Andy Hunt is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Isotope and Chemical Methods for Mineral and Geoenvironmental Assessments and Support of USGS Science Strategy
This Project integrates several geochemical tools—stable isotope geochemistry, noble gas geochemistry, active gas geochemistry, single fluid inclusion chemistry, and fluid inclusion solute chemistry—in studies of the processes that form mineral deposits and the processes that disrupt them during mining or natural weathering. Research is directed toward fundamental scientific questions or, in...
Trace element chemistry of sulfides and quartz, in situ sulfur isotope values of sulfides, cathodoluminescence of quartz, fluid inclusion microthermometry and raman, and radiogenic isotope and whole rock geochemistry from the Stibnite-Yellow Pine district
This dataset is a collection of geochemical data on samples from the Stibnite-Yellow Pine district of Idaho. The datasets include: whole rock geochemistry; lead, strontium and neodymium isotope chemistry of sulfides and whole rock samples by isotope dilution-thermal-mass spectrometry (ID-TIMS); in situ sulfur isotope chemistry of sulfides by laser ablation-multi collector-inductively coupled-mass
Water-Chemistry and Isotope Data for Selected Springs, Geysers, Streams, and Rivers in Yellowstone National Park, Wyoming
There are over 10,000 hydrothermal features in Yellowstone National Park (YNP), where waters have pH values ranging from about 1 to 10 and surface temperatures up to 95 °C. Active geothermal areas in YNP provide insight into a variety of processes occurring at depth, such as water-rock and oxidation-reduction (redox) reactions, the formation of alteration minerals, and microbial (thermophile) meta
Water chemistry data for selected hot springs and rivers in Southwest Yellowstone National Park, Wyoming
Water analyses are reported for 66 samples collected from numerous thermal and non-thermal (rivers and streams) features in the southwestern areas of Yellowstone National Park (YNP) during 2009, 2017, and 2018. Water samples were collected from sources near Boundary Creek, Bechler River, Falls River, Mountain Ash Creek, Upper Snake River, Spirea Creek, and Lewis Lake. These water samples were coll
Chemical and isotopic data on gases and waters for thermal and non-thermal features across Yellowstone National Park (2003-2015)
Degassing thermal features at Yellowstone National Park include spectacular geysers, roiling hot springs, bubbling mud pots, fumaroles, frying pans, and areas of passive degassing characterized by steaming ground. Most of these features are readily identified by visible clouds of steam that are occasionally accompanied by a strong rotten egg odor from emissions of hydrogen sulfide gas. Gas composi
Fumarole gas geochemistry and tree-ring radiocarbon data at Mammoth Mountain, California (1989-2016)
Mammoth Mountain is a dacitic dome complex located on the southwestern rim of Long Valley Caldera, California. Mammoth Mountain has exhibited unrest over the past ~30 years, characterized by seismicity over a broad range of depths, elevated 3He/4He ratios in fumarolic gas and large-scale diffuse CO2 emissions. Monitoring of this unrest has included collection of fumarole gas samples for geochemica
Filter Total Items: 57
Water quality at Chaco Culture National Historical Park and the potential effects of hydrocarbon extraction
Study regionChaco Culture National Historical Park (CCNHP) is in the San Juan Basin of northwestern New Mexico, U.S.A. Its only water supply is in Gallup Sandstone aquifer, stratigraphically surrounded by layers long targeted for oil and natural gas extraction.Study focusTo assess groundwater flow direction, age, mixing between aquifers, and whether hydrocarbons extraction may affect water quality
Authors
Benjamin S. Linhoff, Kimberly R. Beisner, Andrew Hunt, Zachary M. Shephard
Groundwater quality near the Montebello Oil Field, Los Angeles County, California
Groundwater quality and potential sources and migration pathways of chemical constituents associated with hydrocarbon-bearing formations were assessed by the U.S. Geological Survey for the California State Water Resources Control Board Oil and Gas Regional Monitoring Program (RMP). Groundwater samples were collected as part of the RMP from 21 preexisting wells used for public supply, monitoring, o
