Leonid Neymark

Biography

I am currently a Research Chemist in the Central Mineral and Environmental Resources 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.  My area of expertise is isotope geochemistry and geochronology. I received my MS degree in Radiochemistry and Ph.D. in Geochemistry in St. Petersburg, Russia. As a deputy head of the Isotope lab at the Institute for Precambrian Geology and Geochronology, Russian Academy of Sciences, I conducted isotope-geochemical research of Precambrian rocks and ore deposits utilizing Rb-Sr, Sm-Nd and U-Th-Pb isotope systems. My first project with the USGS was on lower crustal granulites in 1992 and I joined Yucca Mountain Project Branch, WRD in 1993.

I am currently a Research Chemist in the Central Mineral and Environmental Resources Science Center. 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.  

 

My 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)

  

Prior to joining the YMPB I was leading and participating in a number of projects involving application of isotope geochemistry and geochronology to studies of Precambrian rocks and ore deposits. In general, these studies sought to determine the source of matter and timing of processes responsible for mineral formation. Also, a certain part of my career was devoted to the development of new approaches and techniques in isotope-geochemistry and geochronology.

 

PREVIOUS PROFESSIONAL POSITIONS

2001 – 2004. S.M. Stoller Corporation, Senior Geochemist. I continued to work for the YMPB, USGS. PI for studies of U-series radioactive disequilibrium in waters and rocks at the Yucca Mountain area as an indication of low-temperature water-rock interaction processes. Involved in36Cl isotope–geochemical studies aimed to constrain water percolation processes through the thick unsaturated zone at Yucca Mountain. I developed applications of SIMS ion-microprobe techniques for dating of uraniferous opal using U-series (together with J. Paces and J. Wooden, USGS) and U-Pb (together with A. Nemchin, Curtin University, Western Australia) methods.

1996 – 2001.   Pacific Western Technologies, Ltd. Senior Scientist-I. I continued to work for the YMPB, USGS. Involved in U-series disequilibrium isotope-geochemical studies of waters and secondary minerals at the Yucca Mountain area. PI on the implementation of U-Pb dating of Neogene-Quaternary opals with initial radioactive disequilibrium. Worked on development of mass-spectrometric isotope dilution analysis of femtogram amounts of Ra.

1993 - 1996.  US Geological Survey Visiting Research Scientist. I was involved in design and implementation of geochemical studies directed largely at the evaluation of Yucca Mountain in southern Nevada as a potential site for the storage of nuclear waste. In 1995 completed a report (Neymark et al., 1995, USGS OFR 95-134) summarizing studies that evaluated fault zones as potential pathways for hydrothermal fluids with regard to precious metal mineralization. I conducted critical research on the U and Th geochemistry of low temperature calcite and opal with particular emphasis on U-series and U-Pb dating using thermal ionization mass-spectrometric technique. Co-author of five USGS-YMPB Milestone reports on Paleohydrology and Paleoclimate of the Yucca Mountain area.

1985 - 1993.  Institute of Precambrian Geology and Geochronology (IPGG), St. Petersburg, Russian Academy of Sciences. Senior research scientist and deputy head of the laboratory for isotope geology and geochronology. Chief of a group conducting geochronological and isotope-geochemical studies of Precambrian rocks and ore deposits using the Rb-Sr, Sm-Nd and U-Th-Pb isotope systems. Co-chair of the monthly isotope-geochemical seminar.

1985-1989. PI in a part of the IPGG Project "Geochronological Scale of the Precambrian" devoted to the Baikal region, Eastern Siberia. This part of the Project used U-Pb zircon dating of igneous and volcanic rocks to constrain ages of major Late Precambrian geologic events in the region.

1988-1992. Scientific Secretary of Russian working group for an international project “The Oldest Rocks on Earth”, UNESCO International Geological Correlation Program (IGCP) Project #280. Chief: A. Kröner (Germany). I was responsible for organizing and conducting an international scientific meeting and a field trip to the Aldan Shield, Eastern Siberia (1989) and also was a co-editor of and contributor to the Field Guide for this field trip.

1989-1992. Chief of the IPGG project "Isotopic evolution of the Precambrian Lithosphere within the Aldan Shield, Baikal Region, and the Baltic Shield".  The Project was focused on combining U-Pb zircon ages of Precambrian igneous and metamorphic rocks with their Nd isotope characteristics in order to establish a sequence of the crust-forming and crust-reworking events in Precambrian of the Aldan Shield and Baikal region (Eastern Siberia), and of the Baltic Shield. 

1991-1992. PI in the IPGG project "Behavior of Radiogenic Isotopes under Different P-T-X Conditions". The project was devoted to the study of the radiogenic isotopes migration (U-Pb, Rb-Sr, Sm-Nd, and K-Ar systems) in zones developed at a contact of a basaltic dyke intrusion and host metamorphic rocks of variable mineralogy and chemical compositions. The project’s outcome was a better understanding of distances in the host rocks where thermal impulse and fluid migration caused disturbance of different isotope systems.

1991-1993. Co-chair of the Russian working group for the international project “Rapakivi Granites and Related Rocks”, UNESCO International Geological Correlation Program (IGCP) Project #315. Chiefs: I. Haapala (Finland) and R.F. Emslie (Canada). Responsible for organizing and conducting an international field trip to the Salmi granite-anorthosite batholith, Russian Karelia (1992). Co-author of the Field Guide for the trip. PI in conducting Pb-Sr-Nd isotope studies of Salmi batholith, Russian Karelia.

1991-1993. Chief of the Project “Pb-isotope Characteristics of the Gold Deposits from Siberian Craton” (Russian Foundation for Basic Research, Project #93-05-8006). Conducted a comparative Pb-isotope study of a large gold deposit Sukhoy Log, Bodaibo gold-bearing region, and a series of smaller gold deposits in Eastern Siberia.

1991-1993. Co-PI in a Project “The Role of Lower Crust in the Formation of Anorthosite-Rapakivi Granite Association”, George Soros Foundation, Grant ISF # RIE 000. Conducted Pb-Sr-Nd isotope studies of Ulkan Pluton, Eastern Siberia and Berdiaoush Pluton, South Urals region.

1971 -1985.  All Union Geological Research Institute, Leningrad (USSR Ministry of Geology). Engineer (1971-1981) and Junior Research Scientist (1981-1985).

 

 

PROFESSIONAL AFFILIATIONS

Member of the American Geophysical Union, Geological Society of America, the International Geochemistry Association, the Geochemical Society.

 

Publications

Paces, J.B, Nichols, P.J., Neymark, L.A, Rajaram, H., 2013. Evaluation of Pleistocene groundwater flow through fractured tuffs at Pahute Mesa, Nevada, using a U-series disequilibrium approach. Chemical Geology 358, 101-118.

1              S.L. Mirkina, L.A.Neymark, B.B. Golubev, I.G. Smyslova. 1976. Radiologic dating of Neogene-Quaternary uranium minerals by Pb-isotope method. Geokhimia, no. 9, 43-48 (in Russian).

2              L.A. Neymark, O.A. Levchenkov. 1979. A method of age calculation for open U-Pb isotope systems. Geochemistry International. vol.16, no.3, 34-39.

3              G.V. Ovchinnikova, L.A. Neymark. 1981. The excess lead in meteorites. Geochemistry International. vol.18, no.4, 102-115.

4              L.A. Neymark, A.D. Iskanderova, A.P. Chukhonin, et al. 1981. U-Pb data on the Archean age of metamorphic rocks of the Stanovoy Range: Geochemistry International, vol.18, no.5, 55-64.

5              L.A. Neymark. 1983. Quantitative models for the evolution of the crust-mantle system utilizing Pb isotope data. In: Geochemistry of radiogenic isotopes in the early stages of the Earth's evolution. Shukol’ukov J.A. (Ed.), Moscow, Nauka, p.151-167 (in Russian).

6              L.A. Neymark, A.D. Iskanderova, E.P. Miron'uk et al. 1984. U-Pb age of the Charskoje  ore deposit of BIF, Eastern Siberia. Doklady Akademii  Nauk SSSR. vol. 234. 1246-1249. (in Russian).

7              L.A. Neymark. 1986 U-Pb isotopic constraints on the age and primordial materials of the Earth. In: Isotope methods in geochemistry and cosmochemistry. L.K.Levsky (Ed.) Leningrad, Nauka, p. 3-21 (in Russian).

8              L.A. Neymark, S.L. Mirkina, A.G. Rublev et al. 1987. Isotope age of the granites in the Irelsky Complex, Baikal Region. Izvestiya   Akademii Nauk SSSR. vol. 5, 18-25 (in Russian).

9              A.G. Rublev, G.A. Murina, A.P. Chukhonin, L.A. Neimark, et al. 1987. Geochronology of early-Proterozoic granitoid magmatism in the Kodar-Udokan Zone. Soviet Geology and Geophysics, vol. 28, no.6, 26-33, 1987 (in Russian).

