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

Conference · Tue Jan 01 00:00:00 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-
• Journal Information: Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
• Country of Publication: United States
• Language: English

Related Subjects

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