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
Uranium-series dating of pedogenic silica and carbonate, Crater Flat, Nevada
U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone
Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada
Age constraints on fluid inclusions in calcite at Yucca Mountain
Paleohydrologic record of spring deposits in and around Pleistocene pluvial Lake Tecopa, southeastern California
Ages and Origins of Calcite and Opal in the Exploratory Studies Facility Tunnel, Yucca Mountain, Nevada
Hydrologic and geologic characteristics of the Yucca Mountain site relevant to the performance of a potential repository; Day 2, Beatty to Yucca Mountain; Stop 7B, Secondary minerals and paleohydrologic implications
206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal, Yucca Mountain, Nevada
Consequences of slow growth for 230Th/U dating of Quaternary opals, Yucca Mountain, NV, USA
Isotope hydrology of ground-water flow systems, southern Nevada
Constraints on Quaternary unsaturated- and saturated-zone hydrology from geochronological and isotopic studies of calcite and silica, Yucca Mountain, Nevada
The climatic and hydrologic history of southern Nevada during the Late Quaternary
Non-USGS Publications**
**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
Uranium-series dating of pedogenic silica and carbonate, Crater Flat, Nevada
U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone
Physical and stable-isotope evidence for formation of secondary calcite and silica in the unsaturated zone, Yucca Mountain, Nevada
Age constraints on fluid inclusions in calcite at Yucca Mountain
Paleohydrologic record of spring deposits in and around Pleistocene pluvial Lake Tecopa, southeastern California
Ages and Origins of Calcite and Opal in the Exploratory Studies Facility Tunnel, Yucca Mountain, Nevada
Hydrologic and geologic characteristics of the Yucca Mountain site relevant to the performance of a potential repository; Day 2, Beatty to Yucca Mountain; Stop 7B, Secondary minerals and paleohydrologic implications
206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal, Yucca Mountain, Nevada
Consequences of slow growth for 230Th/U dating of Quaternary opals, Yucca Mountain, NV, USA
Isotope hydrology of ground-water flow systems, southern Nevada
Constraints on Quaternary unsaturated- and saturated-zone hydrology from geochronological and isotopic studies of calcite and silica, Yucca Mountain, Nevada
The climatic and hydrologic history of southern Nevada during the Late Quaternary
Non-USGS Publications**
**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.