HR: 18:05h
AN: GP24A-08    [Abstracts]
TI: On the age of human footprints in Central Mexico: paleomagnetic constraints
AU: * Rocha Fernandez, J
EM: al_minhadj@yahoo.com
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria s/n, Mexico, Mexico
AU: Gogichaishvili, A
EM: avto@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria s/n, Mexico, Mexico
AU: Martin del Pozo, A
EM: analil@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria s/n, Mexico, Mexico
AU: Urrutia Fucugauchi, J
EM: juf@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria s/n, Mexico, Mexico
AB: Until recently, we thought we knew where ancestral Native Americans came from (central Siberia, then across Beringia), and when they arrived (about 13 000 cal BP, after a trek between the recently separated Canadian ice sheets after Fiedel, 2006). Recent theories of American origins postulate multiple pre-Clovis migrations including Transpacific or coastal voyages by Australians, Melanesians, or Ainu, and even a Transatlantic migrations by Caucasoid Solutreans from Iberia. Thus, timing, route and origin of the first colonization to the Americas remains one of the most important topics in human evolution. Human and animal footprints have been found within the upper bedding surfaces of the Xalnene volcanic ash layer that outcrops in the Valsequillo Basin, south of Puebla, Mexico (Gonzalez et al., 2005). The ash has been dated to at least 40 ka BP. Paleomagnetic investigation yielded an intermediate magnetic polarity for Xalnene ash deposits while nearby Toluquilla volcano is reversely magnetized. Moreover, the absolute geomagnetic paleointensity derived from the volcanic lava flow is significantly reduced with respect to the present day geomagnetic field strength. It is quite possible that the ash as well as volcanic lava flow formed during worldwide observed Laschamp geomagnetic event.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1513 Geomagnetic excursions
DE: 1519 Magnetic mineralogy and petrology
DE: 1520 Magnetostratigraphy
DE: 1521 Paleointensity
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly