Conduit-vent structures and related proximal deposits in the Las Cañadas caldera, Tenerife, Canary Islands

被引：0
作者：
Carles Soriano
Inés Galindo
Joan Martí
John Wolff
机构：
[1] Institut de Ciències de la Terra Jaume Almera CSIC,Department of Geology
[2] Instituto Tecnológico de Energías Renovables ITER,undefined
[3] Washington State University,undefined
来源：
Bulletin of Volcanology | 2006年 / 69卷
关键词：
Stratigraphy; Welded fallout; Vent; Conduit filling; Rheomorphism; fragmentation;
D O I：
暂无
中图分类号：
学科分类号：
摘要：
The Las Cañadas caldera wall and the outer slopes of the caldera provide three-dimensional exposures of numerous proximal-welded fallout deposits and have been mapped in detail. As a result, some parts of the Ucanca and Guajara Formations of the stratigraphy of Martí et al. (1994) have been divided into members that correspond to individual eruptions. Mapping has also revealed the occurrence of conduit-vent structures associated with proximal-welded fallout deposits. Conduit-vent structures consist of an upper flaring area and a lower narrow conduit. Conduit-vent geometry and dimensions include cylindrical plugs and eruptive fissures steeply dipping towards the caldera depression and elongated vents. The flaring area can be rather asymmetric and is usually filled by down-vent rheomorphic flow of the proximal fallout deposit. The lower conduits are filled by lava plug, agglutination of juveniles onto conduit walls and dyke intrusion with eventual dome extrusion. The eruption dynamics of welded fallout deposits and magma fragmentation within the conduit are consistent with an evolution from explosive to effusive. In this context conduit flow regimes evolve from turbulent to annular flow in which the conduit is progressively choked, and laminar flow leading to the final conduit closure.
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页码：217 / 231
页数：14
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