Dynamics of the 1902 Eruptions of Montagne Pelee Determined from Size, Shape, and Textures of Vitric Pyroclasts

该项目将研究1902年蒙塔涅·佩雷灾难性喷发产生的核沉积中的幼年玻璃状火山灰，以此为基础解释火山作用在这一活动周期的喷发动力学中所起的作用。进行这项研究的目的是为了更深入地了解导致如此大规模和毁灭性的爆炸性喷发的物理过程。电子探针(EMP)、扫描电子显微镜(SEM)、图像分析和粒度分布分析将是研究马提尼克圣皮埃尔附近连续北风或沉积物重力流留下的特弗拉矿床的主要技术手段。从核岩矿床中观察到的幼年玻璃碎屑的内部和表面结构信息将有助于揭示(1)幼年岩浆挥发分的岩浆泡蚀和碎裂过程，(2)喷发过程中热液岩浆作用的作用和时间，(3)核岩的成因；(4)核被片输运和沉积过程中的颗粒相互作用机理。使用新的顺序破碎和运移模型进行的粒度分布分析将允许识别破碎的成熟度和运移过程的成熟度，以评估离源不同距离的核不同部分。这些信息在评估有大规模喷发历史的火山，如蒙塔涅·佩雷火山的火山危害时，应极为有用。

This project will investigate juvenile glassy tephra from the nuee-ardente deposits produced the cataclysmic eruptions on Montagne Pelee in 1902, as a basis for interpretation of the role of hydrovolcanism in the eruption dynamics of this cycle of activity. The research is undertaken specifically to provide sharper insights into the physical processes responsible for such large and devastating explosive eruptions. Electron microprobe (EMP), scanning electron microscope (SEM), image analysis, and size distribution analysis will be the main techniques used to investigate tephra deposits left by the passage of successive nuees ardentes or sediment gravity flows in the vicinity of St. Pierre, Martinique. Internal and surficial textural information observed on juvenile vitric fragments from the nuee ardente deposits will shed light on (1) processes of magma vesiculavesiculation and fragmentamentation as a result of sion of juvenile magmatic volatiles; (2) the role and timing of hydromagmatism during the eruption; (3) the genesis of nuee ardentes; and (4) the mechanics of particle-particle interaction during transtransport and deposition of nuee-ardente tephra. Grain size distribution analysis using the new model of sequential fragmentation and transport will allow the identification of maturity of fragmentation and transportation processes to be evaluated for various parts of the nuees at various distances from the source. This information should be extremely useful in the evaluation of volcanic hazards at volcanoes with a history of large expolosions such as those of Montagne Pelee.