Andrew G Hunt
Andy Hunt is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 57
Dissolved gases in hydrothermal (phreatic) and geyser eruptions at Yellowstone National Park, USA
Multiphase and multicomponent fluid flow in the shallow continental crust plays a significant role in a variety of processes over a broad range of temperatures and pressures. The presence of dissolved gases in aqueous fluids reduces the liquid stability field toward lower temperatures and enhances the explosivity potential with respect to pure water. Therefore, in areas where magma is actively deg
Authors
Shaul Hurwitz, Laura Clor, R. Blaine McCleskey, D. Kirk Nordstrom, Andrew G. Hunt, William C. Evans
Helium as a tracer for fluids released from Juan de Fuca lithosphere beneath the Cascadia forearc
The ratio between helium isotopes (3He/4He) provides an excellent geochemical tracer for investigating the sources of fluids sampled at the Earth's surface. 3He/4He values observed in 25 mineral springs and wells above the Cascadia forearc document a significant component of mantle-derived helium above Juan de Fuca lithosphere, as well as variability in 3He enrichment across the forearc. Sample si
Authors
Patricia A. McCrory, James E. Constantz, Andrew G. Hunt, J. Luke Blair
U.S. Geological Survey Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples
This report addresses the standard operating procedures used by the U.S. Geological Survey’s Noble Gas Laboratory in Denver, Colorado, U.S.A., for the measurement of dissolved gases (methane, nitrogen, oxygen, and carbon dioxide) and noble gas isotopes (helium-3, helium-4, neon-20, neon-21, neon-22, argon-36, argon-38, argon-40, kryton-84, krypton-86, xenon-103, and xenon-132) dissolved in water.
Authors
Andrew G. Hunt
Origins of geothermal gases at Yellowstone
Gas emissions at the Yellowstone Plateau Volcanic Field (YPVF) reflect open-system mixing of gas species originating from diverse rock types, magmas, and crustal fluids, all combined in varying proportions at different thermal areas. Gases are not necessarily in chemical equilibrium with the waters through which they vent, especially in acid sulfate terrain where bubbles stream through stagnant ac
Authors
Jacob B. Lowenstern, Deborah Bergfeld, William C. Evans, Andrew G. Hunt
High influx of carbon in walls of agglutinated foraminifers during the Permian-Triassic transition in global oceans
The Permian–Triassic mass extinction is postulated to be related to the rapid volcanism that produced the Siberian flood basalt (Traps). Unrelated volcanic eruptions producing several episodes of ash falls synchronous with the Siberian Traps are found in South China and Australia. Such regional eruptions could have caused wildfires, burning of coal deposits, and the dispersion of coal fly ash. The
Authors
Galina P. Nestell, Merlynd K. Nestell, Brooks B. Ellwood, Bruce R. Wardlaw, Asish R. Basu, Nilotpal Ghosh, Luu Thi Phuong Lan, Harry D. Rowe, Andrew G. Hunt, Jonathan H. Tomkin, Kenneth T. Ratcliffe
Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism
Silicic lavas have erupted repeatedly in the Mono Basin over the past few thousand years, forming the massive domes and coulees of the Mono Craters chain and the smaller island vents in Mono Lake. We report here on the first systematic study of magmatic CO2 emissions from these features, conducted during 2007–2010. Most notably, a known locus of weak steam venting on the summit of North Coulee is
Authors
D. Bergfeld, William C. Evans, James F. Howle, Andrew G. Hunt
Quality and age of shallow groundwater in the Bakken Formation production area, Williston Basin, Montana and North Dakota
The quality and age of shallow groundwater in the Bakken Formation production area were characterized using data from 30 randomly distributed domestic wells screened in the upper Fort Union Formation. Comparison of inorganic and organic chemical concentrations to health based drinking-water standards, correlation analysis of concentrations with oil and gas well locations, and isotopic data give no
Authors
Peter B. McMahon, Rodney R. Caldwell, Joel M. Galloway, Joshua F. Valder, Andrew G. Hunt
