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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: 21
No Result Found
Filter Total Items: 88

Pliocene to Holocene Lakes in the Western Great Basin, USA: New perspectives on paleoclimate, landscape dynamics, tectonics, and paleodistribution of aquatic species Pliocene to Holocene Lakes in the Western Great Basin, USA: New perspectives on paleoclimate, landscape dynamics, tectonics, and paleodistribution of aquatic species

No abstract available.
Authors
Marith C. Reheis, Joanna L. Redwine, K. Adams, S. Stine, K. Parker, R. Negrini, R. M. Burke, G. Kurth, John McGeehin, James B. Paces, F. Phillips, Andrei M. Sarna-Wojcicki, J. Smoot
By
Geosciences and Environmental Change Science Center

Uranium-series dating of pedogenic silica and carbonate, Crater Flat, Nevada Uranium-series dating of pedogenic silica and carbonate, Crater Flat, Nevada

A 230Th-234U-238U dating study on pedogenic silica-carbonate clast rinds and matrix laminae from alluvium in Crater Flat, Nevada was conducted using small-sample thermal-ionization mass spectrometry (TIMS) analyses on a large suite of samples. Though the 232Th content of these soils is not particularly low (mostly 0.1-9 ppm), the high U content of the silica component (mostly 4-26 ppm)...
Authors
K.R. Ludwig, J.B. Paces

234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA 234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA

Uranium concentrations and 234U/238U ratios in saturated-zone and perched ground water were used to investigate hydrologic flow and downgradient dilution and dispersion in the vicinity of Yucca Mountain, a potential high-level radioactive waste disposal site. The U data were obtained by thermal ionization mass spectrometry on more than 280 samples from the Death Valley regional flow...
Authors
J.B. Paces, K.R. Ludwig, Z. E. Peterman, L.A. Neymark

U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone

Uranium, Th and Pb isotopes were analyzed in layers of opal and chalcedony from individual mm- to cm-thick calcite and silica coatings at Yucca Mountain, Nevada, USA, a site that is being evaluated for a potential high-level nuclear waste repository. These calcite and silica coatings on fractures and in lithophysal cavities in Miocene-age tuffs in the unsaturated zone (UZ) precipitated...
Authors
L.A. Neymark, Y. Amelin, J.B. Paces, Z. E. Peterman

Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada

Calcite and silica form coatings on fracture footwalls and cavity floors in the welded tuffs at Yucca Mountain, the potential site of a high-level radioactive waste repository. These secondary mineral deposits are heterogeneously distributed in the unsaturated zone (UZ) with fewer than 10% of possible depositional sites mineralized. The paragenetic sequence, compiled from deposits...
Authors
J. F. Whelan, J.B. Paces, Z. E. Peterman

Age constraints on fluid inclusions in calcite at Yucca Mountain Age constraints on fluid inclusions in calcite at Yucca Mountain

No abstract available.
Authors
Leonid A. Neymark, Yuri V. Amelin, James B. Paces, Zell E. Peterman, Joseph F. Whelan
By
Geology, Geophysics, and Geochemistry Science Center

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: 21
No Result Found
Filter Total Items: 88

Pliocene to Holocene Lakes in the Western Great Basin, USA: New perspectives on paleoclimate, landscape dynamics, tectonics, and paleodistribution of aquatic species Pliocene to Holocene Lakes in the Western Great Basin, USA: New perspectives on paleoclimate, landscape dynamics, tectonics, and paleodistribution of aquatic species

No abstract available.
Authors
Marith C. Reheis, Joanna L. Redwine, K. Adams, S. Stine, K. Parker, R. Negrini, R. M. Burke, G. Kurth, John McGeehin, James B. Paces, F. Phillips, Andrei M. Sarna-Wojcicki, J. Smoot
By
Geosciences and Environmental Change Science Center

Uranium-series dating of pedogenic silica and carbonate, Crater Flat, Nevada Uranium-series dating of pedogenic silica and carbonate, Crater Flat, Nevada

A 230Th-234U-238U dating study on pedogenic silica-carbonate clast rinds and matrix laminae from alluvium in Crater Flat, Nevada was conducted using small-sample thermal-ionization mass spectrometry (TIMS) analyses on a large suite of samples. Though the 232Th content of these soils is not particularly low (mostly 0.1-9 ppm), the high U content of the silica component (mostly 4-26 ppm)...
Authors
K.R. Ludwig, J.B. Paces

234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA 234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA

Uranium concentrations and 234U/238U ratios in saturated-zone and perched ground water were used to investigate hydrologic flow and downgradient dilution and dispersion in the vicinity of Yucca Mountain, a potential high-level radioactive waste disposal site. The U data were obtained by thermal ionization mass spectrometry on more than 280 samples from the Death Valley regional flow...
Authors
J.B. Paces, K.R. Ludwig, Z. E. Peterman, L.A. Neymark

U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone

Uranium, Th and Pb isotopes were analyzed in layers of opal and chalcedony from individual mm- to cm-thick calcite and silica coatings at Yucca Mountain, Nevada, USA, a site that is being evaluated for a potential high-level nuclear waste repository. These calcite and silica coatings on fractures and in lithophysal cavities in Miocene-age tuffs in the unsaturated zone (UZ) precipitated...
Authors
L.A. Neymark, Y. Amelin, J.B. Paces, Z. E. Peterman

Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada

Calcite and silica form coatings on fracture footwalls and cavity floors in the welded tuffs at Yucca Mountain, the potential site of a high-level radioactive waste repository. These secondary mineral deposits are heterogeneously distributed in the unsaturated zone (UZ) with fewer than 10% of possible depositional sites mineralized. The paragenetic sequence, compiled from deposits...
Authors
J. F. Whelan, J.B. Paces, Z. E. Peterman

Age constraints on fluid inclusions in calcite at Yucca Mountain Age constraints on fluid inclusions in calcite at Yucca Mountain

No abstract available.
Authors
Leonid A. Neymark, Yuri V. Amelin, James B. Paces, Zell E. Peterman, Joseph F. Whelan
By
Geology, Geophysics, and Geochemistry Science Center

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.

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