Current Projects
Ooids and the geologic record of shallow water carbonate chemistry
Ooids are concentrically coated chemical sand grains composed of calcium carbonate (calcite or aragonite) that occur ubiquitously in carbonate sequences of all ages. Our recent work using experiments, modeling, and modern field investigations has demonstrated that ooid size reflects a dynamic equilibrium between chemical and physical processes (i.e., precipitation and abrasion, respectively). Current and ongoing projects, including collaborations at CU with Carl Simpson and Jeff Cameron, will build on this project to better characterize the links between physical transport and ooid growth in modern environments and revisiting the enigmatic phenomena of giant ooids (ooids larger than 2 mm in diameter) in the context of the dynamic equilibrium model.
Ooids are concentrically coated chemical sand grains composed of calcium carbonate (calcite or aragonite) that occur ubiquitously in carbonate sequences of all ages. Our recent work using experiments, modeling, and modern field investigations has demonstrated that ooid size reflects a dynamic equilibrium between chemical and physical processes (i.e., precipitation and abrasion, respectively). Current and ongoing projects, including collaborations at CU with Carl Simpson and Jeff Cameron, will build on this project to better characterize the links between physical transport and ooid growth in modern environments and revisiting the enigmatic phenomena of giant ooids (ooids larger than 2 mm in diameter) in the context of the dynamic equilibrium model.
Granular iron formation
Granular iron formations (GIF) are iron- and silica-rich rocks that, in contrast with banded iron formations, are composed of individual silt- to sand-sized chemical sedimentary grains. This granular nature necessarily means that GIF record information about the physical properties and transport histories of the original particles. In collaboration with Latisha Brengman at the University of Minnesota Duluth, we are using experiments, modeling, petrography, and in situ geochemistry to investigate the consequences of physical transport on sedimentary components of varying compositions in GIF, with the goal of understanding what they record about paleoredox conditions after the Rise of Oxygen, secular changes in silica concentration and chemistry, and transport dynamics of unusual sedimentary grains.
Granular iron formations (GIF) are iron- and silica-rich rocks that, in contrast with banded iron formations, are composed of individual silt- to sand-sized chemical sedimentary grains. This granular nature necessarily means that GIF record information about the physical properties and transport histories of the original particles. In collaboration with Latisha Brengman at the University of Minnesota Duluth, we are using experiments, modeling, petrography, and in situ geochemistry to investigate the consequences of physical transport on sedimentary components of varying compositions in GIF, with the goal of understanding what they record about paleoredox conditions after the Rise of Oxygen, secular changes in silica concentration and chemistry, and transport dynamics of unusual sedimentary grains.
Si isotope ratios of cherts spanning Precambrian time, from Trower and Fischer (2019).
Secular evolution of the silica cycle
Late Proterozoic time marks a major change in marine silica cycle - a biological revolution when early eukaryotes (first sponges, then radiolarians) began to precipitate skeletons composed of amorphous silica. This marked the end of a Precambrian era in which the silica cycle was controlled by chemical processes like abiotic precipitation and adsorption onto other materials including clays and iron phases, with significant consequences for the concentration of dissolved silica in seawater and the size and distribution of chemical silica sinks. We are applying sedimentology, petrography, and in situ Si isotope geochemistry to understand the spatial and temporal pace of this transition from a chemically- to biologically-dominated silica cycle - in particular how it might record the evolution and spread of early silica-biomineralizing organisms.
Late Proterozoic time marks a major change in marine silica cycle - a biological revolution when early eukaryotes (first sponges, then radiolarians) began to precipitate skeletons composed of amorphous silica. This marked the end of a Precambrian era in which the silica cycle was controlled by chemical processes like abiotic precipitation and adsorption onto other materials including clays and iron phases, with significant consequences for the concentration of dissolved silica in seawater and the size and distribution of chemical silica sinks. We are applying sedimentology, petrography, and in situ Si isotope geochemistry to understand the spatial and temporal pace of this transition from a chemically- to biologically-dominated silica cycle - in particular how it might record the evolution and spread of early silica-biomineralizing organisms.
Publications
13. Ingalls, M., Frantz, C. M., Snell, K., and Trower, E. J. (in press) Carbonate facies-specific stable isotope data record climate, hydrology, and microbial communities in Great Salt Lake, UT. Geobiology.
12. Trower, E. J. (2020) The enigma of Neoproterozoic giant ooids—Fingerprints of extreme climate? Geophysical Research Letters.