Noble gas isotopes in mineral springs within the Cascadia Forearc, Washington and Oregon
This U.S. Geological Survey report presents laboratory analyses along with field notes for a pilot study to document the relative abundance of noble gases in mineral springs within the Cascadia forearc of Washington and Oregon. Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath the sample sites are derived from the McCrory and others (2012) slab model. Some of these spring
Authors
Patricia A. McCrory, James E. Constantz, Andrew G. Hunt
Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone
Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the Yellowstone ho
Authors
Jacob B. Lowenstern, William C. Evans, D. Bergfeld, Andrew G. Hunt
Geochemical investigation of the hydrothermal system on Akutan Island, Alaska, July 2012
We have studied the geochemistry of the hot springs on Akutan Island in detail for the first time since the early 1980s. Springs in four discrete groups (A-D) along Hot Springs Creek showed generally higher temperatures and substantially higher Na, Ca, and Cl concentrations than previously reported, and total hot-spring discharge has also increased markedly. The springs now account for a heat outp
Authors
D. Bergfeld, Jennifer L. Lewicki, William C. Evans, Andrew G. Hunt, Kinga Revesz, Mark Huebner
Noble gas geochemistry investigation of high CO2 natural gas at the LaBarge Platform, Wyoming, USA
A regional sampling of gases from thermal springs near the LaBarge Field, Wyoming, USA to determine the extent of the total carbon dioxide system (TCDS) indicates that the system may extend up to 70 km to the northwest of the field. Geochemical evidence from noble gas isotopes, stable element isotopes, and gas composition provide the foundation for these conclusions. Samples from Soda Springs to t
Authors
Matthew D. Merrill, Andrew G. Hunt, Celeste D. Lohr
Evidence for high salinity of Early Cretaceous sea water from the Chesapeake Bay crater
High salinity groundwater more than 1000 metres deep in the Atlantic Coastal Plain of the United States has been documented in several locations1,2, most recently within the 35 million-year-old Chesapeake Bay impact crater3,4,5. Suggestions for the origin of increased salinity in the crater have included evaporite dissolution6, osmosis6, and evaporation from heating7 associated with the bolide imp
Authors
Ward E. Sanford, Michael W. Doughten, Tyler B. Coplen, Andrew G. Hunt, Thomas D. Bullen
Science and Products
Filter Total Items: 57
Dissolved gases in hydrothermal (phreatic) and geyser eruptions at Yellowstone National Park, USA
Multiphase and multicomponent fluid flow in the shallow continental crust plays a significant role in a variety of processes over a broad range of temperatures and pressures. The presence of dissolved gases in aqueous fluids reduces the liquid stability field toward lower temperatures and enhances the explosivity potential with respect to pure water. Therefore, in areas where magma is actively deg
Authors
Shaul Hurwitz, Laura Clor, R. Blaine McCleskey, D. Kirk Nordstrom, Andrew G. Hunt, William C. Evans
Helium as a tracer for fluids released from Juan de Fuca lithosphere beneath the Cascadia forearc
The ratio between helium isotopes (3He/4He) provides an excellent geochemical tracer for investigating the sources of fluids sampled at the Earth's surface. 3He/4He values observed in 25 mineral springs and wells above the Cascadia forearc document a significant component of mantle-derived helium above Juan de Fuca lithosphere, as well as variability in 3He enrichment across the forearc. Sample si
Authors
Patricia A. McCrory, James E. Constantz, Andrew G. Hunt, J. Luke Blair
U.S. Geological Survey Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples
This report addresses the standard operating procedures used by the U.S. Geological Survey’s Noble Gas Laboratory in Denver, Colorado, U.S.A., for the measurement of dissolved gases (methane, nitrogen, oxygen, and carbon dioxide) and noble gas isotopes (helium-3, helium-4, neon-20, neon-21, neon-22, argon-36, argon-38, argon-40, kryton-84, krypton-86, xenon-103, and xenon-132) dissolved in water.
