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The composition of melt inclusions in basalts erupted at mid-ocean ridges may be modified by post-entrapment processes, so the present composition of melt inclusions may not represent their original composition at the time of entrapment. By combining the melt inclusion composition in samples from the South Mid-Atlantic Ridge at 19°S analyzed in this study, and from the Petrological Database, we found that post-entrapment crystallization processes resulted in higher Ca/Al, Mg#[100 atomic Mg2+/(Mg2++Fe2+)], MgO and FeO contents, and lower CaO and Al2O3 contents of plagioclase-hosted melt inclusions relative to those hosted in olivine. In addition, melt inclusions hosted in plagioclase with anorthite content larger than 80mol.% had been modified more readily than others. By discussing the relationships between Ca/Al and fractional crystallization, post-entrapment crystallization, and the original melt composition, we propose that Ca/Al can be regarded as an indicator of the effect of post-entrapment processes on melt inclusion composition. Specifically, i) when Ca/Al<0.78, melt inclusion compositions corrected for fractional crystallization to Mg#=72 can represent the primary magma at mid-ocean ridges; ii) when 0.781.0, the compositions of melt inclusions do not reflect the original melt composition nor preserve information about the mantle source. According to these criteria, plagioclase-hosted melt inclusions with Ca/Al>1.0 in basalts from the South Mid-Atlantic Ridge at19±S cannot represent the composition of the melt at the moment of their entrapment. [ABSTRACT FROM AUTHOR]

The crystallization behaviors of the (Ti36.1Zr33.2Ni5.8Be24.9)100-xCux (x = 5, 7, 9, 11, 13, 15, 17; at. %) metallic glasses are investigated under both the continuous heating and isothermal conditions by the differential scanning calorimetry. Quasicrystals are found in the crystallization products under both conditions by X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The evolution of the primary crystallization products of these alloys is discussed in detail. The effects of the increasing distortion energy of the icosahedral short-range order with the increasing Cu content in the(Ti36.1Zr33.2Ni5.8Be24.9)100-xCux (x = 5, 7, 9, 11, 13, 15, 17) alloys are found to be responsible for the evolution of the crystallization products. The isothermal crystallization kinetics deviates from the Johnson-Mehl-Avrami-Kolmogoroff (JMAK) model. A modified JMAK model with an impingement parameter is found to be suitable for the isothermal crystallization kinetics of the current alloys. The effects of quasicrystal formation on the crystallization kinetics are disscussed in detail. And it is found that the isothermal crystallization kinetics are influenced by both of the 'soft impingement' effect and the formation of the quasicrystals. [ABSTRACT FROM AUTHOR]