Farley KA, Malespin C, Mahaffy P, Grotzinger JP, Vasconcelos PM, Milliken RE, Malin M, Edgett KS, Pavlov AA, Hurowitz JA, Grant JA, Miller HB, Arvidson R, Beegle L, Calef F, Conrad PG, Dietrich WE, Eigenbrode J, Gellert R, Gupta S, Hamilton V, Hassler DM, Lewis KW, McLennan SM, Ming D, Navarro-González R, Schwenzer SP, Steele A, Stolper EM, Sumner DY, Vaniman D, Vasavada A, Williford K, Wimmer-Schweingruber RF. In situ radiometric and exposure age dating of the martian surface.
Science 2013;
343:1247166. [PMID:
24324273 DOI:
10.1126/science.1247166]
[Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced (3)He, (21)Ne, and (36)Ar yield concordant surface exposure ages of 78 ± 30 million years. 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.
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