Authors
Jennifer S. Stanton, Michael Land, Matthew K. Landon, David H. Shimabukuro, Peter B. McMahon, Tracy A. Davis, Andrew G. Hunt, Theron A. Sowers
Geochemistry and fluxes of gases from hydrothermal features at Newberry Volcano, Oregon, USA
We present the chemical and isotopic compositions of gases and fluxes of CO2 from the hydrothermal features of Newberry Volcano, a large composite volcano located in Oregon's Cascade Range with a summit caldera that hosts two lakes, Paulina and East Lakes. Gas samples were collected from 1982 to 2021 from Paulina Hot Springs (PHS) on the shore of Paulina Lake, East Lake Hot Springs (ELHS) on the s
Authors
Jennifer L. Lewicki, William C. Evans, Steven E. Ingebritsen, Laura E. Clor, Peter J. Kelly, Sara Peek, Robert A. Jensen, Andrew Hunt
Improving gas-derived parameterization of groundwater using free phase gas measurements
Dissolved atmogenic gasses in groundwater provide significant information about recharge conditions, flowpath, and age. Free phase gas in aquifers is largely ignored in these analyses and there is a lack of quantitative analysis for gas flux mechanisms. Many related fields encountering multiphase flow acknowledge that the presence of bubbles allows for the rapid exsolution of dissolved gasses and
Authors
Robert J Agnew, Andrew Hunt, Todd Halihan
Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination
The distribution of groundwater age is useful for evaluating the susceptibility and sustainability of groundwater resources. Here, we compute the aquifer-scale cumulative distribution function to characterize the age distribution for 21 Principal Aquifers that account for ~80% of public-supply pumping in the United States. The aquifer-scale cumulative distribution function for each Principal Aquif
Authors
Bryant Jurgens, Kirsten Faulkner, Peter B. McMahon, Andrew Hunt, Gerolamo C. Casile, Megan B. Young, Kenneth Belitz
Occurrence of water and thermogenic gas from oil-bearing formations in groundwater near the Orcutt Oil Field, California, USA
Study regionSanta Barbara County, California, USA.Study focusTo analyze a wide array of newly collected chemical, isotopic, dissolved gas, and age dating tracers in conjunction with historical data from groundwater and oil wells to determine if water and/or thermogenic gas from oil-bearing formations have mixed with groundwater in the Orcutt Oil Field and surrounding area.New hydrological insights
Authors
Robert Anders, Matthew K. Landon, Peter B. McMahon, Justin T. Kulongoski, Andrew Hunt, Tracy Davis
Noble gas signatures constrain oil-field water as the carrier phase of hydrocarbons occurring in shallow aquifers in the San Joaquin Basin, USA
Noble gases record fluid interactions in multiphase subsurface environments through fractionation processes during fluid equilibration. Water in the presence of hydrocarbons at the subsurface acquires a distinct elemental signature due to the difference in solubility between these two fluids. We find the atmospheric noble gas signature in produced water is partially preserved after hydrocarbons pr
Authors
Ruta Karolyte, Peter H. Barry, Andrew Hunt, Justin T. Kulongoski, R. L. Tyne, Tracy Davis, Michael Wright, Peter B. McMahon, C. J. Ballentine
Relative risk of groundwater-quality degradation near California (USA) oil fields estimated from 3H, 14C, and 4He
Relative risks of groundwater-quality degradation near selected California oil fields are estimated by examining spatial and temporal patterns in chemical and isotopic data in the context of groundwater-age categories defined by tritium and carbon-14. In the Coastal basins, western San Joaquin Valley (SJV), and eastern SJV; 82, 76, and 0% of samples are premodern (pre-1953 recharge), respectively;
Authors
Peter B. McMahon, Matthew K. Landon, Tracy Davis, Michael Wright, Celia Z. Rosecrans, Robert Anders, Michael Land, Justin T. Kulongoski, Andrew Hunt
Groundwater quality of aquifers overlying the Oxnard Oil Field, Ventura County, California
Groundwater samples collected from irrigation, monitoring, and municipal supply wells near the Oxnard Oil Field were analyzed for chemical and isotopic tracers to evaluate if thermogenic gas or water from hydrocarbon-bearing formations have mixed with surrounding groundwater. New and historical data show no evidence of water from hydrocarbon-bearing formations in groundwater overlying the field. H
