Anomalous arc volcanism and subduction of linear topographic features

ADAM, C.; ICHIHARA, M.; VIDAL, V.; GROSSE, P.

San Francisco

Congreso; American Geophysical Union Fall Meeting 2019; 2019

The subduction of linear topographic features such as hotspot tracks, aseismic ridges or fracture zones has a significant effect on the dynamics of the subduction zones. One of the most important consequences is the change in arc volcanism. According to some authors, the subduction of linear topographic features creates volcanic gaps. For other authors, it actually enhances arc magmatism by generating large arc volcanoes or volcano clusters. To understand the phenomena occurring in the subduction zones, it is important to have an accurate characterization of the correlation between the subduction of linear oceanic features and the arc magmatism. In this study, we investigate this correlation by using new and accurate datasets. In particular, we design an accurate volcano volume estimation method. We also design methods to accurately quantify the topographic anomalies on the oceanic side, and to project their location under the arc chain, by taking into account the direction of these subducting features relative to the trench, and the slab dip. Our quantitative statistical study shows that in most cases, the subduction of linear topographic features is associated with enhanced arc magmatism, although there are some features associated with volcanic gaps. We also find that the largest arc volcanoes are associated with the subduction of these linear features.