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Published April 2009 | Published
Journal Article Open

Amazonian‐aged fluvial valley systems in a climatic microenvironment on Mars: Melting of ice deposits on the interior of Lyot Crater

Abstract

Valley networks, regional drainage patterns suggesting liquid water stability at the surface, are confined to early in the history of Mars (the Noachian/Hesperian boundary and before), prior to a major climate transition to the hyperarid cold conditions of the Amazonian. Several later fluvial valley systems have been documented in specific Hesperian and Early Amazonian environments, and are thought to have formed due to local conditions. Here we describe fluvial valley systems within Lyot crater that have the youngest well-constrained age reported to date (Middle or Late Amazonian) for systems of this size (tens of km). These valleys are linked to melting of near-surface ice-rich units, extend up to ∼50 km in length, follow topographic gradients, and deposit fans. The interior of Lyot crater is an optimal micro-environment, since its low elevation leads to high surface pressure, and temperature conditions at its location in the northern mid-latitudes are sufficient for melting during periods of high-obliquity. This micro-environment in Lyot apparently allowed melting of surface ice and the formation of the youngest fluvial valley systems of this scale yet observed on Mars.

Additional Information

© 2009 by the American Geophysical Union. Received 25 January 2009; revised 17 March 2009; accepted 20 March 2009; published 17 April 2009. We appreciate helpful discussions with Joseph Levy, Samuel Schon, Francois Forget, J.-B. Madeleine, and Aymeric Spiga. Insightful reviews from Vic Baker and an anonymous reviewer improved the final manuscript. We greatly acknowledge financial assistance from the NASA Mars Data Analysis Program grants NNG04GJ99G and NNX07AN95G, the NASA Mars Fundamental Research Program grant GC196412NGA, the NASA Applied Information Systems Research Program grant NNG05GA61G, and the Mars Express Guest Investigator Program, JPL contract 1237163.

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August 21, 2023
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