Leonid Neymark
Leonid Neymark is a Scientist Emeritus with the Geology, Geophysics, and Geochemistry Science Center.
I am currently a Scientist Emeritus in the Geology, Geophysics, and Geochemistry Science Center after being transferred from the Geochemistry Team, Yucca Mountain Project Branch where I conducted U-series studies of soils, fracture minerals and water-rock interaction processes.
I conduct a wide spectrum of isotope-geochemical studies involving radiogenic isotopes of U, Pb, Sr, and Nd and using ICP-MS and TIMS techniques. Before 2010 I was a principal investigator and a member of the Geochemistry Team in the Yucca Mountain Project Branch, WRD. The team's task was to evaluate geochemical aspects of the hydrogeologic suitability of Yucca Mountain to permanently store high-level radioactive waste. My focus was on the history of secondary mineral deposition (largely calcite and silica) in soil and unsaturated- and saturated-zone settings and on isotope-geochemical indicators of water-rock interaction as evidence of past water flow. These studies used U-Pb and U-series and other isotope-geochemical methods to characterize the timing of low-temperature surface processes of mineral deposition and to evaluate past water-rock interaction. In 2004 I was closely involved in the installation and detailed testing of a new ThermoFinnigan thermal-ionization mass-spectrometer Triton. I developed reproducible mass-spectrometric methods of U-series isotope measurements for whole rock samples with large Th/U and 232Th/230Th ratios. Previous YMPB work included systematic characterization of subsurface and soil hydrogenic minerals to provide a basis for understanding past hydrologic and climate variability in the Yucca Mountain region.
Current Projects
- Sources of Pb contamination in domestic well water in SW Missouri
- Matrix Pore Waters - Ultracentrifugation Method for Low-Permeability Sedimentary and Crystalline Rocks
- The U-Th-Pb whole-rock isotope system in the Chalk River core and past redox conditions
- Impact of Exhalative Hydrothermal Systems on Marine Chemistry: Applications for Mineral Assessment
- Conditions and Processes Affecting Radionuclide Transport (writing a chapter for the GSA Memoir devoted to Yucca Mountain, volume 2
Professional Experience
Research Chemist, Geology, Geophysics, and Geochemistry Science Center, USGS
Principal investigator and member of the Geochemistry Team in the Yucca Mountain Project Branch, USGS
2001-2004. S.M. Stoller Corporation, Senior Geochemist
1996-2001. Pacific Western Technologies, Ltd. Senior Scientist
1993-1996. US Geological Survey Visiting Research Scientist
1985-1993. Institute of Precambrian Geology and Geochronology (IPGG), St. Petersburg, Russian Academy of Sciences
1971-1985. All Union Geological Research Institute, Leningrad (USSR Ministry of Geology). Engineer (1971-1981) and Junior Research Scientist (1981-1985)
Education and Certifications
Ph.D. in Geochemistry, St. Petersburg, Russia
MS degree in Radiochemistry, St. Petersburg, Russia
Affiliations and Memberships*
American Geophysical Union
Geological Society of America
International Geochemistry Association
Geochemical Society
Science and Products
Geochemistry of dust in the Exploratory Studies Facility, Yucca Mountain, Nevada
Summary of Chlorine-36 validation studies at Yucca Mountain, Nevada
U-series disequilibrium as a test for unsaturated-zone hydrologic models at Yucca Mountain, Nevada
Estimation of past seepage volumes from calcite distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada
U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone
Uranium-series disequilibrium in tuffs from Yucca Mountain, Nevada, as evidence of pore-fluid flow over the last million years
234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA
Age constraints on fluid inclusions in calcite at Yucca Mountain
Ages and Origins of Calcite and Opal in the Exploratory Studies Facility Tunnel, Yucca Mountain, Nevada
Garnet granulite xenoliths from the Northern Baltic shield: The underplated lower crust of a palaeoproterozoic large igneous province
Quaternary geochronology using combined U-Pb and U-series methods: The opal perspective
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
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
Geochemistry of dust in the Exploratory Studies Facility, Yucca Mountain, Nevada
Summary of Chlorine-36 validation studies at Yucca Mountain, Nevada
U-series disequilibrium as a test for unsaturated-zone hydrologic models at Yucca Mountain, Nevada
Estimation of past seepage volumes from calcite distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada
U-Pb ages of secondary silica at Yucca Mountain, Nevada: Implications for the paleohydrology of the unsaturated zone
Uranium-series disequilibrium in tuffs from Yucca Mountain, Nevada, as evidence of pore-fluid flow over the last million years
234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA
Age constraints on fluid inclusions in calcite at Yucca Mountain
Ages and Origins of Calcite and Opal in the Exploratory Studies Facility Tunnel, Yucca Mountain, Nevada
Garnet granulite xenoliths from the Northern Baltic shield: The underplated lower crust of a palaeoproterozoic large igneous province
Quaternary geochronology using combined U-Pb and U-series methods: The opal perspective
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
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.
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government