Chemical Evolution of High-Temperature Silicic Magmas

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NekvasilEAR-0000926Experiments simulating step-wise fractional crystallization will be continued on natural alkalic magmas ranging from basalts to rhyolite that are found world-wide on ocean islands and in continental hotspot and rifted regions as both volcanic and plutonic suites. These experiments will determine if crystal fractionation can play a dominant role in generating the compositional diversity of magmas in such suites, and if so, under which conditions of pressure, dissolved volatile content, and oxygen fugacity this fractionation may have taken place. Such information is invaluable for placing constraints on the thermal and compositional profiles of the mantle and lower crust and on magma diversification processes in general. Furthermore, since silica-rich lavas of quartz-oversaturated alkalic suites are highly volatile-rich and such volatiles play a major role in volcanic explosivity, experimental data on the increase of magmatic volatile content during fractionation of water-bearing minerals is directly applicable to the evaluation of potential volcanic hazards.