Andrew G Hunt
Andy Hunt is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 61
Groundwater quality near the Placerita Oil Field, California, 2018
Groundwater-quality data and potential fluid-migration pathways near the Placerita Oil Field in Los Angeles County, California, were examined by the U.S. Geological Survey to determine if oil-field fluids (water and gas from oil-producing and non-producing zones) have mixed with groundwater resources. Six of the 13 new groundwater samples collected for this study contained petroleum...
Authors
Jennifer S. Stanton, Matthew K. Landon, David H. Schoellhamer, Justin T. Kulongoski, Andrew G. Hunt, Peter B. McMahon, Isabelle M. Cozzarelli, Robert Anders, Theron A. Sowers
Assessing potential effects of oil and gas development activities on groundwater quality near and overlying the Elk Hills and North Coles Levee Oil Fields, San Joaquin Valley, California
Groundwater resources are utilized near areas of intensive oil and gas development in California’s San Joaquin Valley. In this study, we examined chemical and isotopic data to assess if thermogenic gas or saline water from oil producing formations have mixed with groundwater near the Elk Hills and North Coles Levee Oil Fields in the southwestern San Joaquin Valley. Major ion...
Authors
John G. Warden, Matthew K. Landon, Michael J. Stephens, Tracy Davis, Janice M. Gillespie, Peter B. McMahon, Justin T. Kulongoski, Andrew G. Hunt, David H. Schoellhamer, Riley Gannon, Lyndsay B. Ball
The dominance and growth of shallow groundwater resources in continuous permafrost environments
Water is a limited resource in Arctic watersheds with continuous permafrost because freezing conditions in winter and the impermeability of permafrost limit storage and connectivity between surface water and deep groundwater. However, groundwater can still be an important source of surface water in such settings, feeding springs and large aufeis fields that are abundant in cold regions...
Authors
Joshua C. Koch, Craig T. Connolly, Carson Baughman, Marisa Repasch, Heather Best, Andrew G. Hunt
Land-use interactions, Oil-Field infrastructure, and natural processes control hydrocarbon and arsenic concentrations in groundwater, Poso Creek Oil Field, California, USA
Like many hydrocarbon production areas in the U.S., the Poso Creek Oil Field in California includes and is adjacent to other land uses (agricultural and other developed lands) that affect the hydrology and geochemistry of the aquifer overlying and adjacent to oil development. We hypothesize that the distributions of hydrocarbons and arsenic in groundwater in such areas will be controlled...
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Michael Wright, Angela Hansen, Tamara E. C. Kraus, Isabelle M. Cozzarelli, David H. Schoellhamer, Theron A. Sowers, Justin T. Kulongoski, Andrew G. Hunt, Ruta Karolyte, Darren J. Hillegonds, Chris J. Ballentine
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...
Authors
Benjamin S. Linhoff, Kimberly R. Beisner, Andrew G. 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...
Authors
Jennifer S. Stanton, Michael Land, Matthew K. Landon, David H. Schoellhamer, Peter B. McMahon, Tracy 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...
Authors
Jennifer L. Lewicki, William C. Evans, Steven E. Ingebritsen, Laura Clor, Peter J. Kelly, Sara E. Peek, Robert A. Jensen, Andrew G. 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...
Authors
Robert J Agnew, Andrew G. 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...
Authors
Bryant Jurgens, Kirsten Faulkner, Peter B. McMahon, Andrew G. 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...
Authors
Robert Anders, Matthew K. Landon, Peter B. McMahon, Justin T. Kulongoski, Andrew G. 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...
Authors
Ruta Karolyte, Peter H. Barry, Andrew G. 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)...
Authors
Peter B. McMahon, Matthew K. Landon, Tracy Davis, Michael Wright, Celia Zamora, Robert Anders, Michael Land, Justin T. Kulongoski, Andrew G. Hunt
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...
Chemical and isotopic compositions of gases from volcanic and geothermal areas in California
Gas chemical and isotopic compositions are reported for samples collected from 9 volcanic and geothermal areas in California: Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Mono Lake Volcanic Field, Long Valley Caldera, Mammoth Mountain, Coso Volcanic Field, and Salton Sea Geothermal Field. Beginning in 2014, gas samples were collected as part of...
Noble Gas Isotopic Data from Fluid Inclusions Contained in the Te-bearing Adularia-Sericite Epithermal Au-Ag Deposits in a Calc-Alkaline Magmatic Arc, NE China
The contents of this data release represent the results of the noble gas composition analysis and are presented in support of the planned publication Gao et al., 2023, titled Lead and noble gas isotopic constraints on the origin of Te-bearing adularia-sericite epithermal Au-Ag deposits in a calc-alkaline magmatic arc. Tellurium (Te)-bearing adularia-sericite epithermal Au-Ag deposits are...
Hydrochemistry and Age Date Tracers from Springs, Streams, and Rivers in the Arctic National Wildlife Refuge, 2019-2022
These data include water chemistry from springs, streams, rivers, and shallow groundwater collected in the Arctic National Wildlife Refuge in northern Alaska. Chemical analyses were performed for hydrochemical parameters including field parameters, major ions, nutrients, metals, stable isotopes of water, and tritium, as well as for dissolved gases useful for determining the timescale...
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...
Water-Chemistry and Isotope Data for Selected Springs, Geysers, Streams, and Rivers in Yellowstone National Park, Wyoming (ver. 2.0, March 2025)
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 hydrothermal 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...
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...
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...
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...
