Sedimentology and geomorphology of the deposits from the August 2006 pyroclastic density currents at Tungurahua volcano, Ecuador.
Sedimentology and geomorphology of the deposits from the August 2006 pyroclastic density currents at Tungurahua volcano, Ecuador.
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DOI：
10.1007/s00445-013-0765-7
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发表时间：
2013
影响因子：
3.5
通讯作者：
Dingwell, Donald B.
中科院分区：
文献类型：
--
作者：
Douillet, Guilhem Amin;Tsang-Hin-Sun, Eve;Kueppers, Ulrich;Letort, Jean;Pacheco, Daniel Alejandro;Goldstein, Fabian;Von Aulock, Felix;Lavallee, Yan;Hanson, Jonathan Bruce;Bustillos, Jorge;Robin, Claude;Ramon, Patricio;Hall, Minard;Dingwell, Donald B.
沉积的火山碎屑密度流从2006年8月喷发的通古拉瓦显示三个相协会取决于地形环境：大规模的，近端的交叉分层，和远端的交叉分层相。(1)块状相仅限于火山斜坡上的山谷。它含有直径大于1米的碎屑到细灰物质，是块状的，被解释为从致密的火山碎屑流中沉积而成。它的表面可以显示出被盘状和泡状大碎屑覆盖的裂片和堤坝。这些脆弱的大碎屑必须在流的表面沿沿着漂流，以便保存，因此意味着这些流的表面附近的尖锐的密度边界。(2)近端交叉分层相暴露在火山上部的山谷漫滩上，包含大量的粗粒层和交叉分层的火山灰和火山砾层。它被解释为沉积从（a）密集的火山碎屑流溢出的火山上部的山谷和（B）稀释的火山碎屑密度流从密集的流动所产生的空气夹带在陡峭的上侧翼的平缓的山脊。(3)远端交叉分层相作为位于河谷漫滩悬崖下游的交叉分层灰沉积物的空间有限、孤立和楔形体露头。它包含了许多加积沙丘床型，其波峰方向揭示父母的流动方向。下游的沙丘底形的大小减少，连同下游细化的粒度分布的趋势，观察到在100米的规模。这种相被解释为已经从稀释的火山碎屑密度流与基底牵引边界层沉积。我们认为，母流产生的密集流夹带的空气在悬崖上，这些稀释的电流可能会迅速存款通过“气动跳跃”。三种模式存在于所有样品的粒度分布独立的相，这进一步支持的解释，所有三个相来自相同的初始流。本研究强调地形对小体积火山碎屑密度流的影响，以及流动转化和流动剥离过程的重要性。
The deposits of the pyroclastic density currents from the August 2006 eruption of Tungurahua show three facies associations depending on the topographic setting: the massive, proximal cross-stratified, and distal cross-stratified facies. (1) The massive facies is confined to valleys on the slopes of the volcano. It contains clasts of >1 m diameter to fine ash material, is massive, and interpreted as deposited from dense pyroclastic flows. Its surface can exhibit lobes and levees covered with disk-shaped and vesicular large clasts. These fragile large clasts must have rafted at the surface of the flows all along the path in order to be preserved, and thus imply a sharp density boundary near the surface of these flows. (2) The proximal cross-stratified facies is exposed on valley overbanks on the upper part of the volcano and contains both massive coarse-grained layers and cross-stratified ash and lapilli bedsets. It is interpreted as deposited from (a) dense pyroclastic flows that overflowed the gentle ridges of valleys of the upper part of the volcano and (b) dilute pyroclastic density currents created from the dense flows by the entrainment of air on the steep upper flanks. (3) The distal cross-stratified facies outcrops as spatially limited, isolated, and wedge-shaped bodies of cross-stratified ash deposits located downstream of cliffs on valleys overbanks. It contains numerous aggrading dune bedforms, whose crest orientations reveal parental flow directions. A downstream decrease in the size of the dune bedforms, together with a downstream fining trend in the grain size distribution are observed on a 100-m scale. This facies is interpreted to have been deposited from dilute pyroclastic density currents with basal tractional boundary layers. We suggest that the parental flows were produced from the dense flows by entrainment of air at cliffs, and that these diluted currents might rapidly deposit through “pneumatic jumps”. Three modes are present in the grain size distribution of all samples independently of the facies, which further supports the interpretation that all three facies derive from the same initial flows. This study emphasizes the influence of topography on small volume pyroclastic density currents, and the importance of flow transformation and flow-stripping processes.
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影响因子：
3.5
作者：
Douillet, Guilhem Amin;Pacheco, Daniel Alejandro;Kueppers, Ulrich;Letort, Jean;Tsang-Hin-Sun, Eve;Bustillos, Jorge;Hall, Minard;Ramon, Patricio;Dingwell, Donald B.
通讯作者：
Dingwell, Donald B.
DOI：
10.1016/j.jvolgeores.2008.07.008
发表时间：
2008-11-20
影响因子：
2.9
作者：
Charbonnier, S. J.;Gertisser, R.
通讯作者：
Gertisser, R.
DOI：
10.1144/gsl.mem.2002.021.01.11
发表时间：
2002-01-01
期刊：
ERUPTION OF SOUFRIERE HILLS VOLCANO, MONTSERRAT, FROM 1995 TO 1999
影响因子：
--
作者：
Cole, PD;Calder, ES;Norton, GE
通讯作者：
Norton, GE
影响因子：
2.7
作者：
Barber, CB;Dobkin, DP;Huhdanpaa, H
通讯作者：
Huhdanpaa, H
DOI：
10.1016/j.jvolgeores.2012.02.011
发表时间：
2012-05-01
影响因子：
2.9
作者：
Andrews, Benjamin J.;Manga, Michael
通讯作者：
Manga, Michael