Authors
Andrew G. Hunt
Origins of geothermal gases at Yellowstone
Gas emissions at the Yellowstone Plateau Volcanic Field (YPVF) reflect open-system mixing of gas species originating from diverse rock types, magmas, and crustal fluids, all combined in varying proportions at different thermal areas. Gases are not necessarily in chemical equilibrium with the waters through which they vent, especially in acid sulfate terrain where bubbles stream through stagnant ac
Authors
Jacob B. Lowenstern, Deborah Bergfeld, William C. Evans, Andrew G. Hunt
High influx of carbon in walls of agglutinated foraminifers during the Permian-Triassic transition in global oceans
The Permian–Triassic mass extinction is postulated to be related to the rapid volcanism that produced the Siberian flood basalt (Traps). Unrelated volcanic eruptions producing several episodes of ash falls synchronous with the Siberian Traps are found in South China and Australia. Such regional eruptions could have caused wildfires, burning of coal deposits, and the dispersion of coal fly ash. The
Authors
Galina P. Nestell, Merlynd K. Nestell, Brooks B. Ellwood, Bruce R. Wardlaw, Asish R. Basu, Nilotpal Ghosh, Luu Thi Phuong Lan, Harry D. Rowe, Andrew G. Hunt, Jonathan H. Tomkin, Kenneth T. Ratcliffe
Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism
Silicic lavas have erupted repeatedly in the Mono Basin over the past few thousand years, forming the massive domes and coulees of the Mono Craters chain and the smaller island vents in Mono Lake. We report here on the first systematic study of magmatic CO2 emissions from these features, conducted during 2007–2010. Most notably, a known locus of weak steam venting on the summit of North Coulee is
Authors
D. Bergfeld, William C. Evans, James F. Howle, Andrew G. Hunt
Quality and age of shallow groundwater in the Bakken Formation production area, Williston Basin, Montana and North Dakota
The quality and age of shallow groundwater in the Bakken Formation production area were characterized using data from 30 randomly distributed domestic wells screened in the upper Fort Union Formation. Comparison of inorganic and organic chemical concentrations to health based drinking-water standards, correlation analysis of concentrations with oil and gas well locations, and isotopic data give no
Authors
Peter B. McMahon, Rodney R. Caldwell, Joel M. Galloway, Joshua F. Valder, Andrew G. Hunt
Noble gas isotopes in mineral springs within the Cascadia Forearc, Washington and Oregon
This U.S. Geological Survey report presents laboratory analyses along with field notes for a pilot study to document the relative abundance of noble gases in mineral springs within the Cascadia forearc of Washington and Oregon. Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath the sample sites are derived from the McCrory and others (2012) slab model. Some of these spring
Authors
Patricia A. McCrory, James E. Constantz, Andrew G. Hunt
Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone
Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the Yellowstone ho
Authors
Jacob B. Lowenstern, William C. Evans, D. Bergfeld, Andrew G. Hunt
Geochemical investigation of the hydrothermal system on Akutan Island, Alaska, July 2012
We have studied the geochemistry of the hot springs on Akutan Island in detail for the first time since the early 1980s. Springs in four discrete groups (A-D) along Hot Springs Creek showed generally higher temperatures and substantially higher Na, Ca, and Cl concentrations than previously reported, and total hot-spring discharge has also increased markedly. The springs now account for a heat outp
Authors
D. Bergfeld, Jennifer L. Lewicki, William C. Evans, Andrew G. Hunt, Kinga Revesz, Mark Huebner
Noble gas geochemistry investigation of high CO2 natural gas at the LaBarge Platform, Wyoming, USA
A regional sampling of gases from thermal springs near the LaBarge Field, Wyoming, USA to determine the extent of the total carbon dioxide system (TCDS) indicates that the system may extend up to 70 km to the northwest of the field. Geochemical evidence from noble gas isotopes, stable element isotopes, and gas composition provide the foundation for these conclusions. Samples from Soda Springs to t
Authors
Matthew D. Merrill, Andrew G. Hunt, Celeste D. Lohr
Evidence for high salinity of Early Cretaceous sea water from the Chesapeake Bay crater
High salinity groundwater more than 1000 metres deep in the Atlantic Coastal Plain of the United States has been documented in several locations1,2, most recently within the 35 million-year-old Chesapeake Bay impact crater3,4,5. Suggestions for the origin of increased salinity in the crater have included evaporite dissolution6, osmosis6, and evaporation from heating7 associated with the bolide imp
Authors
Ward E. Sanford, Michael W. Doughten, Tyler B. Coplen, Andrew G. Hunt, Thomas D. Bullen