Magma mixing process by fractal dimensions

1.对玛干和大泽火山进行了地质调查，特别参考了火山史和包括镁铁质包裹体在内的不均匀喷射物的取样。2.用X射线荧光和电子探针对两座火山的岩石和矿物进行了化学分析。斑晶边缘的化学分带表明，安山岩和英安岩是通过岩浆室和岩浆道中的多期岩浆混合作用喷发出来的。3.玛干火山喷出物非均质形态的分维值在0.9~1.6之间，这与岩浆的混合发育阶段和流动机制密切相关。在火山碎屑喷发的情况下，混合岩浆由于较高的上升速率而处于湍流状态，从而产生较高的分维。随着混合作用的进行，分维降低，长英质岩浆和镁铁质岩浆之间的完全均一化导致分维结构消失，形成中间成分岩浆，镁铁质包裹体对理解岩浆室和管道中的混合过程起着关键作用。大泽火山熔岩中的镁铁质包裹体根据斜长石结构可分为三种类型。由于这些镁铁质包裹体的约束条件，提出了多阶段混合的观点。

1.Geological survey of Me-akan and Taisetsu volcanoes was performed with special reference to the volcanic history and sampling for heterogeneous ejecta including mafic inclusions.2.Chemical analyzes of the rocks and minerals of Me-akan and Taisetsu volcanoes were carried out with XRF and EPMA achines. Chemical zonings at the rim of phenocrysts indicate that andesite and dacite magmas were erupted through the multi-stage magma mixing in magma chamber and conduit.3.Measured fractal dimensions of morphological patterns of heterogeneous ejecta from Me-akan volcano vary from 0.9 to 1.6, which are intimately correlated with mixing development stage and flow mechanism of magmas. In the case of pyroclastic eruptions, mixed magmas are in a turbulent state on account of higher ascending rate, which yields higher fractal dimensions. As mixing proceeds fractal dimensions decrease, and then perfect homogenization between felsic and mafic magmas causes the disappearance of the fractal structure to form intermediate composition magmas.Mafic inclusions have a key role in understanding the mixing process in magma chamber and conduit. The mafic inclusions in lavas from Taisetsu volcano are classified into three types based on the plagioclase texture. As a result of constraints for these mafic inclusions, multi-stage mixing scenario was proposed.