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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ftunivbruxelles:oai:dipot.ulb.ac.be:2013/282975 2023-05-15T13:58:15+02:00 Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites Suttle, Martin M.D. Folco, Luigi Genge, Matthew M.J. Russell, S.S. Najorka, Jens Van Ginneken, Matthias 2019-01 1 full-text file(s): application/pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/282975 https://dipot.ulb.ac.be/dspace/bitstream/2013/282975/1/Elsevier_266602.pdf en eng uri/info:doi/10.1016/j.gca.2018.11.019 uri/info:pii/S0016703718306495 uri/info:scp/85056988307 https://dipot.ulb.ac.be/dspace/bitstream/2013/282975/1/Elsevier_266602.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/282975 1 full-text file(s): info:eu-repo/semantics/restrictedAccess Geochimica et cosmochimica acta, 245 Géochimie Pétrologie aqueous alteration CM chondrites micrometeorites pseudomorphic chondrules info:eu-repo/semantics/article info:ulb-repo/semantics/articlePeerReview info:ulb-repo/semantics/openurl/article 2019 ftunivbruxelles 2022-06-12T21:53:29Z 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. SCOPUS: ar.j DecretOANoAutActif info:eu-repo/semantics/published Article in Journal/Newspaper Antarc* Antarctic DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) Antarctic |
institution |
Open Polar |
collection |
DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) |
op_collection_id |
ftunivbruxelles |
language |
English |
topic |
Géochimie Pétrologie aqueous alteration CM chondrites micrometeorites pseudomorphic chondrules |
spellingShingle |
Géochimie Pétrologie aqueous alteration CM chondrites micrometeorites pseudomorphic chondrules Suttle, Martin M.D. Folco, Luigi Genge, Matthew M.J. Russell, S.S. Najorka, Jens Van Ginneken, Matthias Intense aqueous alteration on C-type asteroids: Perspectives from giant fine-grained micrometeorites |
topic_facet |
Géochimie Pétrologie aqueous alteration CM chondrites micrometeorites pseudomorphic chondrules |
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. SCOPUS: ar.j DecretOANoAutActif info:eu-repo/semantics/published |
format |
Article in Journal/Newspaper |
author |
Suttle, Martin M.D. Folco, Luigi Genge, Matthew M.J. Russell, S.S. Najorka, Jens Van Ginneken, Matthias |
author_facet |
Suttle, Martin M.D. Folco, Luigi Genge, Matthew M.J. Russell, S.S. Najorka, Jens Van Ginneken, Matthias |
author_sort |
Suttle, Martin 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 |
publishDate |
2019 |
url |
http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/282975 https://dipot.ulb.ac.be/dspace/bitstream/2013/282975/1/Elsevier_266602.pdf |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Geochimica et cosmochimica acta, 245 |
op_relation |
uri/info:doi/10.1016/j.gca.2018.11.019 uri/info:pii/S0016703718306495 uri/info:scp/85056988307 https://dipot.ulb.ac.be/dspace/bitstream/2013/282975/1/Elsevier_266602.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/282975 |
op_rights |
1 full-text file(s): info:eu-repo/semantics/restrictedAccess |
_version_ |
1766266442853908480 |