Science and Products
Filter Total Items: 61
Groundwater quality near the Placerita Oil Field, California, 2018
Groundwater-quality data and potential fluid-migration pathways near the Placerita Oil Field in Los Angeles County, California, were examined by the U.S. Geological Survey to determine if oil-field fluids (water and gas from oil-producing and non-producing zones) have mixed with groundwater resources. Six of the 13 new groundwater samples collected for this study contained petroleum...
Authors
Jennifer S. Stanton, Matthew K. Landon, David H. Schoellhamer, Justin T. Kulongoski, Andrew G. Hunt, Peter B. McMahon, Isabelle M. Cozzarelli, Robert Anders, Theron A. Sowers
Assessing potential effects of oil and gas development activities on groundwater quality near and overlying the Elk Hills and North Coles Levee Oil Fields, San Joaquin Valley, California
Groundwater resources are utilized near areas of intensive oil and gas development in California’s San Joaquin Valley. In this study, we examined chemical and isotopic data to assess if thermogenic gas or saline water from oil producing formations have mixed with groundwater near the Elk Hills and North Coles Levee Oil Fields in the southwestern San Joaquin Valley. Major ion...
Authors
John G. Warden, Matthew K. Landon, Michael J. Stephens, Tracy Davis, Janice M. Gillespie, Peter B. McMahon, Justin T. Kulongoski, Andrew G. Hunt, David H. Schoellhamer, Riley Gannon, Lyndsay B. Ball
The dominance and growth of shallow groundwater resources in continuous permafrost environments
Water is a limited resource in Arctic watersheds with continuous permafrost because freezing conditions in winter and the impermeability of permafrost limit storage and connectivity between surface water and deep groundwater. However, groundwater can still be an important source of surface water in such settings, feeding springs and large aufeis fields that are abundant in cold regions...
Authors
Joshua C. Koch, Craig T. Connolly, Carson Baughman, Marisa Repasch, Heather Best, Andrew G. Hunt
Land-use interactions, Oil-Field infrastructure, and natural processes control hydrocarbon and arsenic concentrations in groundwater, Poso Creek Oil Field, California, USA
Like many hydrocarbon production areas in the U.S., the Poso Creek Oil Field in California includes and is adjacent to other land uses (agricultural and other developed lands) that affect the hydrology and geochemistry of the aquifer overlying and adjacent to oil development. We hypothesize that the distributions of hydrocarbons and arsenic in groundwater in such areas will be controlled...
Authors
Peter B. McMahon, Matthew K. Landon, Michael J. Stephens, Kimberly A. Taylor, Michael Wright, Angela Hansen, Tamara E. C. Kraus, Isabelle M. Cozzarelli, David H. Schoellhamer, Theron A. Sowers, Justin T. Kulongoski, Andrew G. Hunt, Ruta Karolyte, Darren J. Hillegonds, Chris J. Ballentine
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...
Authors
Benjamin S. Linhoff, Kimberly R. Beisner, Andrew G. 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...
Authors
Jennifer S. Stanton, Michael Land, Matthew K. Landon, David H. Schoellhamer, Peter B. McMahon, Tracy 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...
Authors
Jennifer L. Lewicki, William C. Evans, Steven E. Ingebritsen, Laura Clor, Peter J. Kelly, Sara E. Peek, Robert A. Jensen, Andrew G. 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...
Authors
Robert J Agnew, Andrew G. 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...
Authors
Bryant Jurgens, Kirsten Faulkner, Peter B. McMahon, Andrew G. 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...
Authors
Robert Anders, Matthew K. Landon, Peter B. McMahon, Justin T. Kulongoski, Andrew G. 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...
Authors
Ruta Karolyte, Peter H. Barry, Andrew G. 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)...
Authors
Peter B. McMahon, Matthew K. Landon, Tracy Davis, Michael Wright, Celia Zamora, Robert Anders, Michael Land, Justin T. Kulongoski, Andrew G. Hunt
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...
Chemical and isotopic compositions of gases from volcanic and geothermal areas in California
Gas chemical and isotopic compositions are reported for samples collected from 9 volcanic and geothermal areas in California: Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Mono Lake Volcanic Field, Long Valley Caldera, Mammoth Mountain, Coso Volcanic Field, and Salton Sea Geothermal Field. Beginning in 2014, gas samples were collected as part of...
Noble Gas Isotopic Data from Fluid Inclusions Contained in the Te-bearing Adularia-Sericite Epithermal Au-Ag Deposits in a Calc-Alkaline Magmatic Arc, NE China
The contents of this data release represent the results of the noble gas composition analysis and are presented in support of the planned publication Gao et al., 2023, titled Lead and noble gas isotopic constraints on the origin of Te-bearing adularia-sericite epithermal Au-Ag deposits in a calc-alkaline magmatic arc. Tellurium (Te)-bearing adularia-sericite epithermal Au-Ag deposits are...
Hydrochemistry and Age Date Tracers from Springs, Streams, and Rivers in the Arctic National Wildlife Refuge, 2019-2022
These data include water chemistry from springs, streams, rivers, and shallow groundwater collected in the Arctic National Wildlife Refuge in northern Alaska. Chemical analyses were performed for hydrochemical parameters including field parameters, major ions, nutrients, metals, stable isotopes of water, and tritium, as well as for dissolved gases useful for determining the timescale...
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...
Water-Chemistry and Isotope Data for Selected Springs, Geysers, Streams, and Rivers in Yellowstone National Park, Wyoming (ver. 2.0, March 2025)
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 hydrothermal 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...
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...
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...
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...