The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water
We analysed the heterogenous fine-grained (sub-μm) matrix of a small (58x93μm), unmelted and minimally heated (<350°C) micrometeorite (CP94-050-052) recovered from Antarctic blue ice. This particle contains some unaltered highly primitive phases, including refractory anhydrous high-Mg silicates a...
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Online Access: | http://hdl.handle.net/11568/1060509 https://doi.org/10.1016/j.gca.2020.11.006 |
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ftunivpisairis:oai:arpi.unipi.it:11568/1060509 2024-02-27T08:33:49+00:00 The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water Suttle, M. D. Folco, L. Genge, M. J. Franchi, I. A. Campanale, F. Mugnaioli, E. Zhao, X. Suttle, M. D. Folco, L. Genge, M. J. Franchi, I. A. Campanale, F. Mugnaioli, E. Zhao, X. 2021 STAMPA http://hdl.handle.net/11568/1060509 https://doi.org/10.1016/j.gca.2020.11.006 eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000600550100021 volume:293 firstpage:399 lastpage:421 numberofpages:23 journal:GEOCHIMICA ET COSMOCHIMICA ACTA http://hdl.handle.net/11568/1060509 doi:10.1016/j.gca.2020.11.006 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85097153835 info:eu-repo/semantics/article 2021 ftunivpisairis https://doi.org/10.1016/j.gca.2020.11.006 2024-01-31T17:51:39Z We analysed the heterogenous fine-grained (sub-μm) matrix of a small (58x93μm), unmelted and minimally heated (<350°C) micrometeorite (CP94-050-052) recovered from Antarctic blue ice. This particle contains some unaltered highly primitive phases, including refractory anhydrous high-Mg silicates and submicron crystalline needle-shaped acicular grains interpreted as enstatite whiskers. The particle also contains an abundance of micron-sized Fe-rich grains, which span a compositional and textural continuum between amorphous oxygen-rich silicate and poorly crystalline Fe-rich phyllosilicate (cronstedtite). These Fe-rich grains are here interpreted as secondary phases formed by aqueous alteration. Their inferred anhydrous precursors were likely primitive “GEMS-like” amorphous Fe-Mg-silicates. This micrometeorite’s bulk chemical composition and mineralogy suggest either a carbonaceous chondrite or cometary origin. However, the particle’s average O-isotope composition (δ17O: -12.4‰ [±5.0‰], δ18O: -24.0‰ [±2.3‰] and Δ17O at +0.1‰ [±4.8‰] is distinct from all previously measured chondritic materials. Instead this value is intermediate between primitive chondritic materials and the composition of Antarctic water – strongly implying that the particle was heavily affected by Antarctic alteration. Analysis of the micrometeorite’s H-isotopes reveals low deuterium abundances (δD: -217‰ to -173‰ [±43-47‰]) paired with high H abundances (and thus high water contents [<25wt.%]). Although both water contents and H-isotope compositions overlap with those reported in CM chondrites, the datapoints measured from CP94-050-052 extend to more extreme values. Further supporting the idea that the aqueous alteration that affected this micrometeorite operated under different environmental conditions to asteroidal settings. These data collectively demonstrate partial isotopic exchange with light (δ18O-poor, δD-poor) terrestrial fluids whilst the micrometeorite resided in Antarctica. Although this micrometeorite may have been aqueously ... Article in Journal/Newspaper Antarc* Antarctic Antarctica ARPI - Archivio della Ricerca dell'Università di Pisa Antarctic Geochimica et Cosmochimica Acta 293 399 421 |
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Open Polar |
collection |
ARPI - Archivio della Ricerca dell'Università di Pisa |
op_collection_id |
ftunivpisairis |
language |
English |
description |
We analysed the heterogenous fine-grained (sub-μm) matrix of a small (58x93μm), unmelted and minimally heated (<350°C) micrometeorite (CP94-050-052) recovered from Antarctic blue ice. This particle contains some unaltered highly primitive phases, including refractory anhydrous high-Mg silicates and submicron crystalline needle-shaped acicular grains interpreted as enstatite whiskers. The particle also contains an abundance of micron-sized Fe-rich grains, which span a compositional and textural continuum between amorphous oxygen-rich silicate and poorly crystalline Fe-rich phyllosilicate (cronstedtite). These Fe-rich grains are here interpreted as secondary phases formed by aqueous alteration. Their inferred anhydrous precursors were likely primitive “GEMS-like” amorphous Fe-Mg-silicates. This micrometeorite’s bulk chemical composition and mineralogy suggest either a carbonaceous chondrite or cometary origin. However, the particle’s average O-isotope composition (δ17O: -12.4‰ [±5.0‰], δ18O: -24.0‰ [±2.3‰] and Δ17O at +0.1‰ [±4.8‰] is distinct from all previously measured chondritic materials. Instead this value is intermediate between primitive chondritic materials and the composition of Antarctic water – strongly implying that the particle was heavily affected by Antarctic alteration. Analysis of the micrometeorite’s H-isotopes reveals low deuterium abundances (δD: -217‰ to -173‰ [±43-47‰]) paired with high H abundances (and thus high water contents [<25wt.%]). Although both water contents and H-isotope compositions overlap with those reported in CM chondrites, the datapoints measured from CP94-050-052 extend to more extreme values. Further supporting the idea that the aqueous alteration that affected this micrometeorite operated under different environmental conditions to asteroidal settings. These data collectively demonstrate partial isotopic exchange with light (δ18O-poor, δD-poor) terrestrial fluids whilst the micrometeorite resided in Antarctica. Although this micrometeorite may have been aqueously ... |
author2 |
Suttle, M. D. Folco, L. Genge, M. J. Franchi, I. A. Campanale, F. Mugnaioli, E. Zhao, X. |
format |
Article in Journal/Newspaper |
author |
Suttle, M. D. Folco, L. Genge, M. J. Franchi, I. A. Campanale, F. Mugnaioli, E. Zhao, X. |
spellingShingle |
Suttle, M. D. Folco, L. Genge, M. J. Franchi, I. A. Campanale, F. Mugnaioli, E. Zhao, X. The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water |
author_facet |
Suttle, M. D. Folco, L. Genge, M. J. Franchi, I. A. Campanale, F. Mugnaioli, E. Zhao, X. |
author_sort |
Suttle, M. D. |
title |
The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water |
title_short |
The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water |
title_full |
The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water |
title_fullStr |
The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water |
title_full_unstemmed |
The aqueous alteration of GEMS-like amorphous silicate in a chondritic micrometeorite by Antarctic water |
title_sort |
aqueous alteration of gems-like amorphous silicate in a chondritic micrometeorite by antarctic water |
publishDate |
2021 |
url |
http://hdl.handle.net/11568/1060509 https://doi.org/10.1016/j.gca.2020.11.006 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000600550100021 volume:293 firstpage:399 lastpage:421 numberofpages:23 journal:GEOCHIMICA ET COSMOCHIMICA ACTA http://hdl.handle.net/11568/1060509 doi:10.1016/j.gca.2020.11.006 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85097153835 |
op_doi |
https://doi.org/10.1016/j.gca.2020.11.006 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
293 |
container_start_page |
399 |
op_container_end_page |
421 |
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1792048175397208064 |