David A John
David is a Scientist Emeritus with the Geology, Minerals, Energy, and Geophysics Science Center
Science and Products
Filter Total Items: 59
Field guide to hydrothermal alteration in the White River altered area and in the Osceola Mudflow, Washington Field guide to hydrothermal alteration in the White River altered area and in the Osceola Mudflow, Washington
The Cenozoic Cascades arcs of southwestern Washington are the product of long-lived, but discontinuous, magmatism beginning in the Eocene and continuing to the present (for example, Christiansen and Yeats, 1992). This magmatism is the result of subduction of oceanic crust beneath the North American continent. The magmatic rocks are divided into two subparallel, north-trending continental...
Authors
David A. John, James J. Rytuba, Roger P. Ashley, Richard J. Blakely, James W. Vallance, Grant R. Newport, Gary R. Heinemeyer
A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits
This is the second of two special issues of Economic Geology devoted to gold deposits in northern Nevada. Readers interested in a general overview of these deposits, their economic significance, their context within the tectonic evolution of the region, and synoptic references on each gold deposit type are directed to the preface of the first special issue (John et al., 2003). Volume 98...
Authors
Albert H. Hofstra, David A. John, Ted G. Theodore
Chapter C: Hydrothermal Enrichment of Gallium in Zones of Advanced Argillic Alteration-Examples from the Paradise Peak and McDermitt Ore Deposits, Nevada Chapter C: Hydrothermal Enrichment of Gallium in Zones of Advanced Argillic Alteration-Examples from the Paradise Peak and McDermitt Ore Deposits, Nevada
Gallium is produced as a byproduct from bauxite and zinc sulfide ores and rarely from primary Ga ores. High Ga contents (>60 ppm) can occur in zones of advanced argillic alteration consisting of alunite+kaolinite+quartz associated with quartz-alunite (high sulfidation Au-Ag) deposits. In a magmatic-hydrothermal environment, the zones of advanced argillic alteration associated with quartz...
Authors
James J. Rytuba, David A. John, Andrea Foster, Steven D. Ludington, Boris Kotlyar
Style and age of late Oligocene-early Miocene deformation in the southern Stillwater Range, west central Nevada: Paleomagnetism, geochronology, and field relations Style and age of late Oligocene-early Miocene deformation in the southern Stillwater Range, west central Nevada: Paleomagnetism, geochronology, and field relations
Paleomagnetic and geochronologic data combined with geologic mapping tightly restrict the timing and character of a late Oligocene to early Miocene episode of large magnitude extension in the southern Stillwater Range and adjacent regions of west central Nevada. The southern Stillwater Range was the site of an Oligocene to early Miocene volcanic center comprising (1) 28.3 to 24.3 Ma...
Authors
Mark R. Hudson, David A. John, James E. Conrad, Edwin H. McKee
New K-Ar and 40Ar/39Ar ages of plutonism, hydrothermal alteration, and mineralization in the central Wasatch Mountains, Utah New K-Ar and 40Ar/39Ar ages of plutonism, hydrothermal alteration, and mineralization in the central Wasatch Mountains, Utah
Twenty-one new K-Ar and 10 new 40Ar/39Ar ages are reported for igneous and hydrothermal minerals from intrusive rocks of the Wasatch igneous belt in the central Wasatch Mountains. Interpretation of our new data combined with previously published K-Ar ages and with new 40Ar/39Ar and U-Pb ages reported by Vogel et al. (1997) suggests that the Clayton Peak stock was emplaced at about 36 to...
Authors
David A. John, B. D. Turrin, R. J. Miller
Day one road log: Mid-Tertiary igneous rocks and mineral deposits in the central Wasatch Mountains, Utah Day one road log: Mid-Tertiary igneous rocks and mineral deposits in the central Wasatch Mountains, Utah
Today's field trip examines late Eocene and Oligocene granitoid intrusions, cogenetic volcanic rocks (Keetley Volcanics), and associated hydrothermally altered and mineralized rocks in the central Wasatch Mountains. Because of late Cenozoic tilting related to Basin and Range extension, a continuum of mid-Tertiary paleodepths is exposed that ranges from about 11 km on the west side of the...
