1
|
Cassata WS, Cohen BE, Mark DF, Trappitsch R, Crow CA, Wimpenny J, Lee MR, Smith CL. Chronology of martian breccia NWA 7034 and the formation of the martian crustal dichotomy. SCIENCE ADVANCES 2018; 4:eaap8306. [PMID: 29806017 PMCID: PMC5966191 DOI: 10.1126/sciadv.aap8306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 04/10/2018] [Indexed: 06/08/2023]
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.
Collapse
Affiliation(s)
- William S. Cassata
- Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Benjamin E. Cohen
- Isotope Geoscience Unit, Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride, G75 0QF, UK
- School of Geographical and Earth Sciences, University of Glasgow, G12 8QQ, UK
| | - Darren F. Mark
- Isotope Geoscience Unit, Scottish Universities Environmental Research Centre, Rankine Avenue, East Kilbride, G75 0QF, UK
- Department of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, KY16 9AJ, UK
| | - Reto Trappitsch
- Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Carolyn A. Crow
- Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Joshua Wimpenny
- Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Martin R. Lee
- School of Geographical and Earth Sciences, University of Glasgow, G12 8QQ, UK
| | - Caroline L. Smith
- School of Geographical and Earth Sciences, University of Glasgow, G12 8QQ, UK
- Department of Earth Sciences, Natural History Museum, London, SW7 5BD, UK
| |
Collapse
|
2
|
Treiman AH, McKay GA, Bogard DD, Mittlefehldt DW, Wang MS, Keller L, Lipschutz ME, Lindstrom MM, Garrison D. Comparison of the LEW88516 and ALHA77005 martian meteorites: Similar but distinct. ACTA ACUST UNITED AC 2012. [DOI: 10.1111/j.1945-5100.1994.tb00771.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
3
|
Hammerschmidt K, Engelhardt WOLF. 40Ar/39Ar dating of the Araguainha impact structure, Mato Grosso, Brazil. ACTA ACUST UNITED AC 2012. [DOI: 10.1111/j.1945-5100.1995.tb01116.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
5
|
Bogard D, Hörz F, Johnson P. Shock-implanted noble gases II: Additional experimental studies and recognition in naturally shocked terrestrial materials. ACTA ACUST UNITED AC 2012. [DOI: 10.1111/j.1945-5100.1989.tb00951.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
6
|
Rao MN, Nyquist LE, Bogard DD, Garrison DH, Sutton SR, Michel R, Reedy RC, Leya I. Isotopic evidence for a Martian regolith component in shergottite meteorites. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010je003764] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
7
|
|
8
|
Rao MN, Borg LE, McKay DS, Wentworth SJ. Martian soil component in impact glasses in a Martian meteorite. GEOPHYSICAL RESEARCH LETTERS 1999; 26:3265-3268. [PMID: 11543347 DOI: 10.1029/1999gl005388] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Chemical compositions of impact melt glass veins, called Lithology C (Lith C) in Martian meteorite EET79001 were determined by electron microprobe analysis. A large enrichment of S, and significant enrichments of Al, Ca, and Na were observed in Lith C glass compared to Lithology A (Lith A). The S enrichment is due to mixing of plagioclase- enriched Lith A material with Martian soil, either prior to or during impact on Mars. A mixture of 87% Lith A, 7% plagioclase, and 6% Martian soil reproduces the average elemental abundances observed in Lith C. Shock melting of such a mixture of plagioclase-enriched, fine-grained Lith A host rock and Martian soil could yield large excesses of S (observed in this study) and Martian atmospheric noble gases (found by Bogard et al., 1983) in Lith C. These mixing proportions can be used to constrain the elemental abundance of phosphorus in Martian soil.
Collapse
Affiliation(s)
- M N Rao
- NASA Johnson Space Center, Houston, Texas, USA.
| | | | | | | |
Collapse
|
10
|
Marti K, Kim JS, Thakur AN, McCoy TJ, Keil K. Signatures of the martian atmosphere in glass of the Zagami meteorite. Science 1995; 267:1981-4. [PMID: 7701319 DOI: 10.1126/science.7701319] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Isotopic signatures of nitrogen, argon, and xenon have been determined in separated millimeter-sized pockets of shock-melted glass in a recently identified lithology of the meteorite Zagami, a shergottite. The ratio of nitrogen-15 to nitrogen-14, which is at least 282 per mil larger than the terrestrial value, the ratio of xenon-129 to xenon-132 = 2.40, and the argon isotopic abundances match the signatures previously observed in the glassy lithology of the Antarctic shergottite EETA 79001. These results show that the signatures in EETA 79001 are not unique but characterize the trapped gas component in shock-melted glass of shergottites. The isotopic and elemental ratios of nitrogen, argon, and xenon closely resemble the Viking spacecraft data for the martian atmosphere and provide compelling evidence for a martian origin of the two shergottites and, by extension, of the meteorites in the shergottites-nakhlites-chassignites (SNC) group.
Collapse
Affiliation(s)
- K Marti
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla 92093, USA
| | | | | | | | | |
Collapse
|