Primary research responsibilities includes collection of radiogenic isotope data (U-series and Sr) used to date Quaternary deposits and provide natural tracers of mass flow through near-surface environments.
EMPLOYMENT HISTORY
Scientist Emeritus, USGS, Geology and Environmental Change Science Center, (2021-)
Research Geologist, USGS, Geology and Environmental Change Science Center, (2010 - 2020)
Geochronological and radiogenic isotope studies associated with 1) Quaternary landscape evolution for Geologic-Mapping Studies at Buffalo National River, AR; Greater Platte River basin, CO; Rio Grande Rift, NM & CO, 2) probabilistic seismic hazard analyses, eastern WA, 3) Pleistocene water-table fluctuations and aquifer sources at Wind Cave NP, SD, 4) ages of megafauna and archaeological sites, CO & CA, 5) hydrologic sources and mixing in modern and paleohydrologic environments (Pahranagat NWR, NV; Sacramento-San Joaquin Delta, CA; Yellowstone NP, WY; Gallatin Valley, MT; upper Santa Cruz River basin; AZ), 6) structural evolution of Channel Islands NP, CA, 7) timing of U mineralization, TX & VA.
Research Hydrologist, USGS, Yucca Mountain Project Branch, (1992 - 2010)
Geochemical and isotopic characterization of the Nation’s proposed high-level radioactive waste repository at Yucca Mountain, NV. Studies of both surface- and subsurface-based geochronology, hydrology, and paleoclimate investigations using Sr and U-Th isotopes to characterize modern and Pleistocene hydrologic processes.
Geologist, Natl. Res. Council Post-doc, USGS, Branch of Isotope Geology (1990 - 1991)
1) Isotopic (U-Pb, Rb-Sr, Sm-Nd) investigation of lower crustal nodules from Jurassic kimberlites, MI, 2) High-precision, single-zircon U-Pb dating of 1.1 Ga mafic intrusions in the Duluth Complex, MN.
Geologist, Post-doc fellow, Univ. Tennessee (1989)
Sr- and Nd-isotope study of whole rocks and mineral separates of Apollo 17 mare basalts.
EDUCATION
Ph.D. in Geology, Michigan Technological University, Houghton, Michigan, 1988; Magmatic processes, evolution and mantle source characteristics contributing to the petrogenesis of Midcontinent Rift Basalts: Portage Lake Volcanics, Keweenaw Peninsula, MI
B.S. in Geology (with honors), University of Oregon, Eugene, Oregon, 1978
AWARDS
USGS Superior Service Award, 2005
GSA Fellow
Colorado Scientific Society President, 2020
PROFESSIONAL AFFILIATIONS
Geological Society of America
American Geophysical Union
Geochemical Society
International Association of Geochemistry
Science and Products
Serving the U.S. Geological Survey’s geochronological data
Geochronological data provide essential information necessary for understanding the timing of geologic processes and events, as well as quantifying rates and timescales key to geologic mapping, mineral and energy resource and hazard assessments. The USGS’s National Geochronological Database (NGDB) contains over 30,000 radiometric ages, but no formal update has occurred in over 20 years. This proj
Sr-, U-, H- and O-isotope data used to evaluate water sources in the Potrero Creek Wetlands, Upper Santa Cruz Basin, southern Arizona, USA
This data release includes a table of 87Sr/86Sr, 234U/238U, δ2H, and δ18O isotope data used to evaluate groundwater- and surface-water-sources contributing to water in perennial wetlands near the mouth of Potrero Creek within the Upper Santa Cruz Basin near Nogales, AZ. Interpretations of those data are discussed in the pamphlet accompanying the USGS Scientific Investigations Map SIM-XXX
Uranium- and thorium-isotope data used to estimate uranium-series ages of Pleistocene lake deposits in the Lake Manix basin, Mojave Desert, California
This data release contains numerical U- and Th-isotopic data used to calculate uranium-series age estimates and initial 234U/238U activity ratios for samples of carbonate-rich clast coatings, oncoidal tufa rinds, calcite-replaced rhizoliths, carbonate nodules, and ostracod shells from sites associated with different lake levels of paleo Lake Manix near Barsow, CA. In addition, measured U concentra
Uranium-, thorium-, strontium-, carbon- and oxygen-isotope data used to evaluate a 300,000-year history of water-table fluctuations at Wind Cave, South Dakota, USA - scale, timing, and groundwater mixing in the Madison Aquifer
Tables of U- and Th-isotopic data used to calculate uranium-series age estimates and initial 234U/238U activity ratios as well as 87Sr/86Sr, delta 13C, and delta 18O for samples of phreatic speleothems from Wind Cave National Park and U- and Sr-isotopic compositions of waters from the southern Black Hills of South Dakota, USA
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
Data release for Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
This dataset includes tables of 3He-isotopic data used to calculate surface exposure ages for samples of basalt, and U- and Th-isotopic data used to calculate uranium-series age estimates (230Th/U method) and initial 234U/238U activity ratios for samples of pedogenic carbonate formed in soils on alluvial fans in the San Luis Valley, Colorado, USA. These data are included in the publication: Rule
U-series isotope data used to date a 130,000-year-old archaeological site in southern California, U.S.A.
