Paragenesis, fluid inclusions and Ar-dating of the Big Creek mining district, Valley County, central Idaho

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

OSTI ID:6863095

Gammons, C H; Rose, A W; Snee, L W; Lund, K

The Big Creek District includes a number of small vein deposits hosted by Cretaceous granitic rocks of the Idaho batholith and metamorphic roof pendants of disputed age. Mineralization is confined to a NNE-trending fault zone occupied by a swarm of post-ore porphyritic dikes. Petrographic studies suggest several episodes of mineralization. State I consists of widespread silicification and replacement of wallrock biotite by sericite and weakly auriferous Fe-As sulfides. Stage II includes smaller quartz (+/- fluorite,adularia) veins rich in base metal sulfides, sulfosalts, electrum and local huebnerite, Stage III includes discordant veins with complex mineralogy, including sulfides, Ag-tellurides, Ag-Sb-Pb sulfosalts, electrum, stibnite, cinnabar, barite, dolomite, quartz and Mn-rich gangue. Radiometric ages of State I sericite (78.0 m.y.), Stage II adularia (76.8 m.y.) and Stage III sericite (76.1 m.y.) suggest consanguinity in time, as well as space. Fluid inclusions in Stage II and III veins show a wide range in T/sub h/ (200 to 400/sup 0/C), salinity (0.0 to 7.2 wt% NaCl/sub eq/) and CO/sub 2/-content (up to 1M). All veins with inclusions trapped above 300/sup 0/C display evidence of boiling, although acidic alteration typical of many boiling epithermal systems is absent. Depth of mineralization assuming hydrostatic pressure is estimated at 2.0 to 5.0 km, consistent with a deep epithermal origin for the deposits. Depositional mechanisms proposed to explain the complex paragenesis include fluid mixing, temperature decrease, and boiling.

• Research Organization: Pennsylvania State Univ., University (USA)
• OSTI ID: 6863095
• 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

58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400* -- Geochemistry-- (-1989)
AGE ESTIMATION
ARGON ISOTOPES
CHEMISTRY
CRETACEOUS PERIOD
FEDERAL REGION X
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC HISTORY
GRANITES
HYDROTHERMAL SYNTHESIS
IDAHO
IGNEOUS ROCKS
INCLUSIONS
ISOTOPE DATING
ISOTOPES
MESOZOIC ERA
MINERALIZATION
MINERALOGY
MINERALS
NORTH AMERICA
PARAGENESIS
PETROGRAPHY
PLUTONIC ROCKS
ROCKS
SULFIDE MINERALS
SYNTHESIS
USA