James Paces

1989-1990: Postdoc, Univ. Tenn.; Sr-Nd isotopes of Apollo 17 basalts

1990-1992: Postdoc, USGS, Branch of Isotope Geology: Lower crustal nodules from Michigan kimberlites;  High-precision U-Pb dating of Duluth Complex single zircons

1992-2010: USGS, Yucca Mtn. Project Branch: Site characterization studies (paleoseismicity, geomorphology, groundwater and vadose-zone hydrology, paleoclimate) focusing on U-series isotope approaches

2010-present: USGS, Geosciences and Environmental Change Science Center: Various studies of climate change, landscape evolution, paleoseismicity, paleontology, and water sources/flow processes using U-series- and Sr-isotope data obtained from opaline silica, tufa, travertine, speleothems, bone, paleosols, peat, and water

EDUCATION

Ph.D. in Geology, Michigan Technological University, Houghton, Michigan, 1988

• Dissertation: Magmatic processes, evolution, and mantle source characteristics contributing to the petrogenesis of Midcontinent Rift basalts: Portage Lake Volcanics, Keweenaw Peninsula, Michigan, 413 p.

B.S. in Geology (with honors), University of Oregon, Eugene, Oregon, 1978

EMPLOYMENT HISTORY

Research Geologist, USGS, Geology and Environmental Change Science Center, (2010 to present)
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.  Projects I am currently or recently (last 4 years) involved in include:

• Geologic Mapping Studies at Buffalo National River, AR (Funding source: USGS-GEC SC)

• Greater Platte River Basins and N. Plains Geologic Framework Studies, CO & NE (USGS-GEC SC)

• Cenozoic Landscape Evolution of the Southern Rocky Mountains, NW & CO (USGS-GEC SC)

• Underground Test Area (UGTA) Environmental Restoration Project, NV (DOE)

• Pleistocene water-table fluctuations and aquifer contributions at Wind Cave National Park, SD (NPS)

• Snowmastodon Studies, Snowmass, CO (Denver Museum of Nature & Science)

• Uranium-series dating of megafauna sites in the western U.S. (Center for American Paleolithic Research)

• Hydrologic Processes at Pahranagat National Wildlife Refuge, NV (USFWS)

• Rates and Evolution of Peat Accretion through Time, Sacramento-San Joaquin Delta, CA (USGS-CA WSC)

• Radiogenic isotope tracers as a tool to understand groundwater flow, mixing, and hydrologic connectivity in the Upper Geyer Basin, Yellowstone National Park (NPS)

• ²³⁰Th/U ages supporting Hanford Site‐wide probabilistic seismic hazard analysis, WA (DOE)

• Missouri caves paleoseismic study (USGS – Earthquake Hazards Program)

Research Hydrologist, USGS, Yucca Mountain Project Branch, (1992 to 2010)

Primary research responsibilities focused on geochemical and isotopic characterization of the Nation’s proposed high-level radioactive waste repository at Yucca Mountain, Nevada.  Research involved both surface- and subsurface-based investigations of geochronology, hydrology, and paleoclimate using natural isotopes of strontium and the uranium-series disequilibrium chain for tracing hydrologic pathways and for isotopic dating a wide range of hydrogenic deposits.  Major tasks included (1) providing paleoenvironmental histories and the timing of seismic events by dating surface deposits at numerous faults across the site, (2) understanding the paleohydrologic significance of secondary minerals in the deep unsaturated zone (UZ) in terms of the timing and amounts of percolation flux, sources of fracture water, and impacts of climate change on deep UZ flow, (3) determine the degrees of Pleistocene water-rock interaction to evaluate UZ-flow processes such as flow focusing in fault zones and fractures, capillary barrier effects, extent of past water-table rises beneath the repository, (4) defining flow paths in the regional saturated-zone ground-water system, and (5) studying the history and nature of Pleistocene discharge deposits in nearby areas to determine how the regional ground-water system responded to Pleistocene climate change.  

Geologist, Natl. Res. Council Post-doc, USGS, Branch of Isotope Geology (1990 to 1991)
1) Geochemical, isotopic (Pb, Sr, Nd), and geochronological investigation of granulite nodules from southern Superior Province kimberlites.  2) High-precision, single-zircon U-Th-Pb geochronological study of mafic intrusive rocks of the 1.1 Ga Duluth Complex that led to major rethinking of magma generation and differentiation processes during Midcontinent Rifting.

Geologist, Post-doc fellow, Univ. Tennesse (Mar. to Dec., 1989)
Collected Sr and Nd isotope compositions on whole rocks and mineral separates of Apollo 17 mare basalts and interpreted results with respect to eruptive ages and mantle differentiation events. 

AWARDS

USGS Superior Service Award – August 2005 – for development and application of innovative U-series disequilibrium analyses

PROFESSIONAL AFFILIATIONS

Geological Society of America

American Geophysical Union

Geochemical Society

International Association of Geochemistry

OTHER PUBLICATIONS (See tab below for main list)

Paces, J.B., and Miller, J.D., Jr., 1993 Precise U-Pb ages of Duluth Complex and related mafic intrusions, northeastern Minnesota:  Geochronological insights to physical, petrogenetic, paleomagnetic and tectonomagmatic processes associated with the 1.1. Ga Midcontinent Rift system.  Journal of Geophysical Research, vol. 98, p. 13,997-14,013.

