Dr. Nelson's research interests include Volcanology, Igneous Petrology, Mexican Volcanic Belt, Geological Hazards and Thermodynamics

Select Publications

Nelson, S.A., Myths of Katrina: Field Notes from a Geoscientist. The Minnesota Review, 2015(84): p 60-68, 2015.

Nelson, S.A. and Leclair, S.F., Katrina’s unique splay deposits in a New Orleans neighborhood. GSA Today, 16:4-9, 2006.

Nelson, S.A. E. Gonzalez-Caver and T.K. Kyser. Constrains on the origin of alkaline and calc-alkaline magmas from the Tuxtla volcanic field, Veracruz, Mexico. Contr. Mineral. Petrol. 122:191-211. 1995.

Nelson, S.A. and E. Gonzalez-Caver. Geology and K-Ar dating of the Tuxtla volcanic field, Veracruz, Mexico. Bull. Volcanology. 55:85-96, 1992.

Verma, S.P., and Nelson, S.A.. Isotopic and trace-element constraints on the origin and evolution of calc-alkaline and alkaline magmas in the northwestern portion of the Mexican Volcanic Belt. J. Geophys. Res. 94:4531-44, 1989.

Grand Canyon

• Grand Canyon Colloquium 2017 Photos & Videos
• Grand Canyon Colloquium 2016 Photos & Videos
• Grand Canyon Colloquium 2015 Photos & Videos
• Grand Canyon Colloquium 2014 Photos & Videos
• Grand Canyon Colloquium 2013 Videos
• Grand Canyon Colloquium 2013 Photos
• Grand Canyon Colloquium 2012 Videos
• Grand Canyon Colloquium 2012 Photos
• Grand Canyon Colloquium 2011 Photos
• Grand Canyon Colloquium 2010 Photos
• Grand Canyon Colloquium 2009 Photos

Dr. Whitten's research interests include Planetary Science, Volcanism, Impact Cratering, Geomorphology, and Radar

More detailed descriptions of this work can be found at Dr. Whitten's research page

Recent Publications

Whitten, J.L., Campbell, B.A. (2018) Lateral continuity of layering in the Mars South Polar Layered Deposits from SHARAD sounding data, J. Geophys. Res., in press, doi:10.1029/2018JE005578.

Campbell, B., Weitz, C., Morgan, G., Whitten, J.L. (2018) Evidence for Impact Melt Sheets in Lunar Highland Smooth Plains and Implications for Polar Landing Sites, Icarus, in press, doi:10.1016/j.icarus.2018.05.025.

Whitten, J.L., Campbell, B.A., Morgan, G.A. (2017) A subsurface depocenter in the South Polar Layered Deposits of Mars, Geophysical Research Letters 44, doi:10.1002/2017GL074069.

Campbell, B.A., Schroeder, D.M., Whitten, J.L. (2017) Mars radar clutter and surface roughness characteristics from MARSIS data, and inferences regarding Europa Sounder Flybys, Icarus 299, 22-30, doi:10.1016/j.icarus.2017.07.011.

Suer, T.-A., Padovan, S., Whitten, J.L., Potter, R.W., Shkolyar, S., Cable, M., Walker, C.C., Szalay, J., Parker, C., Cumbers, J., Gentry, D., Harrison, T., Naidu, S., Trammel, H., Reimuller, J., Budney, C., Lowes, L.L. (2017) FIRE – Flyby of Io with Repeat Encounters: A conceptual design for a New Frontiers mission to Io, Advances in Space Research 60, 10801100, doi:10.1016/j.asr.2017.05.019.

Campbell, B.A., Morgan, G.A., Whitten, J.L., Carter, L.M., Glaze, L.S., Campbell, D.B. (2017) Pyroclastic flow deposits on Venus as indicators of renewed plume activity, J. Geophys. Res. 122, doi:10.1002/2017JE005299.

Whitten, J.L., Campbell, B.A. (2016) Recent volcanic resurfacing of Venusian craters, Geology G3768-1, doi:10.1130/G37681.1. Cover Image, Geology July 2016.

Dr. Törnqvist's research interests include Quaternary geology, Sea-level change, Coastal sustainability, Fluvial and deltaic sedimentology, Sequence stratigraphy, Applied geochronology and Paleoclimatology

Research Directions

Holocene ice sheet‒sea level connections.
The sedimentary record of the Mississippi Delta offers unique opportunities to investigate Holocene relative sea-level (RSL) change at very high resolution, and to develop connections with paleoclimate records. Our past efforts have focused, among others, on an abrupt sea-level rise associated with the 8.2 ka cooling event that was likely caused by the final drainage of proglacial Lake Agassiz. More recent work has pushed this record back beyond 10 ka, providing one of the first high-resolution RSL curves for the early Holocene. Combined with glacial isostatic adjustment (GIA) modeling, this sheds light on the relative contribution of the North American and Antarctic ice sheets to global sea-level rise during the second half of the last deglaciation.

Mechanisms and rates of subsidence in low-elevation coastal zones.
Subsidence in rapidly urbanizing, low-lying coastal environments is evolving into a “slow-motion catastrophe.” Our primary focus is on coastal Louisiana and involves the collection and analysis of field data (both geological and instrumental) that is combined with various modeling approaches (GIA models, compaction models) which involves several collaborators. Our Holocene RSL records are a cornerstone of this work, more recently augmented by surface-elevation table – marker horizon data available from the unparalleled Coastwide Reference Monitoring System. A recent addition is the “subsidence superstation” near Myrtle Grove, Louisiana, where a wide range of instrumental and geological methods are integrated to gain a more fundamental understanding about subsidence mechanisms and rates over a range of depth and timescales.

Holocene delta evolution.
There is a resurgence of interest in delta evolution over timescales longer than the instrumental record, motivated by the increasing challenge to successfully manage deltas throughout this century and beyond. Our research involves a variety of projects concerned with rates of delta growth (both vertically and horizontally) as well as patterns of sediment dispersal in the Mississippi Delta. This work relies heavily on geochronology as provided by 14C dating (including novel methods such as ramped PyrOx 14C) and optically stimulated luminescence dating. Much of this research is closely tied to questions that emanate from coastal restoration efforts, such as deciphering the patterns and rates of fluviodeltaic deposition that can serve as analogs for coastal restoration projects by means of river diversions.

