the central Appalachians are revealed by analyzing their fluid inclusions. Samples from two areas were studied and compared: (l) the Silurian and Devonian Delaware Water Gap area and (2) the anthracite region of eastern Pennsylvania. Gaseous CH.-CO2 and aqueous (+CHr) inclusions were studied by microthermometry; gas compositions were measured by Raman analysis. The two fluids are thought to have been immiscible, saturated fluids. The isochores calculated for both types ofinclusions indicate fluid trapping P-Zconditions ofabout 195-245 "C, 0.8-1.3 kbar for the anthracite region, but higher pressures (1.3-1.9 kbar at 180-230'C, and possibly as much as 2.2-2.5 kbar) for the Delaware Water Gap area. The pressure difference reflects the relative stratigraphic position of the rock formations, and a higher thermal gradient for the anthracite region. The fluid trapping temperatures and pressures are consistent with conodont alteration indices (CAI), illite crystallinities, the anthracite rank, slaty cleavage development, and the stability of pyrophyllite.

CH 4 -rich inclusions from quartz veins in the Valley-and-Ridge Province and the anthracite fields of the Pennsylvania Appalachians; reply

The enderbites from Tromoy in the central, granulite facies part of the Proterozoic Bamble sector of southern Norway contain dominantly CO2 and N2 fluid inclusions. CO2 from fluid inclusions in quartz segregations in enderbites was extracted by mechanical (crushing) and thermal decrepitation and the δ13C measured. Measurement was also made on samples washed in 10% HCl, oxidized with CuO at high temperatures, and step-wise extracted with progressive heating. Results between the different techniques are systematic. The main results show δ13C of -4.5±1.5% for crushing and -7±2% for thermal decrepitation. δ13C is about constant for CO2 extracted at different temperatures and points to a homogeneous isotopic composition. Due to the presence of carbonate particles and/or induced contaminations for the extraction by thermal decrepitation, the results for the crushing experiments are assumed the most reliable for fluid-inclusion CO2. Very low values of δ13C have not been found in enderbite samples and δ13C combined with δ18O of the host quartzes (8-11%) indicates juvenile values. In addition, the fluid inclusions were examined by microthermometry and Raman analysis and host quartz by acoustic emission and cathodoluminescence. CO2 fluid inclusions have varying densities with a frequency maximum of 0.92 g cm-3 and generally do not concur with trapping densities at granulite conditions. Textures show that CO2 must have been trapped in fluid inclusions in one early event, but transformed to different extents during late isothermal uplift without important fractionation of isotope compositions. The present data support a model of intrusion and crystallization of a CO2-rich enderbitic magma at granuiite conditions.

Juvenile CO2in enderbites of Tromøy near Arendal, southern Norway: a fluid inclusion and stable isotope study

The Grunehogna and Kullen sills of western Dronning Maud Land were emplaced into water-saturated, partially lithified sediments of the mid-Proterozoic Ritscherflya Supergroup. Fluid inclusion and optical and scanning electron microscope cathodoluminescence studies of quartz grains within and adjacent to the sills (the ‘sill-sediment interactive zone’, referred to as the ‘interactive zone’) showed that only a single generation of later fluid inclusions is present. The fluids are Na-K-Ca-Cl aqueous solutions with temperatures of homogenization between 95 and 105 °C. Individual quartz particles in the sedimentary rocks above the interactive zone have unique fluid inclusion populations. Petrographic and cathodoluminescence evidence indicated that there are three types of quartz grains in the interactive zone. These consist of (i) a xenocrystic type, (ii) a high-temperature quartz that crystallized either from the magma or as a result of anatectic melting of xenolithic (and/or xenocrystic) material, and (iii) euhedral quartz crystals that have grown in vugs in the peripheral zone. Cathodoluminescence of xenocrystic grains indicated the existence of healed microfractures along which fluid inclusions were concentrated and secondary and authigenic overgrowths on older generation quartz grains had developed. The presence of zonal luminescence patterns of detrital particles, coupled with evidence for equilibrium polygonization in the sedimentary rocks adjacent to the peripheral zone up to about 8 m above the upper contact of the Grunehogna sill suggested local thermal tempering or sintering and recrystallization. Luminescence of detrital quartz particles in the overlying Hogfonna Formation reflected variation in the characteristics of their source terrains, and showed limited evidence of heating by the magma. The interactive zone fluid inclusions are formation waters which penetrated microfractures during diagenesis. We show that no large-scale hydrothermal circulation system is likely to develop following intrusion into a water-saturated environment.

A. M. van den Kerkhof

Papers

The Role of Advective Fluid Flow and Diffusion during Localized, Solid-State Dehydration: Sondrum Stenhuggeriet, Halmstad, SW Sweden

Retrograde methane-dominated fluid inclusions from high-temperature granulites of Rogaland, southwestern Norway

CH 4 -rich inclusions from quartz veins in the Valley-and-Ridge Province and the anthracite fields of the Pennsylvania Appalachians; reply

Juvenile CO2in enderbites of Tromøy near Arendal, southern Norway: a fluid inclusion and stable isotope study

Sill emplacement in wet sediments: fluid inclusion and cathodoluminescence studies at Grunehogna, western Dronning Maud Land, Antarctica