Data release for "A 130,000-year-old archaeological site in southern California, U.S.A", published as a Letter to Nature. Includes sample information, U-Th isotope compositions, calculated U-series (230Th/U) ages and initial 234U/238U activity ratios, for mastodon bones from the Cerutti Mastodon site in National City, CA. Formatted data tables can be found in the Supplementary Informat
Data Rease for "Isotopic constraints on middle Pleistocene cave evolution, paleohydrologic flow, and environmental conditions from Fitton Cave speleothems, Buffalo National River, Arkansas"
Data release for "Isotopic constraints on middle Pleistocene cave evolution, paleohydrologic flow, and environmental conditions from Fitton Cave speleothems, Buffalo National River, Arkansas". Extended abstract for the 2017 Karst Interest Group meeting. Includes sample information, U-Th isotope compositions, calculated U-series (230Th/U) ages and initial 234U/238U activity ratios, Sr isotopic co
Data Release of Geologic Map of the Weldona 7.5' Quadrangle, Morgan County, Colorado
The Weldona 7.5' quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The Sout
Data Release of OSL, 14C, and U-series age data supporting geologic mapping along the South Platte River corridor in northeastern Colorado
In conjunction with geologic mapping of four 7.5′ quadrangles along the South Platte River corridor in northeastern Colorado (Masters, Orchard, Weldona, and Fort Morgan), geochronology samples were collected and analyzed using optically stimulated luminescence (OSL), radiocarbon (14C), or U-series methods to provide age control for mapping units. This section of river corridor is largely covered b
Geologic map of the Fort Morgan 7.5' quadrangle, Morgan County, Colorado
The Fort Morgan 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the late Pliocene to the present. Th
Geologic map of the Weldona 7.5' quadrangle, Morgan County, Colorado
The Weldona 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The Sout
Geologic map of the Masters 7.5' quadrangle, Weld and Morgan Counties, Colorado
The Masters 7.5' quadrangle is located along the South Platte River corridor on the semiarid plains of eastern Colorado and contains surficial deposits that record alluvial, eolian, and hillslope processes that have operated in concert with environmental changes from Pleistocene to present time. The South Platte River, originating high in the Colorado Front Range, has played a major role in shapin
Geologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California
Las Vegas and Pahrump are two of the fastest growing cities in the US, and the shortage of water looms as among the greatest future problems for these cities. These new maps of the Las Vegas 30 x 60-minute quadrangle provide a geologic and geophysical framework and fundamental earth science database needed to address societal issues such as ground water supply and contamination, surface flood, la
Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California
The Mound Spring quadrangle, the southwestern-most 7.5' quadrangle of the area of the Las Vegas 1:100,000-scale quadrangle, is entirely within the Pahrump Valley, spanning the Nevada/California State line. New geologic mapping of the predominantly Quaternary materials is combined with new studies of gravity and geochronology in this quadrangle. Eleven predominantly fine-grained units are delinea
Filter Total Items: 87
Geomorphic history of Lake Manix, Mojave Desert, California: Evolution of a complex terminal lake basin
The US Environmental Protection Agency's short-term freshwater effluent test methods include a fish (Pimephales promelas), a cladoceran (Ceriodaphnia dubia), and a green alga (Raphidocelis subcapitata). There is a recognized need for additional taxa to accompany the three standard species for effluent testing. An appropriate additional taxon is unionid mussels because mussels are widely distribute
Dating silica sinter (geyserite): A cautionary tale
We describe a new effort to date hydrothermal silica sinter deposits (geyserite) from the Upper Geyser Basin of Yellowstone National Park using 14C of co-deposited organic matter, U-series and cosmogenic 10Be methods. A majority of the samples were collected from stratigraphic sections, mainly at Riverside, Giant, and Castle Geysers. Ages obtained from 41 14C analyses range from modern to 12.1 cal
Hydrothermal activity in the southwest Yellowstone Plateau Volcanic Field
In the past two decades, the U.S. Geological Survey and the National Park Service have studied hydrothermal activity across the Yellowstone Plateau Volcanic Field (YPVF) to improve the understanding of the magmatic-hydrothermal system and to provide a baseline for detecting future anomalous activity. In 2017 and 2018 we sampled water and gas over a large area in the southwest YPVF and used Landsat
Pleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River
The Tecopa basin in eastern California was a terminal basin that episodically held lakes during most of the Quaternary until the basin and its modern stream, the Amargosa River, became tributary to Death Valley. Although long studied for its sedimentology, diagenesis, and paleomagnetism, the basin’s lacustrine and paleoclimate history has not been well understood, and conflicting interpretations e
300,000 yr history of water-table fluctuations at Wind Cave, South Dakota, USA—Scale, timing, and groundwater mixing in the Madison Aquifer
Deposits of calcite coating the lower passages of Wind Cave in the southern Black Hills of South Dakota were precipitated under phreatic conditions. Data from samples associated with a new cave survey and hydrologic studies indicate that past water tables within Wind Cave reached a maximum height of 45 m above modern levels but were mostly confined to 25 m or less. Uranium-series ages for basal la
Multivariate analysis of hydrochemical data for Jewel Cave, Wind Cave, and surrounding areas
Jewel Cave National Monument and Wind Cave National Park in South Dakota contain two of the six longest caves worldwide. These caves contain subterranean lakes that are important points of intersection between the water table of the Madison aquifer and the caves. During 2015 to 2017, several subterranean lakes were discovered in Jewel Cave, which previously was thought to be above the regional wat
Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
The Rio Grande is the fourth longest river in North America extending over 3,000 km from the Rocky Mountains to the Gulf of Mexico. The Pleistocene evolution of this river from individual subbasins into a coalesced fluvial system has been long debated. Herein, we constrain the middle Pleistocene evolution of the northernmost and largest Rio Grande basin, the San Luis basin, and the timing of incis
Calcrete uranium deposits in the Southern High Plains, USA
The Southern High Plains (SHP) is a new and emerging U.S. uranium province. Here, uranyl vanadates form deposits in Pliocene to Pleistocene sandstone, dolomite, and limestone. Fifteen calcrete uranium occurrences are identified; two of these, the Buzzard Draw and Sulfur Springs Draw deposits, have combined in-place resources estimated at about 4 million pounds of U3O8. Ore minerals carnotite and f
Disparate perspectives on evidence from the Cerutti Mastodon site: A reply to Braje et al.
The Perspective editorial by Braje, T., T. D. Dillehay, J. M. Erlandson, S. M. Fitzpatrick, D. K. Grayson, V. T. Holliday, R. L. Kelly, R. G. Klein, D. J. Meltzer, and T. C. Rick (2017. “Were Hominins in California ∼130,000 Years Ago?” PaleoAmerica 3 (3): 200–202) takes issue with our argument [Holen, S. R., T. A. Deméré, D. C. Fisher, R. Fullagar, J. B. Paces, G. T. Jefferson, J. M. Beeton, et al
Comment on “The earliest modern humans outside Africa”
Hershkovitz et al. (Reports, 26 January 2018, p. 456) interpreted the Misliya-1 fossil maxilla as evidence of the earliest known anatomically modern human outside Africa. However, the fossil’s reported age of 177,000 to 194,000 years relies on flawed interpretations of uranium-series data. We contend that those data support a minimum age of no more than ~60,000 to 70,000 years.
