Wes Hildreth (Former Employee)
Science and Products
Filter Total Items: 70
The Bishop Tuff: New insights from eruptive stratigraphy The Bishop Tuff: New insights from eruptive stratigraphy
The 0.76 Ma Bishop Tuff, from Long Valley caldera in eastern California, consists of a widespread fall deposit and voluminous partly welded ignimbrite. The fall deposit (F), exposed over an easterly sector below and adjacent to the ignimbrite, is divided into nine units (F1‐F9), with no significant time breaks, except possibly between F8 and F9. Maximum clast sizes are compared with...
Authors
C. J. N. Wilson, W. Hildreth
Primitive magmas at five Cascade volcanic fields: Melts from hot, heterogeneous sub-arc mantle Primitive magmas at five Cascade volcanic fields: Melts from hot, heterogeneous sub-arc mantle
Major and trace element concentrations, including REE by isotope dilution, and Sr, Nd, Pb, and O isotope ratios have been determined for 38 mafic lavas from the Mount Adams, Crater Lake, Mount Shasta, Medicine Lake, and Lassen volcanic fields, in the Cascade arc, northwestern part of the United States. Many of the samples have a high Mg# [100Mg/(Mg + FeT) > 60] and Ni content (>140 ppm)...
Authors
C. R. Bacon, P. E. Bruggman, R.L. Christiansen, M.A. Clynne, J.M. Donnelly-Nolan, W. Hildreth
Complexities of plinian fall deposition at vent: An example from the 1912 Novarupta eruption (Alaska) Complexities of plinian fall deposition at vent: An example from the 1912 Novarupta eruption (Alaska)
An extremely proximal ejecta ring, with exposures to within 100 m of vent, was deposited during later-stage plinian fall activity during the 1912 Novarupta eruption in Alaska. One bed in the ejecta ring (bed S) contains predominantly andesitic clasts which serve to delineate the striking contrast in thinning rates along dispersal axis of the ejecta ring [Pyle bt values of 70 m (bed S...
Authors
J. Fierstein, Bruce F. Houghton, C. J. N. Wilson, W. Hildreth
Kulshan caldera: A quaternary subglacial caldera in the North Cascades, Washington Kulshan caldera: A quaternary subglacial caldera in the North Cascades, Washington
Calderas that collapse during large pyroclastic eruptions are anomalously rare in the Cascade arc. Recognition of the early Pleistocene 4.5 × 8 km Kulshan caldera, filled with rhyodacite ignimbrite at the northeast foot of Mount Baker, brings to only three the Quaternary calderas identified in the Cascades. A near-vertical ring fault cut in basement rocks of the North Cascades encloses...
Authors
W. Hildreth
Potassium-argon geochronology of a basalt-andesite-dacite arc system: the Mount Adams volcanic field, Cascade Range of southern Washington Potassium-argon geochronology of a basalt-andesite-dacite arc system: the Mount Adams volcanic field, Cascade Range of southern Washington
High-precision K-Ar dating and detailed mapping have established an eruptive chronology for a Cascade stratovolcano and its surrounding array of coeval basaltic centers. The time-volume-composition data bear upon several fundamental questions concerning the long-term behavior of arc volcanoes. -from Authors
Authors
W. Hildreth, M. A. Lanphere
The plinian eruptions of 1912 at Novarupta, Katmai National Park, Alaska The plinian eruptions of 1912 at Novarupta, Katmai National Park, Alaska
The three-day eruption at Novarupta in 1912 consisted of three discrete episodes. Episode I began with plinian dispersal of rhyolitic fallout (Layer A) and contemporaneous emplacement of rhyolitic ignimbrites and associated proximal veneers. The plinian column was sustained throughout most of the interval of ash flow generation, in spite of progressive increases in the proportions of...
Authors
J. Fierstein, W. Hildreth
Non-USGS Publications**
Hildreth, W., 1976, Death Valley Geology: Death Valley Natural History Association, Furnace Creek, CA, 64 p.
