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
Precise determination of δ88Sr in rocks, minerals, and waters by double-spike TIMS: A powerful tool in the study of chemical, geologic, hydrologic and biologic processes
Evaluation of Pleistocene groundwater flow through fractured tuffs using a U-series disequilibrium approach, Pahute Mesa, Nevada, USA
U–Pb, Rb–Sr, and U-series isotope geochemistry of rocks and fracture minerals from the Chalk River Laboratories site, Grenville Province, Ontario, Canada
234U/238U and δ87Sr in peat as tracers of paleosalinity in the Sacramento-San Joaquin Delta of California, USA
Ion-probe U–Pb dating of authigenic and detrital opal from Neogene-Quaternary alluvium
Conditions and processes affecting radionuclide transport
Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan Basin, New Mexico: COMMENT
Potential effects of alpha-recoil on uranium-series dating of calcrete
Limited hydrologic response to Pleistocene climate change in deep vadose zones - Yucca Mountain, Nevada
Modern U-Pb chronometry of meteorites: advancing to higher time resolution reveals new problems
Lead isotopes and trace metals in dust at Yucca Mountain
Thermal history of the unsaturated zone at Yucca Mountain, Nevada, USA
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
Precise determination of δ88Sr in rocks, minerals, and waters by double-spike TIMS: A powerful tool in the study of chemical, geologic, hydrologic and biologic processes
Evaluation of Pleistocene groundwater flow through fractured tuffs using a U-series disequilibrium approach, Pahute Mesa, Nevada, USA
U–Pb, Rb–Sr, and U-series isotope geochemistry of rocks and fracture minerals from the Chalk River Laboratories site, Grenville Province, Ontario, Canada
234U/238U and δ87Sr in peat as tracers of paleosalinity in the Sacramento-San Joaquin Delta of California, USA
Ion-probe U–Pb dating of authigenic and detrital opal from Neogene-Quaternary alluvium
Conditions and processes affecting radionuclide transport
Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan Basin, New Mexico: COMMENT
Potential effects of alpha-recoil on uranium-series dating of calcrete
Limited hydrologic response to Pleistocene climate change in deep vadose zones - Yucca Mountain, Nevada
Modern U-Pb chronometry of meteorites: advancing to higher time resolution reveals new problems
Lead isotopes and trace metals in dust at Yucca Mountain
Thermal history of the unsaturated zone at Yucca Mountain, Nevada, USA
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