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
Thermal history of the unsaturated zone at Yucca Mountain, Nevada, USA
U-Pb SHRIMP dating of uraniferous opals
Uranium-series constraints on subrepository water flow at yucca mountain, nevada
Testing the concept of drift shadow at Yucca Mountain, Nevada
Impact of quaternary climate on seepage at Yucca Mountain, Nevada
Reply to “Commentary: Assessment of past infiltration fluxes through Yucca Mountain on the basis of the secondary mineral record—Is it a viable methodology?” by Y.V. Dublyansky and S.Z. Smirnov
Geochemical and C, O, Sr, and U-series isotopic evidence for the meteoric origin of calcrete at Solitario Wash, Crater Flat, Nevada, USA
U-Series isotopes as indicators of water/rock interaction in the unsaturated zone at Yucca Mountain, Nevada, USA
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
Improved spatial resolution for U-series dating of opal at Yucca Mountain, Nevada, USA, using ion-microprobe and microdigestion methods
Thermochronology of secondary minerals from the Yucca Mountain unsaturated zone
Reliability of U-Th-Pb dating of secondary silica at Yucca Mountain, Nevada
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
Thermal history of the unsaturated zone at Yucca Mountain, Nevada, USA
U-Pb SHRIMP dating of uraniferous opals
Uranium-series constraints on subrepository water flow at yucca mountain, nevada
Testing the concept of drift shadow at Yucca Mountain, Nevada
Impact of quaternary climate on seepage at Yucca Mountain, Nevada
Reply to “Commentary: Assessment of past infiltration fluxes through Yucca Mountain on the basis of the secondary mineral record—Is it a viable methodology?” by Y.V. Dublyansky and S.Z. Smirnov
Geochemical and C, O, Sr, and U-series isotopic evidence for the meteoric origin of calcrete at Solitario Wash, Crater Flat, Nevada, USA
U-Series isotopes as indicators of water/rock interaction in the unsaturated zone at Yucca Mountain, Nevada, USA
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
Improved spatial resolution for U-series dating of opal at Yucca Mountain, Nevada, USA, using ion-microprobe and microdigestion methods
Thermochronology of secondary minerals from the Yucca Mountain unsaturated zone
Reliability of U-Th-Pb dating of secondary silica at Yucca Mountain, Nevada
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