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An extended period of episodic northern mid-latitude glaciation on Mars during the Middle to Late Amazonian: Implications for long-term obliquity history

Fassett, Caleb I. and Levy, Joseph S. and Dickson, James L. and Head, James W. (2014) An extended period of episodic northern mid-latitude glaciation on Mars during the Middle to Late Amazonian: Implications for long-term obliquity history. Geology, 42 (9). pp. 763-766. ISSN 0091-7613. https://resolver.caltech.edu/CaltechAUTHORS:20161129-095525797

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Abstract

Mars is the only planet other than Earth in the Solar System that has a preserved nonpolar geological record of glaciation on its surface. Nonpolar ice deposits on Mars have been linked to variations in spin-axis obliquity that cause mobilization of polar ice and redeposition at lower latitudes, forming ice-rich and glacial deposits. Remnant nonpolar glacial deposits are found across the northern mid-latitudes where surface ice is not currently stable, implying that different climatic conditions existed on Mars in the past. Individual glacial deposits are often too small to date reliably using impact crater size-frequency data. We describe a novel approach that allows us to derive new information about when glaciation occurred in broad areas of the northern mid-latitudes. In this region we have classified (1) craters that superpose preexisting glacial deposits and were modified by later accumulation (and therefore formed during an epoch when glaciation was occurring), and (2) craters that are superposed on glacial deposits but are themselves unmodified by ice accumulation (and thus post-date significant glaciation). The sparse population of post-glacial craters reveals that the last period of extensive ice deposition of this type in this latitude band was recent (Late Amazonian). The substantial number of craters formed during the recurring glacial periods implies that northern mid-latitude glaciation was a long-lived recurring process, occurring over a period of at least ∼600 m.y. On the basis of Mars atmospheric general circulation models, these results are consistent with higher obliquity being common in the past, with recurring periods of obliquity exceeding the 25° axial tilt of Mars today. These observations support the statistical prediction of J. Laskar and colleagues that the median obliquity during the Amazonian was ∼35°–40°.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1130/G35798.1DOIArticle
http://geology.gsapubs.org/content/42/9/763PublisherArticle
http://geology.geoscienceworld.org/content/42/9/763PublisherArticle
ORCID:
AuthorORCID
Fassett, Caleb I.0000-0001-9155-3804
Head, James W.0000-0003-2013-560X
Additional Information:© 2014 Geological Society of America. Manuscript received 24 April 2014; Revised manuscript received 10 June 2014; Manuscript accepted 11 June 2014. Fassett and Levy were supported by National Aeronautics and Space Administration (NASA) Mars Data Analysis program award NNX13AN50G, and Head was supported by NASA Mars Data Analysis program award NNX11AI81G. Donna Jurdy, Nadine Barlow, Stuart Robbins, and an anonymous reviewer provided comments that improved the manuscript.
Funders:
Funding AgencyGrant Number
NASANNX13AN50G
NASANNX11AI81G
Issue or Number:9
Record Number:CaltechAUTHORS:20161129-095525797
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20161129-095525797
Official Citation:An extended period of episodic northern mid-latitude glaciation on Mars during the Middle to Late Amazonian: Implications for long-term obliquity history Caleb I. Fassett, Joseph S. Levy, James L. Dickson, James W. Head Geology Sep 2014, 42 (9) 763-766; DOI: 10.1130/G35798.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72393
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:29 Nov 2016 18:05
Last Modified:09 Mar 2020 13:18

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