Hydrothermal geochemistry of silver-gold vein formation in the Tayoltita mine and San Dimas mining district, Durango and Sinaloa, Mexico

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6320498

Clarke, M

The San Dimas mining district, including the Tayoltita mine, is a Tertiary silver-gold epithermal vein system deposited in a calcalkaline volcanic pile. Hydrothermal alteration and vein formation is temporally related to a granite batholith intruded into the volcanics. Alteration mineralogy in andesites is compatible with a hydrothermal flow model in which heated water rises through the batholith, cools to 260 C, and flows out into the volcanics. Lateral elongation of Ag:Au ratio zoning plotted on vertical projections of veins is interpreted to reflect hydrothermal fluid flow principally in a horizontal direction during ore deposition. Quartz vein-filling, accompanied by chlorite, calcite, rhodonite, and adularia, is widest in a vertical interval approximately 500 to 1000 meters below the original surface. Pyrite is widely distributed, but silver minerals, electrum, and base-metal sulfides are restricted to the upper portion of the vertical interval of veining in a zone termed the ore horizon. Fluid inclusion studies of quartz from the Cinco Senores vein indicate that ore deposited at an average temperature of 260 C from boiling fluids of apparent salinities ranging from 0.15 to 0.3 m/sub NaCl/ equivalent. The greater apparent salinities probably reflect dissolved gases as well as chloride salts. Correlation of Ag:Au ratios in deposited vein with ice-melting temperatures in fluid inclusions suggests that evolution of ore fluids in space was accompanied by both increase in deposited Ag:Au ratios and decline in fluid solute concentration. Correlation of ice-melting temperatures with paragenetic age of associated quartz suggests that vein-depositing hydrothermal fluids evolved in both space and time from relatively concentrated to dilute conditions.

• Research Organization: Arizona Univ., Tucson (USA)
• OSTI ID: 6320498
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
580400* -- Geochemistry-- (-1989)
CHALCOGENIDES
CHEMISTRY
DEPOSITION
DEVELOPING COUNTRIES
ELEMENTS
FLUID FLOW
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GOLD
GRANITES
HYDROTHERMAL ALTERATION
IGNEOUS ROCKS
INTRUSION
LATIN AMERICA
METALS
MEXICO
MINERALOGY
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALEOTEMPERATURE
PLUTONIC ROCKS
QUARTZ
ROCKS
SALINITY
SILICON COMPOUNDS
SILICON OXIDES
SILVER
TRANSITION ELEMENTS
VOLCANIC REGIONS