Richard Gaschnig

Expertise

Research Interests

I am broadly interested in the use of radiogenic isotopes, stable isotopes, and trace elements to understand processes such as the formation and evolution of continents through the study of both igneous and sedimentary materials.

Education

• Doctor of Philosophy (Ph. D.): Geology, (2010), Washington State University - Pullman, Washington
• Master of Science (MS): Geology, (2005), University of North Carolina at Chapel Hill - Chapel Hill, North Carolina
• Bachelor of Science (BS): Geology, (2003), University of Delaware - Newark, Delaware

Selected Publications

• Boudreau, E., Gaschnig, R., Vervoort, J., Schwartz, J., Housen, B., Tikoff, B. (2015) Heavy mineral provenance and paleomagnetic studies of Mesozoic rocks in the Gold Beach terrane: GSA Bulletin.
• Gaschnig, R.M., Mato, K., Leonard, A., Lewis, R.S., Vervoort, J.D. (2025) New insight on Mesoproterozoic paleogeography from the age and geochemistry of detrital minerals in the Belt Supergroup, USA: GSA Bulletin
• Stegner, C., Gaschnig, R.M., *Marshall, S., Rader, S., Bebout, G., Penniston-Dorland, S. (2025) Molybdenum isotope behavior during subduction zone metamorphism in the Catalina Schist, California: Geochimica et Cosmochimica Acta, v. 388, p. 294-306.
• Bindeman, I., Rudnick, R., Gaschnig, R., Hofmann, A. (2024) Triple oxygen and hydrogen isotope investigation of glacial diamictites through time: Chemical Geology, v. 670, 122458.
• Gaschnig, R.M., Lewis, R.S., Buddington, A., Mato, K. (2024) Basement, Belt, and batholith: bedrock geology of the Idaho Panhandle in McFadden, M.D., Pritchard, C.J., eds., Proterozoic Nuna to Pleistocene Megafloods: Sharing Geology of the Inland Northwest: GSA Field Guide 69, p. 1-25.
• Mazza S.E., Gaschnig, R.M., Rudnick, R.L., Kleine, T. (2024) Tungsten stable isotope composition of the upper continental crust: Geochimica et Cosmochimica Acta, v. 370, p. 161-172.
• Eseller, K.E., Safi, A., Adler, HG., Conboy, L., Gaschnig, R.M., Melikechi, N. (2024) Assessment of acupuncture's effectiveness in treating Gulf War Illness using Laser Induced Breakdown Spectroscopy and Induced Coupled-Mass Spectrometry: Spectrochimica Acta Part B: Atomic Spectroscopy, v. 222., 107076.
• Safi, A., Melikechi, N., Esseler, K.E., Gaschnig, R.M., Xia, W. (2024) Label free, machine learning informed plasma-based elemental biomarkers of Alzheimer’s disease: Journal of Analytical Atomic Spectrometry, v. 39, p. 1961-1970.
• Gaschnig, R.M., Lewis, R.S., Vervoort, J.D. (2023) Age and origin of Early Cretaceous magmatism in the southernmost Omineca Belt, northern U.S. Cordillera: GSA Bulletin.
  https://doi.org/10.1130/B36845.1
• Han, P.-Y., Rudnick, R. L., He, T., Marks, M. A. W., Wang, S.-J., Gaschnig, R. M., and Hu, Z.-C., 2023, Halogen (F, Cl, Br, and I) concentrations of the upper continental crust through time as recorded in ancient glacial diamictite composites: Geochimica et Cosmochimica Acta, v. 341, p. 28-45.
• Li, W., Nakada, R., Takahashi, Y., Gaschnig, R.M., Hu, Y., Shakouri, M., Liu, X-M. (2023) Cerium geochemical composition in the upper continental crust through time: Implications for tracing past redox environment: Geochimica et Cosmochimica Acta, v. 359, p. 20-29.
• Tian, S., Ding, X., Qi, Y., Wu, F., Yue, C., Gaschnig, R.M., Xiao, Z., Lv, W., Rudnick, R.L., Huang, F. (2023) Vanadium isotope evidence for emergence of felsic crust after 3 billion years: Proceedings of the National Academy of Sciences, v. 121, no. 11, e2220563120. https://doi.org/10.1073/pnas.2220563120
