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Stratigraphy of Aeolis Dorsa, Mars: Stratigraphic context of the great river deposits

Kite, Edwin S. and Howard, Alan D. and Lucas, Antoine S. and Armstrong, John C. and Aharonson, Oded and Lamb, Michael P. (2015) Stratigraphy of Aeolis Dorsa, Mars: Stratigraphic context of the great river deposits. Icarus, 253 . pp. 223-242. ISSN 0019-1035. https://resolver.caltech.edu/CaltechAUTHORS:20150522-081302314

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Abstract

Unraveling the stratigraphic record is the key to understanding ancient climate and past climate changes on Mars (Grotzinger, J. et al. [2011]. Astrobiology 11, 77–87). Stratigraphic records of river deposits hold particular promise because rain or snowmelt must exceed infiltration plus evaporation to allow sediment transport by rivers. Therefore, river deposits when placed in stratigraphic order could constrain the number, magnitudes, and durations of the wettest (and presumably most habitable) climates in Mars history. We use crosscutting relationships to establish the stratigraphic context of river and alluvial-fan deposits in the Aeolis Dorsa sedimentary basin, 10°E of Gale crater. At Aeolis Dorsa, wind erosion has exhumed a stratigraphic section of sedimentary rocks consisting of at least four unconformity-bounded rock packages, recording three or more distinct episodes of surface runoff. Early deposits (>700 m thick) are embayed by river deposits (>400 m thick), which are in turn unconformably draped by fan-shaped deposits (<100 m thick) which we interpret as alluvial fans. Yardang-forming layered deposits (>900 m thick) unconformably drape all previous deposits. River deposits embay a dissected landscape formed of sedimentary rock. The river deposits are eroding out of at least two distinguishable units. There is evidence for pulses of erosion during the interval of river deposition. The total interval spanned by river deposits is >(1 × 10^6–2 × 10^7) yr, and this is extended if we include alluvial-fan deposits. Alluvial-fan deposits unconformably postdate thrust faults which crosscut the river deposits. This relationship suggests a relatively dry interval of >4 × 10^7 yr after the river deposits formed and before the fan-shaped deposits formed, based on probability arguments. Yardang-forming layered deposits unconformably postdate all of the earlier deposits. They contain rhythmite and their induration suggests a damp or wet (near-) surface environment. The time gap between the end of river deposition and the onset of yardang-forming layered deposits is constrained to >1 × 10^8 yr by the high density of impact craters embedded at the unconformity. The time gap between the end of alluvial-fan deposition and the onset of yardang-forming layered deposits was at least long enough for wind-induced saltation abrasion to erode 20–30 m into the alluvial-fan deposits. We correlate the yardang-forming layered deposits to the upper layers of Gale crater’s mound (Mt. Sharp/Aeolis Mons), and the fan-shaped deposits to Peace Vallis fan in Gale crater. Alternations between periods of low mean obliquity and periods of high mean obliquity may have modulated erosion–deposition cycling in Aeolis. This is consistent with the results from an ensemble of simulations of Solar System orbital evolution and the resulting history of the obliquity of Mars. 57 of our 61 simulations produce one or more intervals of continuously low mean Mars obliquity that are long enough to match our Aeolis Dorsa unconformity data.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.icarus.2015.03.007 DOIArticle
http://www.sciencedirect.com/science/article/pii/S0019103515001001PublisherArticle
ORCID:
AuthorORCID
Kite, Edwin S.0000-0002-1426-1186
Aharonson, Oded0000-0001-9930-2495
Lamb, Michael P.0000-0002-5701-0504
Additional Information:© 2015 Elsevier Inc. Received 31 July 2014; Revised 4 March 2015; Accepted 5 March 2015; Available online 14 March 2015. We thank Devon Burr, Lynn Carter, Laura Kerber, Robert Jacobsen, Misha Kreslavsky, Caleb Fassett, David Mohrig, Ben Cardenas, Stephen Scheidt, and Bethany Ehlmann, for sharing their ideas about Aeolis Dorsa in many discussions that have made this a stronger paper. We thank Noah Finnegan, Jonathan Stock and Ross Irwin for discussions on paleohydrology, and Gary Kocurek, Dick Heermance and Paul Olsen for discussions on aeolian-fluvial interactions. We thank all the participants in the Caltech Mars Geomorphology Reading Group, especially Katie Stack, Kirsten Siebach, Roman DiBiase, Ajay Limaye, Joel Scheingross, Woody Fischer, Lauren Edgar, and Jeff Prancevic. Kevin Lewis, Frederik Simons, and Or Bialik provided useful feedback on an early draft. Brian Hynek shared an enlightening pre-publication map of Meridiani. Jenny Blue coordinated the naming of Obock, Neves, Kalba, Asau and Gunjur craters. We thank Ross Beyer, Sarah Mattson, Audrie Fennema, Annie Howington-Kraus, and especially Cynthia Phillips for help with DTM generation. We thank Sanjeev Gupta, and another reviewer who chose to remain anonymous, for suggestions that improved the paper. We are particularly grateful to the HiRISE team for maintaining the HiWish program, which led to the acquisition of multiple images that were essential to this study. This work was completed in part with resources provided by the University of Chicago Research Computing Center (MIDWAY cluster). This work was financially supported by the US taxpayer through NASA grant NNX11AF51G (to O.A.), by Caltech through the award of an O.K. Earl Fellowship (to E.S.K.), by Princeton University through the award of a Harry Hess Fellowship (to E.S.K.), and by the Helen Kimmel Center for Planetary Science and I-CORE program.
Funders:
Funding AgencyGrant Number
NASANNX11AF51G
O. K. Earl Postdoctoral FellowshipUNSPECIFIED
Princeton UniversityUNSPECIFIED
Helen Kimmel Center for Planetary ScienceUNSPECIFIED
I-CORE ProgramUNSPECIFIED
Subject Keywords:Mars; Mars, surface; Geological processes
Record Number:CaltechAUTHORS:20150522-081302314
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150522-081302314
Official Citation:Edwin S. Kite, Alan D. Howard, Antoine S. Lucas, John C. Armstrong, Oded Aharonson, Michael P. Lamb, Stratigraphy of Aeolis Dorsa, Mars: Stratigraphic context of the great river deposits, Icarus, Volume 253, June 2015, Pages 223-242, ISSN 0019-1035, http://dx.doi.org/10.1016/j.icarus.2015.03.007. (http://www.sciencedirect.com/science/article/pii/S0019103515001001)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57762
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:22 May 2015 20:40
Last Modified:03 Oct 2019 08:28

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