当火山岩上升到地表时，它的成分是如何变化的?-地江南体育网页版球科学堆栈交换江南电子竞技平台

当火山岩上升到地表时，它的成分是如何变化的?

2014 - 09 - 10 - t05:34:12z

火山流体力学的示意图如下所示。

^{慷慨地从下面引用的参考资料的图1中借鉴}

从图的标题中:

在爆炸爆发期间，气泡壁在碎片表面发生了破坏性的破裂。释放的气体迅速膨胀，岩浆上升从带有悬浮气泡的粘性熔体转变为带有悬浮岩浆碎片的气体流。< / p > < /引用>
My assumption is that this boundary between the magma column and the steam above it is critical to the crystallization of the minerals to form the volcanic rock.

Does the composition of the volcanic rock change drastically according to the distance between the magma column and the mouth of the volcano at the time the rock is formed?

(Or) do the rocks melt and recrystallize frequently as the boundary moves, only attaining their final composition before they are ejected into the air?

How important is the steam/air interface at the top of the volcano to the rock's formation?

I realize this is going to change based on the composition of the magma itself, but I'm looking for the behavior of an "average" rock species, though specific examples are great, too.

Reference:

Gonnermann, H.M. and Manga, M. (2007). The fluid mechanics inside a volcano. Annu. Rev. Fluid Mech, 39, 321–56. [PDF] [DOI].

由Gimelist回答的问题:当火山岩上升到地表时，它的成分是如何变化的?

2014 - 09 - 10 - t18:16:27z

根据岩石形成时岩浆柱与火山口之间的距离，火山岩的成分是否发生了巨大的变化?

岩浆的金属成分不会发生剧烈变化。所谓金属，我指的是岩石的基本成分:主要是硅，但也有铁、钙、铝、镁等。我要补充的是，有一些过程可以影响金属成分(主要是矿物分馏)，但我认为，当你谈论火山喷发的最上面部分时，它的影响是次要的。

能改变并且确实改变的是挥发性成分。岩浆中的气体已耗尽。以一瓶可乐为例。当你打开它，CO<下标>2冒出来。焦炭本身仍然是焦炭，但它的化学性质发生了一些变化(而且味道很差)，因为CO₂被排出了。岩浆也可能改变氧化态。再加上挥发性脱气作用，可能最终会影响岩浆结晶的矿物。

(Or) do the rocks melt and recrystallize frequently as the boundary moves, only attaining their final composition before they are ejected into the air?

No. Once a rock crystallises you are going to need quite a lot of energy to melt it again, and this is not a likely process to occur in a system open to the atmosphere where heat is free to leave the volcanic system.