Open Access

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

  • Avto Goguitchaichvili122Email author,
  • Ana Lillian Martin-Del Pozzo222,
  • Jose Luis Rocha-Fernandez322,
  • Jaime Urrutia-Fucugauchi422 and
  • Ana Maria Soler-Arechalde422
Earth, Planets and Space200961:BF03352900

https://doi.org/10.1186/BF03352900

Received: 19 October 2007

Accepted: 10 April 2008

Published: 23 January 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