Ewart, A., Hildreth, W., and Carmichael, I.S. E., 1975, Quaternary acid magma in New Zealand: Contributions to Mineralogy and Petrology, v. 51, p. 1–27.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 70
The Bishop Tuff: New insights from eruptive stratigraphy The Bishop Tuff: New insights from eruptive stratigraphy
The 0.76 Ma Bishop Tuff, from Long Valley caldera in eastern California, consists of a widespread fall deposit and voluminous partly welded ignimbrite. The fall deposit (F), exposed over an easterly sector below and adjacent to the ignimbrite, is divided into nine units (F1‐F9), with no significant time breaks, except possibly between F8 and F9. Maximum clast sizes are compared with...
Authors
C. J. N. Wilson, W. Hildreth
Primitive magmas at five Cascade volcanic fields: Melts from hot, heterogeneous sub-arc mantle Primitive magmas at five Cascade volcanic fields: Melts from hot, heterogeneous sub-arc mantle
Major and trace element concentrations, including REE by isotope dilution, and Sr, Nd, Pb, and O isotope ratios have been determined for 38 mafic lavas from the Mount Adams, Crater Lake, Mount Shasta, Medicine Lake, and Lassen volcanic fields, in the Cascade arc, northwestern part of the United States. Many of the samples have a high Mg# [100Mg/(Mg + FeT) > 60] and Ni content (>140 ppm)...
Authors
C. R. Bacon, P. E. Bruggman, R.L. Christiansen, M.A. Clynne, J.M. Donnelly-Nolan, W. Hildreth
Complexities of plinian fall deposition at vent: An example from the 1912 Novarupta eruption (Alaska) Complexities of plinian fall deposition at vent: An example from the 1912 Novarupta eruption (Alaska)
An extremely proximal ejecta ring, with exposures to within 100 m of vent, was deposited during later-stage plinian fall activity during the 1912 Novarupta eruption in Alaska. One bed in the ejecta ring (bed S) contains predominantly andesitic clasts which serve to delineate the striking contrast in thinning rates along dispersal axis of the ejecta ring [Pyle bt values of 70 m (bed S...
Authors
J. Fierstein, Bruce F. Houghton, C. J. N. Wilson, W. Hildreth
Kulshan caldera: A quaternary subglacial caldera in the North Cascades, Washington Kulshan caldera: A quaternary subglacial caldera in the North Cascades, Washington
Calderas that collapse during large pyroclastic eruptions are anomalously rare in the Cascade arc. Recognition of the early Pleistocene 4.5 × 8 km Kulshan caldera, filled with rhyodacite ignimbrite at the northeast foot of Mount Baker, brings to only three the Quaternary calderas identified in the Cascades. A near-vertical ring fault cut in basement rocks of the North Cascades encloses...
Authors
W. Hildreth
Potassium-argon geochronology of a basalt-andesite-dacite arc system: the Mount Adams volcanic field, Cascade Range of southern Washington Potassium-argon geochronology of a basalt-andesite-dacite arc system: the Mount Adams volcanic field, Cascade Range of southern Washington
High-precision K-Ar dating and detailed mapping have established an eruptive chronology for a Cascade stratovolcano and its surrounding array of coeval basaltic centers. The time-volume-composition data bear upon several fundamental questions concerning the long-term behavior of arc volcanoes. -from Authors
Authors
W. Hildreth, M. A. Lanphere
The plinian eruptions of 1912 at Novarupta, Katmai National Park, Alaska The plinian eruptions of 1912 at Novarupta, Katmai National Park, Alaska
The three-day eruption at Novarupta in 1912 consisted of three discrete episodes. Episode I began with plinian dispersal of rhyolitic fallout (Layer A) and contemporaneous emplacement of rhyolitic ignimbrites and associated proximal veneers. The plinian column was sustained throughout most of the interval of ash flow generation, in spite of progressive increases in the proportions of...
Authors
J. Fierstein, W. Hildreth
Non-USGS Publications**
Hildreth, W., 1976, Death Valley Geology: Death Valley Natural History Association, Furnace Creek, CA, 64 p.
Ewart, A., Hildreth, W., and Carmichael, I.S. E., 1975, Quaternary acid magma in New Zealand: Contributions to Mineralogy and Petrology, v. 51, p. 1–27.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government