title: Extreme decay of meteoric beryllium-10 as a proxy for persistent aridity.
abstract: The modern Antarctic Dry Valleys are locked in a hyper-arid, polar climate that enables the East Antarctic Ice Sheet (EAIS) to remain stable, frozen to underlying bedrock. The duration of these dry, cold conditions is a critical prerequisite when modeling the long-term mass balance of the EAIS during past warm climates and is best examined using terrestrial paleoclimatic proxies. Unfortunately, deposits containing such proxies are extremely rare and often difficult to date. Here, we apply a unique dating approach to tundra deposits using concentrations of meteoric beryllium-10 ((10)Be) adhered to paleolake sediments from the Friis Hills, central Dry Valleys. We show that lake sediments were emplaced between 14-17.5 My and have remained untouched by meteoric waters since that time. Our results support the notion that the onset of Dry Valleys aridification occurred ~14 My, precluding the possibility of EAIS collapse during Pliocene warming events. Lake fossils indicate that >14 My ago the Dry Valleys hosted a moist tundra that flourished in elevated atmospheric CO2 (>400 ppm). Thus, Dry Valleys tundra deposits record regional climatic transitions that affect EAIS mass balance, and, in a global paleoclimatic context, these deposits demonstrate how warming induced by 400 ppm CO2 manifests at high latitudes.
authors.affiliation: Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Rachel D
authors.initials: RD
authors.lastname: Valletta
authors.affiliation: Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Jane K
authors.initials: JK
authors.lastname: Willenbring
authors.affiliation: Department of Geosciences, North Dakota State University, Fargo, North Dakota 58108, USA.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Lewis
authors.affiliation: Department of Geosciences, North Dakota State University, Fargo, North Dakota 58108, USA.
authors.forename: Allan C
authors.initials: AC
authors.lastname: Ashworth
authors.affiliation: Department of Physics and Astronomy, PRIME Lab, Purdue University, West Lafayette, Indiana 47907, USA.|Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Caffee