HR: 0800h
AN: B41A-02    [Abstracts]
TI: Preliminary results of high resolution magneto-biostratigraphy of continental sequences in Chapala Basin, Southwestern Mexico
AU: * Mendez Cardenas, D L
EM: dorislmendezc@gmail.com
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria Del Coyoacan, Mexico, DF 04510, Mexico
AU: Benammi, M
EM: mouloud@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria Del Coyoacan, Mexico, DF 04510, Mexico
AB: Chapala Lake is south from Guadalajara, Jalisco State (Southwestern Mexico). Belongs to a series of Pliocenic lakes along the Mexican Volcanic Belt. It is localized in the Chapala rift, and the entire area is controlled by the tectonic setting of the Colima, Tepic and Chapala rifts, constituting the triple junction rift-rift-rift. The deposits studied belong to volcanosedimentary sequences, composed by lacustrine and fluvial associations alternated with units of ash and pumice. The faunistic component reported consists at least of 27 mammals species, and the sediments were there're in have to work with special attention for seek rodents by handpicking. Probably these rodents will be the clue to determine the deposits correlation. Core demagnetization shows that they are low-coercivity magnetic minerals like magnetite or Ti-magnetite. It was verified that the characteristic magnetization corresponds to MNRp and the inversion test resulted good. Rodents are represented by Geomynae, Sigmondontinae and Sciurinae. The Geomynae family is the most common, and the faunistic association indicates Blancan age. This also allows a correlation with the polarity pattern in the GSS between 3,6 and 2,6 Ma. Actually, is known that this kind of studies in continental sequences supported with paleontological record of vertebrates could give us a more precised calibration of the age of such deposits. Allowing better understanding of the evolution of these mammals and their path trough geological record. This work shows the preliminary results of rodents palaeontology and high resolution magneto-stratigraphy in the units from to Chapala Basin.
DE: 1520 Magnetostratigraphy
SC: Biogeosciences [B]
MN: 2007 Joint Assembly