James Paces
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
Filter Total Items: 20
Data Release of Geologic Map of the Weldona 7.5' Quadrangle, Morgan County, Colorado 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...
Data Release of OSL, 14C, and U-series age data supporting geologic mapping along the South Platte River corridor in northeastern Colorado 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...
Filter Total Items: 88
Holen et al. reply 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...
Authors
Steven R. Holen, Thomas A. Demere, Daniel C. Fisher, Richard Fullagar, James B. Paces, George T. Jefferson, Jared M. Beeton, Richard A. Cerutti, Adam N. Rountrey, Lawrence Vescera, Kathleen A. Holen
Miocene−Pleistocene deformation of the Saddle Mountains: Implications for seismic hazard in central Washington, USA 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...
Authors
Lydia M. Staisch, Harvey Kelsey, Brian Sherrod, Andreas Moller, James B. Paces, Richard J. Blakely, Richard Styron
Broken bones and hammerstones at the Cerutti Mastodon site: A reply to Haynes Broken bones and hammerstones at the Cerutti Mastodon site: A reply to Haynes
Haynes [2017 “The Cerutti Mastodon.” PaleoAmerica 3 (3): 196–199] criticizes numerous aspects of our analysis of the Cerutti Mastodon (CM) site, but central among his points is the claim that heavy equipment broke the bones and stones that we interpret as evidence of ancient human activity. This notion can be discounted primarily because most of the relevant CM fragments were found...
Authors
Steven R. Holen, Thomas A. Demere, Daniel C. Fisher, Richard Fullagar, James B. Paces, George T. Jefferson, Jared M. Beeton, Adam N. Rountrey, Kathleen A. Holen
A 130,000-year-old archaeological site in southern California, USA A 130,000-year-old archaeological site in southern California, USA
The earliest dispersal of humans into North America is a contentious subject, and proposed early sites are required to meet the following criteria for acceptance: (1) archaeological evidence is found in a clearly defined and undisturbed geologic context; (2) age is determined by reliable radiometric dating; (3) multiple lines of evidence from interdisciplinary studies provide consistent...
Authors
Steven R. Holen, Thomas A. Deméré, Daniel C. Fisher, Richard Fullagar, James B. Paces, George T. Jefferson, Jared M. Beeton, Richard A. Cerutti, Adam N. Rountrey, Lawrence Vescera, Kathleen A. Holen
A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento-San Joaquin Delta of California, USA A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento-San Joaquin Delta of California, USA
In this paper, we provide the first record of millennial patterns of Pb and Hg concentrations on the west coast of the United States. Peat cores were collected from two micro-tidal marshes in the Sacramento-San Joaquin Delta of California. Core samples were analyzed for Pb, Hg, and Ti concentrations and dated using radiocarbon, 210Pb, and 137Cs. Pre-anthropogenic concentrations of Pb and...
Authors
Judith Z. Drexler, Charles N. Alpers, Leonid A. Neymark, James B. Paces, Howard E. Taylor, Christopher C. Fuller
Geomorphic evolution of the San Luis Basin and Rio Grande in southern Colorado and northern New Mexico Geomorphic evolution of the San Luis Basin and Rio Grande in southern Colorado and northern New Mexico
The San Luis Basin encompasses the largest structural and hydrologic basin of the Rio Grande rift. On this field trip, we will examine the timing of transition of the San Luis Basin from hydrologically closed, aggrading subbasins to a continuous fluvial system that eroded the basin, formed the Rio Grande gorge, and ultimately, integrated the Rio Grande from Colorado to the Gulf of Mexico...
Authors
Chester A. Ruleman, Michael Machette, Ren A. Thompson, Dan M Miggins, Brent M Goehring, James B. Paces
Non-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.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 20
Data Release of Geologic Map of the Weldona 7.5' Quadrangle, Morgan County, Colorado 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...
Data Release of OSL, 14C, and U-series age data supporting geologic mapping along the South Platte River corridor in northeastern Colorado 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...
Filter Total Items: 88
Holen et al. reply 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...
Authors
Steven R. Holen, Thomas A. Demere, Daniel C. Fisher, Richard Fullagar, James B. Paces, George T. Jefferson, Jared M. Beeton, Richard A. Cerutti, Adam N. Rountrey, Lawrence Vescera, Kathleen A. Holen
Miocene−Pleistocene deformation of the Saddle Mountains: Implications for seismic hazard in central Washington, USA 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...
Authors
Lydia M. Staisch, Harvey Kelsey, Brian Sherrod, Andreas Moller, James B. Paces, Richard J. Blakely, Richard Styron
Broken bones and hammerstones at the Cerutti Mastodon site: A reply to Haynes Broken bones and hammerstones at the Cerutti Mastodon site: A reply to Haynes
Haynes [2017 “The Cerutti Mastodon.” PaleoAmerica 3 (3): 196–199] criticizes numerous aspects of our analysis of the Cerutti Mastodon (CM) site, but central among his points is the claim that heavy equipment broke the bones and stones that we interpret as evidence of ancient human activity. This notion can be discounted primarily because most of the relevant CM fragments were found...
Authors
Steven R. Holen, Thomas A. Demere, Daniel C. Fisher, Richard Fullagar, James B. Paces, George T. Jefferson, Jared M. Beeton, Adam N. Rountrey, Kathleen A. Holen
A 130,000-year-old archaeological site in southern California, USA A 130,000-year-old archaeological site in southern California, USA
The earliest dispersal of humans into North America is a contentious subject, and proposed early sites are required to meet the following criteria for acceptance: (1) archaeological evidence is found in a clearly defined and undisturbed geologic context; (2) age is determined by reliable radiometric dating; (3) multiple lines of evidence from interdisciplinary studies provide consistent...
Authors
Steven R. Holen, Thomas A. Deméré, Daniel C. Fisher, Richard Fullagar, James B. Paces, George T. Jefferson, Jared M. Beeton, Richard A. Cerutti, Adam N. Rountrey, Lawrence Vescera, Kathleen A. Holen
A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento-San Joaquin Delta of California, USA A millennial-scale record of Pb and Hg contamination in peatlands of the Sacramento-San Joaquin Delta of California, USA
In this paper, we provide the first record of millennial patterns of Pb and Hg concentrations on the west coast of the United States. Peat cores were collected from two micro-tidal marshes in the Sacramento-San Joaquin Delta of California. Core samples were analyzed for Pb, Hg, and Ti concentrations and dated using radiocarbon, 210Pb, and 137Cs. Pre-anthropogenic concentrations of Pb and...
Authors
Judith Z. Drexler, Charles N. Alpers, Leonid A. Neymark, James B. Paces, Howard E. Taylor, Christopher C. Fuller
Geomorphic evolution of the San Luis Basin and Rio Grande in southern Colorado and northern New Mexico Geomorphic evolution of the San Luis Basin and Rio Grande in southern Colorado and northern New Mexico
The San Luis Basin encompasses the largest structural and hydrologic basin of the Rio Grande rift. On this field trip, we will examine the timing of transition of the San Luis Basin from hydrologically closed, aggrading subbasins to a continuous fluvial system that eroded the basin, formed the Rio Grande gorge, and ultimately, integrated the Rio Grande from Colorado to the Gulf of Mexico...
Authors
Chester A. Ruleman, Michael Machette, Ren A. Thompson, Dan M Miggins, Brent M Goehring, James B. Paces
Non-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.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.