TERRAPUB Earth, Planets and Space
Back

Earth Planets Space, Vol. 61 (No. 1), pp. 205-211, 2009

Paleomagnetic and rock-magnetic study on volcanic units of the Valsequillo Basin: implications for early human occupation in central Mexico

Avto Goguitchaichvili1, Ana Lillian Martin-Del Pozzo2, Jose Luis Rocha-Fernandez3, Jaime Urrutia-Fucugauchi4, and Ana Maria Soler-Arechalde4

1Laboratorio Interinstitucional de Magnetismo Natural, Instituto de Geofisica, Sede Michoacán, Universidad Nacional Autónoma de México, Morelia, Mexico
2Departamento de Vulcanología, Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria s/n, 04510 México DF, Mexico
3Programa de Posgrado en Ciencias de la Tierra, Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria s/n, 04510 México DF, Mexico
4Laboratorio de Paleomagnetismo, Departamento de Geomagnetismo y Exploración Geofísica, Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad Universitaria s/n, 04510 México DF, Mexico

(Received October 19, 2007; Revised April 8, 2008; Accepted April 10, 2008; Online published January 23, 2009)

Abstract: Alleged human and animal footprints were 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 at 40 ka by optically stimulated luminescence analysis, thereby providing new evidence that America was colonized earlier than the Clovis culture (about 13.5 Ma). We carried out paleomagnetic and rock magnetic analysis on 18 Xalnene ash block and core samples collected at two distinct localities and 19 standard paleomagnetic cores belonging to nearby monogenetic volcanoes. Our data provide evidence that both the volcanic lava flow and Xalnene ash were emplaced during the Laschamp geomagnetic event spanning from about 45 to 39 ka.
Key words: Paleomagnetism, volcanic ash, central Mexico, Lashamp event, human evolution.


Corresponding author E-mail: avto@geofisica.unam.mx


[Full text] (PDF 936 KB)