• Gaschnig, R.M., Horan, M., Rudnick, R.L., Vervoort, J.D., Fisher, C.M. (2022) History of crustal growth in Africa and the Americas from detrital zircon and Nd isotopes in glacial diamictites: Precambrian Research, v. 373, 106641.
  https://doi.org/10.1016/j.precamres.2022.106641
• Liu, X-M., Gaschnig, R.M., Rudnick, R.L., Hazen, R.M., Shahar, A. (2022) Tracing the secular evolution of the upper continental crust using iron isotopes in glacial diamictites: Geochemical Perspectives Letters, v. 22, p. 16-19.
  https://doi.org/10.7185/geochemlet.2221
• Murphy, M.E., Savage, P.S., Gardiner, N.J., Prave, A.R., Rudnick, R.L., Gaschnig, R.M. (2022) Homogenizing the upper continental crust: the Si isotope evolution of the crust recorded by ancient glacial diamictites: Earth and Planetary Science Letters, v. 591, 1176. https://doi.org/10.1016/j.epsl.2022.117620
• Tikoff, B., Kelso, P., Fayon, A.K., Gaschnig, R.M., Russo, R.M., Vervoort, J., Jicha, B., Kahn, M.J. (2022) The jagged western edge of Laurentia: The role of inherited rifted lithospheric structure in subsequent tectonism in the Pacific Northwest, in Whitmeyer, S.J., Williams, M.L., Kellett, D.A., Tikoff, B., eds, Laurentia: Turning Points in the Evolution of a Continent: GSA Memoir 220.
• Gaschnig, R.M., Rader, S., Reinhard, C.T., Owens, J., Planavsky, N., Wang, X., Asael, D., Greaney, A., Helz, R. (2021) Behavior of the Mo, Tl, and U isotope systems during 1 differentiation in the Kilauea Iki lava lake. Chemical Geology, v. 574, 12039. https://doi.org/10.1016/j.chemgeo.2021.120239
• Gaschnig, R.M., Reinhard, C.T., Planavsky, N., Wang, X., Asael, D., Jackson, M. (2021) The impact of primary processes and secondary alteration on the stable isotope composition of ocean island basalts: Chemical Geology, v. 81, 120416.
  https://doi.org/10.1016/j.chemgeo.2021.120416
• Rader, S.T., Gaschnig, R.M., Newby, S.M., Bebout, G.E., Mirakian, M.J., Owens, J.D. (2021) Thallium behavior during high-pressure metamorphism in the western Alps, Europe: Chemical Geology, v. 579, 120349 https://doi.org/10.1016/j.chemgeo.2021.120349
• Tian, S., Moynier, F., Inglis, E.C., Rudnick, R.L., Huang, F., Chauvel, C., Creech, J.B., Gaschnig, R.M., Wang, Z., Guo, J.-L., 2021. Zirconium isotopic composition of the
  upper continental crust through time. Earth and Planetary Science Letters, 572: 117086. https://doi.org/10.1016/j.epsl.2021.117086
• Chen, K., Wang, Z., Tang, M., Rudnick, R.L., Gaschnig, R.M., Zou, Z., He, T., Hu, Z., Liu, Y. (2020) How mafic was the Archean upper continental crust? Insights from Cu and Ag in ancient glacial diamictites: Geochimica et Cosmochimica Acta, v. 278, p. 16-29. https://doi.org/10.1016/j.gca.2019.08.002
• Greaney, A.T., Rudnick, R.L., Romaniello, S.J., Johnson, A.C., Gaschnig, R.M., Anbar, A. (2020) Molybdenum isotope fractionation in glacial diamictites tracks onset of oxidative weathering of the continental crust: Earth and Planetary Science Letters, v. 534, 116083. https://doi.org/10.1016/j.epsl.2020.116083
• Li, S., Junkin, W., Gaschnig, R.M., Ash, R.D., Piccoli, P., Candela, P., Rudnick, R.L. (2020) Molybdenum contents of sulfides in ancient glacial diamictites: implications for molybdenum delivery to the oceans prior to the Great Oxidation Event: Geochimica et Cosmochimica Acta, v. 278, p. 30-50. https://doi.org/10.1016/j.gca.2019.09.011
• Gaschnig, R.M. (2019) Benefits of a multi-proxy approach to detrital mineral provenance analysis: an example from New England: Geochemistry, Geophysics, and Geosystems, v. 20, no. 3, p. 1557-1573. https://doi.org/10.1029/2018gc008005
