Most volcanism on Earth reflects plate-tectonic processes, occurring along the boundaries between the moving plates. Volcanism occurring within plate interiors is instead typically explained by deep-rooted "plumes" that transport hot material upward to feed stationary "hotspots" of volcanism. As the plate moves above them, these hotspots produce chains of volcanoes, such as the Hawaiian Islands. One volcano chain, with the exotic name "Pukapuka," submerged beneath the southeastern Pacific, lacks a characteristic hotspot feature: Its source of volcanism is not stationary. Instead, it has been moving eastward rather quickly. By comparing computer simulations with ship-based observations of the chemistry, volumes, and ages of Pukapuka lavas, Ballmer and coauthors demonstrate a new mechanism for migrating intraplate volcanism. They show that the massive injection of hot material by multiple plumes producing many of the Polynesian island chains also spreads out beneath the Pacific plate. As it spreads, it breaks up into multiple fingers, which melt at their tips to sustain volcanism. The Pukapuka volcano chain is formed by one such finger, which has traversed the Pacific plate and recently emerged beneath the neighboring Nazca Plate. These findings are important for understanding our planet's interior dynamics and how they produce volcanism.
Pervasive aeolian activity along rover Curiosity's traverse in Gale Crater, Mars Simone Silvestro et al., Carl Sagan Center, SETI Institute, 189 North Bernardo Avenue, Suite 100, Mountain View, California 94043, USA. Posted online 7 Feb. 2013; http://dx.doi.org/10.1130/G34162.1.
Simone Silvestro and colleagues present evidence of dune and ripple migration over the dune field that lies along Curiosity's traverse to Aeolis Mons in the NASA Mars Science Laboratory (MSL) landing site. They further e
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Geological Society of America