10            L.A. Neymark. 1987. Potential and restrictions of the lead-isochron method in dating Precambrian polymetamorphic rocks. In: Isotopic dating of  metamorphic and metasomatic process. Shukoljukov Yu.A. (Ed.). Moscow, Nauka, p. 29-44 (in Russian).

11            L.A Neymark. 1987. The application of U-Pb to the geochronological studies of Precambrian metallic ore deposits. In: Gorokhov I.M., Levchenkov O.A. (Editors) Isotopic methods on Geochronology. Leningrad, Nauka, p.29-44 (in Russian).

12            Yu.V. Amelin, L.A. Neymark, D.I. Matukov et al. 1988.  Analytical parameters and operation experience of MI1320-PRM2 mass-spectrometers . In: Isotopic methods in geology, geochemistry and metallogeny. Leningrad, Nauka, p.102-116. (in Russian).

13            L.A. Neymark, G.V. Ovchinnikova, B.M. Gorokhovsky et al. 1988. Pb isotopes in sulfides from rocks of the Sumozero--Kenozero  greenstone belt. In: Isotopic methods in geology, geochemistry and metallogeny. Leningrad, Nauka. p. 42-48. (in Russian).

14            L.A. Neymark, A.B. Kotov, D.P. Vinogradov et al. 1988. Age and occurrence of early folded and post-folded granitoids of  northwestern Lake Ladoga region according to data of Pb, O isotopes. In: Isotopic methods in geology, geochemistry and metallogeny. Leningrad, Nauka p. 21-41. (in Russian).

15            V.L. Dook, L.A. Neymark, and V.A. Rudnik (Eds.). 1989. The Oldest Rocks of the Aldan-Stanovik Shield, Eastern Siberia, USSR. IGCP Project 280 “The Oldest Rocks on Earth”, Excursion guide, Leningrad-Mainz, 121 p.

16            S.A. Sergeyev,  Ye.V. Bibikova,  O.A. Levchenkov,  S.B. Lobach-Zhuchenko, S.Z. Yakovleva, G.V. Ovchinnikova, L. A. Neymark, A.N. Komarov, B.M. Gorokhovskiy, 1990. Isotope geochronology of the Vodlozerskiy gneiss complex, Geokhimiya, vol.1990, no.1, 73-83. (in Russian).

17            G.V. Ovchinnikova, S.B. Lobach-Zhuchenko, S.A. Sergeyev, S.Z. Yakovleva, O.A. Levchenkov,  L.A. Neymark,  A.N. Komarov, B.M. Gorokhovskiy, A.M. Fedoseyenko, I.N. Krylov, 1990. Geochronology and petrology of the late kinematic granites of southeastern Karelia based on geochemical and isotopic data. Geokhimiya, vol.1990, no.11, 1561-1573 (in Russian).

18            L.A. Neymark, A.M.Larin, S.Z. Yakovleva, N.A. Sryvtsev, and V.V. Buldygerov. 1991. New U-Pb zircon age data on the Akitkan suite, Baikal-Patom fold area. Transactions of the USSR Academy of Sciences. vol. 321, n.8, 197-201.

19            A.M. Larin, Yu.V.Amelin, and L.A.Neymark. 1991, Age and genesis of the complex scarn ores of the Pitkaranta ore district associated with the Salmi rapakivi massif (Southern Karelia). Geologia Rudnykh Mestorozhdenij (Geology of Ore Deposits), vol. 6, 15-33 (in Russian).

20            L.A. Neymark, E.Yu. Ritzk, B.M. Gorokhovsky et al., 1991, Lead isotopic composition and genesis of the Pb-Zn mineralization of the Olokit zone of the Northern Baikal region. Geologia Rudnykh Mestorozhdenij (Geology of Ore Deposits), vol. 6, 34-49 (in Russian).

21            L.K. Levsky and L.A. Neymark. 1991, Isotopic constraints on a prototerrestrial matter. In: The Early Crust : its composition and age. Moscow, Nauka, p. 48-63 (in Russian).

22            Yu. Amelin, A. Beljaev, A. Larin, L. Neymark, I. Stepanov,  1991. Rapakivi granites and related rocks symposium, July 29-31, 1991, Helsinki, Finland; Salmi batholith and Pitkaranta ore field in Soviet Karelia excursion, August 1-4, 1991 Haapala, Ilmari; Ramo, O Tapani; Salonsaari, Pekka T; GCP, International Geological Correlation Programme Opas - Geologian Tutkimuskeskus, vol.33, 57 pp.