Coastal wetland sustainability.
The wetland loss problem in coastal Louisiana is widely documented and there is an enormous interest in the future fate of these highly valuable ecosystems. Our research attempts to determine, among others, which rates of RSL rise coastal wetlands can withstand. Our work has shown that marsh collapse in this area occurs at rates of RSL rise of 3-7 mm/yr, not unlike recent findings for coastal ecosystems worldwide. Many intriguing questions remain, including the need for a better understanding of the conditions that cause marsh drowning and subsequent re-emergence (including possible hysteresis effects), both in coastal Louisiana and elsewhere.

Carbon in the coastal zone.
Coastal plains are increasingly recognized as important repositories of organic carbon, commonly referred to as “blue carbon.” However, the rates and mechanisms of carbon burial are inadequately understood, contributing to uncertainties around the terrestrial sink in global carbon models. Our work examines both modern carbon accumulation rates as well as the ultimate burial of carbon in the stratigraphic record, and relies on a combination of instrumental records, sediment core analysis, and geochronology in a variety of deltaic, coastal, and marine environments.

For more information, please visit the website of the Quaternary Research Group.

Selected Recent Publications

Saintilan, N., Horton, B., Törnqvist, T.E., Ashe, E.L., Khan, N.S., Schuerch, M., Perry, C., Kopp, R.E., Garner, G.G., Murray, N., Rogers, K., Albert, S., Kelleway, J., Shaw, T.A., Woodroffe, C.D., Lovelock, C.E., Goddard, M.M., Hutley, L.B., Kovalenko, K., Feher, L. and Guntenspergen, G., 2023. Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C. Nature 621, 112-119.

Nienhuis, J.H., Kim, W., Milne, G., Quock, M., Slangen, A.B.A. and Törnqvist, T.E., 2023. River deltas and sea-level rise. Annual Review of Earth and Planetary Sciences, 51: 79-104.

Dangendorf, S., Hendricks, N., Sun, Q., Klinck, J., Ezer, T., Frederikse, T., Calafat, F.M., Wahl, T. and Törnqvist, T.E., 2023. Acceleration of U.S. Southeast and Gulf coast sea-level rise amplified by internal climate variability. Nature Communications, 14: 1935.

Törnqvist, T.E., Cahoon, D.R., Morris, J.T. and Day, J.W., 2021. Coastal wetland resilience, accelerated sea-level rise, and the importance of timescale. AGU Advances, 2: e2020AV000334.

Shirzaei, M., Freymueller, J., Törnqvist, T.E., Galloway, D.L., Dura, T. and Minderhoud, P.S.J., 2021. Measuring, modelling and projecting coastal land subsidence. Nature Reviews Earth & Environment, 2: 40-58.

Törnqvist, T.E., Jankowski, K.L., Li, Y.-X. and González, J.L., 2020. Tipping points of Mississippi Delta marshes due to accelerated sea-level rise. Science Advances, 6: eaaz5512.

Nienhuis, J.H., Ashton, A.D., Edmonds, D.A., Hoitink, A.J.F., Kettner, A.J., Rowland, J.C. and Törnqvist, T.E., 2020. Global-scale human impact on delta morphology has led to net land area gain. Nature, 577: 514-518.

You can find these as well as my other papers at ResearchGate.

Dr. Straub's research interests include Experimental Sedimentology, Quantitative Stratigraphy, Submarine Morphodynamics and Seismic Geomorphology

More detailed descriptions of this work can be found at the website of the TSDS Group.

Recent Publications

Griffin, C., Duller, R.A, Straub, K.M., 2023, The degradation and detection of environmental signals in sediment transport systems, Science Advances, v. 9, eadi8046, DOI: 10.1126/sciadv.adi8046.

Zapp, S., Silvestre, J.R., Sanks, K.M., Shaw, J.B., Dutt, R., Straub, K.M., 2023, Exploring sediment compaction in experimental deltas: Towards a meso-scale understanding of coastal subsidence patterns, Journal of Geophysical Research – Earth Surface, DOI: 10.1029/2023JF007238.

Sanks, K.M., Shaw, J.B., Zapp, S.M., Silvestre, J.R., Dutt, R., Straub, K.M., 2023, Marsh-induced backwater: the influence of non-fluvial sedimentation on a delta’s channel morphology and kinematics, v. 11, p. 1035-1060 Earth Surface Dynamics, DOI: 10.5194/esurf-11-1035-2023.

Straub, K.M., Dutt, R., Duller, R.A., 2023, Coupled channel-floodplain dynamics and resulting stratigraphic architecture viewed through a mass-balance lens, Journal of Sedimentary Research, v. 93, p. 595-616, DOI: 10.2110/jsr.2022.112.

Barefoot, E.A., Nittrouer, J.A., Straub, K.M., 2023, Sedimentary processes and the temporal resolution of sedimentary strata, Geophysical Research Letters, 50, e2023GL103925, DOI: 10.1029/2023GL103925.

Wahab, A., Hoyal, D.C., Shringarpure, M., Straub, K.M., 2022, A dimensionless framework for predicting submarine fan morphology, Nature Communications, v. 13, DOI: 10.1038/s41467-022-34455-7.

Sanks, K.M., Zapp, S.M., Silvestre, J.R., Dutt, R., Shaw, J.B., Straub, K.M., 2022, Experimental investigation of the influence of marsh sedimentation on morphology and mass balance of river deltas, Geophysical Research Letters, 49, e2022GL098513, DOI: 10.1029/2022GL098513.

Toby, S.C., Duller, R.A., De Angelis, S., Straub, K.M., 2022, Morphodynamic limits to environmental signal propagation across landscapes and into strata, Nature Communications, v. 13, DOI: 10.1038/s41467-021-27776-6.

