Bibliography - G. Dreyfus
- Dreyfus, G., J. Jouzel, Michael Bender, and Amaelle Landais, et al., 2010: Firn processes and δ15N: potential for a gas-phase climate proxy. Quaternary Science Reviews, 29(28-42), doi:10.1016/j.quascirev.2009.10.012
[ Abstract ]In order to quantify the sequence of events between changes in atmospheric composition and climate changes recorded in ice cores, we must accurately account for the age difference between ice and gas at a given depth. This gas age–ice age difference depends on the age of the ice at the bottom of the firn layer, where the bubbles are closed-off. Firn densification models are used to calculate how this age difference varied in the past, but have an uncertainty on the order of 1000 years for central Antarctic sites. Here we explore the possibility that δ15N of N2 is a gas phase proxy of climate, which can be used to synchronize gas and ice records. We present the δ15N record from the EPICA Dome C (EDC) ice core covering the last three glacial terminations and five glacial-interglacial cycles between 300 and 800 ka. Previous studies have shown that gravitational settling enriches δ15N as a function of the diffusive column height in the firn. If densification models’ prediction of deeper firn close-off under glacial conditions is correct, then we would expect heavier δ15N during glacial periods, and a negative correlation with temperature. Instead, EDC δ15N is positively correlated with the ice deuterium content, a proxy for temperature, as previously reported at Vostok, Dome Fuji, and EPICA Dronning Maud Land. We propose a mechanism that links accumulation rate, firn permeability, and convective mixing in the top meters of the firn to explain this correlation between δ15N and ice deuterium content. The tightest correlation is observed over glacial terminations, supporting the idea that δ15N is a property in the gas phase that records changes in surface conditions linked to deglacial warming.
- Bender, Michael, B. Barnett, G. Dreyfus, J. Jouzel, and D. Porcelli, 2008: The contemporary degassing rate of 40Ar from the solid Earth. Proceedings of the National Academy of Sciences of the United States of America, 105(24), doi:10.1073/pnas.0711679105
[ Abstract ]Knowledge of the outgassing history of radiogenic 40Ar, derived over geologic time from
the radioactive decay of 40K, contributes to our understanding of the geodynamic
history of the planet and the origin of volatiles on Earth’s surface. The 40Ar inventory of
the atmosphere equals total 40Ar outgassing during Earth history. Here, we report the
current rate of 40Ar outgassing, accessed by measuring the Ar isotope composition of
trapped gases in samples of the Vostok and Dome C deep ice cores dating back to
almost 800 ka. The modern outgassing rate (1.1 ± 0.1 x 108 mol/yr) is in the range of
values expected by summing outgassing from the continental crust and the upper
mantle, as estimated from simple calculations and models. The measured outgassing
rate is also of interest because it allows dating of air trapped in ancient ice core samples
of unknown age, although uncertainties are large (±180 kyr for a single sample or ±11%
of the calculated age, whichever is greater).
Direct link to page: http://cmi.princeton.edu/bibliography/results.php?author=3547
