Estimation of volume fractions of liquid and vapor phases in fluid inclusions, and definition of inclusion shapes
-
Ronald J. Bakker
and
Larryn W. Diamond
Abstract
The molar volume (Vm) and chemical composition (x) of saline aqueous inclusions and gas inclusions in minerals can be calculated satisfactorily from microthermometric and other analytical data. For complex gas-bearing aqueous inclusions, however, calculation of Vm-x properties requires additional input of the volume-fractions of the inclusion phases (φ). Traditional estimation of φ in non-fluorescing inclusions involves measuring area-fractions of the phases projected in the microscope and then making rough corrections for the third dimension. The uncertainties in the results are unknown and therefore the accuracies of the calculated Vm-x properties are also unknown.
To alleviate this problem we present a new, routine method to estimate φ using the petrographic microscope in conjunction with a spindle-stage. Inclusions in normal thick-sections are rotated stepwise and their projected areas and area-fractions are plotted against rotation angle. The resulting data arrays are systematically related to inclusion orientation, to inclusion shape, and to φ. The dependency on orientation is minimized when area fractions are measured at the position where the inclusions project their largest total areas. The shape dependency is accounted for using a new objective classification of inclusion projections, based on parameters from digital image processing. The method has been verified with synthetic fluid inclusions of known φ. For individual liquid + vapor inclusions with regular (not .negative-crystal.) shapes, the new procedure yields φ with a relative accuracy of ±4%. This degree of accuracy permits Vm . x properties of gas-bearing, aqueous fluid inclusions to be calculated with sufficient certainty for many geochemical applications. Even better accuracy (e.g., down to ±0.6%) can be obtained by combining results from several inclusions in the same homogeneously trapped petrographic assemblage.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Structural model for the biogenic Mn oxide produced by Pseudomonas putida
- Electron-beam (5–10 keV) damage in triplite-group phosphates: Consequences for electron-microprobe analysis of fluorine
- Vacancy defects in MgO at high pressure
- Plastic flow of pyrope at mantle pressure and temperature
- Parvo-mangano-edenite, parvo-manganotremolite, and the solid solution between Ca and Mn2+ at the M4 site in amphiboles
- Reinvestigation of the MgSiO3 perovskite structure at high pressure
- The mechanism and kinetics of α-NiS oxidation in the temperature range 670–700°C
- Influence of charge location on 29Si NMR chemical shift of 2:1 phyllosilicates
- The size distribution of exsolution lamellae in iron-free clinopyroxene
- The high-pressure phase transformation and breakdown of MgFe2O4
- Elastic behavior, phase transition, and pressure induced structural evolution of analcime
- A new chemical etching technique for peridotites using molten anhydrous borax
- Poppiite, the V3+ end-member of the pumpellyite group: Description and crystal structure
- Cation redistribution in the octahedral sheet during diagenesis of illite-smectites from Jurassic and Cambrian oil source rock shales
- A shock-induced polymorph of anatase and rutile from the Chesapeake Bay impact structure, Virginia, U.S.A.
- Water in the interlayer region of birnessite: Importance in cation exchange and structural stability
- In situ HAFM study of the thermal dehydration on gypsum (010) surfaces
- Influence of dehydration kinetics on T-O-T bridge breaking in zeolites with framework type STI: The case of stellerite
- Estimation of volume fractions of liquid and vapor phases in fluid inclusions, and definition of inclusion shapes
- Thermodynamics of uranyl minerals: Enthalpies of formation of uranyl oxide hydrates
- SIMS investigation of electron-beam damage to hydrous, rhyolitic glasses: Implications for melt inclusion analysis
- Synthetic Ag-rich tourmaline: Structure and chemistry
- Genesis and compositional heterogeneity of smectites. Part III: Alteration of basic pyroclastic rocksA case study from the Troodos Ophiolite Complex, Cyprus
- Ganterite, the barium mica Ba0.5K0.5Al2(Al1.5Si2.5)O10(OH)2, from Oreana, Nevada
- Letter. Transformation of pentlandite to violarite under mild hydrothermal conditions