Barefoot, E.A., Nittrouer, J.A., Straub, K.M., 2021, Non-monotonic floodplain responses to changes in flooding intensity, Journal of Geophysical Research – Earth Surface, 126, e2021JF006310, DOI: 10.1029/2021JF006310.

Professional Service

Co-Editor-in-Chief, Chemical Geology, 2016 - present
Associate Editor, American Mineralogist, 2014 - present
Associate Editor, Geochimica et Cosmochimica Acta, 2006 - present

Awards

Clair C. Patterson Medal of the Geochemical Society, 2015
Fellow, Geochemical Society, 2015
Fellow, European Association of Geochemistry, 2015
Fellow, International Association of GeoChemistry, 2014
Fellow, Geological Society of America, 2010

Dr. Johannesson's research interests include low-temperature aqueous geochemistry and biogeochemistry, emphasizing trace element speciation, chemical hydrogeology, and biogeochemical cycling of trace elements (e.g., arsenic, selenium, and REEs) in the environment.

Current Funded Research

EAR-1714030: Quantifying thioarsenate formation constants to advance understanding of arsenic biogeochemical cycling in anoxic waters. Project Location: Tulane University. National Science Foundation, Geobiology and Low-Temperature Geochemistry Program.

PRF #56237-ND2. Tungsten in Petroleum Systems: A Potential Paleo-Environment Indicator. Project Location: Tulane University Chemical Society, The Petroleum Research Fund.

EAR-1141692:  Collaborative Research:  Are buried paleochannels effective reactors for water and solute transport in the deltaic subterranean estuary?  Project location:  Tulane University.  National Science Foundation.

Select Publications

Telfeyan, K., Breaux, A., Kim, J., Cable, J.E., Kolker, A.S., Grimm, D.A., and Johanesson, K.H., 2017. Arsenic, vanadium, iron, and manganese biochemistry in a deltaic wetland, southern Louisiana, USA. Marine Chemistry 192, 32-48

Cui, M. and Johannesson, K.H., 2017. Comparison of tungstate and tetrathiotungstate adsorption onto pyrite. Chemical Geology 464, 57-68

Marsac, R., Banik, N.L., Lutzenkirchen, J., Catrouillet, C., Marquardt, C.M., and Johanesson, K.H., 2017. Modeling metal ion-humic substances complexation in highly saline conditions. Applied Geochemistry 79, 52-64

Prouty, N.G., Swarzenski, P.W., Frackell, J.K., Johannesson, K., and Palmore, D., 2017. Groundwater-derived nutrient and trace element transport to a nearshore Kona coral ecosystem: Experimental mixing model results. Journal of Hydrology: Regional Studies 11, 166-177.

Coleman, D.J., Kolker, A.S., and Johanesson, K.H., 2017. Submarine groundwater discharge and alkaline earth element dynamics in a deltaic coastal setting. Hydrology Research 48.5, 1169-1176.

Vega, M.A., Kulkarni, H.V., Mladenov, N., Johannesson, K., Hettiarachchi, G.M., Bhattacharya, P., Kumar, N., Weeks, J., Galkaduwa, M., and Datta S., 2017. Biogeochemical controals on the release and accumulation of Mn and As in shallow aquifers, West Bengal, India. Frontiers in Environmental Science, 5:20. doi:10.3389/fenvs.2017.00029.

Johannesson, K. H., Palmore, C.D., Frackell, J., Prouty, N.G., Swarzenski, P.W., Chevis, D. A., Telfeyan, K., White, C. D., and Burdige, D.J., 2017. Rare earth element behavior during groundwater - seawater mixing along the Kona Coast of Hawaii. Geochimica et Cosmochimica Acta 198, 229-258.

Blake, J. M., Peters, S.C., and Johannesson, K., 2017. Application of REE geochemical signatures for Mesozoic sediment provenance to the Gettysburg Basin, Pennsylvannia. Sedimentary Geology 349, 103-111.

Datta, S., Vero, S. E., Hettiarchchi, G. M., and Johannesson, K. H., 2017. Tungsten contamination of soils and sediments: Current state of science. Current Pollution Reports, http://dx.doi.org/10.1007/s-40726-016-0046-0.

Kulkarni, H.V., Mladenov, N., Johannesson, K.H., and Datta, S., 2017. Contrasting dissolved organic matter quality in groundwater in Holocene and Pleistocene aquifers and implications for influencing arsenic mobility. Applied Geochemistry 77, 194-205

Mohajerin, T. J., Helz, G. R., and Johannesson, K. H., 2016. Tungsten - molybdenum fractionation in estuarine environments. Geochimica et Cosmochimica Acta 177, 105-119.

Prouty, N. G., Swarzenski, P.W., Frackell, J. K., Johannesson, K., and Palmore, D., 2016. Groundwater-derived  nutrient and trace element transport to a nearshore Kona coral ecosystem: Experimental mixing model results. Journal of Hydrology: Regional Studies, http://dx.doi.org/10.16/j.ejrh.2015.12.058

Yang, N., Shen, Z., Datta, S., and Johannesson, K.H., 2016. High aresenic (As) concentrations in shallow groundwaters of southern Louisiana: Evidence of microbial controls on As mobilization from sediments. Journal of Hydrology: Regional Studies, 5, 100-113.

Telfeyan, K., Johannesson, K.H., Mohajerin, T.J., and Palmore, C.D., 2015. Vanadium geochemistry along groundwater flow paths in contrasting aquifers of the United States: Carrizo Sand (Texas) and Oasis Valley (Nevada) aquifers. Chemicals Geology 410, 63-78

Chevis, D.A., Johannesson, K.H., Burdige, D.J., Cable, J.E., Martin, J.B., and Roy, M., 2015. Rare earth element cycling in a sandy subterranean estuary in Florida, USA. Marine Chemistry, 176, 34-50

Yang, N., Welch, K. A., Mohajerin, T. J., Telfeyan, K., Chevis, D. A., Grimm, D. A., Lyons, W. B., White, C. D., and Johannesson, K. H., 2015. Comparison of arsenic and molybdenum geochemistry in meromictic lakes of the McMurdo Dry Valleys, Antarctica: Implications for oxyanion-forming trace element behavior in permanently stratified lakes. Chemical Geology, 404, 110-125.

