Geochemical exploration studies in the Coeur d'Alene district, Idaho

Gott, Garland Bayard; Cathrall, John B.

doi:10.3133/ofr77216

Cited by 3 publications

(3 citation statements)

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“…The Hope, Ninemile, St. Mary's, Osburn, and St. Joe faults represent significant vertical and horizontal displacements within the Lewis and Clark zone, but an abrupt transition from a northerly structural trend to a penetrative WNW tectonic fabric occurs near the Osburn fault (Wallace, et al, 1960;Hobbs et al, 1965;Harrison et al, 1985;Bennett and Venkatakrishnan, 1982;White, 1998a;White and Applegate, 2000). The Osburn fault, which bisects the Coeur d'Alene mining district along the same WNW trend, has about 26 km of rightlateral, strike-slip displacement (Hershey, 19 16;Umpelby and Jones, 1923;Umpelby, 1924;Hobbs et al, 1965;Gott and Cathrall, 1980;Bennett and Venkatakrishnan, 1982). Strike-slip movement on the Osburn fault postdates much of the folding in the Coeur d'Alene district (Hobbs et al 1965;White, 1998a), although we suggest that structural trends near the fault could have been modified by synchronous development of compressional features and strike-slip faulting, which is well documented along other major strike-slip structures such as the San Andreas fault (Mount and Suppe, 1987;Miller, 1998).…”

Section: Geologic Settingmentioning

confidence: 99%

“…Clearly, neither the most profoundly enriched mantle nor ancient lower crust is a potential source of the radiogenic Sr. The most obvious source of highly radiogenic 87SrP6Sr is the variably metamorphosed, high-Rb/Sr sedimentary rocks of the Belt Supergroup (H6bbs et al, 1965;Harrison, 1972;Gott and Cathrall, 1980;Hietanen, 1962;1967;1984;Criss and Fleck, 1987;1990). Not coincidentally, the Belt rocks have long been viewed as the source of the ore metals (e.g.…”

Section: Source Of Strontium In Coeur D'alene Carbonate Veinsmentioning

confidence: 99%

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Age and Origin of Base- And Precious-Metal Veins of the Coeur d'ALENE Mining District, Idaho

Fleck¹,

Criss²,

Eaton³

et al. 2000

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Ore-bearing quartz-carbonate veins of the Coeur d'Alene mining district yield 87Sr/86Sr ratios of 0.74 to >1.60 for low-Rb/Sr, carbonate gangue minerals, similar to current ranges measured in Middle Proterozoic, high-Rb/Sr rocks of the Belt Supergroup. Stable-isotope and fluid-inclusion studies establish a genetic relationship between vein formation and metamorphic-hydrothermal systems of the region. These extraordinary 87Sr/86Sr ratios require accumulation of radiogenic 87Sr in a high Rb/Sr system over an extended period prior to incorporation of Sr into the veins by hydrothermal processes. Evaluation of the age and composition of potential sources of highly radiogenic Sr indicates that the ore-bearing veins of the Coeur d'Alene district formed within the last 200 Ma from components scavenged from sedimentary and metasedimentary rocks of the Belt Supergroup, the primary host-rocks of the district. These results are consistent with a Cretaceous or Early Tertiary age for these veins. Pb-Zn deposits that yield Pb isotope, K-Ar, and Ar-Ar results indicative of a Proterozoic age probably formed during deposition or diagenesis of the Belt Supergroup at 1350-1500 Ma, possibly as Sullivan-type syngenetic deposits. K-Ar and Rb-Sr apparent ages and 6l80 values of Belt Supergroup rocks decrease southward from the Coeur d'Alene district toward the Idaho batholith, normal to the trends of metamorphic isograds, fold axes, foliation, and the major reverse faults of the district. Isoclinal folding, thrust faulting, high-temperature metamorphism, granitic plutonism, and regional-scale metamorphic-hydrothermal activity is documented in the region between 140 Ma and 45 Ma, but no similar combination of events is recognized for Late Proterozoic time. Combined with Sr P results from the veins, the evidence strongly favors formation of the ore-bearing carbonate veins of the district by fluids related to a complex metamorphic-hydrothermal system during Cretaceous and/or early Tertiary time. Proterozoic Pb-Zn deposits were probably deformed, remobilized along younger structures, and incorporated into the younger hydrothermal deposits during this event.

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Section: Geologic Settingmentioning

confidence: 99%

Section: Source Of Strontium In Coeur D'alene Carbonate Veinsmentioning

confidence: 99%

Age and Origin of Base- And Precious-Metal Veins of the Coeur d'ALENE Mining District, Idaho

Fleck¹,

Criss²,

Eaton³

et al. 2000

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“…A survey of metals in foodstuffs throughout the United States has not yet been released. Another major source of background data of an areal nature is the large-scale sampling of soils and plants for prospecting carried out in mineral districts, such as the Coeur d'Alene district (Gott & Cathrall 1977), and in wilderness areas.…”

mentioning

confidence: 99%

A review of recent activity in the United States

Cannon

Petrie

1979

Phil. Trans. R. Soc. Lond. B

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Either an overabundance or a deficiency of trace metals in the food chain can ultimately affect adversely the health of livestock and man. Increasing interest in the United States in the distribution of metals in the environment and in metal pollutants has led to widespread interdisciplinary research sponsored by governmental, private and academic groups concerning the availability of trace elements for absorption by plants and animals, and the effects of trace elements throughout the food chain. The state of the art and the needs for research are reviewed by interdisciplinary committees in the National Academy of Sciences and in many government agencies. Research is encouraged through contracts and grants awarded by federal and state agencies and the National Science Foundation to universities for studies of specific metals, specific diseases and correlations between metals and health in specific geographic areas. Effects on the environment of coal-fired power plants, the mining and processing of metals, asbestos, and phosphate, and the disposal of industrial and nuclear wastes have also received much attention in the past few years.

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