Holen et al. reply
Contrary to our hypothesis that the Cerutti Mastodon (CM) site represents a 130,000-year-old archaeological site, in the accompanying Comment Ferraro et al. argue that the site formed through ‘common’ geological and taphonomic processes. As a source for the cobbles that we interpreted as hammerstones and anvils, they postulate a previously unrecognized alluvial fan, later removed by fluvial winnow
Miocene−Pleistocene deformation of the Saddle Mountains: Implications for seismic hazard in central Washington, USA
The Yakima fold province, located in the backarc of the Cascadia subduction zone, is a region of active strain accumulation and deformation distributed across a series of fault-cored folds. The geodetic network in central Washington has been used to interpret large-scale N-S shortening and westward-increasing strain; however, geodetic data are unable to resolve shortening rates across individual s
Pre-USGS Publications
Paces, J.B., Nakai, S., Neal, C.R., Taylor, L.A., Halliday, A.N., and Lee, D-C, 1991, A Sr and Nd isotopic study of Apollo 17 high-Ti basalts: resolution of ages, evolution of magmas, and origins of source heterogeneities: Geochimica et Cosmochimica Acta, v. 55, p. 2025-2043.
Neal, C.R., Taylor, L.A., Davidson, J.P., Holden, P., Halliday, A.N., Paces, J.B., Clayton, R.N., and Mayeda, T.K., 1990, Eclogites with oceanic crustal and mantle signatures from the Bellsbank Kimberlite, South Africa, Part II: Radiogenic isotopes and geochemical evolution: Earth and Planetary Science Letters, v. 99, p. 362-379.
Davis, D.W., and Paces, J.B., 1990, Time resolution of geological events on the Keweenaw Peninsula and implications for development of the Midcontinent Rift system: Earth and Planetary Science Letters, v. 97, p. 54-64.
Paces, J.B., and Bell, K., 1989, Non-depleted sub-continental mantle beneath the Superior Province of the Canadian Shield: Nd-Sr isotopic and trace element evidence from Midcontinent Rift basalts: Geochimica et Cosmochimica Acta, v. 53, p. 2023-2035.
Zolensky, M.E., Sylvester, P.J., and Paces, J.B., 1988, Origin and significance of blue coloration in quartz from Llano Rhyolite (Llanite), north-central Llano County, Texas: American Mineralogist, v. 73, p. 313-323.
Bornhorst, T.J., Kalliokoski, J., and Paces, J.B., 1986, The Keweenaw Native-Copper District, in Brown, A.C., Kirkham, R.V. (eds.), Proterozoic Sediment-hosted Stratiform Copper Deposits of Upper Michigan and Belt Supergroup of Idaho and Montana: Geological Association of Canada/Mineralogical Association of Canada/Canadian Geophysical Union Joint Annual Meeting, Ottawa '86, Field Trip 1 Guidebook, p. 21-36.
McDowell, S.D., and Paces, J.B., 1985, Carbonate alteration minerals in the Salton Sea geothermal system, California, USA: Mineral Magazine, v. 49, p. 469-479.
Wilson, M.L., Paces, J.B., and Ruotsala, A.P., 1984, Fluorapatite from the King Lithia mine, Custer County, South Dakota: Mineral Record v. 15, p. 361-366.
