TY - JOUR
T1 - Mineralogical changes upon heating in the Millbillillie meteorite
T2 - Implications for paleointensity determination in Apollo samples
AU - Cournède, Cécile
AU - Garrick-Bethell, Ian
AU - Coe, Robert S.
AU - Le Goff, Maxime
AU - Gallet, Yves
N1 - Publisher Copyright:
© 2016 Académie des sciences
PY - 2016/11/1
Y1 - 2016/11/1
N2 - Measuring the intensity of the Moon's ancient magnetic field is an important goal of lunar sample analysis. Paleointensity estimates using thermal methods (Thellier–Thellier) raise the problem of sample alteration, especially for lunar samples carrying sulfides. To address this problem, we made real-time measurements of sample magnetization during heating with a three-axis vibrating sample magnetometer (the Triaxe, LeGoff and Gallet, 2004), in the hope that rapid heating would minimize alteration (Coe et al., 2014). We studied the Millbillillie meteorite, which has a lunar-like mineralogy. We find that after repeated heating phases to ∼600 °C, we form pyrrhotite, magnetite, and magnetic phases with low (200–270 °C) Curie temperatures. These low-temperature phases appear after pyrrhotite has apparently been destroyed by subsequent heating phases, and their mineralogy is unknown. These results have implications for the paleomagnetic study of any extraterrestrial samples with even small amounts of sulfides, and further experiments are required to understand them.
AB - Measuring the intensity of the Moon's ancient magnetic field is an important goal of lunar sample analysis. Paleointensity estimates using thermal methods (Thellier–Thellier) raise the problem of sample alteration, especially for lunar samples carrying sulfides. To address this problem, we made real-time measurements of sample magnetization during heating with a three-axis vibrating sample magnetometer (the Triaxe, LeGoff and Gallet, 2004), in the hope that rapid heating would minimize alteration (Coe et al., 2014). We studied the Millbillillie meteorite, which has a lunar-like mineralogy. We find that after repeated heating phases to ∼600 °C, we form pyrrhotite, magnetite, and magnetic phases with low (200–270 °C) Curie temperatures. These low-temperature phases appear after pyrrhotite has apparently been destroyed by subsequent heating phases, and their mineralogy is unknown. These results have implications for the paleomagnetic study of any extraterrestrial samples with even small amounts of sulfides, and further experiments are required to understand them.
KW - Apollo samples
KW - Millbillillie meteorite
KW - Mineralogical changes
KW - Paleointensity recovery
KW - Sulfides
KW - Thermal method
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U2 - 10.1016/j.crte.2016.10.001
DO - 10.1016/j.crte.2016.10.001
M3 - Article
AN - SCOPUS:84999767757
SN - 1631-0713
VL - 348
SP - 551
EP - 560
JO - Comptes Rendus - Geoscience
JF - Comptes Rendus - Geoscience
IS - 8
ER -