Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite
Mesosiderite meteorites consist of a mixture of crustal basaltic or gabbroic material and metal. Their formation process is still debated due to their unexpected combination of crust and core materials, possibly derived from the same planetesimal parent body, and lacking an intervening mantle compon...
Main Authors: | , , , , , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2019
|
Subjects: | |
Online Access: | http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/296640 https://dipot.ulb.ac.be/dspace/bitstream/2013/296640/3/Pittarelloetal2019.pdf |
id |
ftunivbruxelles:oai:dipot.ulb.ac.be:2013/296640 |
---|---|
record_format |
openpolar |
spelling |
ftunivbruxelles:oai:dipot.ulb.ac.be:2013/296640 2023-05-15T14:05:26+02:00 Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite Pittarello, Lidia McKibbin, Seann Yamaguchi, Akira Ji, Gang Schryvers, Dominique Debaille, Vinciane Claeys, Philippe 2019-11-01 1 full-text file(s): application/pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/296640 https://dipot.ulb.ac.be/dspace/bitstream/2013/296640/3/Pittarelloetal2019.pdf en eng uri/info:doi/10.2138/am-2019-7001 uri/info:scp/85075329448 https://dipot.ulb.ac.be/dspace/bitstream/2013/296640/3/Pittarelloetal2019.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/296640 1 full-text file(s): info:eu-repo/semantics/openAccess The American mineralogist, 104 (11 Géochimie Pétrologie Géographie physique cooling rate exsolution mesosiderite Pyroxene thermal history info:eu-repo/semantics/article info:ulb-repo/semantics/articlePeerReview info:ulb-repo/semantics/openurl/article 2019 ftunivbruxelles 2022-06-12T21:48:46Z Mesosiderite meteorites consist of a mixture of crustal basaltic or gabbroic material and metal. Their formation process is still debated due to their unexpected combination of crust and core materials, possibly derived from the same planetesimal parent body, and lacking an intervening mantle component. Mesosiderites have experienced an extremely slow cooling rate from ca. 550 °C, as recorded in the metal (0.25-0.5 °C/Ma). Here we present a detailed investigation of exsolution features in pyroxene from the Antarctic mesosiderite Asuka (A) 09545. Geothermobarometry calculations, lattice parameters, lamellae orientation, and the presence of clinoenstatite as the host were used in an attempt to constrain the evolution of pyroxene from 1150 to 570 °C and the formation of two generations of exsolution lamellae. After pigeonite crystallization at ca. 1150 °C, the first exsolution process generated the thick augite lamellae along (100) in the temperature interval 1000-900 °C. By further cooling, a second order of exsolution lamellae formed within augite along (001), consisting of monoclinic low-Ca pyroxene, equilibrated in the temperature range 900-800 °C. The last process, occurring in the 600-500 °C temperature range, was likely the inversion of high to low pigeonite in the host crystal, lacking evidence for nucleation of orthopyroxene. The formation of two generations of exsolution lamellae, as well as of likely metastable pigeonite, suggest non-equilibrium conditions. Cooling was sufficiently slow to allow the formation of the lamellae, their preservation, and the transition from high to low pigeonite. In addition, the preservation of such fine-grained lamellae limits long-lasting, impact reheating to a peak temperature lower than 570 °C. These features, including the presence of monoclinic low-Ca pyroxene as the host, are reported in only a few mesosiderites. This suggests a possibly different origin and thermal history from most mesosiderites and that the crystallography (i.e. space group) of low-Ca pyroxene ... Article in Journal/Newspaper Antarc* Antarctic DI-fusion : dépôt institutionnel de l'Université libre de Bruxelles (ULB) Antarctic The 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 Géographie physique cooling rate exsolution mesosiderite Pyroxene thermal history |
spellingShingle |
Géochimie Pétrologie Géographie physique cooling rate exsolution mesosiderite Pyroxene thermal history Pittarello, Lidia McKibbin, Seann Yamaguchi, Akira Ji, Gang Schryvers, Dominique Debaille, Vinciane Claeys, Philippe Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite |
topic_facet |
Géochimie Pétrologie Géographie physique cooling rate exsolution mesosiderite Pyroxene thermal history |
description |
Mesosiderite meteorites consist of a mixture of crustal basaltic or gabbroic material and metal. Their formation process is still debated due to their unexpected combination of crust and core materials, possibly derived from the same planetesimal parent body, and lacking an intervening mantle component. Mesosiderites have experienced an extremely slow cooling rate from ca. 550 °C, as recorded in the metal (0.25-0.5 °C/Ma). Here we present a detailed investigation of exsolution features in pyroxene from the Antarctic mesosiderite Asuka (A) 09545. Geothermobarometry calculations, lattice parameters, lamellae orientation, and the presence of clinoenstatite as the host were used in an attempt to constrain the evolution of pyroxene from 1150 to 570 °C and the formation of two generations of exsolution lamellae. After pigeonite crystallization at ca. 1150 °C, the first exsolution process generated the thick augite lamellae along (100) in the temperature interval 1000-900 °C. By further cooling, a second order of exsolution lamellae formed within augite along (001), consisting of monoclinic low-Ca pyroxene, equilibrated in the temperature range 900-800 °C. The last process, occurring in the 600-500 °C temperature range, was likely the inversion of high to low pigeonite in the host crystal, lacking evidence for nucleation of orthopyroxene. The formation of two generations of exsolution lamellae, as well as of likely metastable pigeonite, suggest non-equilibrium conditions. Cooling was sufficiently slow to allow the formation of the lamellae, their preservation, and the transition from high to low pigeonite. In addition, the preservation of such fine-grained lamellae limits long-lasting, impact reheating to a peak temperature lower than 570 °C. These features, including the presence of monoclinic low-Ca pyroxene as the host, are reported in only a few mesosiderites. This suggests a possibly different origin and thermal history from most mesosiderites and that the crystallography (i.e. space group) of low-Ca pyroxene ... |
format |
Article in Journal/Newspaper |
author |
Pittarello, Lidia McKibbin, Seann Yamaguchi, Akira Ji, Gang Schryvers, Dominique Debaille, Vinciane Claeys, Philippe |
author_facet |
Pittarello, Lidia McKibbin, Seann Yamaguchi, Akira Ji, Gang Schryvers, Dominique Debaille, Vinciane Claeys, Philippe |
author_sort |
Pittarello, Lidia |
title |
Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite |
title_short |
Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite |
title_full |
Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite |
title_fullStr |
Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite |
title_full_unstemmed |
Two generations of exsolution lamellae in pyroxene from Asuka 09545: Clues to the thermal evolution of silicates in mesosiderite |
title_sort |
two generations of exsolution lamellae in pyroxene from asuka 09545: clues to the thermal evolution of silicates in mesosiderite |
publishDate |
2019 |
url |
http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/296640 https://dipot.ulb.ac.be/dspace/bitstream/2013/296640/3/Pittarelloetal2019.pdf |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
The American mineralogist, 104 (11 |
op_relation |
uri/info:doi/10.2138/am-2019-7001 uri/info:scp/85075329448 https://dipot.ulb.ac.be/dspace/bitstream/2013/296640/3/Pittarelloetal2019.pdf http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/296640 |
op_rights |
1 full-text file(s): info:eu-repo/semantics/openAccess |
_version_ |
1766277340764045312 |