Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites
This study explores the petrology of five giant (>400 μm) hydrated fine-grained micrometeorites from the Transantarctic Mountain (TAM) micrometeorite collection. For the first time, the extent and mechanisms of aqueous alteration in unmelted cosmic dust are evaluated and quantified. We use a rang...
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Online Access: | https://kar.kent.ac.uk/88144/ https://doi.org/10.1016/j.gca.2018.11.019 |
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ftkentuniv:oai:kar.kent.ac.uk:88144 2023-05-15T13:38:02+02:00 Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites Suttle, M.D. Folco, L. Genge, M.J. Russell, S.S. Najorka, J. van Ginneken, M. 2019-01-15 https://kar.kent.ac.uk/88144/ https://doi.org/10.1016/j.gca.2018.11.019 unknown Meteoritical Society Suttle, M.D., Folco, L., Genge, M.J., Russell, S.S., Najorka, J., van Ginneken, M. (2019) Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites. Geochimica et Cosmochimica Acta, 245 . pp. 352-373. ISSN 0016-7037. (doi:10.1016/j.gca.2018.11.019 <https://doi.org/10.1016/j.gca.2018.11.019>) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:88144 </88144>) QE515 Geochemistry Article PeerReviewed 2019 ftkentuniv https://doi.org/10.1016/j.gca.2018.11.019 2023-03-12T19:19:15Z This study explores the petrology of five giant (>400 μm) hydrated fine-grained micrometeorites from the Transantarctic Mountain (TAM) micrometeorite collection. For the first time, the extent and mechanisms of aqueous alteration in unmelted cosmic dust are evaluated and quantified. We use a range of criteria, previously defined for use on hydrated chondrites, including phyllosilicate fraction, matrix geochemistry and micro textures. Collectively, these micrometeorites represent ∼2.22 mm2 of intensely altered hydrated chondritic matrix (with petrologic subtypes of <1.2 in the scheme of Howard et al. (2015)) and reveal a range of alteration styles. Two particles are found to contain pseudomorphic chondrules with thick fine-grained rims, while another micrometeorite contains several aqueously altered CAIs. Their outlines range from well-defined to indistinct, demonstrating that the advanced stages of aqueous alteration progressively remove evidence of coarse-grained components. The remaining two micrometeorites entirely lack coarse-grained components but are similarly altered. Thus, the combined chondrule-to-matrix ratio among these giant micrometeorites is extremely low (6.45 area%), and significantly below the average ratio found in typical CM or CR chondrites (∼20%, Weisberg et al., 2006). Our findings are consistent with previous analyses from smaller Antarctic micrometeorites, which suggest that chondrules (and CAIs) derived from hydrated carbonaceous chondrite parent bodies are underrepresented among the micrometeorite flux, even when considering contributions from coarse-grained micrometeorites. Therefore, to explain the relative paucity of anhydrous material, we propose that the flux of fine-grained micrometeorites is primarily derived from intensely aqueously altered, primitive C-type asteroids, which have lost the majority of their refractory coarse-grained components by replacement with secondary phyllosilicate minerals. Article in Journal/Newspaper Antarc* Antarctic University of Kent: KAR - Kent Academic Repository Antarctic Geochimica et Cosmochimica Acta 245 352 373 |
institution |
Open Polar |
collection |
University of Kent: KAR - Kent Academic Repository |
op_collection_id |
ftkentuniv |
language |
unknown |
topic |
QE515 Geochemistry |
spellingShingle |
QE515 Geochemistry Suttle, M.D. Folco, L. Genge, M.J. Russell, S.S. Najorka, J. van Ginneken, M. Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites |
topic_facet |
QE515 Geochemistry |
description |
This study explores the petrology of five giant (>400 μm) hydrated fine-grained micrometeorites from the Transantarctic Mountain (TAM) micrometeorite collection. For the first time, the extent and mechanisms of aqueous alteration in unmelted cosmic dust are evaluated and quantified. We use a range of criteria, previously defined for use on hydrated chondrites, including phyllosilicate fraction, matrix geochemistry and micro textures. Collectively, these micrometeorites represent ∼2.22 mm2 of intensely altered hydrated chondritic matrix (with petrologic subtypes of <1.2 in the scheme of Howard et al. (2015)) and reveal a range of alteration styles. Two particles are found to contain pseudomorphic chondrules with thick fine-grained rims, while another micrometeorite contains several aqueously altered CAIs. Their outlines range from well-defined to indistinct, demonstrating that the advanced stages of aqueous alteration progressively remove evidence of coarse-grained components. The remaining two micrometeorites entirely lack coarse-grained components but are similarly altered. Thus, the combined chondrule-to-matrix ratio among these giant micrometeorites is extremely low (6.45 area%), and significantly below the average ratio found in typical CM or CR chondrites (∼20%, Weisberg et al., 2006). Our findings are consistent with previous analyses from smaller Antarctic micrometeorites, which suggest that chondrules (and CAIs) derived from hydrated carbonaceous chondrite parent bodies are underrepresented among the micrometeorite flux, even when considering contributions from coarse-grained micrometeorites. Therefore, to explain the relative paucity of anhydrous material, we propose that the flux of fine-grained micrometeorites is primarily derived from intensely aqueously altered, primitive C-type asteroids, which have lost the majority of their refractory coarse-grained components by replacement with secondary phyllosilicate minerals. |
format |
Article in Journal/Newspaper |
author |
Suttle, M.D. Folco, L. Genge, M.J. Russell, S.S. Najorka, J. van Ginneken, M. |
author_facet |
Suttle, M.D. Folco, L. Genge, M.J. Russell, S.S. Najorka, J. van Ginneken, M. |
author_sort |
Suttle, M.D. |
title |
Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites |
title_short |
Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites |
title_full |
Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites |
title_fullStr |
Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites |
title_full_unstemmed |
Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites |
title_sort |
intense aqueous alteration on c-type asteroids: perspectives from giant fine-grained micrometeorites |
publisher |
Meteoritical Society |
publishDate |
2019 |
url |
https://kar.kent.ac.uk/88144/ https://doi.org/10.1016/j.gca.2018.11.019 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
Suttle, M.D., Folco, L., Genge, M.J., Russell, S.S., Najorka, J., van Ginneken, M. (2019) Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites. Geochimica et Cosmochimica Acta, 245 . pp. 352-373. ISSN 0016-7037. (doi:10.1016/j.gca.2018.11.019 <https://doi.org/10.1016/j.gca.2018.11.019>) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:88144 </88144>) |
op_doi |
https://doi.org/10.1016/j.gca.2018.11.019 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
245 |
container_start_page |
352 |
op_container_end_page |
373 |
_version_ |
1766100675151790080 |