Chevis, D. A., Johannesson, K. H., Burdige, D. J., Moran, S. B., and Kelly, R. P., 2015. Submarine groundwater fluxes of rare earth elements to a tidally-mixed estuary in southern Rhode Island. Chemical Geology, 397, 128-142.

Mohajerin T. J., Helz G. R., White C. D., and Johannesson K. H., 2014. Tungsten speciation in sulfidic waters: Determination of thiotungstate formation constants and modeling their distribution in natural waters. Geochimica et Cosmochimica Acta, 144, 157-172.

Yang, N., Winkel, L., and Johannesson, K. H., 2014. Predicting arsenic contamination in shallow groundwater of southern Louisiana, USA. Environmental Science and Technology, 48, 5660-5666.

Leybourne, M. I., Johannesson, K. H., and Asfaw, A., 2014. Chapter 5: Measuring arsenic speciation in environmental media: Sampling, preservation and analysis. In: R. J. Bowell, C. N. Alpers, H. E. Jamieson, D. K. Nordstrom, and J. Majzlan (eds.) Environmental Geochemistry, Mineralogy, and Microbiology of Arsenic. Reviews in Mineralogy and Geochemistry, v. 79, pp. 371-390.

Sankar, M. S., Vega, M. A., Defoe, P. P., Kibria, M. G., Ford, S., Telfeyan, K., Neal, A., Mohajerin, T. J., Hettiarachchi, G. M., Barua, S., Hobson, C., Johannesson, K., and Datta, S., 2014. Elevated arsenic and manganese in groundwaters of Murshidabad, West Bengal, India. Science of the Total Environment, 488-489, 570-579.

Raychowdhury, N., Mukherjee, A., Bhattacharya, P., Johannesson, K., Bundschuh, J., Sifuentes, G. B., Nordberg, E., Martin, R. A., and del Rosario, A., 2014. Provenance and fate of arsenic and other solutes in the Chaco-Pampean plain of the Andean foreland, Argentina: From perspectives of hydrogeochemical modeling and regional tectonic setting. Journal of Hydrology, 518, 300-316.

Mohajerin, T. J., Neal, A. W., Telfeyan, K., Sasihharan, S. M., Ford, S., Yang, N., Chevis, D. A., Grimm, D. A., Datta, S., White, C. D., and Johannesson, K. H., 2014. Geochemistry of tungsten and arsenic in aquifer systems: A comparative study of groundwaters from West Bengal, India, and Nevada, USA. Water, Air, & Soil Pollution, 225, 1792, DOI: 0.1007/s11270-013-1792-x

Johannesson, K. H., Telfeyan, K., Chevis, D. A., Rosenheim, B. E., and Leybourne, M. I. (2014). Rare earth elements in stromatolites – 1. Evidence that modern terrestrial stromatolites fractionate rare earth elements during incorporation from ambient waters. In: Y. Dilek and H. Furnes (eds.) Archean Earth and Early Life. Springer (Dordrecht), pp. 385-411.

Kolker, A. S., Cable, J. E., Johannesson, K. H., Allison, M. A., and Inniss, L. V. (2013) Pathways and processes associated with the transport of groundwater in deltaic systems. Journal of Hydrology 498, 319-334

Johannesson, K. H., Dave, H. B., Mohajerin, T. J., and Datta, S. (2013) Controls on tungsten concentrations in groundwater flow systems:  The role of adsorption, aquifer sediment Fe(III) oxide/oxyhydroxide content, and thiotungstate formation. Chemical Geology (315). 76-94.  PDF Version

Rosenheim, B. E., K. M. Roe, B. J. Roberts, A. S. Kolker, M. A. Allison, and K. H. Johannesson (2013), River discharge influences on particulate organic carbon age structure in the Mississippi/Atchafalaya River System, Global Biogeochemical Cycles, 27, doi:10.1002/gbc.20018.     http://onlinelibrary.wiley.com/doi/10.1002/gbc.20018/abstract

Leybourne M. I., Cameron E. M., Reich M., Palacios C., Faure K., and Johannesson K. H. (2013) Stable isotopic composition of soil calcite (O, C) and gypsum (S) overlying Cu deposits in the Atacama Desert, Chile: Implications for mineral exploration, salt sources, and paleoenvironmental reconstruction. Applied Geochemistry 29, 55-72.

Johannesson K. H. and Neumann K. (2013) Geochemical cycling of mercury in a deep, confined aquifer: Insights from biogeochemical reactive transport modeling. Geochimica et Cosmochimica Acta 106, 25-43.

Johannesson K. H. (2012) "Rare earth element geochemistry of scleractinian coral skeleton during meteoric diagenesis: a sequence through neomorphism of aragonite to calcite: by Webb et al., Sedimentology, 56, 1433-1463: Discussion. Sedimentology 59, 729-732.   http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3091.2011.01264.x/full

Datta S., Neal A. W., Mohajerin T. J., Ocheltree T., Rosenheim B. E., White C. D., and Johannesson K. H. (2011) Perennial ponds are not an important source of water or dissolved organic matter to groundwaters with high arsenic concentrations in West Bengal, India. Geophysical Research Letters 38, L20404, doi:10.1029/2011GL049301     (http://www.agu.org/pubs/crossref/2011/2011GL049301.shtml)

 Willis S. S., Haque S. E., and Johannesson K. H. (2011) Arsenic and antimony in groundwater flow systems: A comparative study. Aquatic Geochemistry 17, 775-807.    (http://www.springerlink.com/content/fv5p9h14765784xu/)

 Willis, S. S. and Johannesson, K. H. (2011) Controls on the geochemistry of rare earth elements in sediments and groundwaters of the Aquia aquifer, Maryland USA. Chemical Geology 285, 32-49   https://authoring.tulane.edu/sse/eens/faculty/kjohanne/upload/Willis-and-Johannesson-2011.pdf

