Chemical Evolution of High-Temperature Silicic Magmas

模拟分步结晶的实验将继续在从玄武岩到流纹岩的天然碱性岩浆上进行，这些岩浆在世界范围内的海洋岛屿和大陆热点地区以及裂谷地区都是火山和深成岩浆岩。这些实验将确定晶体分馏是否能够在形成这些套中岩浆成分多样性的过程中发挥主导作用，如果是的话，在何种压力、溶解挥发性含量和氧逸度条件下，这种分馏可能发生。这些信息对于确定地幔和下地壳的热剖面和成分剖面以及岩浆多样化过程的总体限制是非常宝贵的。此外，由于石英-过饱和碱性套体的富硅熔岩具有丰富的挥发物，而挥发物在火山爆发中起着重要作用，因此，含水矿物分馏过程中岩浆挥发物含量增加的实验数据可直接用于火山潜在危害的评价。

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.