Authors
Celia Z. Rosecrans, Matthew K. Landon, Katherine Marie Ransom, Janice M. Gillespie, Justin T. Kulongoski, Michael J. Stephens, Andrew G. Hunt, David H. Shimabukuro, Tracy Davis
DGMETA (version 1)—Dissolved gas modeling and environmental tracer analysis computer program
DGMETA (Dissolved Gas Modeling and Environmental Tracer Analysis) is a Microsoft Excel-based computer program that is used for modeling air-water equilibrium conditions from measurements of dissolved gases and for computing concentrations of environmental tracers that rely on air-water equilibrium model results. DGMETA can solve for the temperature, salinity, excess air, fractionation of gases, or
Authors
Bryant C. Jurgens, J. K. Böhlke, Karl Haase, Eurybiades Busenberg, Andrew G. Hunt, Jeffrey A. Hansen
Geochemistry and age of groundwater in the Williston Basin, USA: Assessing potential effects of shale-oil production on groundwater quality
Thirty water wells were sampled in 2018 to understand the geochemistry and age of groundwater in the Williston Basin and assess potential effects of shale-oil production from the Three Forks-Bakken petroleum system (TBPS) on groundwater quality. Two geochemical groups are identified using hierarchical cluster analysis. Group 1 represents the younger (median 4He = 21.49 × 10−8 cm3 STP/g), less chem
Authors
Peter B. McMahon, Joel M. Galloway, Andrew Hunt, Kenneth Belitz, Bryant Jurgens, Tyler D. Johnson
A post-eruption study of gases and thermal waters at Okmok Volcano, Alaska
We report here on the first focused study of gas discharges and thermal spring waters at Okmok Volcano since the 2008 phreatomagmatic eruptions. Results include the first compositional gas data from Okmok with minimal air contamination and the first data on magmatic carbon in Okmok spring waters. Chemical and isotopic analyses of the waters and gases are used to assess the character of Okmok fluid
Authors
Deborah Bergfeld, William C. Evans, Andrew Hunt, Taryn Lopez, Janet Schaefer
Science and Products
- Science
Isotope and Chemical Methods for Mineral and Geoenvironmental Assessments and Support of USGS Science Strategy
This Project integrates several geochemical tools—stable isotope geochemistry, noble gas geochemistry, active gas geochemistry, single fluid inclusion chemistry, and fluid inclusion solute chemistry—in studies of the processes that form mineral deposits and the processes that disrupt them during mining or natural weathering. Research is directed toward fundamental scientific questions or, in... - Data
Trace element chemistry of sulfides and quartz, in situ sulfur isotope values of sulfides, cathodoluminescence of quartz, fluid inclusion microthermometry and raman, and radiogenic isotope and whole rock geochemistry from the Stibnite-Yellow Pine district
This dataset is a collection of geochemical data on samples from the Stibnite-Yellow Pine district of Idaho. The datasets include: whole rock geochemistry; lead, strontium and neodymium isotope chemistry of sulfides and whole rock samples by isotope dilution-thermal-mass spectrometry (ID-TIMS); in situ sulfur isotope chemistry of sulfides by laser ablation-multi collector-inductively coupled-massWater-Chemistry and Isotope Data for Selected Springs, Geysers, Streams, and Rivers in Yellowstone National Park, Wyoming
There are over 10,000 hydrothermal features in Yellowstone National Park (YNP), where waters have pH values ranging from about 1 to 10 and surface temperatures up to 95 °C. Active geothermal areas in YNP provide insight into a variety of processes occurring at depth, such as water-rock and oxidation-reduction (redox) reactions, the formation of alteration minerals, and microbial (thermophile) metaWater chemistry data for selected hot springs and rivers in Southwest Yellowstone National Park, Wyoming
Water analyses are reported for 66 samples collected from numerous thermal and non-thermal (rivers and streams) features in the southwestern areas of Yellowstone National Park (YNP) during 2009, 2017, and 2018. Water samples were collected from sources near Boundary Creek, Bechler River, Falls River, Mountain Ash Creek, Upper Snake River, Spirea Creek, and Lewis Lake. These water samples were collChemical and isotopic data on gases and waters for thermal and non-thermal features across Yellowstone National Park (2003-2015)