  Pearcy, C. A., Chevis, D. A., Haug, T. J., Jeffries, H. A., Yang, N., Tang, J., Grimm, D. A., and Johannesson, K. H. (2011) Evidence of microbially mediated arsenic mobilization from sediments of the Aquia aquifer, Maryland, USA. Applied Geochemistry 26, 575-586.    http://www.sciencedirect.com/science/article/pii/S0883292711000163

  Johannesson, K. H., Chevis, D.A., Burdige, D.J., Cable, J.E., Martin, J.B., and Roy, M. (2011) Submarine groundwater discharge is an important net source of light and middle REEs to coastal waters of the Indian River Lagoon, Florida, USA, Geochimica et Cosmochimica Acta 75, (2011) 825-843.    https://authoring.tulane.edu/sse/eens/faculty/kjohanne/upload/Johannesson-et-al-2011.pdf

 Tang J. and Johannesson K. H. (2010) Rare earth elements adsorption onto Carrizo sand: Influence of strong solution complexation. Chemical Geology 279, 120-133.  https://authoring.tulane.edu/sse/eens/faculty/kjohanne/upload/Tang-and-Johannesson-2010b-2.pdf

 Tang, J. and Johannesson, K.H. (2010) Ligand extraction of rare earth elements from aquifer sediments: Implications for rare earth element complexation with organic matter in natural waters.Geochimica et Cosmochimica Acta 74.  https://authoring.tulane.edu/sse/eens/faculty/kjohanne/upload/Tang-and-Johannesson-2010.pdf

 Johannesson, K.H. and Tang J. (2009) Conservative behavior of arsenic and other oxyanion-forming trace elements in an oxic groundwater flow system. Journal of Hydrology 378, 13-28. https://authoring.tulane.edu/sse/eens/faculty/kjohanne/upload/Johannesson-and-Tang-2009.pdf

 Leybourne M. I. and Johannesson K. H. (2008) Rare earth elements (REE) and yttrium in stream waters, stream sediments, and Fe–Mn oxyhydroxides: Fractionation, speciation, and controls over REE + Y patterns in the surface environment. Geochimica et Cosmochimica Acta 72, 5962-5983   https://authoring.tulane.edu/sse/eens/faculty/kjohanne/upload/Leybourne-and-Johannesson2008.pdf

 Haque S., Ji. J., and Johannesson K. H. (2008) Evaluating mobilization and transport of arsenic in sediments and groundwaters of Aquia aquifer, Maryland, USA. Journal of Contaminant Hydrology 99, 68-84. https://authoring.tulane.edu/sse/eens/faculty/kjohanne/upload/Haque-et-al-2008.pdf

Leybourne M. I., Peter J. M., Johannesson K. H., and Boyle D. R. (2008) The Lake St. Martin bolide has big impact on groundwater fluoride concentrations. Geology 36, 115-118.

Haque S. E., Tang J., Bounds W. J., Burdige D. J., and Johannesson K. H. (2007) Arsenic geochemistry of the Great Dismal Swamp, Virginia, USA: Possible organic matter controls. Aquatic Geochemistry 13, 289-308.

Basu R., Haque S. E., Tang J., Ji J., and Johannesson K. H. (2007) Evolution of selenium concentrations and speciation in groundwater flow systems: Upper Floridan (Florida) and Carrizo Sand (Texas) aquifers. Chemical Geology 246, 147-169.

Bounds W. J. and Johannesson K. H. (2007) Arsenic addition to soils from airborne coal dust originating at a major coal shipping terminal. Water, Air, and Soil Pollution 185, 195-207.

Cizdziel J. V., Guo C., Steinberg S. M., Yu Z., and Johannesson K. H. (2007) Chemical and colloidal analyses of natural seep water collected from the exploratory studies facility inside Yucca Mountain, Nevada, USA. Environmental Geochemistry and Health 30, 31-44.

Johannesson K. H.and Burdige D. J. (2007) Balancing the global oceanic neodymium budget: Evaluating the role of groundwater. Earth and Planetary Science Letters 253, 129-142.

Johannesson K. H., Hawkins D. L., Jr., and Cortés A. (2006) Do Archean chemical sediments record ancient seawater rare earth element patterns? Geochimica et Cosmochimica Acta 70, 871-890.

Tang J. and Johannesson K. H. (2006) Controls on the geochemistry of rare earth elements along a groundwater flow path in the Carrizo Sand aquifer, Texas, USA. Chemical Geology 225, 156-171.

Haque S. E. and Johannesson K. H. (2006) Concentrations and speciation of arsenic along a groundwater flow-path in the Upper Floridan aquifer, Florida, USA. Environmental Geology 50, 219-228.

Haque S. E. and Johannesson K. H. (2006) Arsenic concentrations and speciation along a groundwater flow path: The Carrizo Sand aquifer, Texas, USA. Chemical Geology 228, 57-71.

Tang J. and Johannesson K. H. (2005) Adsorption of rare earth elements onto Carrizo sand: Experimental investigations and modeling with surface complexation. Geochimica et Cosmochimica Acta 69, 5259-5272.

Johannesson K. H. (2005) Rare Earth Elements in Groundwater Flow Systems. Springer, Dordrecht. (http://www.springeronline.com/sgw/cda/frontpage/0,11855,5-10006-72-3734…)

Johannesson K. H., Cortés A., Ramos Leal J. A., Ramírez A. G., and Durazo J. (2005) Geochemistry of rare earth elements in groundwater from a rhyolite aquifer, central México. In: K. H. Johannesson (ed.) Rare Earth Elements in Groundwater Flow Systems. Springer, (Dordrecht), pp. 187-222.

Tang J. and Johannesson K. H. (2005) Rare earth element concentrations, speciation, and fractionation along groundwater flow paths: The Carrizo Sand (Texas) and Upper Floridan aquifers. In: K. H. Johannesson (ed.) Rare Earth Elements in Groundwater Flow Systems. Springer, (Dordrecht), pp. 223-251.

