Relationship Between Magma Recharge and Eruption Revealed Through In Situ Geochemical Fingerprinting and Crystal Size Distribution Analysis

通过原位地球化学指纹和晶体尺寸分布分析揭示岩浆补给与喷发之间的关系

• 批准号: 0073884
• 负责人: Wendy Bohrson
• 金额: $ 12.63万
• 依托单位: Central Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0073884&HistoricalAwards=false
• 关键词: Relationship; Between; Magma; Recharge; Eruption

EAR-0073884BohrsonThe process of magma recharge, which is intrusion of hotter magma into the base of a magma reservoir, is thought to be a catalyst for some volcanic eruptions. Newly intruded and standing magma may mix, and by one of a number of mechanisms, vesiculation may occur. Vesiculation leads to increased pressure in the magma reservoir, which, in turn, may lead to eruption. Previous work suggests that the degree of explosivity of the eruption may be critically dependent on the rate of intrusion and volume of recharge magma: slow intrusion of relatively small volumes of recharge magma may lead to gentle eruption whereas rapid intrusion of relatively large volumes of recharge magma may cause explosive eruption. These contrasting scenarios predict that the associated volcanic deposits may record differences in the extent and style of magma mixing and in the timing of recharge relative to eruption. The 1915 eruption of Lassen, a volcanic center located in northeastern California, is an extremely well-documented eruption in which recharge is hypothesized as the eruption catalyst. For volcanic products of this eruption, the chemical fingerprint of magma mixing will be determined using in situ laser-ablation ICP-MS, and the location of formation, crystallization history, and residence times of crystals will be determined from crystal size distribution analysis. Together, these data will reveal the timing of the recharge event relative to eruption and will also permit a description of the fluid dynamics of mixing in this reservoir. Through studies such as this one, quantitative constraints on the timing between recharge and eruption and on the relationships among recharge rate, recharge volume and explosivity will emerge. Such information will lead to enhanced understanding of dynamics and timing of volcanic eruptions.

Bohrson岩浆补给的过程，即较热的岩浆侵入岩浆库的底部，被认为是一些火山爆发的催化剂。 新侵入的岩浆和静止的岩浆可以混合，并且通过许多机制之一，可以发生泡状形成。 泡状作用导致岩浆库中的压力增加，这反过来可能导致喷发。 以前的工作表明，喷发的爆炸性程度可能是严重依赖于侵入的速度和体积的补给岩浆：缓慢侵入体积相对较小的补给岩浆可能会导致温和的喷发，而快速侵入体积相对较大的补给岩浆可能会导致爆炸性喷发。 这些对比的情景预测，相关的火山沉积物可能记录的岩浆混合的程度和风格的差异，并在相对于喷发的补给时间。1915年位于加州东北部的火山中心拉森火山爆发是一次记录非常完整的火山爆发，其中补给被假设为火山爆发的催化剂。 对于这次喷发的火山产物，将使用原位激光消融ICP-MS确定岩浆混合的化学指纹，并从晶体粒度分布分析确定晶体的形成位置、结晶历史和停留时间。 总之，这些数据将揭示相对于喷发的补给事件的时间，也将允许在这个水库混合的流体动力学的描述。 通过诸如此类的研究，将对补给与喷发之间的时间以及补给率、补给量和爆炸性之间的关系提出定量限制。 这些资料将有助于加深对火山爆发的动态和时间的了解。