GMEG - Mineral and Environmental Resources
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| Publications listing | ||
Interests: |
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Hydrothermal alteration of igneous rocks |
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Epithermal gold-silver deposits |
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Cenozoic magmatism and metallogenesis of the northwestern United States |
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Contact: |
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| Telephone: (650) 329-5424
Fax: (650) 329-5491 Email: djohn@usgs.gov |
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Education |
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| 1976 B.S., Earth Sciences, University of California at Santa Cruz
1979 M.S., Geology, Stanford University 1987 Ph.D, Geology, Stanford University |
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Experience |
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| Beginning in 1975, I worked 4 summers in mineral exploration in the western United States. Since 1979, I have worked as a research geologist in the USGS Mineral Resources Team in Menlo Park, CA. My previous work at the USGS has included regional mapping and mineral resource assessments in eastern California and Nevada; detailed mapping and studies of Tertiary volcanism and tectonics of western Nevada; detailed studies of hydrothermal systems related to middle Tertiary magmatism in the central Wasatch Mountains, Utah; detailed studies of several epithermal gold-silver deposits in Nevada; study of the northern Nevada rift; regional studies of Tertiary epithermal gold-silver deposits in the Great Basin; and detailed studies of hydrothermal alteration on Quaternary volcanoes in the High Cascades. In these studies, I have used a combination of detailed field mapping and petrographic, geochronologic, geochemical, fluid inclusion, stable isotope, geophysical, and paleomagnetic studies to better understand igneous, tectonic, and hydrothermal histories. I am an associate editor of Economic Geology and former member of the Council of the Society of Economic Geologists. | ||
Current Activities |
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| I am chief of the Mineral Systems of the Ancestral and Modern Cenozoic Cascades Arcs and Central California Coast Ranges, Western USA projects and a member of the Updated National Mineral Resource Assessment project. On these projects my work involves (1) metallogenic study of the ancestral Tertiary Cascades arc, Washington, Oregon, northeastern California and western Nevada, (2) study of extinct and active hydrothermal systems in Brokeoff Volcano, Lassen Volcanic National Park, (3) study of the Miocene magmatic and metallogenic history of the Bodie Hills, California and Nevada, (4) study of the structurally dismembered, late Eocene Caetano caldera (a “supervolcano”) and related precious-metal mineral deposits in north-central Nevada, (5) metallogeny of Cenozoic igneous rocks in northern Nevada, and (6) development of a new deposit model for porphyry copper deposits. I am also involved in studies of hydrothermal alteration related to extinct hydrothermal systems in Yellowstone National Park. | ||
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