HR: 1400h
AN: V23A-01    [Abstracts]
TI: Origin and age of the Volcanic Rocks of Tláloc Volcano, Sierra Nevada, Central Mexico
AU: * Meier, M
EM: mario.meier@unifr.ch
AF: Dep. of Geosciences, Univ. of Fribourg, Perolles, Fribourg, CH-1700, Switzerland
AU: Grobéty, B
EM: bernard.grobety@unifr.ch
AF: Dep. of Geosciences, Univ. of Fribourg, Perolles, Fribourg, CH-1700, Switzerland
AU: Arce, J L
EM: jlarce@geologia.unam.mx
AF: Instituto de Geologia, UNAM, Ciudad Universitaria Coyoacan, Mexico, DF 04510, Mexico
AU: Rueda, H
EM: hrueda@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria Coyoacan, Mexico, DF 04510, Mexico
AB: The Tláloc volcano (TV) is a 4125 m high stratovolcano of the Trans Mexican Volcanic Belt (TMVB) and is located in the northern end of the N-S trending Sierra Nevada, 30 km NE of Mexico City. Few data on the petrological and temporal evolution of TV have been published to date. Recently dated deposits gave ages between 32'000 and 34'500±500 years BP (Huddart and Gonzalez, 2004). Mapping and sampling of extrusive rocks in the summit region of TV revealed a dome structure with radiating lava flows consisting of dacitic rocks containing plagioclase and hornblende phenocrysts. Some flows, however, seem to be associated with a collapse structure E of the main summit. Crossing relationships indicate that this structure is older (“Paleo Tláloc”). A stratigraphy of the pyroclastic deposits was established along the northern slope of TV. From the numerous pyroclastic flows, separated by paleosoils and fluviatile deposits, only two pumice and one block and ash flow (BAF) have regional extent. Their thickness - distance relationship and their granulometry point to major explosive events. A carbonized wood sample from the BAF deposit gave ages similar to the previous ages (33'180±550 yr BP and 23'170±270 yr BP), a sample from a pyroclastic flow gave even a younger age (16'620±110 yr BP), suggesting that TV remained active also after the volcanoes Iztaccíhuatl and Popocatépetl further to the South started their activity. Based on these preliminary data it may be necessary to reconsider the accepted scenario of the temporal evolution of the central section of the TMVB, which assumes that the activity migrates from North to South with time. Huddart, D. and Gonzalez, S., 2004. Pyroclastic flows and associated sediments, Tláloc-Telapón, piedmont fringe of the eastern basin of Mexico. In: G.J. Aguirre-Diaz, Macías, J.L., and Siebe, C., (Editor), Penrose Conference. UNAM, Metepec, Puebla, Mexico, pp. 35.
DE: 8400 VOLCANOLOGY
DE: 8428 Explosive volcanism
DE: 9350 North America
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly