Intrusion generated topography in monogenetic volcanoes

VAN WYK DE VRIES, B.; MARQUEZ, A.; PETRONIS, M.S.; DELCAMP, A.; KERVYN, M.; GROSSE, P.

Paris

Congreso; 8th IAG International Conference on Geomorphology; 2013

International Association of Geomorphologists

Monogenetic volcanoes are produced by short (less than decades) and low volumes (less than 1 km3) eruptions of usually one magmatic event. They are usually described by their lavas and eruptive products, but in certain eroded or quarried cases, it has become clear that intrusions can play a major roll in their evolution. In other cases it has become clear that the surface morphology has been extensively controlled by late stage intrusions. This presentation describes intrusions seen in several volcanoes, in the Châine des Puys, Central France, either in exposures in quarries, or interpreted after an analysis of the surface morphology and structure. We show that large-scale surface modification can occur at any time before, or during, an eruption and that subsequent intrusion into a previous edifice can also cause large scale-topographic changes. In particular we show: 1) the internal structure of intrusions exposed in the Lemptégy Scoria cone, 2) the large scale topographic remodelling of the Petit Puy de Dôme scoria cone during a latter trachytic intrusion phase, 3) the formation of a lacolith-related bulge before the Killian Plinian eruption, and the collapse of the Puy de Gouttes cone related to a shallow intrusion that formed the Puy Chopine Trachytic eruption. While we concentrate on small-scale monogenetic events, we will compare these with cases from larger stratovolcanoes, such as Teide, Tenerife, and Momotombo, Nicaragua which indicate that such large scale topographic changes can occur at all scales and can significantly alter the shape of a volcano.