11. Trower, E. J. and Fischer, W. W. (2019). Precambrian Si isotope mass balance, weathering, and the significance of the authigenic clay silica sink. Sedimentary Geology 384, 1-11.
10. Trower, E. J., Lamb, M. P., and Fischer, W. W. (2019). The origin of carbonate mud. Geophysical Research Letters 46(5), 2696-2703.
9. Trower, E. J., Cantine, M., Gomes, M., Lingappa, U. F., O'Reilly, S., Present, T. M., Stein, N., Strauss, J. V., Lamb, M. P., Grotzinger, J. P., Knoll, A. H., and Fischer, W. W. (2018). Active ooid growth driven by sediment transport in a high energy shoal, Little Ambergris Cay, Turks and Caicos Islands. Journal of Sedimentary Research 88 (9), 1132-1151.
8. Trower, E. J., Ganti, V., Fischer, W. W., and Lamb, M. P. (2018). Erosional surfaces in the Upper Cretaceous Castlegate Sandstone (Utah, USA): Sequence boundaries or autogenic scour from backwater hydrodynamics? Geology 46 (8), 707-710.
7. Trower, E. J., Lamb, M. P., and Fischer, W. W. (2017). Experimental evidence that ooid size reflects a dynamic equilibrium between rapid precipitation and abrasion rates. Earth and Planetary Science Letters 468, 112-118.
6. Trower, E. J., and Lowe, D. R. (2016). Sedimentology of the ~3.3 Ga upper Mendon Formation, Barberton Greenstone Belt, South Africa. Precambrian Research 281, 473-494.
5. Stefurak, E. J. T., Lowe, D. R., Zentner, D., and Fischer, W. W. (2015). Sedimentology and geochemistry of Archean silica granules. GSA Bulletin 127 (7-8), 1090-1107.
4. Decker, N. B., Byerly, G. R., Thompson Stiegler, M., Lowe, D. R., and Stefurak, E. (2015). High resolution tephra and U/Pb chronology of the 3.33-3.26 Ga Mendon Formation, Barberton Greenstone Belt, South Africa. Precambrian Research 261, 54-74.
3. Stefurak, E. J. T., Fischer, W. W., and Lowe, D. R. (2015). Texture-specific Si isotope variations in Barberton Greenstone Belt cherts record low temperature fractionations in early Archean seawater. Geochimica et Cosmochimica Acta 150, 26-52.
2. Stefurak, E. J. T., Lowe, D. R., Zentner, D., and Fischer, W. W. (2014). Primary silica granules – A new mode of early Archean sedimentation. Geology 42 (4), 283-286.
1. Trower, E. and Grotzinger, J. (2010). Sedimentology, diagenesis, and stratigraphic occurrence of giant ooids in the Ediacaran Rainstorm Member, Johnnie Formation, Death Valley region, California. Precambrian Research 180, 113-124.
12. Trower, E. J. (2020) The enigma of Neoproterozoic giant ooids—Fingerprints of extreme climate? Geophysical Research Letters.
11. Trower, E. J. and Fischer, W. W. (2019). Precambrian Si isotope mass balance, weathering, and the significance of the authigenic clay silica sink. Sedimentary Geology 384, 1-11.
10. Trower, E. J., Lamb, M. P., and Fischer, W. W. (2019). The origin of carbonate mud. Geophysical Research Letters 46(5), 2696-2703.
9. Trower, E. J., Cantine, M., Gomes, M., Lingappa, U. F., O'Reilly, S., Present, T. M., Stein, N., Strauss, J. V., Lamb, M. P., Grotzinger, J. P., Knoll, A. H., and Fischer, W. W. (2018). Active ooid growth driven by sediment transport in a high energy shoal, Little Ambergris Cay, Turks and Caicos Islands. Journal of Sedimentary Research 88 (9), 1132-1151.
8. Trower, E. J., Ganti, V., Fischer, W. W., and Lamb, M. P. (2018). Erosional surfaces in the Upper Cretaceous Castlegate Sandstone (Utah, USA): Sequence boundaries or autogenic scour from backwater hydrodynamics? Geology 46 (8), 707-710.
7. Trower, E. J., Lamb, M. P., and Fischer, W. W. (2017). Experimental evidence that ooid size reflects a dynamic equilibrium between rapid precipitation and abrasion rates. Earth and Planetary Science Letters 468, 112-118.
6. Trower, E. J., and Lowe, D. R. (2016). Sedimentology of the ~3.3 Ga upper Mendon Formation, Barberton Greenstone Belt, South Africa. Precambrian Research 281, 473-494.
