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Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis basin

Mustard, J. F. and Ehlmann, B. L. and Murchie, S. L. and Poulet, F. and Mangold, N. and Head, J. W. and Bibring, J.-P. and Roach, L. H. (2009) Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis basin. Journal of Geophysical Research E, 114 . Art. No. E00D12. ISSN 0148-0227.

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Definitive exposures of pristine, ancient crust on Mars are rare, and the finding that much of the ancient Noachian terrain on Mars exhibits evidence of phyllosilicate alteration adds further complexity. We have analyzed high-resolution data from the Mars Reconnaissance Orbiter in the well-exposed Noachian crust surrounding the Isidis basin. We focus on data from the Compact Reconnaissance Imaging Spectrometer for Mars as well as imaging data sets from High Resolution Imagine Science Experiment and Context Imager. These data show the lowermost unit of Noachian crust in this region is a complex, brecciated unit of diverse compositions. Breccia blocks consisting of unaltered mafic rocks together with rocks showing signatures of Fe/Mg-phyllosilicates are commonly observed. In regions of good exposure, layered or banded phyllosilicate-bearing breccia rocks are observed suggestive of pre-Isidis sedimentary deposits. In places, the phyllosilicate-bearing material appears as a matrix surrounding mafic blocks, and the mafic rocks show evidence of complex folded relationships possibly formed in the turbulent flow during emplacement of basin-scale ejecta. These materials likely include both pre-Isidis basement rocks as well as the brecciated products of the Isidis basin–forming event at 3.9 Ga. A banded olivine unit capped by a mafic unit covers a large topographic and geographic range from northwest of Nili Fossae to the southern edge of the Isidis basin. This olivine-mafic cap combination superimposes the phyllosilicate-bearing basement rocks and distinctly conforms to the underlying basement topography. This may be due to draping of the topography by a fluid or tectonic deformation of a previously flatter lying morphology. We interpret the draping, superposed olivine-mafic cap combination to be impact melt from the Isidis basin–forming event. While some distinct post-Isidis alteration is evident (carbonate, kaolinite, and serpentine), the persistence of olivine from the time of Isidis basin suggests that large-scale aqueous alteration processes had ceased by the time this unit was emplaced.

Item Type:Article
Related URLs:
Ehlmann, B. L.0000-0002-2745-3240
Murchie, S. L.0000-0002-1616-8751
Mangold, N.0000-0002-0022-0631
Head, J. W.0000-0003-2013-560X
Additional Information:© 2009 American Geophysical Union. Received 29 January 2009; accepted 22 July 2009; published 12 December 2009. The DEM from HiRISE image PSP_002176_2025 was produced by Ryan Ollerenshaw, Shigeru Suzuki, and Eric DeJong at the Jet Propulsion Laboratory Imaging Processing Laboratory. Support from NASA and the operation of the Mars Reconnaissance Orbiter is gratefully acknowledged. J.F.M. also acknowledges a contract from the Jet Propulsion Laboratory to participate on the OMEGA Team as a Liaison Member from the CRISM Team, and J.W.H. acknowledges support from a contract from the Jet Proposal Laboratory for participation in the Mars Express High-Resolution Stereo Camera (HRSC).
Funding AgencyGrant Number
Subject Keywords:Mars; Noachian crust; impact melt
Record Number:CaltechAUTHORS:20121016-092000565
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Official Citation:Mustard, J. F., B. L. Ehlmann, S. L. Murchie, F. Poulet, N. Mangold, J. W. Head, J.-P. Bibring, and L. H. Roach (2009), Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis basin, J. Geophys. Res., 114, E00D12, doi:10.1029/2009JE003349, [printed 115(E2), 2010].
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34913
Deposited By: Ruth Sustaita
Deposited On:16 Oct 2012 16:49
Last Modified:09 Mar 2020 13:19

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