Stephen A Wilson
Science and Products
Development of USGS Geochemical Reference Materials
The project focus will be the development of traditional and microanalytical reference materials that support USGS geochemical investigations. Development of new microanalytical reference materials allows USGS scientists and outside customers to examine a greater range of sample types while maintaining a high degree of data reliability.
Variability in results from mineralogical and organic geochemical interlaboratory testing of U. S. Geological Survey shale reference materials
The expansion of unconventional petroleum resource exploration and production in the United States has led to an increase in source rock characterization efforts, particularly related to bulk organic and mineralogical properties. To support the analytical and research needs of industry and academia, as well as internal work, the U.S. Geological...
Birdwell, Justin E.; Wilson, Stephen A. High microscale variability in Raman thermal maturity estimates from shale organic matter
Raman spectroscopy has recently received attention as a means to estimate thermal maturity of organic matter in petroleum generating source rocks to complement more traditional approaches such as vitrinite reflectance and programmed pyrolysis. While many studies have observed positive correlations between...
Jubb, Aaron M.; Botterell, Palma J.; Birdwell, Justin E.; Burruss, Robert C.; Hackley, Paul C.; Valentine, Brett J.; Hatcherian, Javin J.; Wilson, Stephen A. Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars
The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall,...
Grotzinger, J.P.; Gupta, S.; Malin, M.C.; Rubin, D.M.; Schieber, J.; Siebach, K.; Sumner, D.Y.; Stack, K.M.; Vasavada, A.R.; Arvidson, R.E.; Calef, F.; Edgar, Lauren A.; Fischer, W.F.; Grant, J.A.; Griffes, J.L.; Kah, L.C.; Lamb, M.P.; Lewis, K.W.; Mangold, N.; Minitti, M.E.; Palucis, M.C.; Rice, M.; Williams, R.M.E.; Yingst, R.A.; Blake, D.; Blaney, D.; Conrad, P.; Crisp, J.A.; Dietrich, W.E.; Dromart, G.; Edgett, K.S.; Ewing, R.C.; Gellert, R.; Hurowitz, J.A.; Kocurek, G.; Mahaffy, P.G.; McBride, M.J.; McLennan, S.M.; Mischna, M.A.; Ming, D.; Milliken, R.E.; Newsom, H.; Oehler, D.; Parker, T.J.; Vaniman, D.; Wiens, R.C.; Wilson, S.A.
Preparation and characterization of "Libby Amphibole" toxicological testing material
The U.S. Environmental Protection Agency (USEPA) began work in Libby, Mont. in 1999 when an Emergency Response Team was sent to investigate local concern and media reports regarding asbestos-contaminated vermiculite. Since that time, the site has been granted Superfund status and site remediation to a safe level of asbestos has been ongoing. The...
Lowers, Heather; Wilson, Stephen A.; Hoefen, Todd M.; Benzel, William M.; Meeker, Gregory P. GSD-1G and MPI-DING Reference Glasses for In Situ and Bulk Isotopic Determination
This paper contains the results of an extensive isotopic study of United States Geological Survey GSD-1G and MPI-DING reference glasses. Thirteen different laboratories were involved using high-precision bulk (TIMS, MC-ICP-MS) and microanalytical (LA-MC-ICP-MS, LA-ICP-MS) techniques. Detailed studies were performed to demonstrate the large-scale...
Jochum, K.P.; Wilson, S.A.; Abouchami, W.; Amini, M.; Chmeleff, J.; Eisenhauer, A.; Hegner, E.; Iaccheri, L.M.; Kieffer, B.; Krause, J.; McDonough, W.F.; Mertz-Kraus, R.; Raczek, I.; Rudnick, R.L.; Scholz, Donna K.; Steinhoefel, G.; Stoll, B.; Stracke, A.; Tonarini, S.; Weis, D.; Weis, U.; Woodhead, J.D.
Evaluation of extraction methods for hexavalent chromium determination in dusts, ashes, and soils
One of the difficulties in performing speciation analyses on solid samples is finding a suitable extraction method. Traditional methods for extraction of hexavalent chromium, Cr(VI), in soils, such as SW846 Method 3060A, can be tedious and are not always compatible with some determination methods. For example, the phosphate and high levels of...
Wolf, Ruth E.; Wilson, Stephen A.
Geologic Map of MTM -20012 and -25012 Quadrangles, Margaritifer Terra Region of Mars
Mars Transverse Mercator (MTM) -20012 and -25012 quadrangles (lat 17.5 deg - 27.5 deg S., long 345 deg - 350 deg E.) cover a portion of Margaritifer Terra near the east end of Valles Marineris. The map area consists of a diverse assemblage of geologic surfaces including isolated knobs of rugged mountainous material, heavily cratered and dissected...
Grant, J. A.; Wilson, S.A.; Fortezzo, C.M.; Clark, D.A. Development of a standard reference material for Cr(vi) in contaminated soil
Over the last several decades, considerable contamination by hexavalent chromium has resulted from the land disposal of Chromite Ore Processing Residue (COPR). COPR contains a number of hexavalent chromium-bearing compounds that were produced in high temperature industrial processes. Concern over the carcinogenic potential of this chromium species...
Nagourney, S.J.; Wilson, S.A.; Buckley, B.; Kingston, H.M.S.; Yang, S.-Y.; Long, S.E. Development of lunar regolith simulant: From the macro to the micro
[No abstract available]
Lowers, H.A.; Stoeser, D.B.; Wilson, S.A.; Meeker, G.P.
USGS Reference Materials Program: Serving the Needs of the Global Analytical Community
Every year in the United States, millions of measurements are made on the chemical composition of items that affect us on a daily basis. The accuracy of these measurements is routinely determined by the analysis of appropriate reference materials. In the field of earth science, reference materials are particularly important because they help us...
Wolf, Ruth E.; Wilson, Stephen A. Development and certification of the new SRM 695 trace elements in multi-nutrient fertilizer
During the past seven years, several states within the US have enacted regulations that limit the amounts of selected non-nutritive elements in fertilizers. Internationally, several countries, including Japan, China, and Australia, and the European Union also limit the amount of selected elements in fertilizers. The elements of interest include As...
MacKey, E.A.; Cronise, M.P.; Fales, C.N.; Greenberg, R.R.; Leigh, S.D.; Long, S.E.; Marlow, A.F.; Murphy, K.E.; Oflaz, R.; Sieber, J.R.; Rearick, M.S.; Wood, L.J.; Yu, L.L.; Wilson, S.A.; Briggs, Paul H.; Brown, Z.A.; Budahn, J.; Kane, P.F.; Hall, W.L. Homogeneity of the geochemical reference material BRP-1 (paraná basin basalt) and assessment of minimum mass
Reference materials (RM) are required for quantitative analyses and their successful use is associated with the degree of homogeneity, and the traceability and confidence limits of the values established by characterisation. During the production of a RM, the chemical characterisation can only commence after it has been demonstrated that the...
Cotta, Aloisio J. B.; Enzweiler, Jacinta; Wilson, Stephen A.; Perez, Carlos A.; Nardy, Antonio J. R.; Larizzatti, Joao H.