Abstract
Over the past 30 years the cooling rates of terrestrial and extraterrestrial basaltic rocks have commonly been inferred from the size of antiphase domains (APDs) in pigeonite. However, the coarsening rate of APDs has been observed to deviate substantially from an ideal rate. It is believed that this deviation is caused by Ca segregation to the antiphase boundaries (APBs) of domains, since Ca is expected to substantially slow boundary migration rates due to solute drag.
This letter presents direct experimental evidence of Ca segregation to APBs in pigeonite. The local atomic structure and chemistry of APBs in pigeonite were examined using high-resolution and energy-filtered transmission electron microscopy. High-resolution images show that APBs in pigeonite have a structure similar to that of augite, and energy-filtered compositional images reveal that Ca segregates to APBs. These results have direct ramifications for the use of antiphase domain (APD) size as a marker for the thermal history of the rocks in which pigeonite crystallizes.
© 2015 by Walter de Gruyter Berlin/Boston
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- Geochemical modeling of bacterially induced mineralization of schwertmannite and jarosite in sulfuric acid spring water
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- Composition and temperature dependence of cation ordering in Ni-Mg olivine solid solutions: a time-of-flight neutron powder diffraction and EXAFS study
- Thermal conductivity of spinels and olivines from vibrational spectroscopy: Ambient conditions
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- The crystal chemistry of birefringent natural uvarovites: Part I. Optical investigations and UV-VIS-IR absorption spectroscopy
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- Crystal structure of a new (21)-clinopyribole synthesized at high temperature and pressure
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- Raman spectroscopic studies of phase E to 19 GPa
- The crystal structures of the low-temperature phases of leonite-type compounds, K2Me(SO4)2·4H2O (Me2+ = Mg, Mn, Fe)
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Articles in the same Issue
- Recalibration of the GASP geobarometer in light of recent garnet and plagioclase activity models and versions of the garnet-biotite geothermometer
- Compositional zoning and element partitioning in nickeloan tourmaline from a metamorphosed karstbauxite from Samos, Greece
- Occurrence of apatite associated with magnetite in an ophiolite complex (Othrys), Greece
- Overpressures induced by coesite-quartz transition in zircon
- Geochemical modeling of bacterially induced mineralization of schwertmannite and jarosite in sulfuric acid spring water
- H2O-D2O exchange in lawsonite
- Composition and temperature dependence of cation ordering in Ni-Mg olivine solid solutions: a time-of-flight neutron powder diffraction and EXAFS study
- Thermal conductivity of spinels and olivines from vibrational spectroscopy: Ambient conditions
- Elasticity of six polycrystalline silicate garnets at pressure up to 3.0 GPa
- The crystal chemistry of birefringent natural uvarovites: Part I. Optical investigations and UV-VIS-IR absorption spectroscopy
- The crystal chemistry of birefringent natural uvarovites: Part II. Single-crystal X-ray structures
- Ferroanthophyllite in Rockport grunerite: A transmission electron microscopy study
- Crystal structure of a new (21)-clinopyribole synthesized at high temperature and pressure
- The Mg(Fe)SiO3 orthoenstatite-clinoenstatite transitions at high pressures and temperatures determined by Raman-spectroscopy on quenched samples
- Raman spectroscopic studies of phase E to 19 GPa
- The crystal structures of the low-temperature phases of leonite-type compounds, K2Me(SO4)2·4H2O (Me2+ = Mg, Mn, Fe)
- Carraraite and zaccagnaite, two new minerals from the Carrara marble quarries: their chemical compositions, physical properties, and structural features
- Pristine surface growth features on 100 Ma garnet phenocrysts: Interference imaging results
- Oxygen triclusters in crystalline CaAl4O7 (grossite) and in calcium aluminosilicate glasses: 17O NMR
- Low-temperature heat capacity of pentlandite
- Calcium segregation at antiphase boundaries in pigeonite