Insights Into the Dynamics of Planetary Interiors Obtained Through the Study of Global Distribution of Volcanoes: Lessons From Earth and Venus.

Abstract:

The distribution of volcanic features is ultimately controlled by processes taking place beneath the surface of a planet. For this reason, characterization of volcano distribution at a global scale can be used to obtain insights concerning dynamic aspects of planetary interiors. In this work, description of the distribution of volcanic features observed on Earth and Venus is completed using density contours obtained with the Fisher kernel. Attention is focused on similar features observed in both planets. In particular two features are examined with more detail: First, a pattern of groups of clusters defining the boundaries of elliptical regions that tentatively can be associated to large mantle plumes. Second, the existence of a uniform distribution of background volcanism. The former pattern is considered to constitute the first order convective pattern of the mantle in Venus, and although it is present on Earth, it is not as prominent. In contrast, the persistent occurrence of volcanic clusters at a lower significance level, suggests the occurrence of a different scale of mantle convection that controls a more uniformly distributed volcanism. Both, the first order related to large mantle-plumes and the background volcanism are superimposed on Earth to the volcanism controlled by plate tectonics. Consequently, the global distribution of volcanism in both planets reveals that at least three types of mantle convection can take place in the terrestrial planets, and that such types of mantle convection can coexist simultaneously in one given planet, although in each case, a dominant mode is different.