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Robert Roback


Contact

  • Los Alamos National Laboratory
  • Chemistry Division
  • Isotope and Nuclear Chemistry (C-INC), MS J514
  • Los Alamos, NM 87545
  • (505) 667-8916 Office
  • roback at lanl.gov

Field-Scale in situ Measurements of Vadose Zone Transport Using Multiple Tracers at INEEL Vadose Zone Research Park (download ppt. presentation)



Research Interests

  • Application of geochemistry and, in particular, isotope geochemistry to diverse geologic and environmental problems
  • Studies of groundwater flow and transport in saturated and unsaturated settings
  • Application of geochemistry and hydrology to address contaminant transport
  • Tectonics of the western Cordillera


Education


  • Ph.D. Geological Sciences: May 1993, University of Texas at Austin
  • B.A. Geological Sciences: 1981, University of California, Santa Barbara

Recent Employment History


Technical Staff Member - Los Alamos National Laboratory, 5/99 - present.   Geologic, geochemical, and hydrologic studies of groundwater flow and contaminant transport with emphasis on behavior of natural tracers and actinides in the environment.   Typically supervise or co-supervise 1-3 technicians and/or students who assist in this work.



Projects


  • Principal Investigator: Tracer studies to evaluate vadose and saturated zone flow and transport at the Vadose Zone Research Park, INEEL
  • Principal Investigator: Isotopic and geochemical investigations of groundwater flow, contaminant transport in the saturated and unsaturated zones at the INEEL
  • Principal Investigator: Chloride and Chlorine-36 studies of saturated and unsaturated flow at Yucca Mountain
  • Co-Principal Investigator (with Paul Reimus):   Alluvial Testing Complex (ATC), tracer tests to study flow and transport in saturated valley-fill deposits at Yucca Mountain
  • Co-Author (with Edward Kwicklis):   Yucca Mountain Analysis and Models Report on Hydrochemistry of Staurated Zone, Yucca Mountain and Vicinity
  • Investigator: Rapid separations of actinides from geologic media (DTRA-DNEA project

Postdoctoral Research Associate - Los Alamos National Laboratory, Chemical Science and Technology, 1/97 - 5/99.   Laboratory and field study utilizing uranium-series isotopes to characterize groundwater movement and migration of solutes in the Snake River Plain aquifer.

Project Editor - Holt, Rinehart and Winston, Austin TX, 7/96-8/96.   Author, coeditor and co-producer of one-hour video disc to accompany new edition of 10 th -grade-level textbook in earth sciences (Modern Earth Sciences).   Includes full-motion video, still images (approximately 1800), and animation in eight units: five in geology, and one each in oceanography, meteorology and astronomy.

Postdoctoral Fellow - Dept. of Geological Sciences, University of Texas at Austin, 9/93 to 12/96.

Projects include (1) an integrated field, petrologic, geochronologic and isotopic study to evaluate the tectonic evolution of Mesoproterozoic rocks of the Llano uplift, central Texas.   Included the informal supervision of one M.A. student and one senior-level honors research project, and (2) Sm-Nd and Pb isotopic characterization of Paleoproterozoic rocks of the Shackleton Range, Antarctica.

Instructor - Dept. of Geological Sciences, University of Texas at Austin, summers of 1993 to 1996.

Senior-level summer field geology course.   Course involved geologic mapping of diverse lithologies in Montana, Colorado, Arizona and New Mexico, construction of stratigraphic columns and cross-sections, stereonet interpretations and report writing.   Included project development and staff supervision.



Publications


Refereed Journals


Roback, R.C ., Johnson, T.M, McLing, T.L., Murrell, M.T., Luo, Shangde and Ku, Teh-Lung, 2001, Uranium Isotopic Evidence for Groundwater Chemical Evolution and Flow Patterns in the Eastern Snake River Plain Aquifer, Idaho: Geological Society of America Bulletin, v. 113, no. 9, p.1133-1141.