Degassing thermal features at Yellowstone National Park include spectacular geysers, roiling hot springs, bubbling mud pots, fumaroles, frying pans, and areas of passive degassing characterized by steaming ground. Most of these features are readily identified by visible clouds of steam that are occasionally accompanied by a strong rotten egg odor from emissions of hydrogen sulfide gas. Gas composiFumarole gas geochemistry and tree-ring radiocarbon data at Mammoth Mountain, California (1989-2016)
Mammoth Mountain is a dacitic dome complex located on the southwestern rim of Long Valley Caldera, California. Mammoth Mountain has exhibited unrest over the past ~30 years, characterized by seismicity over a broad range of depths, elevated 3He/4He ratios in fumarolic gas and large-scale diffuse CO2 emissions. Monitoring of this unrest has included collection of fumarole gas samples for geochemica - Publications
Filter Total Items: 57
Water quality at Chaco Culture National Historical Park and the potential effects of hydrocarbon extraction
Study regionChaco Culture National Historical Park (CCNHP) is in the San Juan Basin of northwestern New Mexico, U.S.A. Its only water supply is in Gallup Sandstone aquifer, stratigraphically surrounded by layers long targeted for oil and natural gas extraction.Study focusTo assess groundwater flow direction, age, mixing between aquifers, and whether hydrocarbons extraction may affect water qualityAuthorsBenjamin S. Linhoff, Kimberly R. Beisner, Andrew Hunt, Zachary M. ShephardGroundwater quality near the Montebello Oil Field, Los Angeles County, California
Groundwater quality and potential sources and migration pathways of chemical constituents associated with hydrocarbon-bearing formations were assessed by the U.S. Geological Survey for the California State Water Resources Control Board Oil and Gas Regional Monitoring Program (RMP). Groundwater samples were collected as part of the RMP from 21 preexisting wells used for public supply, monitoring, oAuthorsJennifer S. Stanton, Michael Land, Matthew K. Landon, David H. Shimabukuro, Peter B. McMahon, Tracy A. Davis, Andrew G. Hunt, Theron A. SowersGeochemistry and fluxes of gases from hydrothermal features at Newberry Volcano, Oregon, USA
We present the chemical and isotopic compositions of gases and fluxes of CO2 from the hydrothermal features of Newberry Volcano, a large composite volcano located in Oregon's Cascade Range with a summit caldera that hosts two lakes, Paulina and East Lakes. Gas samples were collected from 1982 to 2021 from Paulina Hot Springs (PHS) on the shore of Paulina Lake, East Lake Hot Springs (ELHS) on the sAuthorsJennifer L. Lewicki, William C. Evans, Steven E. Ingebritsen, Laura E. Clor, Peter J. Kelly, Sara Peek, Robert A. Jensen, Andrew HuntImproving gas-derived parameterization of groundwater using free phase gas measurements
Dissolved atmogenic gasses in groundwater provide significant information about recharge conditions, flowpath, and age. Free phase gas in aquifers is largely ignored in these analyses and there is a lack of quantitative analysis for gas flux mechanisms. Many related fields encountering multiphase flow acknowledge that the presence of bubbles allows for the rapid exsolution of dissolved gasses andAuthorsRobert J Agnew, Andrew Hunt, Todd HalihanOver a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination
The distribution of groundwater age is useful for evaluating the susceptibility and sustainability of groundwater resources. Here, we compute the aquifer-scale cumulative distribution function to characterize the age distribution for 21 Principal Aquifers that account for ~80% of public-supply pumping in the United States. The aquifer-scale cumulative distribution function for each Principal AquifAuthorsBryant Jurgens, Kirsten Faulkner, Peter B. McMahon, Andrew Hunt, Gerolamo C. Casile, Megan B. Young, Kenneth BelitzOccurrence of water and thermogenic gas from oil-bearing formations in groundwater near the Orcutt Oil Field, California, USA
