Sector-zoning in Fassaite in Type B2 Refractory Inclusions
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چکیده
منابع مشابه
A comparative study of melilite and fassaite in Types B1 and B2 refractory inclusions
Most of the petrologic data available for Type B inclusions comes from Type B1s. Relatively little comes from the B2s, and there has not been a systematic comparison of the properties of their two most abundant minerals. In this work, we document the compositions and zoning patterns of melilite and fassaite in Type B2 inclusions, and compare and contrast them with the features of their counterp...
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Introduction: Type B1 CAIs are a major type of refractory inclusion in CV3 carbonaceous chondrites. An intriguing feature of fassaite in many Type B1 inclusions is complex zoning within single crystals. Seen in backscattered electron images (BEIs), the zoning reflects irregular, sometimes patchy, distributions of TiO2 and correlated and anticorrelated oxides; this zoning is not synonymous with ...
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Berman’s (1983) activity-composition model for CaO-MgO-Al2O3-SiO2 liquids is used to calculate the change in bulk chemical and isotopic composition during simultaneous cooling, evaporation, and crystallization of droplets having the compositions of reasonable condensate precursors of Types A and B refractory inclusions in CV3 chondrites. The degree of evaporation of MgO and SiO2, calculated to ...
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Introduction: A system of solar composition is so reducing that Ti and Ti can coexist, making the valence of Ti a valuable indicator of fO2 conditions during formation of nebular materials. The Ti/Ti ratios observed in the Ti-rich phases fassaite and rhönite in coarse-grained refractory inclusions from CV3 chondrites have been shown [1,2] to be quantitatively consistent with formation in a gas ...
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