Most of these publications may also be found on my google scholar profile.
If you like the format of the preprints included here, see preprint-template.tex

Curation and Analysis of Global Sedimentary Geochemical Data to Inform Earth History

Akshay Mehra, C. Brenhin Keller, Tianran Zhang, Nicholas J. Tosca, Scott M. McLennan, Erik Sperling, Una Farrell, Jochen Brocks, Donald Canfield, Devon Cole, Peter Crockford, Huan Cui, Tais W. Dahl, Keith Dewing, Joe Emmings, Robert R Gaines, Tim Gibson, Geoffrey J. Gilleaudeau, Romain Guilbaud, Malcolm Hodgkiss, Amber Jarrett, Pavel Kabanov, Marcus Kunzmann, Chao Li, David K Loydell, Xinze Lu, Austin Miller, N. Tanner Mills, Lucas D. Mouro, Brennan O’Connell, Shanan E. Peters, Simon Poulton, Samantha R. Ritzer, Emmy Smith, Philip Wilby, Christina Woltz, Justin V. Strauss
GSA Today, 2021:

The composition and weathering of the continents over geologic time

Alex G. Lipp, Oliver Shorttle, Erik A. Sperling, Jochen J. Brocks, Devon Cole, Peter W. Crockford, Lucas Del Mouro, Keith Dewing, Stephen Q. Dornbos, Joseph F. Emmings, Una C. Farrell, Amber Jarrett, Benjamin W. Johnson, Pavel Kabanov, C. Brenhin Keller, Marcus Kunzmann, Austin J. Miller, N. Tanner Mills, Brennan O’Connell, Shanan E. Peters, Noah J. Planavsky, Samantha R. Ritzer, Shane D. Schoepfer, Philip R. Wilby, and Jianghai Yang
Geochemical Perspectives Letters, 2021:

Increased ecological resource variability during a critical transition in hominin evolution

Richard Potts, René Dommain, Jessica W. Moerman1, Anna K. Behrensmeyer, Alan L. Deino, Simon Riedl, Emily J. Beverly, Erik T. Brown, Daniel Deocampo, Rahab Kinyanjui, Rachel Lupien, R. Bernhart Owen, Nathan Rabideaux, James M. Russell, Mona Stockhecke, Peter deMenocal, J. Tyler Faith, Yannick Garcin, Anders Noren, Jennifer J. Scott, David Western, Jordon Bright, Jennifer B. Clark, Andrew S. Cohen, C. Brenhin Keller, John King, Naomi E. Levin, Kristina Brady Shannon, Veronica Muiruri, Robin W. Renaut, Stephen M. Rucina and Kevin Uno
Science Advances, 2020:

Constraining crustal silica on ancient Earth

C. Brenhin Keller and T. Mark Harrison
Proceedings of the National Academy of Sciences, 2020:
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On geologic timescales, Earth’s habitable climate is maintained by a negative feedback process wherein atmospheric CO₂ is consumed by reaction with silicate rocks during erosion and weathering. However, relative to modern continental crust, many models propose an ancient crust that was thinner, denser, and significantly lower in silica for the first 1 to 2 billion years of Earth history. Like modern oceanic crust, such mafic crust would likely be poorly exposed to the atmosphere, resulting in a less climatically stable early Earth. We find that two geologic processes (mantle cooling and atmospheric oxidation) significantly compromise some previous methods for estimating ancient crustal composition. Accounting for these factors results in estimates much closer to the composition of modern continental crust.

Stepwise chemical abrasion–isotope dilution–thermal ionization mass spectrometry with trace element analysis of microfractured Hadean zircon

C. Brenhin Keller, Patrick Boehnke, Blair Schoene, and T. Mark Harrison
Geochronology, 2019:
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The oldest known minerals on Earth are Hadean (> 4.0 Ga) zircons from the Jack Hills, Australia. We present the first application to such Hadean zircons of stepwise chemical abrasion isotope dilution thermal ionization mass spectrometry with trace element analysis (stepwise CA-ID-TIMS-TEA). We examine the evolution in U-Pb age and trace element chemistry of zircon domains accessed by successive chemical abrasion steps in the context of the geologic history of the Jack Hills zircons.

Chronostratigraphic model of a high-resolution drill core record of the past million years from the Koora Basin, south Kenya Rift: Overcoming the difficulties of variable sedimentation rate and hiatuses

Alan Deino, Rene Dommain, C. Brenhin Keller, Richard Potts, Anna Behrensmeyer, Emily Beverly, John King, Clifford Heil, Mona Stockhecke, Erik Brown, Jessica Moerman, Peter de Menocal, and the Olorgesailie Drilling Project Scientific Team
Quaternary Science Reviews, 2019:

Neoproterozoic glacial origin of the Great Unconformity

C. Brenhin Keller, Jon M. Husson, Ross N. Mitchell, William F. Bottke, Thomas M. Gernon, Patrick Boehnke, Elizabeth A. Bell, Nicholas L. Swanson-Hysell, and Shanan E. Peters
Proceedings of the National Academy of Sciences, 2019:
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It has long been observed that the sequence of sedimentary rocks deposited in the past half-billion years often sharply overlies older igneous or metamorphic basement at an erosional surface known as the Great Unconformity. We provide evidence that this unconformity may record rapid erosion during Neoproterozoic “snowball Earth” glaciations. We show that the extent of Phanerozoic sedimentation in shallow continental seas can be accurately reproduced by modeling the accommodation space produced by the proposed glacial erosion, underlining the importance of glaciation as a means for lowering erosional base level. These results provide constraints on the sedimentary and geochemical environment in which the first multicellular animals evolved and diversified in the “Cambrian explosion” following the unconformity.

Plate tectonics and continental basaltic geochemistry throughout Earth history

Brenhin Keller and Blair Schoene.
Earth and Planetary Science Letters, 2018:
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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.

Temporal variation in relative zircon abundance throughout Earth history

C. Brenhin Keller, Patrick Boehnke, and Blair Schoene
Geochemical Perspectives Letters, 2017:
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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.

Volcanic–plutonic parity and the differentiation of the continental crust

C. Brenhin Keller, Blair Schoene, Melanie Barboni, Kyle M. Samperton, and Jon M. Husson.
Nature, 2015:
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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.

Statistical geochemistry reveals disruption in secular lithospheric evolution about 2.5 Gyr ago

C. Brenhin Keller and Blair Schoene.
Nature, 2012:
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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.