23            L.A. Neymark, A.M. Larin, G.V. Ovchinnikova, and S.Z. Yakovleva. 1992. U-Pb age of the Dzhugdzhur anorthosites. Transactions of the Russian Academy of Sciences. vol.323A, no.3, 57-62.

24            L.A. Neymark, A.M. Larin, S.Z.Yakovleva, B.M. Gorokhovsky. 1992. U-Pb age of igneous rocks of the Ulkan graben in the Southeastern part  of the Aldan Shield. Transactions of the Russian Academy of Sciences. v.324, no.4, 92-96.

25            L.A. Neymark, A.A. Nemchin, O.M. Rozen, V.P. Serenko, V.P. Spetsius, I.K. Shuleshko. 1992. Sm-Nd isotope systematics in the lower crust xenoliths from kimberlites of Yakutia. Transactions of the Russian Academy of Sciences. vol.327, no.3, 88-93.

26            L.A. Neymark, A.A. Nemchin, V.R. Vetrin, E.B. Sal'nikova. 1993. Sm-Nd and Pb-Pb isotope systematics in the lower crust xenoliths from the diatremas in the Southern Kola Peninsula. Transactions of the Russian Academy of Sciences. vol.329, no. 6, 781-784.

27            I.M. Gorokhov, M.S. Dufour, L.A. Neymark et al. 1993,  Early Paleozoic Gondwana fragments in the nappes of the Central Pamirs and Lesser Himalayas: geochemical and isotopic characteristics. Stratigraphy and Geologic Correlation. vol.1, no.3, 250-263.

28            G.V. Ovchinnikova, L.A. Neymark, O.A. Levchenkov et al. 1993. On the use of the apatite as an U-Pb geochronometer. Stratigraphy and Geological Correlation. vol.1, no.1, 9-19.

29            L.A. Neymark, E.Yu. Ritsk, N.G. Rizvanova. 1993. Hercynian age and Precambrian crustal protolith of the Barguzin granitoides of the Angar-Vitim batholith : U-Pb and Sm-Nd isotope evidence. Transactions of the Russian Academy of Sciences, vol.332, no.7, 201-206.

30            L.A. Neymark, V.P. Kovach, A.A. Nemchin et al. 1993. Late Archean intrusive complexes in the Olekma granite-greenstone terrain (Eastern Siberia): geochemical and isotopic study. Prec. Res. vol.62, no.2, 453-472.

31            L.A. Neymark, E.Yu. Ritsk, N.G. Rizvanova, B.M. Gorokhovsky. 1993.  U-Pb zircon age evidence for a polichronous Angaro-Vitim batholith. Transactions of the Russian Academy of Sciences. vol.333, no.5, 634-637.

32            V.A. Vernikovsky, L.A. Neymark, V.F. Proskurin, S.Z. Yakovleva. 1993. Late-Riphean age of the Kunar massif plagiogranites (U-Pb zircon dating). Transactions of the Russian Academy of Sciences. vol. 331, no. 6, 706-708.

33            L.A. Neymark, E.Yu. Ritsk, B.M. Gorokhovsky, Yu.V. Amelin, G.V. Ovchinnikova. 1993. Geochronological and isotope-geochemical study of the gold ore deposits in the Baikal fold area. In: Isotope Dating of Ore Deposits. Moscow, Nauka, p. 124-146 (in Russian).

34            L.A. Neymark, A.M. Larin, E.Yu. Ritsk, G.V. Ovchinnikova, B.M. Gorokhovsky. 1993. U-Pb geochronological and Pb-isotope evidence of the Hercynian ore-forming event within the Proterozoic frame of the South Siberian Platform. Transactions of the Russian Academy of Sciences. vol.333, no.6, 765-768.

35            V.A. Vernikovsky, A.E. Vernikovskaya, S.M. Lyapunov, L.A. Neimark, V.F. Proskurin, A.I. Chernykh, I.Yu. Safonova, 1994, Petrology, geochemistry, and tectonic setting of plagiogranites of the Chelyuskin ophiolite belt: International Geology Review, vol. 36, no. 10, 961-974.

36            L.A. Neymark, Yu.V. Amelin, A.M. Larin. 1994. Pb-Sr-Nd isotopic and geochemical constraints  on the origin of the 1.54-1.56 Ga Salmi rapakivi-granite --  anorthosite batholith (Karelia, Russia). Mineral. Petrol., vol. 50, no.1-3, 173-193.

37            S.A. Alekseenko, S.L. Ivlev, and L.A. Neimark, 1994, Standard reference sample of lead isotopic composition: Journal of Analytical Chemistry, vol. 49, no. 12, 1154-1158.