Lundstrom, S.C., Wesling, J.R., Taylor, E.M., and Paces, J.B., 1994, Preliminary surficial deposits map of the northeast quarter of the Busted Butte 7.5-minute quadrangle:  U.S. Geological Survey Open-File Report 94-341, scale 1:12000.

Paces, J.B., Menges, C.M., Widmann, B., Wesling, J.R., Bush, C.A., Futa, K., Millard, H.T., Maat, P.B., and Whitney, J.W., 1994, Preliminary U-series disequilibrium and thermoluminescence ages of surficial deposits and paleosols associated with Quaternary faults, eastern Yucca Mountain:  in Conference on High-Level Radioactive Waste Management, 5th, Las Vegas, NV, 1994, Proceedings,  American Society of Civil Engineers, p. 2391-2401.

Lundstrom, S.C., Mahan, S.A., and Paces, J.B., 1995a,  Preliminary surficial deposits map of the northwest quarter of the Busted Butte 7.5-minute quadrangle:  U.S. Geological Survey Open-File Report 95-133, scale 1:12000.

Lundstrom, S.C., Whitney, J.W., Paces, J.B., Mahan, S.A., and Ludwig, K.R., 1995c, Preliminary surficial deposits map of the southern half of the Busted Butte 7.5-minute quadrangle, Nye County, NV:  U.S. Geological Survey Open-File Report 95-311, scale 1:12000.

Lundstrom, S.C., Paces, J.B., and Mahan, S.A., 1998, Late Quaternary history of Fortymile Wash in the area near the H-road crossing. In Quaternary Geology of the Yucca Mountain Area, Southern Nevada, Friends of the Pleistocene, Pacific Cell, 1998 Annual Meeting, p. 63-76.

Marshall, B.D., Paces, J.B., Neymark, L.A., Whelan, J.F., and Peterman, Z.E., 1998, Secondary minerals record past percolation flux at Yucca Mountain, Nevada: Proceedings of the Eighth International Conference, High-Level Radioactive Waste Management, Las Vegas, NV, May 11-14, 1998, American Nuclear Society, LaGrange Park, IL., 127-129.

Neymark, L.A., Amelin, Yu. V., Paces, J.B., and Peterman, Z.E., 1998, U-Pb age evidence for long-term stability of the unsaturated zone at Yucca Mountain: Proceedings of the Eighth International Conference, High-Level Radioactive Waste Management, Las Vegas, NV, May 11-14, 1998, American Nuclear Society, LaGrange Park, IL., p. 85-87.

Paces J.B., Peterman, Z.E., Neymark, L.A., Whelan, J.F., and Marshall, B.D., 1998, Constraints on Quaternary Unsaturated- and Saturated-Zone Hydrology from Geochronological and Isotopic Studies of Calcite and Silica, Yucca Mountain, Nevada.  In, Use of Hydrogeochemical Information in Testing Groundwater Flow Models, Technical Summary and Proceedings of a Workshop, organized by the Nuclear Energy Agency Co-ordinating Group on Site Evaluation and Design of Experiments (SEDE) for Radioactive Waste Disposal, Borgholm, Sweden, 1-3 Sept. 1997, p. 329-336.

Paces, J.B., Neymark L.A., Marshall, B.D., Whelan, J.F., and Peterman, Z.E., 1998, Inferences for Yucca Mountain unsaturated-zone hydrology from secondary minerals. Proceedings of the Eighth International Conference, High-Level Radioactive Waste Management, Las Vegas, NV, May 11-14, 1998, American Nuclear Society, LaGrange Park, IL., p. 36-39.

Paces, J.B., Ludwig, K.R., Peterman, Z.E., Neymark, L.A., and Kenneally J.M., 1998, Anomalous groundwater 234U/238U beneath Yucca Mountain: evidence for local recharge?: Proceedings of the Eighth International Conference, High-Level Radioactive Waste Management, Las Vegas, NV, May 11-14, 1998, American Nuclear Society, LaGrange Park, IL., p. 185-188.

Patterson, G.L., Peterman, Z.E., and Paces, J.B., 1998, The implication of a perched-water system based on USW WT-24 hydrochemistry. Proceedings of the Eighth International Conference, High-Level Radioactive Waste Management, Las Vegas, NV, May 11-14, 1998, American Nuclear Society, LaGrange Park, IL., p. 277-278.

Stuckless, J.F., Marshall, B.D., Vaniman, D.T., Dudley, W.W., Peterman, Z.E., Paces, J.B., Whelan, J.F., Taylor, E.M., Forester, R.M., and O’Leary, D.W., 1998, Comments on “Overview of calcite/opal deposits at or near the proposed high-level nuclear waste site, Yucca Mountain, Nevada, USA: pedogenic, hypogene or both” by C.A. Hill, Y.V. Dublyansky, R.S. Harmon, C.M. Schluter: Environmental Geology, v. 34, p. 70-78.

