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
Vendian age of enderbite from a granulite complex of the Baikal-Muya ophiolite belt, Northern Baikal Region
Consequences of slow growth for 230Th/U dating of Quaternary opals, Yucca Mountain, NV, USA
206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal, Yucca Mountain, 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
Geochronologic and isotope studies of calcite and silica constraining Quaternary unsaturated- and saturated zone hydrologic flux at Yucca Mountain, Nevada, USA
U-Pb age evidence for long-term stability of the unsaturated zone at Yucca Mountain
Secondary minerals record past percolation flux at Yucca Mountain, Nevada
Neogene to Quaternary U-Th-Pb geochronology using opal, Yucca Mountain, Nevada, USA
Inferences for Yucca Mountain unsaturated-zone hydrology from secondary minerals
Anomalous groundwater 234U/238U beneath Yucca Mountain: Evidence for local recharge?
Anorogenic nature of magmatism in the Northern Baikal volcanic belt: Evidence from geochemical, geochronological (U-Pb), and isotopic (Pb, Nd) data
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
Vendian age of enderbite from a granulite complex of the Baikal-Muya ophiolite belt, Northern Baikal Region
Consequences of slow growth for 230Th/U dating of Quaternary opals, Yucca Mountain, NV, USA
206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal, Yucca Mountain, 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
Geochronologic and isotope studies of calcite and silica constraining Quaternary unsaturated- and saturated zone hydrologic flux at Yucca Mountain, Nevada, USA
U-Pb age evidence for long-term stability of the unsaturated zone at Yucca Mountain
Secondary minerals record past percolation flux at Yucca Mountain, Nevada
Neogene to Quaternary U-Th-Pb geochronology using opal, Yucca Mountain, Nevada, USA
Inferences for Yucca Mountain unsaturated-zone hydrology from secondary minerals
Anomalous groundwater 234U/238U beneath Yucca Mountain: Evidence for local recharge?
Anorogenic nature of magmatism in the Northern Baikal volcanic belt: Evidence from geochemical, geochronological (U-Pb), and isotopic (Pb, Nd) data
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