38            L.A. Neymark, B.D. Marshall, L.M. Kwak, K. Futa, and S.A. Mahan. 1995. Geochemical and Pb, Sr, and O isotopic study of the Tiva Canyon Tuff and Topopah Spring Tuff, Yucca Mountain, Nye County, Nevada. U.S. Geological Survey. Open-File Report 95-134, 23 p.

39            L.A. Neimark, E.Yu. Ritsk, G.V. Ovchinnikova et al.  1995. Lead isotopes in gold deposits of the Eastern Sayan (Russia). Geology of Ore Deposits. vol. 37, no. 3, 201-212.

40            E.V. Khain, L.A. Neymark, Y.V. Amelin, 1995,  Isotope-geochronological study of the granites and granite-gneisses of the Gargan Block, Eastern Sayan Range, Siberia, by Pb-Pb and U-Pb method on zircons and Sm-Nd method,  Doklady of the Russian Academy of Sciences, vol. 342, no. 5, 776-779 (in Russian).

41            L.A. Neimark, E.Y. Ritsk, B.M. Gorokhovsky, V.F. Guseva, S.Z. Yakovleva, 1995, Age of Muya granites, Baikal-Vitim ophiolite belt (U-Pb and Sm-Nd isotopic evidence), Doklady of the Russian Academy of Sciences, vol. 343, no. 5, 673-676 (in Russian).

42            V.A.Vernikovskii, L.A. Neimark, V.A. Ponomarchuk et al. 1995. Geochemistry and age of collision granitoides and metamorphites of the Kara microcontinent (Northern Taimyr). Russian Geology and Geophysics. vol. 36, no.4, 46-60.

43            L.A. Neymark, E.Yu. Ritsk, B.M. Gorokhovskiy. 1996. Pb isotope characteristics of some late Riphean Pb-Zn deposits in the folded environs of the Siberian platform. Transactions of the Russian Academy of Sciences. vol.342, no.4, p. 183-187.

44            Yu.V. Amelin, L.A. Neymark, E.Yu. Ritzk, A.A. Nemchin. 1996. Enriched Nd-Sr- Pb isotopic signatures in the Dovyren layered intrusion, Eastern Siberia: evidence for source contamination by ancient upper crustal material: Chemical Geology, vol.129, no. 4, 39-69.

45            L.A. Neimark, A.M. Larin, G.V. Ovchinnikova et al., 1996, U-Pb geochronologic and Pb-isotopic evidence for the Mesozoic mineralization stage of the Archean Stanovoi Megablock, Aldan-Stanovoi Shield. Petrology, vol. 4, no.4, 421-435.

46            V.A. Vernikovsky, L.A. Neymark, V.A. Ponomarchuk, and S.Z. Yakovleva, 1996, New U-Pb, Sm-Nd, Rb-Sr, and K-Ar ages for the North Taymyr collisional granites and metamorphites: Transactions of the Russian Academy of Sciences. vol. 345a, no.9, 329-334.

47            R.A. Kumpulainen, J. Mansfeld, K. Sundblad, L. Neymark, and T. Bergman, 1996, Stratigraphy, Age, and Sm-Nd Isotope Systematics of the country rocks to Zn-Pb Sulfide Deposits, Ammeberg District, Sweden: Economic Geology, vol. 91, 1009-1021.

48            Yu.V.Amelin, E.Yu.Ritsk, L.A.Neymark, 1997, Geochronological and Nd-Sr-Pb isotopic study of the relationships between mafic magmatites and ultramafic tectonites in the Chaya massif, Baikal-Muya ophiolite belt. Earth and Planetary Science Letters, vol. 148, 299-316. (Provided U-Pb isotope data and 30 % of interpretations and text writing).

49            J.B. Paces, Z.E. Peterman, L.A. Neymark, J.F. Whelan, and B.D. Marshall, 1997, Geochronologic and isotope studies of calcite and silica constraining Quaternary unsaturated- and saturated zone hydrologic flux at Yucca Mountain, Nevada, USA. SEDE Workshop: “Use of hydrogeochemical information in testing groundwater flow models”, Borgholm, 1-3 September, 1997.

50            A.M. Larin, Yu.V. Amelin, L.A. Neymark, R.Sh. Krimsky, 1997, The origin of the 1.73-1.70 Ga anorogenic Ulkan volcano-plutonic complex, Siberian platform, Russia: inferences from geochronological, geochemical and Nd-Sr-Pb isotopic data. Anais da Academia Brasileira de Ciencias, v. 69, no. 3, 295-312.

