In Situ Radiometric and Exposure Age Dating of the Martian Surface

Creators: Farley, K. A.; Malespin, C.; Mahaffy, P.; Grotzinger, J. P.; Vasconcelos, P. M.; Milliken, R. E.; Malin, M.; Edgett, K. S.; Pavlov, A. A.; Hurowitz, J. A.; Grant, J. A.; Miller, H. B.; Arvidson, R.; Beegle, L.; Calef, F.; Conrad, P. G.; Dietrich, W. E.; Eigenbrode, J.; Gellert, R.; Gupta, S.; Hamilton, V.; Hassler, D. M.; Lewis, K. W.; McLennan, S. M.; Ming, D.; Navarro-González, R.; Schwenzer, S. P.; Steele, A.; Stolper, E. M.; Sumner, D. Y.; Vaniman, D.; Vasavada, A.; Williford, K.; Wimmer-Schweingruber, R. F.; MSL Science Team

Abstract

We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale crater. A K-Ar age of 4.21 ± 0.35 Ga represents a mixture of detrital and authigenic components, and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced ^3He, ^(21)Ne, and ^(36)Ar yield concordant surface exposure ages of 78 ± 30 Ma. Surface exposure occurred mainly in the present geomorphic setting rather than during primary erosion and transport. Our observations are consistent with mudstone deposition shortly after the Gale impact, or possibly in a later event of rapid erosion and deposition. The mudstone remained buried until recent exposure by wind-driven scarp retreat. Sedimentary rocks exposed by this mechanism may thus offer the best potential for organic biomarker preservation against destruction by cosmic radiation.

Additional Information

Copyright 2013 American Association for the Advancement of Science. Received for publication 14 October 2013. Accepted for publication 25 November 2013. Published Online December 9 2013. The authors are indebted to the Mars Science Laboratory Project engineering and management teams for their exceptionally skilled and diligent efforts in making the mission as effective as possible and enhancing science operations. We are also grateful to all those MSL team members who participated in tactical and strategic operations. Without the support of both the engineering and science teams, the data presented here could not have been collected. Three anonymous reviewers provided many helpful suggestions. Some of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Data presented in this paper are archived in the Planetary Data System (pds.nasa.gov).

Additional details

Views

Downloads

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes

More info on how stats are collected....

Resource type: Journal Article
Publisher: American Association for the Advancement of Science
Published in: Science, 343(6169), Art. no. 1247166, ISSN: 0036-8075.