Achondrite ALHA77005 - Alteration of chromite and olivine
The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P2O5 0.9,...
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1984
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ftnasantrs:oai:casi.ntrs.nasa.gov:19850030217 2023-05-15T13:40:59+02:00 Achondrite ALHA77005 - Alteration of chromite and olivine Smith, J. V. Steele, I. M. Unclassified, Unlimited, Publicly available Sep 30, 1984 http://ntrs.nasa.gov/search.jsp?R=19850030217 unknown http://ntrs.nasa.gov/search.jsp?R=19850030217 Accession ID: 85A12368 Copyright Other Sources 91 Meteoritics; 19; 121-133 1984 ftnasantrs 2012-02-15T16:14:11Z The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P2O5 0.9, SiO2 57.9, TiO2 0, Al2O3 0.7, Cr2O3 0.4, V2O3 0, Fe2O3 (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na2O 0, K2O 1.8, SO3 (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt pct; (spinel) P2O5 3.5, SiO2 2.1, TiO2 2.2, Al2O3 2.1, Cr2O3 13.4, V2O3 0.8, Fe2O3 40.7, MgO 0.9, CaO 0.1, Na2O 0, K2O 2.0, SO3 11.1, Cl 0.1, sum 79.0 wt pct. Ion-microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO2 33-35, FeO 30-28, MgO 28-32, sum 93 wt pct. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock-induced oxidation for generation of the brown olivine (McSween and Stoeffler, 1980). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for preterrestrial alteration. Other/Unknown Material Antarc* Antarctic NASA Technical Reports Server (NTRS) Antarctic The Antarctic |
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NASA Technical Reports Server (NTRS) |
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91 |
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91 Smith, J. V. Steele, I. M. Achondrite ALHA77005 - Alteration of chromite and olivine |
topic_facet |
91 |
description |
The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P2O5 0.9, SiO2 57.9, TiO2 0, Al2O3 0.7, Cr2O3 0.4, V2O3 0, Fe2O3 (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na2O 0, K2O 1.8, SO3 (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt pct; (spinel) P2O5 3.5, SiO2 2.1, TiO2 2.2, Al2O3 2.1, Cr2O3 13.4, V2O3 0.8, Fe2O3 40.7, MgO 0.9, CaO 0.1, Na2O 0, K2O 2.0, SO3 11.1, Cl 0.1, sum 79.0 wt pct. Ion-microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO2 33-35, FeO 30-28, MgO 28-32, sum 93 wt pct. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock-induced oxidation for generation of the brown olivine (McSween and Stoeffler, 1980). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for preterrestrial alteration. |
format |
Other/Unknown Material |
author |
Smith, J. V. Steele, I. M. |
author_facet |
Smith, J. V. Steele, I. M. |
author_sort |
Smith, J. V. |
title |
Achondrite ALHA77005 - Alteration of chromite and olivine |
title_short |
Achondrite ALHA77005 - Alteration of chromite and olivine |
title_full |
Achondrite ALHA77005 - Alteration of chromite and olivine |
title_fullStr |
Achondrite ALHA77005 - Alteration of chromite and olivine |
title_full_unstemmed |
Achondrite ALHA77005 - Alteration of chromite and olivine |
title_sort |
achondrite alha77005 - alteration of chromite and olivine |
publishDate |
1984 |
url |
http://ntrs.nasa.gov/search.jsp?R=19850030217 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
Other Sources |
op_relation |
http://ntrs.nasa.gov/search.jsp?R=19850030217 Accession ID: 85A12368 |
op_rights |
Copyright |
_version_ |
1766144167365312512 |