Study of sapphirine and related mineral association in the high-grade region of the Larsemann Hills, East Antarctica, shows that sapphirine of the area is characterized by its magnesio-, iron- and aluminum-rich, but s...Study of sapphirine and related mineral association in the high-grade region of the Larsemann Hills, East Antarctica, shows that sapphirine of the area is characterized by its magnesio-, iron- and aluminum-rich, but silica-poor feature, and the obvious intra- and intergrain changes in compositions. The change is mainly mani- fested as the Tschermark substitution （ Mg, Fe） ＋ Si =2A1. In the high-grade meta-morphism and anatexis process the multistage crystallization of minerals occurred and resulted in the complexity of the mineral association, such as the differentiation of leuco-and melano-components. Among them, the mafic-rich minerals formed earlier, and the differentiation of magnesio-and iron-components is responsible for the earlier presence of iron-rich minerals and later crystallization of magnesio-rich minerals, thus the successive associations of multistage occurred. The rock composition is an important but not critical factor to the occurrence of sapphirine. It is the mobilization of components that accounts for the formation of sapphirine. The multistage evolution of mineral association to some degree reflects the changing composition and opening of the setting. It is therefore deduced that the protolith from which sapphirine is derived is not necessarily magnesio-rich pelite. The heterogeneity of sapphirine composition is resulted from the various media, not the PT changes. Sapphirine formed at 840-880℃ ,not the so-called ultrahigh temperature condition（〉 1000℃）. Its formation is related to both the filtration and diffusion processes in high-grade metamor-phism and anatexis.展开更多
基金supported by the National Natural Science Foundation of China (No.40572041)the Chinese Geological Survey(Grant No.1212010711509)+3 种基金Programme of Excellent Young Scientists of the Ministry of Land and Resources(MLR)Basic outlay of the Ministry (J0704)The logistic was supported by the Chinese Arctic and Antarctic AdministrationThe anonymous reviewers are thanked for their valuable comments of the early version of the paper.
文摘Study of sapphirine and related mineral association in the high-grade region of the Larsemann Hills, East Antarctica, shows that sapphirine of the area is characterized by its magnesio-, iron- and aluminum-rich, but silica-poor feature, and the obvious intra- and intergrain changes in compositions. The change is mainly mani- fested as the Tschermark substitution （ Mg, Fe） ＋ Si =2A1. In the high-grade meta-morphism and anatexis process the multistage crystallization of minerals occurred and resulted in the complexity of the mineral association, such as the differentiation of leuco-and melano-components. Among them, the mafic-rich minerals formed earlier, and the differentiation of magnesio-and iron-components is responsible for the earlier presence of iron-rich minerals and later crystallization of magnesio-rich minerals, thus the successive associations of multistage occurred. The rock composition is an important but not critical factor to the occurrence of sapphirine. It is the mobilization of components that accounts for the formation of sapphirine. The multistage evolution of mineral association to some degree reflects the changing composition and opening of the setting. It is therefore deduced that the protolith from which sapphirine is derived is not necessarily magnesio-rich pelite. The heterogeneity of sapphirine composition is resulted from the various media, not the PT changes. Sapphirine formed at 840-880℃ ,not the so-called ultrahigh temperature condition（〉 1000℃）. Its formation is related to both the filtration and diffusion processes in high-grade metamor-phism and anatexis.