• Wang, S-J., Rudnick R.L., Gaschnig, R.M., Wang, H., Wasylenki, L.E. (2019) Sulfide Weathering sustained methanogenesis during the Great Oxidation Event: Nature Geoscience, v. 12, no. 4, p. 296-300. https://doi.org/10.1038/s41561-019-0320-z
• Greaney, A., Rudnick, R., Ronaniello, S., Johnson, A., Gaschnig, R., Anbar, A. (2020). Molybdenum isotope fractionation in glacial diamictites tracks onset of oxidative weathering of the continental crust. Earth and Planetary Science Letters,534.
• Gaschnig, R. (2019). Benefits of a multi-proxy approach to detrital mineral provenance analysis: an example from New England. Geochemistry, Geophysics, and Geosystems,20 1557-1573.
• Chen, K., Wang, Z., Tang, M., Rudnick, R., Gaschnig, R., Zou, Z., He, T., Hu, Z., Liu, Y. (). How mafic was the Archean upper continental crust? Insights from Cu and Ag in ancient glacial diamictites. Geochimica et Cosmochimica Acta.
• Li, S., Junkin, W., Gaschnig, R., Ash, R., Piccoli, P., Candela, P., Rudnick, R. (). Molybdenum contents of sulfides in ancient glacial diamictites: implications for molybdenum delivery to the oceans prior to the Great Oxidation Event. Geochimica et Cosmochimica Acta
• Wang, S., Rudnick, R., Gaschnig, R., Wang, H., Wasylenki, L. (2019). Sulfide Weathering sustained methanogenesis during the Great Oxidation Event. Nature Geoscience,12 296-300.
• Nan, X., Yu, H., Rudnick, R., Gaschnig, R., Xu, J., Li, W., Zhang, Q., Jin, Z., Li, X., Huang, F. (2018). Barium isotopic composition of the upper continental crust. Geochimica et Cosmochimica Acta,233 33-49.
• Greaney, A., Rudnick, R., Gaschnig, R., Whalen, J., Luais, B., Clemens, J. (2018). Crustal residence of molybdenum. Geochimica et Cosmochimica Acta,238 36-54.
• Mundl, A., Walker, R., Reimink, J., Rudnick, R., Gaschnig, R. (2018). Temporal evolution of 182W in the upper continental crust. Chemical Geology,494 144-152.
• Fayon, A., Tikoff, B., Kahn, M., Gaschnig, R. (2017). Cooling and exhumation of the southern Idaho batholith. Lithosphere, ³¢565–1.
• Gaschnig, R., Macho, A., Fayon, A., Schmitz, M., Ware, B., Vervoort, J., Kelso, P., LaMaskin, T., Kahn, M., Tikoff, B. (2017). Intrusive and depositional constraints on the Cretaceous tectonic history of the southern Blue Mountains, eastern Oregon (pp. L554.1). Lithosphere
• Gaschnig, R., Rudnick, R.L., McDonough, W.F., Kaufman, A.J., Valley, J.W., Hu, Z., Gao, S., Beck, M.L. (2016). Compositional evolution of the upper continental crust through time, as constrained by ancient glacial diamictites. Geochimica et Cosmochimica Acta,186 316-343.
• Gaschnig, R., Vervoort, J., Tikoff, B., Lewis, R. (2016). Construction and preservation of batholiths in the northern US Cordillera. Lithosphere, L497-1.
• Li, S., Gaschnig, R., Rudnick, R.L. (2016). Insights into chemical weathering of the upper continental crust from the geochemistry of ancient glacial diamictites. Geochimica et Cosmochimica Acta,176 96-117.
• Vervoort, J.D., Lewis, R.S., Fisher, C., Gaschnig, R., Jansen, A.C., Brewer, R. (2016). Neoarchean and Paleoproterozoic crystalline basement rocks of north-central Idaho: Constraints on the formation of western Laurentia. Geological Society of America Bulletin,128(1-2) 94-109.
• Chen, K., Walker, R.J., Rudnick, R.L., Gao, S., Gaschnig, R., Puchtel, I.S., Tang, M., Hu, Z. (2016). Platinum-group element abundances and Re–Os isotopic systematics of the upper continental crust through time: Evidence from glacial diamictites. Geochimica et Cosmochimica Acta,191 1-16.
• Braudy, N., Gaschnig, R., Wilford, D., Vervoort, J., Nelson, C., Davidson, C., Kahn, M., Tikoff, B. (2016). Timing and deformation conditions of the western Idaho shear zone, West Mountain, west-central Idaho. Lithosphere, ³¢519–1.
• Vervoort, J., Fisher, C., Lewis, R., Baldwin, J., Wang, D., Jansen, A., Nesheim, T., Zirakparvar, N., McDonie, C., Gaschnig, R. (2016). Evidence for Neoarchean to Paleoproterozoic crustal formation and modification in the northern U.S. Geological Society of America
• Greaney, A., Rudnick, R., Gaschnig, R. (2016). Crustal sources of molybdenum. . Mineralogical Magazine (Goldschmidt Meeting).
• Gaschnig, R., Rudnick, R.L., McDonough, W.F. (2015). Determination of Ga, Ge, Mo, Ag, Cd, In, Sn, Sb, W, Tl and Bi in USGS Whole-Rock Reference Materials by Standard Addition ICP-MS. Geostandards and Geoanalytical Research,39(3) 371-379.
• Tang, M., Rudnick, R.L., McDonough, W.F., Gaschnig, R., Huang, Y. (2015). Europium anomalies constrain the mass of recycled lower continental crust. Geology,43(8) 703-706.
• Gaschnig, R., Rudnick, R.L., McDonough, W.F., Kaufman, A.J., Hu, Z., Gao, S. (2014). Onset of oxidative weathering of continents recorded in the geochemistry of ancient glacial diamictites. Earth and Planetary Science Letters,408(0) 87-99.
• Gaschnig, R., Vervoort, J.D., Lewis, R., Tikoff, B. (2013). Probing for Proterozoic and Archean crust in the northern U.S. Cordillera with inherited zircon from the Idaho batholith. Geological Society of America Bulletin,125(1-2) 73-88.
• Hu, Z., Zhang, W., Liu, Y., Chen, H., Gaschnig, R., Zong, K., Li, M., Gao, S., Hu, S. (2013). Rapid bulk rock decomposition by ammonium fluoride (NH4F) in open vessels at an elevated digestion temperature. Chemical Geology,355 144-152.
• Gray, K., Watkinson, A., Gaschnig, R., Isakson, V. (2012). Age and structure of the Crevice pluton: overlapping orogens in west-central Idaho? Canadian Journal of Earth Science,49 709-731.
• Davis, J., Coleman, D., Gracely, J., Gaschnig, R., Stearns, M. (2012). Magma accumulation rates and thermal histories of plutons of the Sierra Nevada batholith, CA. Contributions to Mineralogy and Petrology,163(3) 449-465.
• Zhang, W., Hu, Z., Liu, Y., Chen, H., Gao, S., Gaschnig, R. (2012). Total Rock Dissolution Using Ammonium Bifluoride (NH4HF2) in Screw-Top Teflon Vials: A New Development in Open-Vessel Digestion. Analytical Chemistry,84(24) 10686-10693.
• Anfinson, O., Leier, A., Gaschnig, R., Embry, A., Dewing, K. (2012). U-Pb and Hf isotopic data from Franklinian Basin strata: insights into the nature of Crockerland and the timing of accretion, Canadian Arctic Islands . Canadian Journal of Earth Science,49 1316-1328.
• Gaschnig, R., Vervoort, J.D., Lewis, R.S., Tikoff, B. (2011). Isotopic evolution of the Idaho batholith and Challis intrusive province, northern US Cordillera. Journal of Petrology,52(12) 2397-2429.
• Gaschnig, R., Vervoort, J., Lewis, R., McClelland, W. (2010). Migrating magmatism in the northern US Cordillera: in situ U–Pb geochronology of the Idaho batholith. Contributions to Mineralogy and Petrology,159(6) 863-883.
• Gaschnig, R., Vervoort, J., Lewis, R., Dufrane, S. (2008). Utilizing U-Pb geochronology of inherited zircon in the Atlanta lobe of the Idaho batholith as a probe of the deep crust in southern Idaho: a progress report. Northwest Geology,37 101-110.

Selected Contracts, Fellowships, Grants and Sponsored Research

• Collaborative Research: Tracking novel metal isotope signatures during subduction metamorphism (2020), Grant - NSF
  Gaschnig, R. (Principal)
• Resolving Mesoproterozoic supercontinent configuration with an integrated multi-tool approach to sedimentary provenance analysis (2020), Grant - NSF
  Gaschnig, R.