Authors
David A. John
Science and Products
Filter Total Items: 59
Field guide to hydrothermal alteration in the White River altered area and in the Osceola Mudflow, Washington Field guide to hydrothermal alteration in the White River altered area and in the Osceola Mudflow, Washington
The Cenozoic Cascades arcs of southwestern Washington are the product of long-lived, but discontinuous, magmatism beginning in the Eocene and continuing to the present (for example, Christiansen and Yeats, 1992). This magmatism is the result of subduction of oceanic crust beneath the North American continent. The magmatic rocks are divided into two subparallel, north-trending continental...
Authors
David A. John, James J. Rytuba, Roger P. Ashley, Richard J. Blakely, James W. Vallance, Grant R. Newport, Gary R. Heinemeyer
A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits
This is the second of two special issues of Economic Geology devoted to gold deposits in northern Nevada. Readers interested in a general overview of these deposits, their economic significance, their context within the tectonic evolution of the region, and synoptic references on each gold deposit type are directed to the preface of the first special issue (John et al., 2003). Volume 98...
Authors
Albert H. Hofstra, David A. John, Ted G. Theodore
Chapter C: Hydrothermal Enrichment of Gallium in Zones of Advanced Argillic Alteration-Examples from the Paradise Peak and McDermitt Ore Deposits, Nevada Chapter C: Hydrothermal Enrichment of Gallium in Zones of Advanced Argillic Alteration-Examples from the Paradise Peak and McDermitt Ore Deposits, Nevada
Gallium is produced as a byproduct from bauxite and zinc sulfide ores and rarely from primary Ga ores. High Ga contents (>60 ppm) can occur in zones of advanced argillic alteration consisting of alunite+kaolinite+quartz associated with quartz-alunite (high sulfidation Au-Ag) deposits. In a magmatic-hydrothermal environment, the zones of advanced argillic alteration associated with quartz...
Authors
James J. Rytuba, David A. John, Andrea Foster, Steven D. Ludington, Boris Kotlyar
Style and age of late Oligocene-early Miocene deformation in the southern Stillwater Range, west central Nevada: Paleomagnetism, geochronology, and field relations Style and age of late Oligocene-early Miocene deformation in the southern Stillwater Range, west central Nevada: Paleomagnetism, geochronology, and field relations
Paleomagnetic and geochronologic data combined with geologic mapping tightly restrict the timing and character of a late Oligocene to early Miocene episode of large magnitude extension in the southern Stillwater Range and adjacent regions of west central Nevada. The southern Stillwater Range was the site of an Oligocene to early Miocene volcanic center comprising (1) 28.3 to 24.3 Ma...
Authors
Mark R. Hudson, David A. John, James E. Conrad, Edwin H. McKee
New K-Ar and 40Ar/39Ar ages of plutonism, hydrothermal alteration, and mineralization in the central Wasatch Mountains, Utah New K-Ar and 40Ar/39Ar ages of plutonism, hydrothermal alteration, and mineralization in the central Wasatch Mountains, Utah
Twenty-one new K-Ar and 10 new 40Ar/39Ar ages are reported for igneous and hydrothermal minerals from intrusive rocks of the Wasatch igneous belt in the central Wasatch Mountains. Interpretation of our new data combined with previously published K-Ar ages and with new 40Ar/39Ar and U-Pb ages reported by Vogel et al. (1997) suggests that the Clayton Peak stock was emplaced at about 36 to...
Authors
David A. John, B. D. Turrin, R. J. Miller
Day one road log: Mid-Tertiary igneous rocks and mineral deposits in the central Wasatch Mountains, Utah Day one road log: Mid-Tertiary igneous rocks and mineral deposits in the central Wasatch Mountains, Utah
Today's field trip examines late Eocene and Oligocene granitoid intrusions, cogenetic volcanic rocks (Keetley Volcanics), and associated hydrothermally altered and mineralized rocks in the central Wasatch Mountains. Because of late Cenozoic tilting related to Basin and Range extension, a continuum of mid-Tertiary paleodepths is exposed that ranges from about 11 km on the west side of the...
Authors
David A. John