The Thompson Creek, Idaho, porphyry molybdenum deposit; an example of a fluorine-deficient molybdenum granodiorite system

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Authors:Hall, W. E.; Schmidt, E. A.; Howe, S. S.; Broch, M. J.
Author Affiliations:Primary:
U. S. Geol. Surv., Menlo Park, CA, United States
Other:
Georgian SSR Acad. Sci., Inst. Geol., USSR
Amoco Miner. Co., United States
Volume Title:Proceedings of the Sixth quadrennial IAGOD symposium; papers presented at the symposium on topics related to general problems on the genesis of ore deposits and on studies of the ore geology of specific districts or deposits
Volume Authors:Janelidze, Tamaz V., editor, Dzhanelidze, Tamaz V.; Tvalchrelidze, Alexander G.
Source:Proceedings of the Quadrennial IAGOD Symposium, 6(1), p.349-357; Sixth quadrennial IAGOD symposium, Tbilisi, USSR, Sept. 6-12, 1982, edited by Tamaz V. Janelidze and Alexander G. Tvalchrelidze. Publisher: E. Schweizerbart'sche Verlagsbuchhandlung (Nägele u. Obermiller), Stuttgart, International. ISBN: 3-510-65095-6
Publication Date:1984
Note:In English. 4 refs.; illus. incl. 4 tables, sects.
Summary:The Thompson Creek molybdenite deposit is in a belt of I-type granitic plutons, extending from SE California to SE Alaska, that host porphyry Mo systems. Molybdenite is associated with a composite biotite granodiorite/biotite granite stock of late Cretaceous age that occurs near the east side of the Idaho batholith. Quartz-molybdenite stockwork veins occur within the stock in an elongate tabular body, closely associated with strong potassic alteration, that trends N 45° W and plunges 23° NW. The geological, fluid-inclusion and isotopic data are consistent with a genetic model wherein magmatic fluids that evolved from differentiation of a granodioritic parent magma, and caused extensive potassic alteration of the core and crest of a dome-shaped stock, mixed with heated meteoric water during quartz-molybdenite deposition. Such mixing resulted in fluids with T of 250°-300°C, salinities of 6-11 wt.% NaCl equivalent, and varying amounts of CO2. Pb-isotopic analyses and heavy delta 34S values indicate a deep crustal source from a 2100 m.y.-old basement for the lead and sulphur. (Authors' abstract) [J.M.H.]
Subjects:Basement; Cretaceous; Differentiation; Economic geology; Fluid inclusions; Fluorine; Geologic thermometry; Granites; Granodiorites; Halogens; Homogenization; Igneous rocks; Inclusions; Intrusions; Isotopes; Magmas; Mesozoic; Metal ores; Mineral deposits, genesis; Models; Molybdenum ores; Paleosalinity; Plutonic rocks; Porphyry; S-34/S-32; Stable isotopes; Stocks; Sulfur; Upper Cretaceous; Veins; Idaho; Idaho Batholith; United States; Igneous processes; Thompson Creek molybdenite deposit
Abstract Numbers:85M/3901
Record ID:1985075710
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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