Effect of fluid flux on the width of contact metamorphic aureoles: evidence from Silver Star, Montana

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

OSTI ID:6874792

Foote, M V; Frost, B R; Angevine, C L

Contact metamorphism of Paleozoic carbonate-rich sediments by the Boulder Batholith near Silver Star, Montana has resulted in the formation of the following six metamorphic zones: (1) calcite (cc) - dolomite (dol) - quartz (q) - phlogopite (phl) +/- kspar (ksp); (b) cc - dol - tremolite (tr) - q - ksp; (c) cc - dol - tr - diopside (di) - phl; (d) cc - dol - di - forsterite (fo) - phl; (e) cc - dol - fo, and cc - di - fo; and (f) cc - fo - periclase +/- dol. The presence of periclase in the highest zone indicates that these rocks crystallized in the presence of a water-rich fluid. Calculations of reaction progress indicate that between zone e and zone f, 4.5 rock-volumes of water had to be introduced. Comparison of the aureole at Silver Star with other contact aureoles studied around the Boulder Batholith shows a distinct correlation between the width of the aureole and the inferred fluid flux. The Boulder and Marysville aureoles are internally buffered throughout and have a width (measured to the tremolite-in isograd) of up to 1.5 km, while the Black Butte aureole, which has largely external control of the fluid, has a width of approximately 80 meters. Silver Star, which is intermediate in behavior, has an aureole width of approximately 250 meters. The indicates that in environments of low fluid flux heat is transported largely by conduction, while in environments of low fluid flux most of the heat is transported upward by convective flow, resulting in correspondingly narrower aureoles.

• Research Organization: Univ. of Wyoming, Laramie (USA)
• OSTI ID: 6874792
• 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

58 GEOSCIENCES
CARBONATE ROCKS
METAMORPHISM
MINERALOGY
METAMORPHIC ROCKS
PETROGENESIS
MONTANA
CALCITE
CHEMICAL REACTIONS
DIOPSIDE
DOLOMITE
FELDSPARS
QUARTZ
ROCK-FLUID INTERACTIONS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHALCOGENIDES
FEDERAL REGION VIII
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PYROXENES
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
USA
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)