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Abstract
Coesite in impact rocks is traditionally considered a retrograde product formed during pressure release by the crystallisation of an amorphous phase (either silica melt or diaplectic glass). Recently, the detailed microscopic and crystallographic study of impact ejecta from Kamil crater and the Australasian tektite strewn field pointed in turn to a different coesite formation pathway, through subsolidus quartz-to-coesite transformation. We report here further evidence documenting the formation of coesite directly from quartz. In Kamil ejecta we found sub-micrometric single-coesite-crystals that represent the first crystallization seeds of coesite. Coesite in Australasian samples show instead well-developed subeuhedral crystals, growing at the expenses of hosting quartz and postdating PDF deformation. Coesite (010) plane is most often parallel to quartz {10-11} plane family, supporting the formation of coesite through a topotactic transformation. Such reaction is facilitated by the presence of pre-existing and shock-induced discontinuities in the target. Shock wave reverberations can provide pressure and time conditions for coesite nucleation and growth. Because discontinuities occur in both porous and non-porous rocks and the coesite formation mechanism appears similar for small and large impacts, we infer that the proposed subsolidus transformation model is valid for all types of quartz-bearing target rocks.
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Affiliation(s)
- F Campanale
- Dipartimento di Scienze della Terra, Università d Pisa, Via S. Maria 53, 56126, Pisa, Italy.
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia (IIT), Piazza San Silvestro 12, 56127, Pisa, Italy.
| | - E Mugnaioli
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia (IIT), Piazza San Silvestro 12, 56127, Pisa, Italy
| | - M Gemmi
- Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia (IIT), Piazza San Silvestro 12, 56127, Pisa, Italy
| | - L Folco
- Dipartimento di Scienze della Terra, Università d Pisa, Via S. Maria 53, 56126, Pisa, Italy
- CISUP, Centro per l'Integrazione della Strumentazione dell'Università di Pisa, Lungarno Pacinotti 43, 56126, Pisa, Italy
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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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Suttle MD, Twegar K, Nava J, Spiess R, Spratt J, Campanale F, Folco L. A unique CO-like micrometeorite hosting an exotic Al-Cu-Fe-bearing assemblage - close affinities with the Khatyrka meteorite. Sci Rep 2019; 9:12426. [PMID: 31455844 PMCID: PMC6711995 DOI: 10.1038/s41598-019-48937-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 08/13/2019] [Indexed: 11/09/2022] Open
Abstract
We report the discovery of a unique micrometeorite, containing an exotic Al-Cu-Fe alloy composed of two intermixed phases: khatyrkite (CuAl2) and stolperite (CuAl) and both containing minor Fe (<1.4 wt%). These phases are dendritic and rapidly co-crystallized at the binary system's peritectic (~550 °C). The host micrometeorite is an otherwise typical S-type micro-porphyritic cosmic spherule containing relict olivine (Fo76-90, Cr2O3: 0.01-0.56 wt%, MnO: 0.03-0.32 wt% and CaO: 0.09-0.22 wt%) and a cumulate layered texture. These properties suggest the micrometeorite is derived from a carbonaceous chondrite (best matched to a CO chondrite) and entered the atmosphere a high speed (~16 kms-1), implying an origin from a highly eccentric orbit. This particle represents the second independent discovery of naturally occurring intermetallic Al-Cu-Fe alloys and is thus similar to the previously reported Khatyrka meteorite - a CV chondrite containing near-identical alloys and the only known natural quasicrystals. We did not observe quasicrystalline phases in this micrometeorite, likely due to the low amounts of Fe in the alloy, insufficient to stabilize quasicrystals. Our discovery confirms the existence of Al-Cu-Fe intermetallic alloys on chondritic parent bodies. These unusual phases require a currently unexplained formation process, we tentatively suggest this could represent the delivery of exotic interstellar material to the inner solar system via impact.
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Affiliation(s)
- M D Suttle
- Dipartimento di Scienze della Terra, Università di Pisa, 56126, Pisa, Italy.
| | - K Twegar
- Department of Chemistry, Istanbul Technological University, 34467, Istanbul, Turkey
| | - J Nava
- Dipartimento di Geoscienze Via Gradenigo 6, 35131, Padova, Italy
| | - R Spiess
- Dipartimento di Geoscienze Via Gradenigo 6, 35131, Padova, Italy
| | - J Spratt
- Department of Earth Science, The Natural History Museum, Cromwell Rd, South Kensington, London, SW7 5BD, UK
| | - F Campanale
- Dipartimento di Scienze della Terra, Università di Pisa, 56126, Pisa, Italy.,Center for Nanotechnology Innovation@NEST, Istituto Italiano di Tecnologia (IIT), Piazza San Silvestro 12, 56127, Pisa, Italy
| | - L Folco
- Dipartimento di Scienze della Terra, Università di Pisa, 56126, Pisa, Italy
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Ingrassia F, Fiore JR, Vimercati A, Tateo MG, Campanale F, Volpe A, Di Stefano MA, Greco P, Pastore G. Isolated antibodies against the core antigen of hepatitis B virus in HIV-infected pregnant women. Minerva Ginecol 2006; 58:255-6. [PMID: 16783299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
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