Johnson, T.M, Roback, R.C ., McLing, T.L., Bullen, T.D., DePoalo, D.J, Doughty, C., Hunt, R. J., Smith, R.W., Cecil L.D., and Murrell, M.T., 2000, Groundwater "Fast Paths" in the Snake River Plain Aquifer: Radiogenic isotope ratios as natural groundwater tracers: Geology, v. 28, no. 10, p. 871-874.

Luo Shangde, Ku, Teh-Lung, Roback, R ., Murrell, M. and McLing, T.L., 2000, Decay-Series Disequilibrium study of in-situ, long-term radionuclide transport in water-rock systems: Materials Research Society Symposium Proceedings, v. 608, p.217-224.

Luo Shangde, Ku, Teh-Lung, Roback, R ., Murrell, M. and McLing, T.L., 2000, In-situ radionuclide transport and preferential groundwater flows at INEEL (Idaho): Decay-series disequilibrium Studies: Geochemica et Cosmochemica Acta, v. 63, no. 3, p. 867-881.

Reese J.F., Mosher, S., Connelly, J., and Roback, R.C. , 2000, Mesoproterozoic chronostratigraphy of the southeastern part of the Llano Uplift, central Texas: Geological Society of America Bulletin, v. 112, no. 2, p 278-291.

Roback, R.C., Hunt, B.B., Helper, M.A., 1999, Mesoproterozoic tectonic evolution of the western Llano uplift, central Texas: The story in an outcrop: Rocky Mountain Geology, v. 34, no. 2, p. 275-287.

Smith, Diane R., Barnes, Calvin B., Shannon, William, Roback, Robert , and James, Eric, 1997, Petrogenesis of Mid-Proterozoic granitic magmas: examples from central and west Texas: Precambrian Research, v. 85, p. 53-79.

Roback, R.C., 1996, Characterization and tectonic evolution of a Mesoproterozoic island arc in the southern Grenville Orogen, Llano uplift, central Texas: Tectonophysics v. 265, p. 29-52.

Roback, R.C. , and Walker, N.W., 1995, Provenance, detrital zircon U-Pb geochronometry, and tectonic significance of Permian to Early Triassic sandstone in southeastern Quesnellia, British Columbia and Washington: Geological Society of America Bulletin, v. 107, no. 6, p. 676-696.

Roback, R.C. , Sevigny, J.H., and Walker, N.W., 1994, Tectonic setting of the Slide Mountain terrane, southern British Columbia: Tectonics, v. 13, p. 1242-1258.


Field Guides


Roback, R.C. , 1996, The Coal Creek Domain: in Mosher, S., ed. Guide to the Precambrian geology of the eastern Llano uplift: Geological Society of America, south-central section annual meeting field-trip guidebook, University of Texas at Austin.

Roback, R.C. , Schiarizza, P., Nelson, J., Fyles J., Ferri, F., Höy, T., and Ash C. and W.R. Danner, 1995, Late Paleozoic arc and oceanic terranes and their external relationships, southern Quesnellia: B2: Field Trip Guidebook: Geological Association of Canada/Mineral Association of Canada, annual general meeting, Victoria, B.C., Canada.

Roback, R.C. , 1995, The Coal Creek Domain: in Mosher, S., ed. Guide to the Precambrian geology of the eastern Llano uplift: Field trip guide for the 12th international basement conference, Norman Oklahoma: Department of Geological Sciences, University of Texas at Austin.


Government Publications and Reports


Roback, R. C. , 2002, Initial Report for the Aquifer Background Study:   Summary of Uranium and Plutonium Data from INEEL Groundwater Samples, Los Alamos National Laboratory Unlimited Release, LA-UR-02-3705, 10 p.

Roback, R.C ., Efurd, D.W., Murrell, M.T., Steiner, R.E., and Duffy, C.J., 2000, Assessment of uranium and plutonium in the saturated and unsaturated zones beneath the Surface Disposal Area, INEEL: Los Alamos National Laboratory Unlimited Release, LA-UR-00-5471, 37 p.

Nokleberg, W.J., Lange, I.M., Roback, R.C. , Yeend, W., and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes Quadrangle, eastern Alaska Range, Alaska: U. S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., scale: 1:250,000.