Shand P., Johannesson K. H., Chudaev O., Chudaeva V., and Edmunds W. M. (2005) Rare earth element contents of high pCO₂groundwaters of Primorye, Russia: Mineral stability and complexation controls. In: K. H. Johannesson (ed.) Rare Earth Elements in Groundwater Flow Systems. Springer, (Dordrecht), pp. 161-186.

Zhou X., Stetzenbach K. J., Yu Z., and Johannesson K. H. (2005) Origin of rare earth element signatures in groundwaters of south Nevada, USA: Implications from preliminary batch leach tests using aquifer rocks. In: K. H. Johannesson (ed.) Rare Earth Elements in Groundwater Flow Systems. Springer, (Dordrecht), pp. 141-160.

Tang J., Whittecar G. R., Johannesson K. H., and Daniels W. L. (2004) Potential contaminants at a dredged spoil placement site, Charles City County, Virginia, as revealed by sequential extraction. Geochemical Transactions 5, 49-60.

Johannesson, K. H., Tang, J., Daniels, J. M., Bounds, W. J., and Burdige, D. J., 2004. Rare earth element concentrations and speciation in organic-rich blackwaters of the Great Dismal Swamp, Virginia, USA. Chemical Geology 208, 217-294.

Johannesson K. H., Cortés A., and Kilroy K. C. (2003) Reconnaissance isotopic and hydrochemical study of Cuatro Ciénegas groundwater, Coahuila, México. Journal of South American Earth Sciences 17, 171-180.

Tang J. and Johannesson K. H. (2003) Speciation of rare earth elements in natural terrestrial waters: Assessing the role of dissolved organic matter from the modeling approach. Geochimica et Cosmochimica Acta 67, 2321-2339.

Ojiambo S. B., Lyons W. B., Welch K. A., Poreda R. J., and Johannesson K. H. (2003) Strontium isotopes and rare earth elements as tracers of groundwater – lake water interactions, Lake Naivasha, Kenya. Applied Geochemistry 18, 1789-1805.

Farnham I. M., Johannesson K. H., Singh A. K., Hodge V. F., and Stetzenbach K. J. (2003) Factor analytical approaches for evaluating groundwater trace element chemistry data. Analytica Chimica Acta  490, 123-138.

Stetzenbach K. J., Hodge V. F., Guo C., Farnham I. M. and Johannesson K. H. (2001). Geochemical and statistical evidence of deep carbonate groundwater within overlying volcanic rock aquifers/aquitards of southern Nevada, USA. Journal of Hydrology 243, 254-271.

Dr. Jackson's research interests include Solid Earth geochemistry and petrology, high temperature and pressure synthesis, and Planetary Science

Publications

CRM Jackson, NR Bennett, Z Du, E Cottrell, Y Fei, (2018), Early episodes of high-pressure core formation preserved in plume mantle, Nature 553 (7689), 491.

AJ Smye, CRM Jackson, M Konrad-Schmolke, MA Hesse, SW Parman, DL Shuster, CJ Ballentine, (2017), Noble gases recycled into the mantle through cold subduction zones Earth and Planetary Science Letters 471, 65-73.

N Dygert, CRM Jackson, MA Hesse, MM Tremblay, DL Shuster, JT Gu, (2018), Plate tectonic cycling modulates Earth's 3He/22Ne ratio Earth and Planetary Science Letters 498, 309-321.

KB Williams*, CRM Jackson, LC Cheek, KL Donaldson-Hanna, SW Parman, CM Pieters, MD Dyar, TC Prissel, (2016), Reflectance spectroscopy of chromium-bearing spinel with application to recent orbital data from the Moon, American Mineralogist 101 (3), 726-734.

Dr. Goehring's research interests include cosmogenic nuclides and surface exposure dating, glacial geology and geomorphology, paleoclimatology and neotectonics

Selected Publications

Menounos, B., Clague, J., Osborn, G., Ponce, F., Davis, P.T., Goehring, B.M., Maurer, M., Rabassa, J., Andrea, Maar, R., 2013. Latest Pleistocene and Holocene Glacier Fluctuations in southernmost Tierra del Fuego, Argentina. Quaternary Science Reviews. 77, 70-79.

Mangerud, J., Goehring, B.M., Lohne, Ø.S., Svendsen, J.-I., Gyllencreutz, R., 2013. The chronology and rate of ice-margin retreat in the major fjords of Western Norway during the Early Holocene. Quaternary Science Reviews. 67, 8-16.

Goehring, B.M., Muzikar, P., Lifton, N.A., 2013. An in situ 14C-10Be Isochron Approach to Interpreting Complex Glacial Histories. Quaternary Geochronology. 15, 61-66.

Goehring, B.M., Vacco, D., Alley, R., 2012. Holocene Dynamics of the Rhone Glacier, Switzerland, Deduced from Ice Flow Models and Cosmogenic Nuclides. Earth and Planetary Science Letters. 351-352, 27-35. doi: 10.1016/j.epsl.2012.07.027.

Sasnett, P.J., Goehring, B.M., Christie-Blick, N., Schaefer, J.M., 2012. Do phreatomagmatic eruptions at Ubehebe Crater (Death Valley, California) relate to a wetter than present hydro-climate?. Geophysical Research Letters. 39(2). doi: 10.1029/2011GL050130.

Goehring, B.M., Schaefer, J.M., Schluechter, C., Lifton, N.A., Finkel, R.C., Jull, A.J.T., Ackçar, N., Alley, R., 2011. The Holocene Rhone Glacier was smaller than today for most of the Holocene. Geology. 39, 679-682.

Goehring, B.M., Kurz, M.D., Balco, G., Schaefer, J.M., and Licciardi, J.M. and Lifton, N.A., 2010. A reevaluation of cosmogenic Helium-3 production rates. Quaternary Geochronology. 5, 410-18.

