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笔者认为,角闪石的感压分解在引起爆发性喷发中可能有着影响。因为角闪石是含水矿物,当压力降低至不到1.5—2kb,分解为无水组合时,释放出的水可以使共存的熔体过饱和,产生引起爆发性喷发所必需的过压.在演化的熔岩和火山碎屑喷出物中通常能观察到再反应的角闪石.溶解于熔体中的挥发分(例如水)的数量是压力、温度和成分的函数,在结晶过程中还是结晶程度和品出矿物性质的函数。这种关系可以用简单的等式表达: X_r(1-f)=X_i-X-(moH)f′这里X_r是残余液体中的水含量,X_i是初始水含量,X_(moH)是含水矿物的水含量,f是总结晶程度.f′是,含矿水的物结晶程度.因而0≤f≤f≤1。笔者认为,储存在角闪石和黑云母等含水矿物中的水,在某些类型岩浆的喷发行为中起着重要作用;这些矿物的分解向熔体释放出水,其速率由再吸收反应的动力学控制。如果水的释放引起液相分异,超过了溶解极限,则气体膨胀造成的过压超过了上覆岩浆和火山通道岩石的承受力,其结果将导致爆发性喷发。角闪石效应可以发生在不同深度的构造层中,主要取决于岩浆性质和导致不稳定性的物理条件。
The author believes that amphibole’s pressure-sensitive decomposition in causing eruptions may have an impact. Because amphiboles are water-containing minerals, when pressure is reduced to less than 1.5-2 kb and decomposed into an anhydrous combination, the released water can supersaturate the coexisting melt and create the overpressure necessary to cause an explosive eruption. The re-reacted amphiboles are usually observed in the evolved lava and pyroclastic discharges.The amount of volatiles (such as water) dissolved in the melt is a function of pressure, temperature, and composition and remains The degree of crystallization and the quality of the product. This relationship can be expressed by a simple equation: X_r (1-f) = X_i-X- (moH) f ’where X_r is the water content in the residual liquid, X_i is the initial water content, X_ (moH) , F is the degree of total crystallinity, f ’is the degree of crystallinity of the mineral containing water, and 0≤f≤f≤1. The author believes that the water stored in hydrous minerals such as amphiboles and biotites plays an important role in the eruption behavior of some types of magma; the decomposition of these minerals releases water to the melt at a rate determined by the kinetics of the reabsorption reaction control. If the release of water causes the liquid phase to diverge beyond the dissolution limit, the overpressurization caused by the gas expansion exceeds the bearing capacity of the overlying magma and volcanic channel rocks and the result will be an explosive eruption. The amphibole effect can occur in structural layers at different depths, depending on the nature of the magma and the physical conditions that lead to instability.