Roback, R.C. , 1989, Lithology, Stratigraphy and Geochronology of late Paleozoic and Mesozoic rocks in a part of Stevens County, Washington: State of Washington, Department of Natural Resources Report, 17p.

Ashley, R. P., Roback, R.C. , Turner, R.L., Jachens, R.C., Close, T.J., and Rains, R.L., 1988, Mineral Resources of the Sheep Mountain Wilderness Study Area, Baker County, Oregon: U.S. Geological Survey Bulletin 1741, 14p.

Roback, R.C. , Vander Muelen, D.B., King, H.D., Plouff D., Munts, S.R., and Willet, S.L., 1987, Mineral resource potential of the Pueblo Mountains Wilderness Study Area, Harney County, Oregon and Humboldt County, Nevada: U. S. Geological Survey Bulletin 1740-B, 30p.

Roback, R.C. , 1986, Geochemical analysis of rock samples from the Pueblo Mountains Wilderness Study Area, Harney County, Oregon and Humboldt County, Nevada: U.S. Geological Survey Open-File Report 86-368, 11p.

Nokleberg, W.J., Lange, I.M., and Roback, R.C. , 1984, Preliminary accretionary terrane model for metallogenesis of the Wrangellia terrane, southern Mount Hayes Quadrangle, eastern Alaska Range, Alaska, in Reed K. M., and Bartsh-Winkler, Susan, eds.: The U.S. Geological Survey in Alaska: Accomplishments During 1982: U. S. Geological Survey Circular 939, p. 60-65.


Abstracts in the Last 12 Years


Roback, R.C , Jones, C.L, Fabryka-Martin, J., Roseborrough, K., Wolfsberg, L., and Dixon P., 2002 Effects of Sample Processing on 36Cl/Cl Ratios in Unsaturated Crystalline Rocks at Yucca Mountain: Implications for Unsaturated Zone Flow, Geological Society of America, Abstracts with Programs, v. 34, No. 6.

Robert R.C. , 2001, Uranium and Plutonium in the Saturated and Unsaturated Zones Beneath the Surface Disposal Area, INEEL: Implications for Actinide Transport, Eighth Biannual Unsaturated Zone Interest Group Meeting, Idaho Falls, ID, July 2001

Murrell, Michael T., Paviet-Hartmann, S.J. Goldstein, A. J. Nunn , R.C. Roback , P.A. Dixon, A. Simmons, 1999, U-Series Natural Analog Studies at Pena Blanca, Mexico: How Mobile is Uranium? American Geophysical Union, American Geophysical Union, v. 80, no. 46, p. F 1205.

Mosher, S., Connelly, J. N., Zumbro, J, Roback, R. C., and Reese, J., F., 1999, Evidence for an active southern Laurentian margin from 1288 - 1232 Ma - Llano Uplift, central Texas: Geological Society of America, Abstracts with Programs, v. 31, no. 7, p. A-108.

Roback, Robert C ., Michael Murrell, Andy Nunn, Shangde Luo, Richard Ku and Travis McLing, 1998, Uranium and Thorium-Series Isotopes in Fresh Groundwater at the INEEL: American Geophysical Union, v. 79, no. 45, p. F 343.

Shangde Luo, T. L. Ku, R. Roback , M. Murrell, and T. McLing, 1998, Assessing In-Situ Radionuclide Transport Based on Uranium-Series Disequilibria in Groundwater: American Geophysical Union, v. 79, no. 45, p. F 354.

K. M. Cooper, M. R. Reid, R. C. Roback, M. T. Murrell, D. A. Clague, 1998, 226 Ra - 230 Th radioactive disequilibrium in mineral separates from an ultramafic xenolith in the 1800 Kaupulehu flow, Hualalai Volcano, Hawaii: American Geophysical Union, v. 79, no. 45, p. F 940.

Luo, S., Ku, T.-L., Roback, R ., Murrell, M., McLing, T., 1998, Uranium-series disequilibrium in groundwater: Assessing radio-nuclide migration:   International Conference on Isotope Geology, Cosmochemistry and Geochronology, Beijing.

 

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