Graham Harper Edwards, PhD

Graham Harper Edwards, PhD

he | him
geo/cosmo chemistry
geo/cosmo chronology
Assistant Professor (Fall 2024)

gedward1 at trinity.edu

Publications

Uranium-series isotopes as tracers of physical and chemical weathering in glacial sediments from Taylor Valley, Antarctica

G.H. Edwards, G.G. Piccione, T. Blackburn, S. Tulaczyk
Chemical Geology, in review       Preprint       Code       Data

Uranium series isotopes are sensitive tracers of both chemical and physical weathering. We report U-series data from fine-grained sediments form Taylor Valley, Antarctica that were deposited over the course of the last million years. Using novel numerical techniques we interpret the coupled chemical-physical weathering histories and show that Taylor Glacier has been eroding into Taylor Valley over the course of the Pleistocene.

An early giant planet instability recorded in asteroidal meteorites

G.H. Edwards, C.B. Keller, E.R. Newton, C.W. Stewart
Nature Astronomy, in review       Web       Preprint       Code

We use a Bayesian statistical code to constrain the timescales of giant planet migration and asteroid belt bombardment in the early solar system. Our results associate giant planet migration with the dissipation of the gaseous protoplanetary disk.
The preprint was summarized by Astrobites, and I was quoted in two recent articles on the topic of giant planet migration in Science Magazine and Sky & Telescope.

Ice retreat in Wilkes Basin of East Antarctica during a warm interglacial

T. Blackburn, G.H. Edwards, S. Tulaczyk, M. Scudder, G. Piccione, B. Hallet, N. McLean, J.C. Zachos, B. Cheney, J.T. Babbe
Nature, 2020       PDF       Web

Press coverage in National Geographic
U-series isotopics of subglacial precipitates from beneath the East Antarctic Ice Sheet (EAIS) record an open-system event ca. 400,000 years ago in the subglacial Wilkes Basin. Our data and models support ice retreat and seawater incursion during this time, suggesting that the Pleistocene EAIS was not as stable as previously assumed. These findings bear important implications for future EAIS stability in a warming climate.

Detecting the extent of ca. 1.1 Ga Midcontinent Rift plume heating using U-Pb thermochronology of the lower crust

G.H. Edwards and T. Blackburn
Geology, 2018       PDF       Web

We combine U-Pb thermochronology of rutile and apatite from middle-to-lower crustal xenoliths form an Attawapiskat kimberlite with paired crustal thermal and Pb-production diffusion models to ascertain the timescales of plume heating beneath the Superior Craton in midwestern Canada. Thermochronologic data are best fit by model simulations in which the Attawapiskat lithosphere experienced a ca. 1.1 Ga heating event triggered by partial lithosphere removal and mantle temperatures >200 °C in excess of that of ambient mantle, consistent with a model of ∼100 m.y. plume head residence beneath the Attawapiskat region.