Science and Products
- Science
Serving the U.S. Geological Survey’s geochronological data
Geochronological data provide essential information necessary for understanding the timing of geologic processes and events, as well as quantifying rates and timescales key to geologic mapping, mineral and energy resource and hazard assessments. The USGS’s National Geochronological Database (NGDB) contains over 30,000 radiometric ages, but no formal update has occurred in over 20 years. This proj - Data
Sr-, U-, H- and O-isotope data used to evaluate water sources in the Potrero Creek Wetlands, Upper Santa Cruz Basin, southern Arizona, USA
This data release includes a table of 87Sr/86Sr, 234U/238U, δ2H, and δ18O isotope data used to evaluate groundwater- and surface-water-sources contributing to water in perennial wetlands near the mouth of Potrero Creek within the Upper Santa Cruz Basin near Nogales, AZ. Interpretations of those data are discussed in the pamphlet accompanying the USGS Scientific Investigations Map SIM-XXXUranium- and thorium-isotope data used to estimate uranium-series ages of Pleistocene lake deposits in the Lake Manix basin, Mojave Desert, California
This data release contains numerical U- and Th-isotopic data used to calculate uranium-series age estimates and initial 234U/238U activity ratios for samples of carbonate-rich clast coatings, oncoidal tufa rinds, calcite-replaced rhizoliths, carbonate nodules, and ostracod shells from sites associated with different lake levels of paleo Lake Manix near Barsow, CA. In addition, measured U concentraUranium-, thorium-, strontium-, carbon- and oxygen-isotope data used to evaluate a 300,000-year history of water-table fluctuations at Wind Cave, South Dakota, USA - scale, timing, and groundwater mixing in the Madison Aquifer
Tables of U- and Th-isotopic data used to calculate uranium-series age estimates and initial 234U/238U activity ratios as well as 87Sr/86Sr, delta 13C, and delta 18O for samples of phreatic speleothems from Wind Cave National Park and U- and Sr-isotopic compositions of waters from the southern Black Hills of South Dakota, USAWater 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 collData release for Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
This dataset includes tables of 3He-isotopic data used to calculate surface exposure ages for samples of basalt, and U- and Th-isotopic data used to calculate uranium-series age estimates (230Th/U method) and initial 234U/238U activity ratios for samples of pedogenic carbonate formed in soils on alluvial fans in the San Luis Valley, Colorado, USA. These data are included in the publication: RuleU-series isotope data used to date a 130,000-year-old archaeological site in southern California, U.S.A.
Data release for "A 130,000-year-old archaeological site in southern California, U.S.A", published as a Letter to Nature. Includes sample information, U-Th isotope compositions, calculated U-series (230Th/U) ages and initial 234U/238U activity ratios, for mastodon bones from the Cerutti Mastodon site in National City, CA. Formatted data tables can be found in the Supplementary InformatData Rease for "Isotopic constraints on middle Pleistocene cave evolution, paleohydrologic flow, and environmental conditions from Fitton Cave speleothems, Buffalo National River, Arkansas"
Data release for "Isotopic constraints on middle Pleistocene cave evolution, paleohydrologic flow, and environmental conditions from Fitton Cave speleothems, Buffalo National River, Arkansas". Extended abstract for the 2017 Karst Interest Group meeting. Includes sample information, U-Th isotope compositions, calculated U-series (230Th/U) ages and initial 234U/238U activity ratios, Sr isotopic coData Release of Geologic Map of the Weldona 7.5' Quadrangle, Morgan County, Colorado
The Weldona 7.5' quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The SoutData Release of OSL, 14C, and U-series age data supporting geologic mapping along the South Platte River corridor in northeastern Colorado
In conjunction with geologic mapping of four 7.5′ quadrangles along the South Platte River corridor in northeastern Colorado (Masters, Orchard, Weldona, and Fort Morgan), geochronology samples were collected and analyzed using optically stimulated luminescence (OSL), radiocarbon (14C), or U-series methods to provide age control for mapping units. This section of river corridor is largely covered b - Maps
Geologic map of the Fort Morgan 7.5' quadrangle, Morgan County, Colorado
The Fort Morgan 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the late Pliocene to the present. ThGeologic map of the Weldona 7.5' quadrangle, Morgan County, Colorado
The Weldona 7.5′ quadrangle is located on the semiarid plains of northeastern Colorado, along the South Platte River corridor where the river has incised into Upper Cretaceous Pierre Shale. The Pierre Shale is largely covered by surficial deposits that formed from alluvial, eolian, and hillslope processes operating in concert with environmental changes from the Pleistocene to the present. The SoutGeologic map of the Masters 7.5' quadrangle, Weld and Morgan Counties, Colorado