51            L.A. Neymark, A.M. Larin, A.A. Nemchin, G.V. Ovchinnikova, E.Yu. Ritsk, 1998, Anorogenic Nature of Magmatism in the Northern Baikal Volcanic Belt: Evidence from Geochemical, Geochronological (U-Pb), and Isotopic (Pb, Nd) Data, Petrology, vol. 6, no. 2, 124-148.

52            Yu.V. Amelin and L.A. Neymark. 1998, Lead isotope geochemistry of Paleoproterozoic layered intrusions in the eastern Baltic Shield: Inferences about magma sources and U-Th-Pb fractionation in the crust-mantle system. Geochim. Cosmochim. Acta., vol. 62, no. 3, 493-505.

53            J.B. Paces, L.A. Neymark, B.D. Marshall, J.F. Whelan, Z.E. Peterman, 1998, Inferences for Yucca Mountain Unsaturated Zone hydrology from Secondary minerals, 1998 International High-Level Radioactive Waste Management Conference, May 11-14, Las Vegas, Nevada, p. 36-39.

54            L.A. Neymark, Yu.V. Amelin, J.B. Paces, Z.E. Peterman, 1998, U-Pb Age Evidence for long-term stability of the unsaturated Zone,  Yucca Mountain, Nevada, 1998 International High-Level Radioactive Waste Management Conference, May 11-14, Las Vegas, Nevada, p. 85-87.

55            J.B. Paces, K.R. Ludwig, Z.E. Peterman, L.A. Neymark, 1998, Anomalous  Groundwater 234U/238U beneath Yucca Mountain: Evidence of Local Recharge? 1998 International High-Level Radioactive Waste Management Conference, May 11-14, Las Vegas, Nevada, p. 185-188.

56            B.D. Marshall, J.B. Paces, L.A. Neymark, J.F. Whelan, Z.E. Peterman, 1998, Secondary Minerals Record Past Percolation Flux at Yucca Mountain, Nevada, 1998 International High-Level Radioactive Waste Management Conference, May 11-14, Las Vegas, Nevada, p. 127-129.

57            E.Yu. Rytsk, L.A. Neimark, Yu.V. Amelin, 1998, Paleozoic granitoids in the Northern Part of the Baikal Orogenic Area: Age and Past Geodynamic Settings. Geotectonics, vol. 32, no. 5, 379-393.

58            L.A. Neymark, J.B. Paces, and Yu.V. Amelin, 1998, Neogene to Quaternary U-Th-Pb geochronology using opal, Yucca Mountain, Nevada, USA. Mineral. Mag., vol. 62A, 1077-1078.

59            R.M. Forester, J.P. Bradbury, C. Carter, A.B. Elvidge-Tuma, M.L. Hemphill, S.C. Lundstrom, S.A. Mahan, B.D. Marshall, L.A. Neymark, J.B. Paces, S.E. Sharpe, J.F. Whelan, and P.E. Wigand, 1999, The Climatic and Hydrologic History of Southern Nevada During the Late Quaternary. US Geological Survey, Open-File Report 98-635, 63 p.

60            J.B. Paces, Z.E. Peterman, L.A. Neymark, J.F. Whelan, and B.D. Marshall, 1999. Constraints on quaternary unsaturated- and saturated-zone hydrology from geochronological and isotopic studies of calcite and silica, Yucca Mountain, Nevada, USA. In:  Use of Hydrogeochemical Information in testing Groundwater Flow Models, Workshop on Use of Hydrogeochemical Information in Testing Groundwater Flow Models. SWEDISH NUCL FUEL & WASTE MANAGEMENT CO, BORGHOLM, SWEDEN, SEP 01-03, 1997.p. 329-336.

61            L.A. Neymark and  J. B. Paces, 2000, Consequences of slow growth for 230Th/U dating of Quaternary opals, Yucca Mountain, Nevada, USA, Chemical Geology, vol. 164, 143-160.

62            L.A. Neymark and Y.V. Amelin. 2000, Quaternary geochronology using combined U-Pb and U-series methods: the opal perspective. In: J.D. Woodhead, J.M. Hergt, W.P. Noble, Eds. Beyond 2000: New Frontiers in Isotope Geoscience, Lorne, Australia, 2000. Abstracts and Proceedings, p. 133-135.

63            L.A. Neymark, Y.V. Amelin, and J.B. Paces, 2000, 206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal,  Yucca Mountain, Nevada, Geochim. Cosmochim. Acta, vol. 64, no. 17, 2913-2928.

64            Y.V. Amelin, E.Y. Rytsk, R.S. Krymskii, L.A. Neimark, and S.G. Skublov, 2000, Vendian age of granulite-enderbite complex, Baikal-Muya ophiolite belt (North Prebaikal'e): U-Pb and Sm-Nd isotopic evidences, Doklady Akademii Nauk, vol. 371, no. 5, 652-654.

65            L.A. Neymark, J.B. Paces, B.D. Marshall, Z.E. Peterman, and J.F. Whelan, 2000, 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. GSA Field Guide, vol.2, p. 401-402.

66            P.D. Kempton, H. Downes, L.A. Neymark, J.A. Wartho, E.V. Sharkov, and R.E. Zartman, 2001, Garnet granulite xenoliths from the northern Baltic Shield – The lower crust of a Paleoproterozoic LIP? Journal of Petrology, vol. 47, no. 4, 731-763.

67            L.A. Neymark, Y.V. Amelin, J.B. Paces, J.F. Whelan, Z.E. Peterman, 2001. Age constraints on fluid inclusions in calcite at Yucca Mountain. International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American Nuclear Society, CD ROM, unpaginated.

68            J.B. Paces, L.A. Neymark, B.D. Marshall, J.F. Whelan, and Z.E. Peterman, 2001. Ages and origins of calcite and opal in the Exploratory Studies Facility tunnel, Yucca Mountain, Nevada. US Geological Survey Water-Resources Investigations Report 01-4049, 95 p.

69            L.A. Neymark, Y.V. Amelin, J.B. Paces, Z.E. Peterman, 2002. U-Pb ages of secondary silica at Yucca Mountain, Nevada: implications for the paleohydrology of the unsaturated zone. Applied Geochemistry, vol. 17, 709-734.

70            J.B. Paces, K.R. Ludwig, Z.E. Peterman, L.A. Neymark, 2002. 234U/238U evidence for local recharge and patterns of groundwater flow in the vicinity of Yucca Mountain, Nevada, USA. Applied Geochemistry, vol. 17, 751-779.

71            M. Gascoyne, N.H. Miller, and L.A. Neymark, 2002. Uranium-series disequilibrium in tuffs from Yucca Mountain, Nevada, as evidence of pore-fluid flow over the last million years. Applied Geochemistry, vol. 17, 781-792.

72            B.D. Marshall, L.A. Neymark, and Z.E. Peterman. 2003. Estimation of past seepage volumes from calcite distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada. J. Contam. Hydrol., vol. 62-63, 237-247.

73            L.A. Neymark, J.B. Paces, and Y.V. Amelin, 2003. Reliability of U-Th-Pb Dating of Secondary Silica at Yucca Mountain, Nevada.  International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American Nuclear Society, CD ROM, p. 1-12.

74            J.B. Paces, and L.A. Neymark, 2003. U-series disequilibrium as a test for UZ Hydrologic Models at Yucca Mountain, Nevada. Proceedings of 10th International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American nuclear Society, La Grange Park, p. 27-38.

75            J.F. Whelan, L.A. Neymark, E. Roedder, and R.J. Moscati, 2003. Thermochronology of secondary minerals from the Yucca Mountain unsaturated zone. Proceedings of 10th International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American Nuclear Society, La Grange Park, p. 357-366.

76            Z.E. Peterman, J.B. Paces, L.A. Neymark, and D. Hudson, 2003. Geochemistry of dust in the Exploratory Studies Facility, Yucca Mountain, Nevada. Proceedings of 10th International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American nuclear Society, La Grange Park, p. 637-645.

77            J.B. Paces, Z.E. Peterman, L.A. Neymark, G.J. Nimz, M. Gascoyne, and B.D. Marshall, 2003. Summary of Chlorine-36 Validation Studies at Yucca Mountain, Nevada. Proceedings of 10th International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American nuclear Society, La Grange Park, p. 348-356.

78            J.B. Paces, L.A. Neymark, H.M. Persing, and J.L Wooden. 2004. Improved spatial resolution for U-series dating of opal at Yucca Mountain, Nevada, USA, using ion-microprobe and microdigestion methods. Geochim. et Cosmochim. Acta, vol. 681591-1606.

79            J.F. Whelan, J.B. Paces, Z.E. Peterman, B.D. Marshall, and L.A. Neymark, 2004. 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. Applied Geochemistry, vol. 19, 1879–1889.

