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Daly L, Lee MR, Piazolo S, Griffin S, Bazargan M, Campanale F, Chung P, Cohen BE, Pickersgill AE, Hallis LJ, Trimby PW, Baumgartner R, Forman LV, Benedix GK. Boom boom pow: Shock-facilitated aqueous alteration and evidence for two shock events in the Martian nakhlite meteorites. Sci Adv 2019; 5:eaaw5549. [PMID: 31517047 PMCID: PMC6726442 DOI: 10.1126/sciadv.aaw5549] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
Nakhlite meteorites are ~1.4 to 1.3 Ga old igneous rocks, aqueously altered on Mars ~630 Ma ago. We test the theory that water-rock interaction was impact driven. Electron backscatter diffraction demonstrates that the meteorites Miller Range 03346 and Lafayette were heterogeneously deformed, leading to localized regions of brecciation, plastic deformation, and mechanical twinning of augite. Numerical modeling shows that the pattern of deformation is consistent with shock-generated compressive and tensile stresses. Mesostasis within shocked areas was aqueously altered to phyllosilicates, carbonates, and oxides, suggesting a genetic link between the two processes. We propose that an impact ~630 Ma ago simultaneously deformed the nakhlite parent rocks and generated liquid water by melting of permafrost. Ensuing water-rock interaction focused on shocked mesostasis with a high density of reactive sites. The nakhlite source location must have two spatially correlated craters, one ~630 Ma old and another, ejecting the meteorites, ~11 Ma ago.
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Affiliation(s)
- L. Daly
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006, Australia
| | - M. R. Lee
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - S. Piazolo
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - S. Griffin
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - M. Bazargan
- Department of Earth Sciences, Uppsala University, Uppsala, Sweden
| | - F. Campanale
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- Dipartimento di Scienze della Terra, Università di Pisa, via Santa Maria 53, 56126, Pisa, Italy
| | - P. Chung
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - B. E. Cohen
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - A. E. Pickersgill
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - L. J. Hallis
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - P. W. Trimby
- Oxford Instruments Nanoanalysis, High Wycombe HP12 3SE, UK
| | - R. Baumgartner
- Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW 2052, Australia
| | - L. V. Forman
- Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
| | - G. K. Benedix
- Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
- Department of Earth and Planetary Sciences, Western Australia Museum, Locked Bag 49, Welshpool, WA 6986, Australia
- Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA
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Pennock GM, Drury MR, Trimby PW, Spiers CJ. Misorientation distributions in hot deformed NaCl using electron backscattered diffraction. J Microsc 2002; 205:285-94. [PMID: 11996193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
EBSD orientation mapping has been used to derive subgrain boundary misorientation distributions in a series of hot deformed and etched NaCl samples. The main objective of this study has been to examine the influence of data processing, noise caused by angular resolution limits and step size on the subgrain misorientation distributions in hot deformed NaCl. Processing of non-indexed EBSD patterns increased the average misorientations in etched NaCl. Noise contributed significantly to low angle misorientation peaks for step sizes less than the minimum subgrain size. Orientation data collected using a step size larger than the average subgrain size cumulated misorientations across individual subgrains and effectively measured an orientation gradient between steps. Orientation gradient distributions were not influenced by noise. Average misorientation values calculated from large step data correlated well with average misorientation from small step size data, Average misorientations showed a power law relationship with strain. Three types of substructures were identified using scanning electron microscopy and EBSD mapping, equiaxed subgrains, long subgrain boundaries and a core-mantle subgrain arrangement.
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Affiliation(s)
- G M Pennock
- Vening Meimesz Research School of Geodynamics, Faculty of Earth Sciences, Utrecht University, The Netherlands.
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