Paces, J.B. and Peterman, Z.E., 1999, Isotope hydrology of ground-water flow systems, southern Nevada: in, B. Faybishenko, ed., Proceedings of the International Symposium on Dynamics of Fluids in Fractured Rocks, Concepts and Recent Advances, Berkeley, California, February 10-12, 1999, Lawrence Berkeley National Laboratory Report LBNL-42718, p. 134-138.

Marshall, B.D., Neymark, L.A., Paces, J.B., Peterman, Z.E., and Whelan, J.F., 2000, Seepage flux conceptualized from secondary calcite in lithophysal cavities in the Topopah Spring Tuff, Yucca Mountain, Nevada., Society for Mining, Metallurgy, and Exploration Annual Meeting Preprint 00-12 , 6 p.

Neymark, L.A., Amelin, Y.V., Paces, J.B., Peterman, Z.E., Whelan, J.F., 2001, Age constraints on fluid inclusions in calcite at Yucca Mountain. Proceedings of the Ninth International High-Level Radioactive Waste Management Conference, Las Vegas, NV, April 29 – May 3, 2001, American Nuclear Society, LaGrange Park, IL., published on CD-ROM.

Paces, J.B. and Whelan, J.F., 2001, Water-table fluctuations in the Amargosa Desert, Nye County, Nevada. Proceedings of the Ninth International High-Level Radioactive Waste Management Conference, Las Vegas, NV, April 29 – May 3, 2001, American Nuclear Society, LaGrange Park, IL., published on CD-ROM

Whelan, J.F., Roedder, E., and Paces, J.B., 2001, Evidence for an unsaturated-zone origin of secondary minerals in Yucca Mountain, Nevada. Proceedings of the Ninth International High-Level Radioactive Waste Management Conference, Las Vegas, NV, April 29 – May 3, 2001, American Nuclear Society, LaGrange Park, IL., published on CD-ROM.

Neymark L.A., Paces, J.B., and Amelin Y.V. (2003) Reliability of U-Th-Pb dating of secondary silica at Yucca Mountain, Nevada. Proceedings of the Tenth International High-Level Radioactive Waste Management Conference, Las Vegas, NV, March 30 – April 2, 2003, American Nuclear Society, LaGrange Park, IL., 1-12.

Paces, J.B. and Neymark, L.A., 2003, U-Series Disequilibrium as a Test for Unsaturated-Zone Hydrologic Models at Yucca Mountain, Nevada. Proceedings of the 10th International High-Level Radioactive Waste Management Conference, Las Vegas, NV, March 30 – April 2, 2003, American Nuclear Society, LaGrange Park, IL., 27-38

Paces, J.B., Peterman, Z.E., Neymark, L.A., Nimz, G.J., Gascoyne, M., and Marshall, B.D., 2003, Summary of Chlorine-36 validation studies at Yucca Mountain, Nevada. Proceedings of the 10th International High-Level Radioactive Waste Management Conference, Las Vegas, NV, March 30 – April 2, 2003, American Nuclear Society, LaGrange Park, IL., 348-356.

Peterman, Z.E., Paces, J.B., Neymark, L.A., and Hudson, D., 2003, Geochemistry of dust in the Exploratory Studies Facility, Yucca Mountain, Nevada.  Proceedings of the 10th International High-Level Radioactive Waste Management Conference, Las Vegas, NV, March 30 – April 2, 2003, American Nuclear Society, LaGrange Park, IL.

Paces, J.B. and Neymark, L.A., 2004, U-Series isotopes as indicators of water/rock interaction in the unsaturated zone at Yucca Mountain, Nevada, USA. In, Proceedings of the Eleventh International Symposium on Water-Rock Interaction, NY, June 27 – July 2, 2004, Saratoga Springs, Wanty R.B., and Seal II, R.R., eds. Balkema Publishers, Leiden, 475-479.

Whelan, J.F., Paces, J.B., Peterman, Z.E., Marshall, B.D., and Neymark, L.A., 2005, Reply to the comment on ‘‘Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada’’, by Y.V. Dublyansky, S.E. Smirnov and G.P. Palyanova.  Applied Geochem. 20, 1039-1050.

Farnham, I.M., Rose, T.P., Kwicklis, E.M., Hershey, R.L., Paces, J.B., 2006, Geochemical and isotopic evaluation of groundwater movement in corrective action unit 97: Yucca Flat/Climax Mine, Nevada Test Site, Nevada:  Stoller-Navarro Joint Venture, Report S-N/99205-070 to DOE, Stoller-Navarro Joint Venture, Las Vegas, NV.

Paces, J.B., 2014.  Uranium series, Opal. In, Rink, W.J., Thompson, J., eds., Encyclopedia of Scientific Dating Methods, SpringerReference, Springer-Verlag, Berlin Heidelberg. http://www.springerreference.com/index/chapterdbid/359191 

Paces, J.B., Weis, D., and Ireland, T.R., 2014.  Mass Spectrometry. In, Rink, W.J., Thompson, J., eds., Encyclopedia of Scientific Dating Methods, SpringerReference, Springer-Verlag, Berlin Heidelberg. http://www.springerreference.com/index/chapterdbid/359191