Interpretation of Precambrian K-Ar biotite dates in the bighorn mountains, wyoming

Condie, Kent C.; Heimlich, R. A.

doi:10.1016/0012-821x(69)90092-2

Cited by 2 publications

(1 citation statement)

References 9 publications

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“…1), was described by Osterwald (1959) and by Heimlich (1969) in papers which emphasize the regional petrology and structure of the rocks. Reconnaissance chemical data for the gneiss were given by Heimlich (1972) and radiometric age data were reported by Heimlich & Banks (1968) and by Condie & Heimlich (1969). Although detailed petrographic and structural studies of several small areas within the gneiss terrain have been published (Hoppin, 1961;Hoppin, Palmquist & Williams, 1965;Palmquist, 1965Palmquist, , 1967and Hudson, 1969), no detailed mineralogical or geochemical studies have been made of the gneiss.…”

Section: Introductionmentioning

confidence: 99%

Mineralogy of Precambrian Gneiss from the Bighorn Mountains, Wyoming

Heimlich

Nelson²,

Malcuit

1972

Geol. Mag.

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SummaryPrecambrian rocks throughout most of the southern part of the Bighorn Mountains, Wyoming, are dominated by a biotite-bearing plagioclase–quartz gneiss containing hornblende-rich or microcline-rich layers locally. Compositional and/or optical data are presented for plagioclase, biotite, and hornblende as well as optical and X-ray data for microcline and preliminary morphologic data for zircon in the gneiss. These data, supplemented by field and petrographic observations, suggest that the gneiss was formed under conditions of the low amphibolite facies, that late-occurring potash metasomatism accompanied the metamorphism, and that the gneiss was derived from a relatively chemically uniform parent rock.

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