Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites
The single-crystal X-lay technique was used to calibrate a new intracrystalline geothermometer based on equilibrium Mg-Fe* fractionation (Fe* = Fe2+ + Mn2+) between M1 and M2 sites of natural P2(1)/c pigeonite, Suitable crystals free of exsolution textures and sharp diffraction maxima were selected...
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MINERALOGICAL SOC AMER, 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA
2000
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ftunivpadovairis:oai:www.research.unipd.it:11577/2461457 2024-02-04T09:53:17+01:00 Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites PASQUAL, DARIA MOLIN, GIANMARIO TRIBAUDINO M. Pasqual, Daria Molin, Gianmario Tribaudino, M. 2000 STAMPA http://hdl.handle.net/11577/2461457 eng eng MINERALOGICAL SOC AMER, 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA info:eu-repo/semantics/altIdentifier/wos/WOS:000087965500009 volume:85 issue:7-8 firstpage:953 lastpage:962 numberofpages:10 journal:AMERICAN MINERALOGIST http://hdl.handle.net/11577/2461457 ORTHO-PYROXENE THERMAL HISTORY ORTHOPYROXENES TEMPERATURE CHEMISTRY THERMODYNAMICS CLINOPYROXENE METEORITE info:eu-repo/semantics/article 2000 ftunivpadovairis 2024-01-10T17:42:59Z The single-crystal X-lay technique was used to calibrate a new intracrystalline geothermometer based on equilibrium Mg-Fe* fractionation (Fe* = Fe2+ + Mn2+) between M1 and M2 sites of natural P2(1)/c pigeonite, Suitable crystals free of exsolution textures and sharp diffraction maxima were selected by careful TEM and XRD investigations from a large number of samples. Two single crystals, PCA82506-3 (Wo(6)En(76)Fs(18)) from the Pecora Escarpment 82506 Antarctic ureilite, and BTS308-2 (Wo(10)En(47)Fs(43)) from the BTS308 Parana rhyodacite, were annealed at temperatures ranging from 600 to 1000 degrees C. The TEM investigation, carried out on fragments of selected single crystals both before and after thermal treatment, shows heating-induced texture modifications preliminary to spinodal decomposition in both crystals and a size increase in antiphase domains in BTS308-2, The two geothermometric equations calculated by linear regression of In K-D* vs. 1/T are: In K-D* = -3291(+/- 269)/T(K) + 0.971(+/-0.253); (r(2) = 0.974) ln K-D* = -2816(+/- 83)/T(K) + 0.542(+/-0.083); (r(2) = 0.995) respectively for PCA82506-3 (X-Fe* = 0.20) and BTS308-2 (X-Fe* = 0.49) [X-Fe* = Fe*/(Fe* + Mg)]. These results imply negligible compositional effects on Mg-Fe* site partitioning within the range of compositions encompassed by the samples. Comparison of the intracrystalline fractionation data of pigeonites with those of Pbca orthopyroxenes shows a similar degree of ordering for both at a given temperature. This result suggests only a small effect of Ca on Fe*-Mg ordering in pyroxene with Ca content up to Wo(10). Article in Journal/Newspaper Antarc* Antarctic Padua Research Archive (IRIS - Università degli Studi di Padova) Antarctic Pecora Escarpment ENVELOPE(-68.707,-68.707,-85.639,-85.639) |
institution |
Open Polar |
collection |
Padua Research Archive (IRIS - Università degli Studi di Padova) |
op_collection_id |
ftunivpadovairis |
language |
English |
topic |
ORTHO-PYROXENE THERMAL HISTORY ORTHOPYROXENES TEMPERATURE CHEMISTRY THERMODYNAMICS CLINOPYROXENE METEORITE |
spellingShingle |
ORTHO-PYROXENE THERMAL HISTORY ORTHOPYROXENES TEMPERATURE CHEMISTRY THERMODYNAMICS CLINOPYROXENE METEORITE PASQUAL, DARIA MOLIN, GIANMARIO TRIBAUDINO M. Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites |
topic_facet |
ORTHO-PYROXENE THERMAL HISTORY ORTHOPYROXENES TEMPERATURE CHEMISTRY THERMODYNAMICS CLINOPYROXENE METEORITE |
description |
The single-crystal X-lay technique was used to calibrate a new intracrystalline geothermometer based on equilibrium Mg-Fe* fractionation (Fe* = Fe2+ + Mn2+) between M1 and M2 sites of natural P2(1)/c pigeonite, Suitable crystals free of exsolution textures and sharp diffraction maxima were selected by careful TEM and XRD investigations from a large number of samples. Two single crystals, PCA82506-3 (Wo(6)En(76)Fs(18)) from the Pecora Escarpment 82506 Antarctic ureilite, and BTS308-2 (Wo(10)En(47)Fs(43)) from the BTS308 Parana rhyodacite, were annealed at temperatures ranging from 600 to 1000 degrees C. The TEM investigation, carried out on fragments of selected single crystals both before and after thermal treatment, shows heating-induced texture modifications preliminary to spinodal decomposition in both crystals and a size increase in antiphase domains in BTS308-2, The two geothermometric equations calculated by linear regression of In K-D* vs. 1/T are: In K-D* = -3291(+/- 269)/T(K) + 0.971(+/-0.253); (r(2) = 0.974) ln K-D* = -2816(+/- 83)/T(K) + 0.542(+/-0.083); (r(2) = 0.995) respectively for PCA82506-3 (X-Fe* = 0.20) and BTS308-2 (X-Fe* = 0.49) [X-Fe* = Fe*/(Fe* + Mg)]. These results imply negligible compositional effects on Mg-Fe* site partitioning within the range of compositions encompassed by the samples. Comparison of the intracrystalline fractionation data of pigeonites with those of Pbca orthopyroxenes shows a similar degree of ordering for both at a given temperature. This result suggests only a small effect of Ca on Fe*-Mg ordering in pyroxene with Ca content up to Wo(10). |
author2 |
Pasqual, Daria Molin, Gianmario Tribaudino, M. |
format |
Article in Journal/Newspaper |
author |
PASQUAL, DARIA MOLIN, GIANMARIO TRIBAUDINO M. |
author_facet |
PASQUAL, DARIA MOLIN, GIANMARIO TRIBAUDINO M. |
author_sort |
PASQUAL, DARIA |
title |
Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites |
title_short |
Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites |
title_full |
Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites |
title_fullStr |
Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites |
title_full_unstemmed |
Single-crystal thermometric calibration of Fe-Mg order-disorder in pigeonites |
title_sort |
single-crystal thermometric calibration of fe-mg order-disorder in pigeonites |
publisher |
MINERALOGICAL SOC AMER, 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA |
publishDate |
2000 |
url |
http://hdl.handle.net/11577/2461457 |
long_lat |
ENVELOPE(-68.707,-68.707,-85.639,-85.639) |
geographic |
Antarctic Pecora Escarpment |
geographic_facet |
Antarctic Pecora Escarpment |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000087965500009 volume:85 issue:7-8 firstpage:953 lastpage:962 numberofpages:10 journal:AMERICAN MINERALOGIST http://hdl.handle.net/11577/2461457 |
_version_ |
1789965057277296640 |