Fluid infiltration through the Big Horse Limestone Member in the Notch Peak contact-metamorphic aureole, Utah

Journal Article · · American Mineralogist; (USA)

OSTI ID:7149361

Labotka, T C ^[1]; Nabelek, P I ^[2]; Papike, J J ^[3]

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1. Univ. of Tennessee, Knoxville (USA)
2. Univ. of Missouri, Columbia (USA)
3. South Dakota School of Mines and Technology, Rapid City (USA)

Calcareous argillites in the Upper Cambrian Big House Limestone Member of the Orr Formation, west-central Utah, have undergone contact metamorphism where they were intruded by the Jurassic Notch Peak stock. Metamorphism of the rocks resulted in nearly complete decarbonation, yet the mineral assemblages indicate that the fluid phase was nearly free of CO{sub 2}, indicating interaction with a substantial volume of water. This study is designed to determine the volume of externally derived water with which the Big Horse Limestone Member interacted and the mode of interaction. The rocks in the aureole are characterized by three grades of metamorphism, separated by the diopside and the wollastonite isograds. Simple calculations of the temperature and fluid flux through the aureole, based on heat- and fluid-transport equations, indicate that heat transport on the margins of the stock occurred primarily by conduction, particularly outside the wollastonite zone, and that the major fluid flux through the aureole occurred within the first year of intrusion, long before the temperature had risen sufficiently for metamorphism to have occurred. Fluid fluxes through the aureole after 1000 yr, when significant metamorphism occurred, dropped to the order of 1 kg/(m{sup 2} yr), or less. This amount is sufficient to have interacted with the diopside-zone rocks, giving water/rock ratios (by mass) of the order 0.1. The fluid flux through the wollastonite zone is given by the rate of advancement of the isograd, which gives fluxes ranging from >42 kg/(m{sup 2} yr) at 50 m from the contact to 0 kg/(m{sup 2} yr) at the maximum distances of 410 m. The results of this study indicate that in those metamorphic terranes in which there is a change from rock-dominated to fluid-dominated systems across an isograd, the water rock ratio in the fluid-dominated system represents not the fluid flux.

• DOE Contract Number: FG01-85ER13407
• OSTI ID: 7149361
• Journal Information: American Mineralogist; (USA), Journal Name: American Mineralogist; (USA) Vol. 73:11-12; ISSN AMMIA; ISSN 0003-004X
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALINE EARTH METAL COMPOUNDS
ANORTHOSITES
ARGILLITE
BIOTITE
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALCULATION METHODS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
CHALCOGENIDES
CHLORITE MINERALS
DIOPSIDE
DOLOMITE
ENERGY TRANSFER
FEDERAL REGION VIII
FELDSPARS
FLUID FLOW
GABBROS
GEOLOGIC DEPOSITS
HEAT TRANSFER
HYDROLOGY
IGNEOUS ROCKS
LIMESTONE
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
METAMORPHISM
MICA
MINERALOGY
MINERALS
MUSCOVITE
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLUTONIC ROCKS
PYROXENES
QUARTZ
ROCKS
SEDIMENTARY ROCKS
SHALES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
USA
UTAH
WATER INFLUX