A new method to analyze anions and cations in fluid inclusions using ion chromatography--Applications to ore genesis

Conference · Wed Jan 01 00:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5721645

Hofstra, A H; Emsbo, P ^[1]

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1. Geological Survey, Denver, CO (United States)

A new method has been developed to extract and analyze ionic species in fluid inclusions utilizing a parallel ion chromatography (IC) system that is computerized for instrument control, data manipulation, and display. Inclusion fluid is released for analysis by crushing ca 100 mg of mineral in a stream of pure, degassed water. The ion-charged water then flows in series through anion and cation preconcentration columns where the respective ions are trapped. Each preconcentration column is isolated in a sample injection loop connected to a separate IC system. The system is calibrated for NH[sub 4]++, K+, Na+, Ca++, Mg++, Mn++, fe++, Sr++, Ba++, F-, Cl-, Br--, I-, NO[sub 3]-, CO[sub 3]--, Po[sub 4]---, HS-, SO[sub 3]--, SO[sub 4]--, S[sub 2]O[sub 3]--, and C[sub 1]-C[sub 6] organic acids using peak areas. Detection limits range from 0.1 to 1.0 ng. Total analysis time is less than 1 hr. Advantages are: small sample size facilitates selection of well-constrained samples; isolation from atmosphere allows analysis of HS-, So[sub 3]--, SO[sub 4]--, S[sub 2]O[sub 3]--, and Co[sub 3]--; analysis of both anions and cations from a single crush allows calculation of charge balance; can discriminate between contributions from host mineral vs. fluid inclusions; relatively low cost of instrumentation. Disadvantages are: sample may contain more than one generation of inclusions; inability to measure water, gases, and uncharged aqueous species; absolute concentrations of ions in the ore fluid must be calculated. Fluid inclusion chemistry can potentially be used to trace fluid sources; determine fluid flow directions; monitor processes such as alteration, fluid mixing, and boiling; calculate T, P, pH, F(S[sub 2]) and f(O[sub 2]); facilitate modeling of mineral solubility, metal transport and ore deposition; improve genetic models; and aid exploration for concealed deposits. Results from a variety of minerals from several deposits illustrate the utility of the method.

• OSTI ID: 5721645
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
INCLUSIONS
GEOCHEMISTRY
RESERVOIR FLUIDS
CHROMATOGRAPHY
ACCURACY
ANIONS
CATIONS
SAMPLE PREPARATION
TECHNOLOGY ASSESSMENT
USES
CHARGED PARTICLES
CHEMISTRY
FLUIDS
IONS
SEPARATION PROCESSES
580000* - Geosciences
400102 - Chemical & Spectral Procedures