Dr. Gasparini's research interests include Fluvial geomorphology; Tectonic geomorphology; Evolution of alluvial and bedrock river networks; Landscape evolution modeling and numerical model development; Interactions among climate, tectonics, and erosion; Effects of climate change on landscape evolution; Sediment production and transport of sediment from hillslopes to rivers to depositional systems; Human influences on landscape evolution.

Recent Publications

(* = student; ^ = post-doc)

*Adams, J.M., Gasparini, N.M., ^Hobley, D.E.J., Tucker, G.E., Hutton, E.W.H., *Siddhartha Nudurupati, S. and Istanbulluoglu, E., 2017, The Landlab OverlandFlow component: a Python library for computing shallow-water flow across watersheds, Geoscientific Model Development (GMD), doi:10.5194/gmd-10-1645-2017

Whipple, K.X., Forte, A., DiBiase, R.A., Gasparini, N.M. and Ouimet, W., 2017, Timescales of landscape response to divide migration and drainage capture: Implications for the role of divide mobility in landscape evolution, accepted at JGR Earth Surface.

^Hobley, D.E.J., *Adams, J.M., *Siddhartha Nudurupati, S. Huttong, E.W.H., Gasparini, N.M., Istanbulluoglu, E., Tucker, G.E., 2017, Creative computing with Landlab: an open-source toolkit for building, coupling, and exploring two-dimensional numerical models of Earth-surface dynamics, ESurf, doi:10.5194esurf-5-21-2017.

Murphy, B. P, Johnson, J. P. L., Gasparini, N. M., and Sklar, L. S., 2016, A mechanism for the climatic control of bedrock river incision, Nature, doi: 10.1038/nature17449.

Murray, A.B., Gasparini, N.M., Goldstein, E.B., and van der Wegen, M., 2016, Uncertainty quantification in modeling earth surface processes: more applicable for some types of models than for others, Computers and Geosciences, doi:10.1016/j.cageo.2016.02.008.

Shen, Z., Dawers, N. H., Tornqvist, T. E., Gasparini, N. M., Hijma, M. P., and Mauz, B., 2016, Mechanisms of late Quaternary fault throw-rate variability along the North-central Gulf of Mexico coast: Implications for coastal subsidence, Basin Research, doi: 10.1111/bre.12184.

Tucker, G.E., Hobley, D.E.J., Hutton, E, Gasparini, N.M., Istanbulluoglu, E., *Adams, J.M. and *Nudurupati, S.S., 2016, CellLab-CTS 2015: A Python library for continuous-time stochastic cellular automaton modeling using Landlab, Geoscientific Model Development, doi:10.5194/gmd-9-823-2016.

Gasparini, N.M, Fischer, G.C., Adams, J.M., Dawers, N.H. and Janoff, A.M., 2015, Morphological signatures of normal faulting in low-gradient alluvial rivers in Southeastern Louisiana, USA. Earth Surface Processes and Landforms, doi: 10.1002/esp.3852

Han, J., Gasparini, N.M. and Johnson, J.P.L., 2015, Measuring the imprint of orographic rainfall gradients on the morphology of steady‐state numerical fluvial landscapes." Earth Surface Processes and Landforms, doi: 10.1002/esp.3723.

Adams, J.M., Nudurupati, S.S., Gasparini, N.M., Hobley, D.E.J., Hutton, E.W.H, Tucker, G.E., and Istanbulluoglu, E., 2014, Landlab: Sustainable Software Development in Practice, reviewed conference paper in the 2nd Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE2), 16 Nov. 2014, http://dx.doi.org/10.6084/m9.figshare.1097629.

Gasparini, N.M., and Whipple, K.X., 2014, Diagnosing climatic and tectonic controls on topography: Eastern flank of the northern Bolivian Andes. Lithosphere, doi: 10.1130/L322.1.

Whipple, K.X., & Gasparini, N.M., 2014, Tectonic control of topography, rainfall patterns, and erosion during rapid post–12 Ma uplift of the Bolivian Andes. Lithosphere, doi:10.1130/L325.1.

Han, J., Gasparini, N.M., Johnson, J.P.L., & Murphy, B.P., 2014, Modeling the influence of rainfall gradients on discharge, bedrock erodibility, and river profile evolution, with application to the Big Island, Hawai'i. Journal of Geophysical Research: Earth Surface, doi: 10.1002/2013JF00296.

Giachetta, E., Caplongo, D., Refice, A., Gasparini, N.M., and Pazzaglia, F.J., 2014, Orogen-scale drainage network evolution and response to climate change: insights from numerical experiments, Earth Surface Processes and Landforms, doi: 10.1002/esp.3579

Willenbring, J.K., Gasparini, N.M., Crosby, B.T., and Brocard, G., 2013, What does a mean mean? The temporal evolution of detrital cosmogenic denudation rates in a transient landscape, Geology, doi:10.1130/G34746.1.

Menking, J.A., Han, J., Gasparini, N.M. and Johnson, J.P.L., 2013, The effects of orographic precipitation gradients on river profile evolution on the Big Island of Hawai’i, GSA Bulletin, doi:10.1130/B30625.1

Dr. Flowers' research interests include Theoretical Geochemistry, Sedimentary Geochemistry, Environmental Geology and Geochemistry and Fate and Transport of Heavy Metals

Publications

Isphording, W. C., Allison, D. T., and Flowers, G. C., 2007, Occurrence of primary magnesium silicates (palygorskite-sepiolite) in karst terranes: Proceedings of the 12thInternational Conference on Water-Rock Interaction, v. 2, p. 1671-1674

Devall, Margaret S., Thien, L. B., Flowers, G. C., Ellgaard, E., 2006.  Lead transport into Bayou Trepagnier wetlands in Louisiana, USA: Journal of Environmental Quality, v. 35, p. 758-765

Marcantonio, F., Flowers, G.C., and Templin, N., 1999, Lead isotopes as fingerprints of pollution in Bayou Trepagnier, Louisiana: Environmental Geology, v. 39, p. 1070-1079

Flowers, G. C., Barber, M. and Jin, P., 1998, Subsurface geology of hazardous waste injection sands near Geismar, Louisiana: Environmental and Engineering Geoscience, v. 4, p. 341-360

Flowers, G.C.,  Suhayda, J. N., Clymire, J. W., McPherson, G. L., Koplitz, L. V., and Poirrier, M. A., 1998, Impact of industrial effluent diversion on Bayou Trepagnier, Louisiana:  Environmental and Engineering Geoscience, v. 4, p. 77-91.

