The evolution of a chemically zoned magma chamber the 1707 eruption of Fuji Volcano, Japan /

by Watanabe, Shizuko.

THE EVOLUTION OF A CHEMICALLY ZONED MAGMA CHAMBER: THE 1707 ERUPTION OF FUJI VOLCANO, JAPAN By Shizuko Watanabe The eruptive history of Fuji Volcano has been dominated by basaltic volcanism. However, the 1707 eruption of Fuji Volcano resulted in a chemically zoned volcanic deposit ranging from basalt to dacite. Explosive, silicic eruptions such as this have occurred only twice in the history of Fuji Volcano, in 2800BP and in 1707AD, and the processes responsible for generating siliceous magmas beneath Fuji Volcano are not well understood. Detailed petrographic, major and trace element, and Sr, Nd, Pb, and Os isotope studies were done in order to constrain the petrogenetic processes that formed a chemically zoned magma chamber prior to the 1707 eruption of Fuji Volcano. Kawamoto (1992) proposed that liquid immiscibility played a major role; however, this study shows that the chemical variations in the Fuji 1707 deposit can be explained by fractional crystallization of the observed mineral assemblage accompanied by minor crustal contamination.