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In March of 2019 I’ll be joining the Department of Earth Sciences at Dartmouth as an assistant professor, so will be looking for future grad students!
UC Berkeley press release for the new paper out this week in Nature “A record of deep-ocean dissolved O2 from the oxidation state of iron in submarine basalts” by Stolper and Keller.
Barbara Ratschbacher, Kyle Samperton, Katie Ardill and I will be convening a session on arc magmatism at the 2018 Goldschmidt Conference in Boston (August 12-18th). Abstract submission will begin in early 2018 - read more here
New paper on basalt geochemistry with implications for the prevalence of plate tectonics and arc-style magmatism (hydrous flux melting) throughout the preserved continental rock record. Read all about it here!
C. Brenhin Keller and Blair Schoene.
Nature, 2012: https://doi.org/10.1038/nature11024
My first significant computational work - originally a side project to work on as a grad student while waiting for Blair's clean lab to be built. We were surprised by the strength and consistency of the geochemical trends we observed on Gyr timescales. The simplest signals directly reflect secular mantle cooling, but others hint at a change in crustal evolution that appears to coincide temporally with oxidation of the surface Earth in the Great Oxygenation Event.
C. Brenhin Keller, Blair Schoene, Melanie Barboni, Kyle M. Samperton, and Jon M. Husson.
Nature, 2015: https://doi.org/10.1038/nature14584
Here we used the weighted bootstrap resampling approach from our 2012 paper to address the longstanding question of volcanic-plutonic parity. The results indicate that felsic plutons are not (on average) significantly more cumulate than felsic volcanics, favor fractional crystallization as the predominant mechanism of geochemical differentiation, and suggest the influence of magmatic water content on magma stalling and intrusion. This paper was my first foray into high-performance computing, running ~1.3 million pMELTS simulations to invert for P-T paths and water contents that produce differentiation trends similar to the those observed in the natural dataset.
Magma emplacement, differentiation and cooling in the middle crust: Integrated zircon geochronological–geochemical constraints from the Bergell Intrusion, Central Alps
Kyle M. Samperton, Blair Schoene, John M. Cottle, C. Brenhin Keller, James L. Crowley, and Mark D. Schmitz.
Chemical Geology, 2015: https://doi.org/10.1016/j.chemgeo.2015.10.024
Chad D. Deering, C. Brenhin Keller, Blair Schoene, Olivier Bachmann, Rachel Beane, and Maria Ovtcharova
Geology, 2016: https://doi.org/10.1130/G37539.1
Melanie Barboni, Patrick Boehnke, Brenhin Keller, Issaku E. Kohl, Blair Schoene, Edward D. Young, and Kevin D. McKeegan
Science Advances, 2017: https://doi.org/10.1126/sciadv.1602365
C. Brenhin Keller, Patrick Boehnke, and Blair Schoene
Geochemical Perspectives Letters, 2017: https://doi.org/10.7185/geochemlet.1721
Here we investigated the variation in the amount of zircon expected to saturate from magmas of different ages throughout Earth history by running full MELTS simulations along with trace element partitioning calculations (on a local Princeton University cluster) for each of the ~70,000 samples in the Keller & Schoene (2012) dataset. We found that older magmas crystallize substantially less zircon per unit mass due to the geochemical consequences of secular mantle cooling – suggesting that a larger volume of felsic magmatism is required to explain the Archean (and perhaps the Hadean) zircon record than previously considered. We note also that anorthosite flotation crust is largely zircon free and thus invisible to zircon-based crustal growth models, with implications explored in the supplement.
Allen J. Schaen, John M. Cottle, Brad S. Singer, C. Brenhin Keller, Nicolas Garibaldi, and Blair Schoene
Geology, 2017: https://doi.org/10.1130/G39167.1
Kyle M. Samperton, Elizabeth A. Bell, Mélanie Barboni, C. Brenhin Keller and Blair Schoene
Geology, 2017: https://doi.org/10.1130/G38645.1
Brenhin Keller and Blair Schoene.
Earth and Planetary Science Letters, 2018: https://doi.org/10.1016/j.epsl.2017.10.031
In this longer-format paper we examine in detail the record of basaltic rocks preserved in the continental crust, building on the weighted bootstrap resampling procedure of Keller and Schoene, 2012. A range of rapid trace element variations in the basaltic record can be explained as a result of mantle melting systematics (changing partition coefficients as a result of Grt and Cpx-out). Both trace element signatures of slab fluid input and major element signatures of calc-alkaline vs tholeiitic differentiation are remarkably stable and consistently arc-like, strongly suggesting the occurence of subduction and plate tectonics throughout the preserved rock record (back to at least 3.85 Ga). While some non-plate tectonic models may produce some flux melting, a virtually constant proportion of flux to decompression melting in the preserved continental record is a tall order for any non-plate model for Archean tectonics.
Daniel A. Stolper and C. Brenhin Keller
Nature, 2018: https://doi.org/10.1038/nature25009
Patrick Boehnke, Elizabeth A. Bell, Thomas Stephan, Reto Trappitsch, C. Brenhin Keller, Olivia S. Pardo, Andrew M. Davis, T. Mark Harrison, and Michael J. Pellin
Proceedings of the National Academy of Sciences, 2018: https://doi.org/10.1073/pnas.1720880115
Undergraduate Course, Cornell University, Department of Earth and Atmospheric Sciences, 2009
As a senior undergraduate, I acted as TA for the lab section of Prof. Sue Kay’s mineralogy course, with a mixed enrollment of undergraduate and graduate students. Topics included crystallography, group theory, identification, and optical mineralogy.
Undergraduate Course, Princeton University, Department of Geosciences, 2011
As a first-year graduate student, I acted as TA and grader for two lab sections of Prof. Allen Rubin’s natural disasters course.
Undergraduate Course, Princeton University, Department of Geosciences, 2015
As a fifth-year graduate student, I acted as TA for Prof. Blair Schoene’s petrology course, where I developed new lab assignments, guided students in selecting and developing independent group research projects, and integrated the mapping and sampling components of student projects into our week-long course field trip. Upon our return, students conducted a range of analyses on field samples, including whole-rock geochemistry by solution ICPMS, thin section petrology, and carbonate isotopic analyses. Several lab sections were devoted to assisting students in completing these analyses and preparing final reports.
Award, Princeton University, Department of Geosciences, 2015
Recognizing graduate student contributions to the teaching mission of the department