Abstract
"Volcanism is a phenomenon of eruptions, which are essentially channeled by weakness in the earth's crust, whose fractures provide preferential routes for lava flows towards the surface. That is why volcanic features are so numerous in rift or subduction zones. The links between tectonics and vulcanicity are both numerous and clearly seen. This is particularly shown by the distortion of surface strata, with swelling, folding and fractures. These constraints and distortions which the relief is subject to consequently guides the erosion process, and particularly karst erosion, as tectonics also guide the flow of water and karstiflcation.
"Volcanism is a phenomenon of eruptions, which are essentially channeled by weakness in the earth's crust, whose fractures provide preferential routes for lava flows towards the surface. That is why volcanic features are so numerous in rift or subduction zones. The links between tectonics and vulcanicity are both numerous and clearly seen. This is particularly shown by the distortion of surface strata, with swelling, folding and fractures. These constraints and distortions which the relief is subject to consequently guides the erosion process, and particularly karst erosion, as tectonics also guide the flow of water and karstiflcation.
Volcanism is a phenomenon of eruptions, which are essentially channeled by weakness in the earth's crust, whose fractures provide preferential routes for lava flows towards the surface. That is why volcanic features are so numerous in rift or subduction zones. The links between tectonics and vulcanicity are both numerous and clearly seen. This is particularly shown by the distortion of surface strata, with swelling, folding and fractures. These constraints and distortions which the relief is subject to consequently guides the erosion process, and particularly karst erosion, as tectonics also guide the flow of water and karstiflcation. When a volcanic phase reaches the surface, it creates specific forms which are linked to nature and size of the eruption. In limestone terrain it gives rise to particular landforms which can be classified according to the dominant process, sometimes karst-volcanic, sometimes volcano-karstic. The author describes a typology of geosystems where karst and vulcanicity are linked, based on field observation in Europe (France, Germany, Ireland) and Africa (Morocco and Madagascar). Included in the criteria for discriminating between different types are the kinds of eruptions and the speed of formation of volcanic features, the evolution and the post-volcanic morphogenetic relationships. Particular attention has been paid to the spread of ash capable of covering karst areas, or not, capable of leading to the formation of aeolian-volcanic crusts indurated with carbonates. In conclusion, it seems that areas of karst and vulcanism are particularly appropriate for the provision of absolute dating (U/Th, palaeomagnetism, etc.). The overlap in the data obtained in both domains should provide scientists with some useful information for the understanding of palaeoenvironments.
Salomon, J.-N. (2008). Zeitschrift fur Geomorphologie, Supplementband, 131: 89-112
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