Khosraviani, M., Pavlov, A. R., Flowers, G. C., and Blake, D. A., 1998, Detection of heavy metals using immunoassay: Optimization and validation of a rapid, portable assay for ionic Cd: Environmental Science and Technology, v. 32, p. 137-142.

Manheim, F. T., Flowers, G. C., McIntire, A. G., Marot, M., and Holmes, C., 1998, Environmental geochemistry and sediment quality in Lake Pontchartrain: Database development and review: Trans. Gulf Coast Assoc. Geological Soc. v. 47, p. 337-349

Flowers, G.C. Environmental sedimentology of the Pontchartrain Estuary. Trans. Gulf Coast Assoc. Geological Soc. 40:237-50, 1990

Marcantonio, F., G. C. Flowers, L. Thien, and E. Ellgaard, 1988, Pb isotopes in tree rings: Chronology of pollution in Bayou Trepagnier, LA. Environ. Sci. Technol., v. 32, p. 2371-2376

Dr. Ebinger's research interests include Earthquake Seismology, Active Tectonics, Potential Fields, Crustal Dynamics and Critical Zone Imaging for Archaeology and Geosciences. 

More detailed descriptions of this work can be found at the website of the GATR Group.

Research Projects

KIVURIFT: On 22 May 2021, following an eruption along the southern flank of Mount Nyiragongo in the Democratic Republic of Congo (DRC), a graben began opening southeast of the volcano in Rwanda and beneath Lake Kivu. Satellite imagery suggests at least a 10 km-long segment opened about seven meters by the end of May. This project with Georgia Tech, Penn State, Rwanda Environmental Management Authority, Rwanda Mines, Petroleum and Gas Board, EAIFR, and Goma Volcano Observatory aims to investigate the magma-fault interactions achieving rift opening during and following the 2021 sequence, and to image crustal structure to understand the consequences of dike intrusion to active and time-averaged deformation. Tulane and partners maintain a temporary network of 9 seismometers, including 2 that were installed during the intrusion event, to both capture the detailed time history and kinematics of the rifting event. New and permanent seismic and 25 magnetotelluric imaging sites will enable determination of lateral variations in physical properties of the crust, and the degree of magmatic modification.
 
TRAILS: Turkana Rift Arrays to Investigate Lithospheric Structure. Our US-UK-Kenya-Ethiopia project in the Turkana Depression between the Ethiopian and East African plateaux combines seismic and geodetic data collection for seismic imaging, earthquake source mechanisms, surface kinematics, crustal strain rates, and lithospheric architecture.  Comparisons of data products to one another, and forward and inverse models will test basic hypotheses about the role of gravitational potential energy, inherited structure from Mesozoic rifting, and mantle plume dynamics.  

BARNZ:  Back-Arc Rifting in New Zealand.  The Taupo Volcanic Zone (TVZ) has the world’s highest silicic magma production rates, and it is a fundamental component of the Hikurangi subduction system. Uniquely, the northern TVX transitions to back-arc spreading in the Whakatane rift zone offshore.  We deployed 7 seismometers in the northern TVZ to densify the New Zealand Geonet stations, so we may distinguish between active magma intrusion vs flank uplift for long-lived earthquake swarms.  Seismicity patterns are providing new details on the distribution of magma bodies, role of fluids in crustal deformation, and kinematics of rifting in the TVZ and back-arc system.  
 
Crustal Loading and Causes of Intraplate Stress: The objectives of spectral analyses of regional gravity and magnetic anomaly data and earthquake catalogues are to systematically evaluate the geometries of crustal density and magnetic susceptibility contrasts (e.g., steep faults, intrusive bodies, Moho topography) giving rise to anomaly patterns. We map faults and sutures beneath New England to test fault interpretations in seismogenic zones. Our results indicate that earthquake epicenters lie within a few kilometers of steep density contrasts imaged using a variety of spectral methods. These maps include structures that are favorably oriented with respect to current stress field, and that could be reactivated.
 

More detailed descriptions of this work can be found at the website of the GATR Group.

Selected Publications

Musila, M.*, C. J. Ebinger, I. D. Bastow, G. Sullivan*, S. J. Oliva, E. Knappe,  M. Perry*, R. Kounoudis*, C. S. Ogden, R. Bendick, S. Mwangi*, N. Mariita, G. Kianji, E. Klein*, F. Illsley-Kemp (2023), Active deformation constraints on the Nubia-Somalia Plate Boundary through Heterogeneous Lithosphere of the Turkana Depression, Geochemistry, Geophysics, Geosystems,. 

Ebinger, C.J., J. van Wijk, L. Olaka, C. Mériaux, K. Fontijn (2023), All scales must be considered to understand rifts, Nature Geoscience, 209-210.  

Olaka, L. and C.J. Ebinger (2023), Tectonic and paleoclimatic setting for hominin evolution in East Africa, in McHenry, L., (editor), Geology and Paleoanthropology of the East African Rift, Elements, DOI: 10.2138/gselements.19.2.82, 2023.  

Kounoudis, R., I.D. Bastow, C.J. Ebinger, C. S. Ogden, R. Bendick, A. Ayele, N. Mariita, G. Kianji, G. Wigham, M. Musila*, and B. Kibret (2021), Body wave tomographic imaging of the Turkana Depression: Implications for rift development and plume-lithosphere interactions, Geochem. Geophys. Geosys., 2021GC009782, 2021.  
 
Zheng, W., S. Oliva, C. J. Ebinger, M. Pritchard, (2020), Aseismic deformation during extension: InSAR and seismic evidence from the 2014 Mw 5.2 earthquake near Karonga, Malawi, Geophysical Research Letters,  doi: doi.org/10.1029/2020GL090930