Publication Date:
2013-12-11
Description:
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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉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-Gonzalez, 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 -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1247166. doi: 10.1126/science.1247166. Epub 2013 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24324273" target="_blank"〉PubMed〈/a〉
Keywords:
Biomarkers/analysis/chemistry
;
*Cosmic Radiation
;
*Evolution, Planetary
;
*Exobiology
;
Extraterrestrial Environment/*chemistry
;
Geologic Sediments
;
Isotopes/analysis/chemistry
;
*Mars
;
Noble Gases/*analysis
;
Organic Chemicals/analysis/chemistry
;
Radiation Dosage
;
Radiometric Dating
;
Surface Properties
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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