80            J.B. Paces and L.A. Neymark. 2004, U-Series isotopes as indicators of water/rock interaction in the unsaturated zone at Yucca Mountain, Nevada, USA. Proceedings of the Eleventh International Symposium on Water-Rock Interaction, NY, June 27 – July 2, 2004, Saratoga Springs, Wanty R.B., and Seal II, R.R., eds. Balkema Publishers, Leiden, p. 475-479.

81            B.D. Marshall, L.A. Neymark, and Z.E. Peterman. 2005. 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. Journal of Contaminant Hydrology, vol. 7, 219– 224.

82            L.A. Neymark, J.B.Paces, B.D. Marshall, Z.E. Peterman and J.F. Whelan. 2005. Geochemical and C, O, Sr, and U-series isotopic evidence for the meteoric origin of calcrete at Solitario Wash, Crater Flat, Nevada, USA. Environmental Geology, vol. 48, 450–465.

83            A.A. Nemchin, L.A. Neymark, S.L. Simons. 2006. U–Pb SHRIMP dating of uraniferous opals. Chemical Geology. vol. 227, 113–132.

84            L.A. Neymark, J.B. Paces, S.J. Chipera,  and D.T. Vaniman. 2006. Uranium-series constraints on subrepository water flow at Yucca Mountain. International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American Nuclear Society. p. 82-88.

85            J.B. Paces, L.A. Neymark, T. Ghezzehei, and P.F. Dobson. 2006. Testing the Concept of Drift Shadow at Yucca Mountain, Nevada. International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American Nuclear Society, p. 278-285.

86            J.F. Whelan, J.B. Paces, L.A. Neymark, A.K. Schmitt, and M. Grove. 2006. Impact of Quaternary Climate on Seepage at Yucca Mountain, Nevada. International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American Nuclear Society, p. 199-206.

87            L.A. Neymark and Y. Amelin. 2008. Natural radionuclide mobility and its influence on the U-Th-Pb dating of secondary minerals from the unsaturated zone, Yucca Mountain, Nevada. Geochim. et Cosmochim. Acta, vol. 72, 2067-2089.

88            J.F. Whelan, L.A. Neymark, R.J. Moscati, B.D. Marshall, and E. Roedder. 2008. Thermal history of the unsaturated zone at Yucca Mountain, Nevada, USA. Applied Geochemistry vol. 23, p. 1041-1075.

89            L.A. Neymark, L.K. Kwak, and Z.E. Peterman. 2008. Lead isotopes and trace metals in dust at Yucca Mountain. International High-Level Radioactive Waste Management Conference, Las Vegas, Nevada, American Nuclear Society, p. 95-100.

90            Amelin, Y., J. Connelly, R.E. Zartman, J.H. Chen, C. Göpel, and L.A. Neymark. 2009. Modern U-Pb chronometry of meteorites: advancing to higher time resolution reveals new problems. Geochim. et Cosmochim. Acta, vol. 73, p. 5212-5223.

91             Paces J.B., L.A. Neymark, J.F. Whelan, J.L. Wooden, S.P. Lund, and B.D. Marshall. 2010. Limited hydrologic response to Pleistocene climate change in deep vadose zones — Yucca Mountain, Nevada. Earth and Planetary Science Letters, vol. 300, p. 287–298.

92             Neymark, L.A. 2011. Potential effects of alpha-recoil on uranium-series dating of calcrete. Chemical Geology, vol. 282, p. 98–112.

93            Koenig, A. E., S.G. Lucas, L.A. Neymark, A.B. Heckert, R.M. Sullivan, S.E. Jasinski, and D.W. Fowler. 2012. Direct U-Pb dating of Cretaceous and Paleocene dinosaur bones, San Juan Basin, New Mexico: COMMENT.  Geology , vol. 40, e262. doi:10.1130/G32154C.1

94           Simmons, A.M. and L.A. Neymark, 2012. Conditions and processes affecting radionuclide transport. In: Stuckless, J.S. (Ed.), Hydrology and Geochemistry of Yucca Mountain and Vicinity, Southern Nevada and California.  Geol. Soc. Amer. Memoir 209, 277–362. 

95          Neymark, L.A. and J.B. Paces, 2013. Ion-probe U-Pb dating of authigenic and detrital opal from Neogene-Quaternary alluvium.  Earth and Planetary Science Letters, vol. 361, p. 98-109.

96         Neymark, L.A., Peterman, Z.E., Moscati, R.J., and Thivierge, R.H., 2013. U–Pb, Rb–Sr, and U-series isotope geochemistry of rocks and fracture 4 minerals from the Chalk River Laboratories site, Grenville Province, Ontario, Canada. Applied Geochemistry, 36, 10-33.