Are Oceanic Sediments Involved?
Kersting’s study of Klyuchevskoy volcano in Kamchatka, Russia, evaluated the influence of oceanic sediments in the generation of island-arc volcanoes. Klyuchevskoy is the most active island-arc volcano in the world (see Figure 3). A recent eruption blew volcanic material 15 to 18 kilometers above sea level and required the diversion of international airline traffic as a safety precaution. The team first measured Pb, Sr, and Nd isotope ratios in basaltic rocks from Klyuchevskoy. They used Livermore’s thermal ionization mass spectrometer, which can measure extremely low levels of these isotopes. The same ratios were measured in oceanic sediments from the North Pacific, parallel to the Kamchatkan arc. These sediments are the best analog for sediments that might have previously subducted with the oceanic slab beneath Kamchatka.