The Masters 7.5' quadrangle is located along the South Platte River corridor on the semiarid plains of eastern Colorado and contains surficial deposits that record alluvial, eolian, and hillslope processes that have operated in concert with environmental changes from Pleistocene to present time. The South Platte River, originating high in the Colorado Front Range, has played a major role in shapinGeologic and geophysical maps of the Las Vegas 30' x 60' quadrangle, Clark and Nye counties, Nevada, and Inyo County, California
Las Vegas and Pahrump are two of the fastest growing cities in the US, and the shortage of water looms as among the greatest future problems for these cities. These new maps of the Las Vegas 30 x 60-minute quadrangle provide a geologic and geophysical framework and fundamental earth science database needed to address societal issues such as ground water supply and contamination, surface flood, laGeologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California
The Mound Spring quadrangle, the southwestern-most 7.5' quadrangle of the area of the Las Vegas 1:100,000-scale quadrangle, is entirely within the Pahrump Valley, spanning the Nevada/California State line. New geologic mapping of the predominantly Quaternary materials is combined with new studies of gravity and geochronology in this quadrangle. Eleven predominantly fine-grained units are delinea - Publications
Filter Total Items: 87
Geomorphic history of Lake Manix, Mojave Desert, California: Evolution of a complex terminal lake basin
The US Environmental Protection Agency's short-term freshwater effluent test methods include a fish (Pimephales promelas), a cladoceran (Ceriodaphnia dubia), and a green alga (Raphidocelis subcapitata). There is a recognized need for additional taxa to accompany the three standard species for effluent testing. An appropriate additional taxon is unionid mussels because mussels are widely distributeDating silica sinter (geyserite): A cautionary tale
We describe a new effort to date hydrothermal silica sinter deposits (geyserite) from the Upper Geyser Basin of Yellowstone National Park using 14C of co-deposited organic matter, U-series and cosmogenic 10Be methods. A majority of the samples were collected from stratigraphic sections, mainly at Riverside, Giant, and Castle Geysers. Ages obtained from 41 14C analyses range from modern to 12.1 calHydrothermal activity in the southwest Yellowstone Plateau Volcanic Field
In the past two decades, the U.S. Geological Survey and the National Park Service have studied hydrothermal activity across the Yellowstone Plateau Volcanic Field (YPVF) to improve the understanding of the magmatic-hydrothermal system and to provide a baseline for detecting future anomalous activity. In 2017 and 2018 we sampled water and gas over a large area in the southwest YPVF and used LandsatPleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River
The Tecopa basin in eastern California was a terminal basin that episodically held lakes during most of the Quaternary until the basin and its modern stream, the Amargosa River, became tributary to Death Valley. Although long studied for its sedimentology, diagenesis, and paleomagnetism, the basin’s lacustrine and paleoclimate history has not been well understood, and conflicting interpretations e300,000 yr history of water-table fluctuations at Wind Cave, South Dakota, USA—Scale, timing, and groundwater mixing in the Madison Aquifer
Deposits of calcite coating the lower passages of Wind Cave in the southern Black Hills of South Dakota were precipitated under phreatic conditions. Data from samples associated with a new cave survey and hydrologic studies indicate that past water tables within Wind Cave reached a maximum height of 45 m above modern levels but were mostly confined to 25 m or less. Uranium-series ages for basal laMultivariate analysis of hydrochemical data for Jewel Cave, Wind Cave, and surrounding areas
Jewel Cave National Monument and Wind Cave National Park in South Dakota contain two of the six longest caves worldwide. These caves contain subterranean lakes that are important points of intersection between the water table of the Madison aquifer and the caves. During 2015 to 2017, several subterranean lakes were discovered in Jewel Cave, which previously was thought to be above the regional watMiddle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
The Rio Grande is the fourth longest river in North America extending over 3,000 km from the Rocky Mountains to the Gulf of Mexico. The Pleistocene evolution of this river from individual subbasins into a coalesced fluvial system has been long debated. Herein, we constrain the middle Pleistocene evolution of the northernmost and largest Rio Grande basin, the San Luis basin, and the timing of incisCalcrete uranium deposits in the Southern High Plains, USA
The Southern High Plains (SHP) is a new and emerging U.S. uranium province. Here, uranyl vanadates form deposits in Pliocene to Pleistocene sandstone, dolomite, and limestone. Fifteen calcrete uranium occurrences are identified; two of these, the Buzzard Draw and Sulfur Springs Draw deposits, have combined in-place resources estimated at about 4 million pounds of U3O8. Ore minerals carnotite and fDisparate perspectives on evidence from the Cerutti Mastodon site: A reply to Braje et al.
The Perspective editorial by Braje, T., T. D. Dillehay, J. M. Erlandson, S. M. Fitzpatrick, D. K. Grayson, V. T. Holliday, R. L. Kelly, R. G. Klein, D. J. Meltzer, and T. C. Rick (2017. “Were Hominins in California ∼130,000 Years Ago?” PaleoAmerica 3 (3): 200–202) takes issue with our argument [Holen, S. R., T. A. Deméré, D. C. Fisher, R. Fullagar, J. B. Paces, G. T. Jefferson, J. M. Beeton, et alComment on “The earliest modern humans outside Africa”
Hershkovitz et al. (Reports, 26 January 2018, p. 456) interpreted the Misliya-1 fossil maxilla as evidence of the earliest known anatomically modern human outside Africa. However, the fossil’s reported age of 177,000 to 194,000 years relies on flawed interpretations of uranium-series data. We contend that those data support a minimum age of no more than ~60,000 to 70,000 years.Holen et al. reply
Contrary to our hypothesis that the Cerutti Mastodon (CM) site represents a 130,000-year-old archaeological site, in the accompanying Comment Ferraro et al. argue that the site formed through ‘common’ geological and taphonomic processes. As a source for the cobbles that we interpreted as hammerstones and anvils, they postulate a previously unrecognized alluvial fan, later removed by fluvial winnowMiocene−Pleistocene deformation of the Saddle Mountains: Implications for seismic hazard in central Washington, USA
The Yakima fold province, located in the backarc of the Cascadia subduction zone, is a region of active strain accumulation and deformation distributed across a series of fault-cored folds. The geodetic network in central Washington has been used to interpret large-scale N-S shortening and westward-increasing strain; however, geodetic data are unable to resolve shortening rates across individual sPre-USGS Publications
Paces, J.B., Nakai, S., Neal, C.R., Taylor, L.A., Halliday, A.N., and Lee, D-C, 1991, A Sr and Nd isotopic study of Apollo 17 high-Ti basalts: resolution of ages, evolution of magmas, and origins of source heterogeneities: Geochimica et Cosmochimica Acta, v. 55, p. 2025-2043.Neal, C.R., Taylor, L.A., Davidson, J.P., Holden, P., Halliday, A.N., Paces, J.B., Clayton, R.N., and Mayeda, T.K., 1990, Eclogites with oceanic crustal and mantle signatures from the Bellsbank Kimberlite, South Africa, Part II: Radiogenic isotopes and geochemical evolution: Earth and Planetary Science Letters, v. 99, p. 362-379.Davis, D.W., and Paces, J.B., 1990, Time resolution of geological events on the Keweenaw Peninsula and implications for development of the Midcontinent Rift system: Earth and Planetary Science Letters, v. 97, p. 54-64.Paces, J.B., and Bell, K., 1989, Non-depleted sub-continental mantle beneath the Superior Province of the Canadian Shield: Nd-Sr isotopic and trace element evidence from Midcontinent Rift basalts: Geochimica et Cosmochimica Acta, v. 53, p. 2023-2035.Zolensky, M.E., Sylvester, P.J., and Paces, J.B., 1988, Origin and significance of blue coloration in quartz from Llano Rhyolite (Llanite), north-central Llano County, Texas: American Mineralogist, v. 73, p. 313-323.Bornhorst, T.J., Kalliokoski, J., and Paces, J.B., 1986, The Keweenaw Native-Copper District, in Brown, A.C., Kirkham, R.V. (eds.), Proterozoic Sediment-hosted Stratiform Copper Deposits of Upper Michigan and Belt Supergroup of Idaho and Montana: Geological Association of Canada/Mineralogical Association of Canada/Canadian Geophysical Union Joint Annual Meeting, Ottawa '86, Field Trip 1 Guidebook, p. 21-36.McDowell, S.D., and Paces, J.B., 1985, Carbonate alteration minerals in the Salton Sea geothermal system, California, USA: Mineral Magazine, v. 49, p. 469-479.Wilson, M.L., Paces, J.B., and Ruotsala, A.P., 1984, Fluorapatite from the King Lithia mine, Custer County, South Dakota: Mineral Record v. 15, p. 361-366. - News