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除玄武质岩浆外,每个大体积岩浆的喷发都是从一个岩浆房中排出的,而这个岩浆房在温度和物质成分上具成带性。大多数体积较小的岩浆喷发也只是排出不均匀的和已经演化的岩浆体系的一部分。几种类型成分分带的火山灰流凝灰岩提供了岩浆喷发前在温度、化学成分和同位素组分,以及斑晶的种类、含量等方面梯度的实例,这些梯度有助于确定发生于各个体系中的岩浆分异机制。较大体积岩浆喷发的一个普遍特征是具成分间断,指示岩浆房中存在着这种间断。地幔来源的岩浆为地壳岩浆房提供了热量和物质,流纹质岩浆房中的成带现象主要是由热重力扩散和挥发份络合作用引起的。液相的结构梯度在其中起着重要作用。
Except for basaltic magma, the eruption of each large volume of magma is expelled from a magma chamber, which is zonal in temperature and composition. Most of the smaller magma eruptions are only part of the magma system that has evolved unevenly and evolved. Volcanic ash tuffs zoned by several types of composition provide examples of gradients in temperature, chemical composition and isotopic composition, as well as the type, content, etc. of the phenocrysts prior to the magma eruption. These gradients can help determine the occurrence of Magmatic differentiation mechanism. A common feature of larger volcanic eruptions is the discontinuity of the composition, indicating that there is such a discontinuity in the magma chamber. The mantle-derived magma provides heat and matter to the crustal magma chamber, and the banding in the rhyolitic magma chamber is mainly caused by the thermogravimetric diffusion and volatile complexation. The structural gradient of the liquid phase plays an important role in this.