5. Stefurak, E. J. T., Lowe, D. R., Zentner, D., and Fischer, W. W. (2015). Sedimentology and geochemistry of Archean silica granules. GSA Bulletin 127 (7-8), 1090-1107.
4. Decker, N. B., Byerly, G. R., Thompson Stiegler, M., Lowe, D. R., and Stefurak, E. (2015). High resolution tephra and U/Pb chronology of the 3.33-3.26 Ga Mendon Formation, Barberton Greenstone Belt, South Africa. Precambrian Research 261, 54-74.
3. Stefurak, E. J. T., Fischer, W. W., and Lowe, D. R. (2015). Texture-specific Si isotope variations in Barberton Greenstone Belt cherts record low temperature fractionations in early Archean seawater. Geochimica et Cosmochimica Acta 150, 26-52.
2. Stefurak, E. J. T., Lowe, D. R., Zentner, D., and Fischer, W. W. (2014). Primary silica granules – A new mode of early Archean sedimentation. Geology 42 (4), 283-286.
1. Trower, E. and Grotzinger, J. (2010). Sedimentology, diagenesis, and stratigraphic occurrence of giant ooids in the Ediacaran Rainstorm Member, Johnnie Formation, Death Valley region, California. Precambrian Research 180, 113-124.
Conference abstracts (* = presenting author, student mentee, postdoc mentee)
2019
2016
2015
2014
2013
2012
2010
- Li, X.*, Trower, E., Lehrmann, D., Minzoni, M., Kelley, B., Schaal, E., Yu, M., and Payne, J. L. “Implications of Giant Ooids for the Carbonate Chemistry of Early Triassic Oceans.” Poster presentation. AGU Annual Meeting. December 2019, San Francisco, CA, USA.
- Lingappa, U. F.*, Fischer, W. W., and Trower, L. “Ecophysiology of Ooid Microborings Excavated by Endolithic Cyanobacteria.” Poster presentation. AGU Annual Meeting. December 2019, San Francisco, CA, USA.
- Phillips, A. A.*, Speth, D. R., Miller, L. G., Wu, F., Wang, X. T., Potocek, D., Medeiros, P. M., Osburn, M. R., Johnson, H., Trower, L., Berelson, W., West, A. J., Fischer, W. W., Orphan, V. J., Betts, H., Sessions, A. L., and Geobiology Course 2017 & 2018. “Microbial Succession in Hypersaline, Alkaline Mono Lake, CA.” Poster presentation. AGU Annual Meeting. December 2019, San Francisco, CA, USA.
- Trower, L.*, Mahseredjian, T., Overeem, I., Gomes, M., Howard, C., Lingappa, U. F., Present, T., and Sibert, E. C. “Grain-Trapping by Microbial Mats—A Key Mechanism of Sediment Accumulation in Mangroves? (Invited)” Oral presentation. AGU Annual Meeting. December 2019, San Francisco, CA, USA.
- Trower, L.*, Bridgers, S. L., Lamb, M. P., and Fischer, W. W. “Cortical Stratigraphy of Ooids from Great Salt Lake, UT.” Poster presentation. AGU Annual Meeting. December 2019, San Francisco, CA, USA.
- Li, X.*, Trower, E., Lehrmann, D., Minzoni, M., Kelley, B., Schaal, E., Yu, M., and Payne, J. L. “Formation of Early Triassic giant ooids: A window revealing coeval tropical ocean chemistry.” Poster presentation. IAS Annual Meeting. September 2019, Rome, Italy.
- Yager, J. A.*, West, A. J., Trower, L., Corsetti, F. A., Bottjer, D. J., Berelson, W., and Fischer, W. W. “A change in silicic acid concentrations across the Triassic-Jurassic boundary? A look from δ30Si of sponge spicules via SIMS.” Poster presentation. AGU Annual Meeting. December 2018, Washington, DC, USA.
- Jamison-Todd, S. K.*, Stein, N., and Trower, L. “Sedimentology of Hurricane Irma Deposits on a Modern Carbonate Platform.” Poster presentation. AGU Annual Meeting. December 2018, Washington, DC, USA.
- Chan, A. M.*, Ingalls, M., Snell, K., and Trower, L. “Variations in Stable Isotope Composition of Great Salt Lake Carbonate: Is there a Microbial Impact on the Sedimentary Record?” Poster presentation. AGU Annual Meeting. December 2018, Washington, DC, USA.
- Trower, E. J.*, Bridgers, S., Lamb, M. P., and Fischer, W. W. “Ooid Cortical Stratigraphy: The Topology of Concentric Laminations in Carbonate Sand Grains Record Grain-Scale Environmental Histories (Invited Presentation)”. Oral presentation. GSA Annual Meeting. November 2018, Indianapolis, IN, USA.
- Trower, E. J.*, Cantine, M., Bergmann, K., Lamb, M. P., and Fischer, W. W. “Revisiting Precambrian Carbonate Mud Production: Evidence that Abrasion Played a Key Role (Invited Presentation)”. Oral presentation. GSA Annual Meeting. November 2018, Indianapolis, IN, USA.
- Brengman, L. A., Johnson, K.*, and Trower, E. J. “Grain Size Distributions and Mineralogy of Coated Grains, Detrital Sand and Silt Within the ∼1.9 Ga Mesabi Iron Range, Minnesota.” Poster presentation. GSA Annual Meeting. November 2018, Indianapolis, IN, USA.
- Ingalls, M.*, Trower, E., Frantz, C., and Snell, K. "Spatial stable isotope variability in modern lacustrine carbonate: How do local processes translate to the sedimentary record?" Oral presentation. Goldschmidt Conference. August 2018, Boston, MA, USA.
- Trower, E.*, Cantine, M., Gomes, M., Lingappa, U. F., O'Reilly, S., Present, T. M., Stein, N., Strauss, J. V., Lamb, M. P., Grotzinger, J. P., Knoll, A. H., Fischer, W. W. “Physical, Chemical, and Microbial Controls on Growth and Degradation of Ooids on Ambergris Shoal, Little Ambergris Cay, Turks and Caicos Islands, British Overseas Territories.” Oral presentation. AAPG Annual Meeting. May 2018, Salt Lake City, UT, USA.
- Grotzinger, J.*, Gomes, M., Lingappa, U., Stein, N., Trower, E., Alleon, J., Bahniuk, A. M., Cantine, M., Grotzinger, H., Metcalfe, K., Morris, D. K., O'Reilly, S., Orzechowski, E., Quinn, D., Sanders, C., Sibert, E., Strauss, J., Tarika, M., Thorpe, M., Fischer, W., Knoll, A. “Diverse and Spatially Extensive Microbial Mat and Ooid Sand Depositional System, Little Ambergris Cay, Turks and Caicos Islands.” Oral presentation. AAPG Annual Meeting. May 2018, Salt Lake City, UT, USA.
- Present, T. M.*, Trower, E., Gomes, M., Lingappa, U., Stein, N., Thorpe, M., Tarika, M., Alleon, J., Bahniuk, A. M., Morris, D. K., Orzechowski, E., Sanders, C., Sibert, E., Fischer, W., Knoll, A., Grotzinger, J. “Sedimentology and Geochemistry of Ooid Sands Buried Beneath Microbial Mats, Little Ambergris Cay, Turks and Caicos Islands.” Oral presentation. AAPG Annual Meeting. May 2018, Salt Lake City, UT, USA.
- Stein, N.*, Quinn, D., Grotzinger, J., Fischer, W., Ehlmann, B., Gomes, M., Hayden, A., Lingappa, U., Knoll, A., Trower, E. “Distribution of and Environmental Impacts on Microbial Mat Ecosystems of Little Ambergris Cay, Turks and Caicos.” Poster presentation. AAPG Annual Meeting. May 2018, Salt Lake City, UT, USA.
- Lingappa, U.*, Gomes, M., Metcalfe, K., Riedman, L., O’Reilly, S., Stein, N., Trower, E., Present, T. M., Fischer, W., Knoll, A., Grotzinger, J. “Ecology and Biogeochemistry of Microbial Mats on Little Ambergris Cay.” Poster presentation. AAPG Annual Meeting. May 2018, Salt Lake City, UT, USA.
- Trower, L.*, Kivrak, L., Lamb, M. P., Fischer, W. W. “Experimental Evidence that Abrasion of Carbonate Sand is a Significant Source of Carbonate Mud.” Oral presentation. AGU Fall Meeting. December 2017, New Orleans, LA, USA.
- Present, T. M.*, Trower, L., Stein, N., Alleon, J., Bahniuk, A., Gomes, M. L., Lingappa, U., Metcalfe, K., Orzechowski, E. A., Riedman, L. A., Sanders, C. B., Morris, D. K., O’Reilly, S., Sibert, E. S., Thorpe, M., Tarika, M., Fischer, W. W., Knoll, A. H., Grotzinger, J. P. “Context, Biogeochemistry, and Morphology of Diverse and Spatially Extensive Microbial Mats, Little Ambergris Cay, Turks and Caicos Islands, B.W.I.” Poster presentation. AGU Fall Meeting. December 2017, New Orleans, LA, USA.
