Chronology of martian breccia NWA 7034 and the formation of the martian crustal dichotomy

Cassata, W. S., Cohen, B. E. , Mark, D. F., Trappitsch, R., Crow, C. A., Wimpenny, J., Lee, M. R. and Smith, C. L. (2018) Chronology of martian breccia NWA 7034 and the formation of the martian crustal dichotomy. Science Advances, 4(5), eaap8306. (doi:10.1126/sciadv.aap8306) (PMID:29806017) (PMCID:PMC5966191)

[img]
Preview
Text
159785.pdf - Published Version
Available under License Creative Commons Attribution Non-commercial.

573kB

Abstract

Martian meteorite Northwest Africa (NWA) 7034 and its paired stones are the only brecciated regolith samples from Mars with compositions that are representative of the average martian crust. These samples therefore provide a unique opportunity to constrain the processes of metamorphism and alteration in the martian crust, which we have investigated via U-Pu/Xe, 40Ar/39Ar, and U-Th-Sm/He chronometry. U-Pu/Xe ages are comparable to previously reported Sm-Nd and U-Pb ages obtained from NWA 7034 and confirm an ancient (>4.3 billion years) age for the source lithology. After almost 3000 million years (Ma) of quiescence, the source terrain experienced several hundred million years of thermal metamorphism recorded by the K-Ar system that appears to have varied both spatially and temporally. Such protracted metamorphism is consistent with plume-related magmatism and suggests that the source terrain covered an areal extent comparable to plume-fed edifices (hundreds of square kilometers). The retention of such expansive, ancient volcanic terrains in the southern highlands over billions of years suggests that formation of the martian crustal dichotomy, a topographic and geophysical divide between the heavily cratered southern highlands and smoother plains of the northern lowlands, likely predates emplacement of the NWA 7034 source terrain—that is, it formed within the first ~100 Ma of planetary formation.

Item Type:Articles
Additional Information:Financial support was provided by the NASA Mars Fundamental Research Program (grant NNH14AX56I to W.S.C.) and an LLNL Laboratory Directed Research and Development project (17-ERD-001), “Uncovering the Origins of the Solar System with Cosmochemical Forensics.” The UK work component was funded by the Science and Technology Facilities Council (grants ST/H002472/1, ST/H002960/1, and ST/K000918/1 to D.F.M. and M.R.L.). NERC is thanked for continued funding of the Argon Isotope Facility at SUERC.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Mark, Professor Darren and Smith, Dr Caroline and Lee, Professor Martin and Cohen, Dr Benjamin
Authors: Cassata, W. S., Cohen, B. E., Mark, D. F., Trappitsch, R., Crow, C. A., Wimpenny, J., Lee, M. R., and Smith, C. L.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Science Advances
Publisher:American Association for the Advancement of Science
ISSN:2375-2548
ISSN (Online):2375-2548
Published Online:23 May 2018
First Published:First published in Science Advances 4(5):eaap8306

University Staff: Request a correction | Enlighten Editors: Update this record

Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
519741Follow the water: insights into the martian hydrosphere from nakhlitesMartin LeeScience & Technology Facilities Council (STFC)ST/H002960/1SCHOOL OF GEOGRAPHICAL & EARTH SCIENCES