Solubility-temperature-salinity diagrams as a means for interpreting fluid-inclusion/mineral-zoning data from the Creede District, Colorado

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6374702

Plumlee, G S; Hayba, D O

Boiling and fluid mixing, which are widely regarded as effective ore-deposition mechanisms, can be differentiated by plotting fluid-inclusion data on temperature (enthalpy)-salinity diagrams. Solubilities of ore and gangue minerals can also be contoured on these diagrams to evaluate the relative chemical effects of mixing and boiling, and thereby reconcile ore-deposition models based on fluid-inclusion data with mineral-zoning patterns. For example, fluid-inclusion data from epithermal vein mineralization at Creede indicate the progressive mixing of metal-bearing brines with overlying ground water. Along this mixing path, solubility contours for sphalerite indicate a change of several orders of magnitude, consistent with the abundant sphalerite found in the northern veins. Temperatures and salinities are as high as 285/sup 0/C and 11.5 wt% NaCl eq. in these sulfide-rich northern veins, but as low as 160-200/sup 0/C and 2-7 wt% NaCl eq. in the barite-rich southern veins. Solubility-temperature-salinity (STS) diagrams show barite solubility changes relatively little at high temperatures and salinities, but drops significantly only at salinities below approx.6 wt% eq. Fluid mixing was the depositional mechanism for barite because most mixing paths cross solubility contours while boiling paths are parallel to them. Thus hot, saline fluids originating in the northern parts of the district deposited mainly sphalerite and galena, but only after significant cooling and dilution did they deposit the large quantities of barite seen in the southern parts of the district. STS diagrams are thus useful for visualizing chemical influences on mineral-zoning patterns and relating mineral solubilities to fluid-inclusion data.

• Research Organization: Geological Survey, Reston, VA (USA)
• OSTI ID: 6374702
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
152001* -- Geothermal Data & Theory-- Properties of Aqueous Solutions
152003 -- Geothermal Data & Theory-- Rock-Water-Gas Interactions
58 GEOSCIENCES
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400 -- Geochemistry-- (-1989)
ALKALINE EARTH METAL COMPOUNDS
BARITE
BARIUM COMPOUNDS
BARIUM SULFATES
BRINES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
COLORADO
ENERGY SYSTEMS
FEDERAL REGION VIII
FLUIDS
GALENA
GEOCHEMISTRY
GEOTHERMAL FLUIDS
GEOTHERMAL SYSTEMS
HYDROTHERMAL SYSTEMS
INCLUSIONS
KINETICS
LEAD COMPOUNDS
LEAD ORES
LEAD SULFIDES
MINERALIZATION
MINERALS
MIXING
NORTH AMERICA
ORES
OXYGEN COMPOUNDS
PETROGENESIS
REACTION KINETICS
ROCK-FLUID INTERACTIONS
SALINITY GRADIENTS
SOLUBILITY
SPHALERITE
SULFATE MINERALS
SULFATES
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE GRADIENTS
USA
ZINC ORES
ZONES