Study regionSanta Barbara County, California, USA.Study focusTo analyze a wide array of newly collected chemical, isotopic, dissolved gas, and age dating tracers in conjunction with historical data from groundwater and oil wells to determine if water and/or thermogenic gas from oil-bearing formations have mixed with groundwater in the Orcutt Oil Field and surrounding area.New hydrological insightsAuthorsRobert Anders, Matthew K. Landon, Peter B. McMahon, Justin T. Kulongoski, Andrew Hunt, Tracy DavisNoble gas signatures constrain oil-field water as the carrier phase of hydrocarbons occurring in shallow aquifers in the San Joaquin Basin, USA
Noble gases record fluid interactions in multiphase subsurface environments through fractionation processes during fluid equilibration. Water in the presence of hydrocarbons at the subsurface acquires a distinct elemental signature due to the difference in solubility between these two fluids. We find the atmospheric noble gas signature in produced water is partially preserved after hydrocarbons prAuthorsRuta Karolyte, Peter H. Barry, Andrew Hunt, Justin T. Kulongoski, R. L. Tyne, Tracy Davis, Michael Wright, Peter B. McMahon, C. J. BallentineRelative risk of groundwater-quality degradation near California (USA) oil fields estimated from 3H, 14C, and 4He
Relative risks of groundwater-quality degradation near selected California oil fields are estimated by examining spatial and temporal patterns in chemical and isotopic data in the context of groundwater-age categories defined by tritium and carbon-14. In the Coastal basins, western San Joaquin Valley (SJV), and eastern SJV; 82, 76, and 0% of samples are premodern (pre-1953 recharge), respectively;AuthorsPeter B. McMahon, Matthew K. Landon, Tracy Davis, Michael Wright, Celia Z. Rosecrans, Robert Anders, Michael Land, Justin T. Kulongoski, Andrew HuntGroundwater quality of aquifers overlying the Oxnard Oil Field, Ventura County, California
Groundwater samples collected from irrigation, monitoring, and municipal supply wells near the Oxnard Oil Field were analyzed for chemical and isotopic tracers to evaluate if thermogenic gas or water from hydrocarbon-bearing formations have mixed with surrounding groundwater. New and historical data show no evidence of water from hydrocarbon-bearing formations in groundwater overlying the field. HAuthorsCelia Z. Rosecrans, Matthew K. Landon, Katherine Marie Ransom, Janice M. Gillespie, Justin T. Kulongoski, Michael J. Stephens, Andrew G. Hunt, David H. Shimabukuro, Tracy DavisDGMETA (version 1)—Dissolved gas modeling and environmental tracer analysis computer program
DGMETA (Dissolved Gas Modeling and Environmental Tracer Analysis) is a Microsoft Excel-based computer program that is used for modeling air-water equilibrium conditions from measurements of dissolved gases and for computing concentrations of environmental tracers that rely on air-water equilibrium model results. DGMETA can solve for the temperature, salinity, excess air, fractionation of gases, orAuthorsBryant C. Jurgens, J. K. Böhlke, Karl Haase, Eurybiades Busenberg, Andrew G. Hunt, Jeffrey A. HansenGeochemistry and age of groundwater in the Williston Basin, USA: Assessing potential effects of shale-oil production on groundwater quality
Thirty water wells were sampled in 2018 to understand the geochemistry and age of groundwater in the Williston Basin and assess potential effects of shale-oil production from the Three Forks-Bakken petroleum system (TBPS) on groundwater quality. Two geochemical groups are identified using hierarchical cluster analysis. Group 1 represents the younger (median 4He = 21.49 × 10−8 cm3 STP/g), less chemAuthorsPeter B. McMahon, Joel M. Galloway, Andrew Hunt, Kenneth Belitz, Bryant Jurgens, Tyler D. JohnsonA post-eruption study of gases and thermal waters at Okmok Volcano, Alaska
We report here on the first focused study of gas discharges and thermal spring waters at Okmok Volcano since the 2008 phreatomagmatic eruptions. Results include the first compositional gas data from Okmok with minimal air contamination and the first data on magmatic carbon in Okmok spring waters. Chemical and isotopic analyses of the waters and gases are used to assess the character of Okmok fluidAuthorsDeborah Bergfeld, William C. Evans, Andrew Hunt, Taryn Lopez, Janet Schaefer