HR: 0800h
AN: V51A-09 INVITED     [Abstracts]
TI: Characteristics and Similarities of Lava Suites from Jorullo and La Pilita Volcanoes, Volcanic Front of the Westernmost Trans-Mexican Volcanic Belt
AU: * Roberge, J
EM: robegre@geofisica.unam.mx
AF: Laboratorio Universitario de Petrologia, Av Universidad 3000 Coyoacan, Mexico, DF 04510, Mexico
AU: Delgado Granados, H
EM: hugo@geofisica.unam.mx
AF: Instituto de Geofisica, Av Universidad 3000 Coyoacan, Mexico, DF 04510, Mexico
AB: The monogenetic volcanic field of Michoacán-Guanajuato is at the westernmost part of the Trans-Mexican Volcanic Belt. This is the region where the influence of the Cocos plate starts under the subduction system beneath North America. Jorullo volcano had eruptive activity between 1759-1774 and La Pilita within the Holocene. The eruption of Jorullo and the products from La Pilita were first treated in the incredible work of Luhr and Carmichael (1985), however nothing else has been done on those lava flows since. We have visited the lava flows from Jorullo and La Pilita volcanoes in January 2007 and many new observations were made. Two flows were emitted from the north cone, the age of these lavas is debatable and apparently are older than Jorullo. Also a big older flow is running from the southern base of the main Jorullo cone. So far, this big flow had been ignored in the literature and we found that it is texturally very similar to the La Pilita flow. In this work we present geochemical and textural analyses of over 20 lava flows samples from Jorullo, and 3 lava samples from La Pilita. These data are then compared with samples from the large flow south of Jorullo to constrain his origin and chronology. The origin of this big flow maybe the proof that Jorullo is in fact a volcanic complex, and it was active before the 1959 eruption. This implies that Jorullo may not be a monogenetic volcano.
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly