Tectonic and magmatic controls on the metal composition of some cenozoic hydrothermal systems of the northwestern US

Conference · Thu Apr 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5164004

Margolis, J ^[1]

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1. Univ. of Oregon, Eugene, OR (United States). Dept. of Geological Sciences

Many Cenozoic, Au-Ag-rich, hydrothermal systems in the northwestern US have formed in two distinct magmatic and tectonic environments: (1) andesitic volcanic piles'' or arcs yield intrusion-related, porphyry-style Cu-Mo-B mineralization and acid-sulfate, advanced argillic alteration; base-metal rich (Pb-Zn-Ag-Ba-Au-Mn), adularia-sericite, epithermal veins form in the peripheral propylitically-altered areas; and (2) Au-Se-Sb-As[+-]Ag-rich, Pb-Zn-Ba-Mn poor, adularia-sericite epithermal deposits in rhyolitic (commonly ash-flow tuffs), andesitic, and locally bimodal volcanic terrains undergoing significant extension or transtension. Porphyry Cu-Mo mineralization, acid-sulfate/advanced-argillic alteration, and base-metal rich veins are apparently absent in the second/environment, possibly owing in part to smaller amounts of magmatic volatiles entering the hydrothermal system. Examples of type 1 are the Miocene Cascades in WA and OR (e.g., Bohemia district) and the Miocene Virginia Range in NW Nevada (Washington Hill and Comstock districts). Examples of type 2 are the deposits at Republic and Wenatchee, WA, which formed during extension in the Eocene; DeLamar, ID and Sleeper, NV, which formed during the onset of rapid Basin and Range extension following Mid Miocene flood-basalt activity; and Wind Mtn., Sulfur, Florida Canyon, and possibly Rosebud, NV.

• OSTI ID: 5164004
• Report Number(s): CONF-9305259--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
152002* -- Geothermal Data & Theory-- Properties of Minerals & Rocks
58 GEOSCIENCES
580000 -- Geosciences
ANDESITES
CENOZOIC ERA
CHEMICAL COMPOSITION
CHEMISTRY
DEVELOPED COUNTRIES
ENERGY SYSTEMS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
GEOTHERMAL SYSTEMS
GOLD ORES
HYDROTHERMAL ALTERATION
HYDROTHERMAL SYNTHESIS
HYDROTHERMAL SYSTEMS
IDAHO
IGNEOUS ROCKS
MAGMATISM
MINERALIZATION
NEVADA
NORTH AMERICA
OREGON
ORES
PETROGENESIS
PETROLOGY
ROCKS
SILVER ORES
SYNTHESIS
TECTONICS
TERTIARY PERIOD
USA
VOLCANIC ROCKS
WASHINGTON