Magmatic Degassing: Experimental Constraints on Bubble Nucleation, Growth, and Coalescence

[804860 .加德纳岩浆中的气泡对许多过程都是至关重要的，比如将金属从岩浆转移到矿体，触发和驱动火山爆发，以及向大气释放气体。尽管它们很重要，但关于岩浆中气泡形成和相互作用的实验数据却很少。为了使气体在岩浆中形成气泡并逃逸到矿体中，气泡必须成核、生长并连接起来，以便气体通过岩浆迁移。本研究将尝试通过实验检查气泡在硅酸盐熔体中的成核和生长，利用广泛的气体成分来解决我们对岩浆中气泡行为的认识上的这一空白。将要研究的一些关键问题是，岩浆条件需要什么样的变化才能促使气泡成核和生长？气泡是均匀成核还是非均匀成核？不同的气体种类，如H2O、CO2、Cl和S，在脱气岩浆中起什么作用？，气泡相互作用之前需要多少体积百分比的气泡？通过解决这些问题，将对岩浆脱气，从而对控制火山喷发和矿体形成的过程，以及火山喷发对大气的影响，获得根本性的新见解。

9804860GardnerGas bubbles in magmas are crucial to many processes, such as transferring metals from magmas to ore bodies, triggering and driving volcanic eruptions, and releasing gas to the atmosphere. Despite their importance, only meager experimental data exists on bubble formation and interaction in magmas. In order for gas to form bubbles in magmas and to escape to ore bodies, bubbles must nucleate, grow, and link up, to allow gas to migrate through the magma. This study will attempt to address this gap in our knowledge about the behavior of bubbles in magmas by experimentally examining nucleation and growth of bubbles in silicate melts using a wide range of gas compositions. Some of the crucial questions that will be investigated are, what changes in magmatic conditions are needed to precipitate bubble nucleation and growth?, do bubbles nucleate heterogeneously or homogeneously?, what roles do different gas species, such as H2O, CO2, Cl, and S, play in degassing magmas?, and what volume percentage of bubbles is needed before bubbles can interact? By addressing these questions, fundamental new insights will be gained on magma degassing and, thus, on process controlling volcanic eruptions and ore body formation, and on the influence of volcanic eruptions on the atmosphere.