The enhanced element enrichment in the supercritical states of granite–pegmatite systems
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In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites, and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas, and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of various elements and compounds, potentially up to extreme levels, and may explain various features both of mineralization and the magmas that produced them.
KeywordsGranites Pegmatites Supercritical state Extreme element enrichment
We would like to take this opportunity to dedicate this paper to Dr. James Webster, with our thanks and gratitude for his unflagging assistance, collaboration and encouragement over the years. Over a long period, Dr. Webster has worked with us unravelling the mysteries of melt–melt immiscibility, in addition to the enormous body of work he has achieved in other areas of geology and geochemistry. We thank Prof. Huaiwei Ni for valuable suggestions and the hint to some important references.
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Conflict of interest
The authors declare that they have no conflict of interest.
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