Comparative analyses of glass fragments from brittle fracture experiments and volcanic ash particles
Comparative analyses of glass fragments from brittle fracture experiments and volcanic ash particles
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DOI：
10.1007/s00445-011-0562-0
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发表时间：
2012-04-01
影响因子：
3.5
通讯作者：
Zimanowski, Bernd
中科院分区：
文献类型：
--
作者：
Duerig, Tobias;Mele, Daniela;Zimanowski, Bernd
爆炸性火山爆发的特征是岩浆熔体迅速碎裂成灰烬颗粒。为了描述破碎过程中的能量耗散，重要的是要了解材料破坏的机制。只有在受控的实验室条件下才可能对碎裂进行定量描述。工业硅酸盐玻璃与岩浆熔体具有高度的结构亲和力，并且具有透明的优点，这使得可以通过光学方法在与爆发性火山作用相关的时间尺度上研究裂缝的演化。为此，对硅酸盐玻璃靶进行了一系列低速侧锤冲击实验，导致火山灰粒度谱中产生碎片。为了验证实验产生的破碎动力学火山过程的一般可转移性，所产生的产品进行了比较，通过统计颗粒形状分析，颗粒产生的标准化岩浆破碎实验和天然灰颗粒来自存款的玄武质和流纹岩成分从2004年格里姆火山和第四纪Tepexitl凝灰岩环喷发，分别。天然灰颗粒从Grimsvotn和Tepexitl显示显着的相似性与实验片段的热预应力浮法玻璃，表明占主导地位的影响，预先存在的应力对颗粒形状，并建议类似的破碎过程中所研究的材料。
Explosive volcanic eruptions are characterized by the rapid fragmentation of a magmatic melt into ash particles. In order to describe the energy dissipation during fragmentation it is important to understand the mechanism of material failure. A quantitative description of fragmentation is only possible under controlled laboratory conditions. Industrial silicate glasses have a high structural affinity with magmatic melts and have the advantage of being transparent, which allows the study of the evolution of fractures by optical methods on a time scale relevant for explosive volcanism. With this aim, a series of low speed edge-on hammer impact experiments on silicate glass targets has been conducted, leading to the generation of fragments in the grain-size spectra of volcanic ash. In order to verify the general transferability of the experimentally generated fragmentation dynamics to volcanic processes, the resulting products were compared, by means of statistical particle-shape analyses, to particles produced by standardized magma fragmentation experiments and to natural ash particles coming from deposits of basaltic and rhyolitic compositions from the 2004 Grimsvotn and the Quaternary Tepexitl tuff-ring eruptions, respectively. Natural ash particles from both Grimsvotn and Tepexitl show significant similarities with experimental fragments of thermally pre-stressed float glasses, indicating a dominant influence of preexisting stresses on particle shape and suggesting analogous fragmentation processes within the studied materials.