- Meixnerova, J.*, Betts, M., Westacott, S., Ingalls, M., Miller, L. G., Sessions, A. L., Trower, L., Agouron Geobiology Course. “Mono Lake sediments preserve a record of recent environmental change.” Poster presentation. AGU Fall Meeting. December 2017, New Orleans, LA, USA.
- Westacott, S.*, Ingalls, M., Meixnerova, J., Betts, M., Lloyd, M. K., Miller, L. G., Sessions, A. L., Trower, L., Agouron Geobiology Course. “δ18O and Carbonate Clumped Isotopes as Proxies of Lake Level Change: Mono Lake Modern Sediments Inform Pleistocene Interpretations.” Poster presentation. AGU Fall Meeting. December 2017, New Orleans, LA, USA.
- Trower, E. J.*, Fischer, W. W. "The Role Of Silica as a Chemical Sediment Prior to the Advent of Metazoan Biomineralization (Invited Presentation)." Oral presentation. GSA Fall Meeting. October 2017, Seattle, WA, USA.
- Betts, M. N.*, Meixnerova, J., Ingalls, M., Westacott, S., Miller, L. G., Sessions, A. L, Trower, E. J., Agouron Geobiology Course 2017. "Mono Lake Sediments: A Record of Recent Environmental Change." Poster presentation. GSA Fall Meeting. October 2017, Seattle, WA, USA.
- Ingalls, M.*, Westacott, S., Betts, M. N., Meixnerova, J., Lloyd, M., Miller, L. G., Sessions, A. L., Trower, E. J., Agouron Geobiology Course 2017. "Sources of Carbonate Precipitation in Mono Lake Sediments: δ18O and Carbonate Clumped Isotopes as Lake Level Proxies." Poster presentation. GSA Fall Meeting. October 2017, Seattle, WA, USA.
- Trower, E.*, Lamb, M. P., Cantine, M., O'Reilly, S., Stein, N., Gomes, M., Strauss, J. V., Grotzinger, J. P., Knoll, A. H., and Fischer, W. W. "Sediment transport controls ooid growth." Poster presentation. Southern California Geobiology Symposium. April 2016, Los Angeles, CA, USA.
- Trower, E.*, Lamb, M. P., Grotzinger, J. P., Cantine, M., O’Reilly, S., and Fischer, W. W. “Sediment Transport Controls Ooid Growth.” Poster presentation. AAPG Annual Meeting. April 2017, Houston, TX, USA.
2016
- Trower, L.*, Cantine, M., O’Reilly, S. S., Strauss, J. V., Gomes, M. L., Grotzinger, H. M., Grotzinger, J. P., Knoll, A. H., Lamb, M. P., Lingappa, U., Metcalfe, K., Orzechowski, E. A., Quinn, D. P., Reidman, L. A., Stein, N., Fischer, W. W. “Evidence of Active Ooid Growth from Little Ambergris Cay, Turks and Caicos Islands, B. W. I.” Oral presentation. AGU. December 2016, San Francisco, CA, USA.
- Gomes, M. L.*, Lingappa, U., Metcalfe, K., O'Reilly, S. S., Riedman, L. A., Cantine, M., Ireland, B., Phillips, R., Stein, N., Orzechowski, E. A., Strauss, J. V., Grotzinger, H. M., Quinn, D. P., Trower, L., Fischer, W. W., Grotzinger, J. P., Knoll, A. H., Fike, D. A. "Linking the modern to the ancient with a comprehensive geobiological understanding of biosignature preservation in microbial mats." Poster presentation. AGU. December 2016, San Francisco, CA, USA.
- Grotzinger, J. P.*, Knoll, A. H., Fischer, W. W., Cantine, M., Gomes, M. L., Grotzinger, H. M., Lingappa, U., Metcalfe, K., O'Reilly, S. S., Orzechowski, E. A., Quinn, D. P., Reidman, L. A., Stein, N., Strauss, J. V., Trower, L. "Context, Biogeochemistry, and Morphology of Diverse and Spatially Extensive Microbial Mats, Little Ambergris Cay, Turks and Caicos Islands, BWI." Oral presentation. AGU. December 2016, San Francisco, CA, USA.
- Stein, N.*, Quinn, D. P., Grotzinger, J. P., Knoll, A. H., Fischer, W. W., Cantine, M., Gomes, M. L., Grotzinger, H. M., Lingappa, U., Metcalfe, K., O'Reilly, S. S., Orzechowski, E. A., Reidman, L. A., Strauss, J. V., Trower, L. "UAV, DGPS, and Laser Transit Mapping of Microbial Mat Ecosystems on Little Ambergris Cay, BWI." Poster presentation. AGU. December 2016, San Francisco, CA, USA.
- Orzechowski, E. A.*, Strauss, J. V., Knoll, A. H., Fischer, W. W., Cantine, M., Gomes, M. L., Grotzinger, H. M., Lingappa, U., Metcalfe, K., O'Reilly, S. S., Quinn, D. P., Reidman, L. A., Stein, N., Trower, L., Grotzinger, J. P. "Age and Construction of Little Ambergris Cay Bedrock Rim, Southeastern Caicos Platform, British West Indies." Poster presentation. AGU. December 2016, San Francisco, CA, USA.
- Ganti, V., Chadwick, A. J., Lamb, M. P., Fischer, W. W., Trower, L. "Autogenic erosional surfaces on backwater-mediated deltas from floods and avulsions." Oral presentation. AGU. December 2016, San Francisco, CA, USA.
- Trower, E. J.*, Lamb, M. P., and Fischer, W. W. “Why Do Ooids Grow So Slowly?” Oral presentation. GSA Fall Meeting. September 2016, Denver, CO, USA.
- Trower, E. J.*, Lamb, M. P., and Fischer, W. W. “Controls on ooid size: An experimental approach.” Oral presentation. Southern California Geobiology Symposium. May 2016, Pasadena, CA, USA.
2015
- Trower, E. J.*, Lamb, M. P., and Fischer, W. W. “What Controls Ooid Grain Size?” Oral presentation. AGU. December 2015, San Francisco, CA, USA.
2014
- Stefurak, E. J. T.*, Lowe, D. R., Zentner, D., and Fischer, W. W. “Primary silica granules – Insights into silica precipitation mechanisms in early Archean seawater.” Oral presentation. GSA Fall Meeting. October 2014, Vancouver, BC, Canada.
2013
- Stefurak, E. J. T.*, Lowe, D. R., Zentner, D., and Fischer, W. W. “The formation and deposition of primary silica granules – A new model of early Archean silica deposition.” Oral presentation. AGU. December 2013, San Francisco, CA, USA.
- Bird, J.*, Stefurak, E., Anderson, R., Menekse, M., Berelson, W., Sessions, A., Osburn, M., Spear, J., Stamps, B., Stevenson, B., Shapiro, R., Torres, M., and Corsetti, F. “Evaluating the biological influences on ooid formation in the Great Salt Lake, Utah.” Poster presentation. AGU. December 2013, San Francisco, CA, USA.
- Anderson, R. P.*, Bird, J. T., Menekse, M., Stefurak, E. J. T., Berelson, W., Petryshyn, V. A., Shapiro, R. S., Sessions, A. L., Tripati, A., and Corsetti, F. A. “Ooid formation in the Great Salt Lake, Utah: insights from clumped isotope paleothermometry.” Poster presentation. AGU. December 2013, San Francisco, CA, USA.
- Stefurak, E. J. T.*, Fischer, W. W., and Lowe, D. R. “δ³⁰Si in early Archean cherts and implications for the silica cycle.” Oral presentation. Goldschmidt. August 2013, Florence, Italy.
2012
- Stefurak, E. J. T.*, Fischer, W. W., and Lowe, D. R. “Evidence of low temperature fractionation of silicon in Archean cherts: SIMS Si and O isotope measurements of 3.42-3.26 Ga banded carbonaceous cherts from the Onverwacht Group, Barberton Greenstone Belt, South Africa.” Oral presentation. AGU. December 2012, San Francisco, CA, USA.
- Decker, N. B.*, Stefurak, E. J. T., Thompson, M. E., Lowe, D. R., and Byerly, G. R. “High resolution tephra and U/Pb chronology of the 3.33-3.26 Ga Mendon Formation, Barberton Greenstone Belt, South Africa.” Poster presentation. AGU. December 2012, San Francisco, CA, USA.
2010
- Trower, E.*, and Grotzinger, J. “Investigating the origin of the Rainstorm giant ooids in the Ediacaran Johnnie Formation, Death Valley region, California.” Poster presentation. Southern California Geobiology Symposium. April 2010, Pasadena, CA, USA.