Stable isotope geochemistry and P-T-X conditions of late vein mineralization at White Pine, Michigan

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

OSTI ID:6194359

Nishioka, G K; Kelly, W C; Lohmann, K C

Numerous calcite veins crosscutting the main cupriferous ore zone at White Pine shed light on the late Precambrian, post-ore history of the district. Vein fluids (Na-Ca-Cl brines; 0-18% NaCl) migrated through enclosing red bed sequences and infiltrated the mineralized Nonesuch Shale, there leaching pre-existing copper (Carpenter, 1968). Based on isotopic analysis of calcites and fluid inclusion extracts, typical vein waters were evolved meteoric fluids initially sourced at high elevations SMOW = -10 to -1 percent per thousand (calculated) which presumably derived their salts by dissolution of evaporites in sediments of the Oronto Group. The carbon isotopic composition of these vein calcites typically ranges from -10 to -6 percent per thousands delta/sup 13/C PDB with rare calcite cement zones possessing anomalously depleted values (-31 percent per thousands). Such depleted values indicate a significant contribution of carbon derived from the oxidation of organic matter a process which may also account for the anomalously light delta D (-93 percent per thousands) composition of some inclusion waters. Integration of several types of evidence indicates vein fluid temperatures were between 50 - 93/sup 0/C, and at times during calcite precipitation, total hydrostatic pressures were certainly below 400 bars and probably below 200 bars. These pressures require erosional removal of the entire Jacobsville Sandstone and a substantial part of the Freda Sandstone before the vein mineralization came to a close in late Precambrian time.

• Research Organization: Univ. of Michigan, Ann Arbor (USA)
• OSTI ID: 6194359
• 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
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400* -- Geochemistry-- (-1989)
ALKALINE EARTH METAL COMPOUNDS
BRINES
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBON ISOTOPES
CARBONATE MINERALS
CARBONATES
CHEMICAL COMPOSITION
CHEMISTRY
COPPER ORES
FEDERAL REGION V
FLUIDS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOTHERMAL FLUIDS
ISOTOPE RATIO
ISOTOPES
MICHIGAN
MINERALIZATION
MINERALOGY
MINERALS
NORTH AMERICA
ORES
OXYGEN COMPOUNDS
PRECAMBRIAN ERA
PRECIPITATION
ROCK-FLUID INTERACTIONS
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
SHALES
USA