HR: 0800h
AN: GP11D-0871    [Abstracts]
TI: Paleosecular variation and time-averaged field recorded in lavas flows from Mexico
AU: * Mejia, V
EM: vmejia@ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, Gainesville, FL 32611-2120 United States
AU: Bohnel, H
EM: hboehnel@geociencias.unam.mx
AF: Centro de Geociencias,Universidad Nacional Aut\'{o}noma de M\'{e}xico -UNAM, Campus Juriquilla, Quer\'{e}taro, 76230 Mexico
AU: Opdyke, N D
EM: drno@ufl.edu
AF: Department of Geological Sciences, University of Florida, 241 Williamson Hall, P.O. Box 112120, Gainesville, FL 32611-2120 United States
AU: Ortega-Rivera, A
EM: amabel@servidor.unam.mx
AF: Centro de Geociencias,Universidad Nacional Aut\'{o}noma de M\'{e}xico -UNAM, Campus Juriquilla, Quer\'{e}taro, 76230 Mexico
AU: Lee, J K
EM: lee@geol.queensu.ca
AF: Department of Geology, Queen's University, Miller Hall, Kingston, ON K7L 3N6 Canada
AU: Aranda-G\'{o}mez, J
EM: jjag@geminis.geociencias.unam.mx
AF: Centro de Geociencias,Universidad Nacional Aut\'{o}noma de M\'{e}xico -UNAM, Campus Juriquilla, Quer\'{e}taro, 76230 Mexico
AB: An analysis of secular variation and time-averaged paleomagnetic field in the Mexico, using data both newly obtained and from the literature is presented. Interpretation regarding time-averaged field and secular variation can best be constrained after excluding from the dataset all the sites from the western part of the Trans-Mexican Volcanic Belt and the sites older than Quaternary from the central and eastern part of the TMVB, which appear to be affected by counterclockwise tectonic rotations. The mean direction among the remaining sites of Quaternary age is Dec = 359.1\deg, Inc = 31.3\deg, \alpha$_{95}$= 2.0\deg, N = 157. This direction doesn't overlap the expected GAD but is consistent with a geocentric axial dipole field (GAD) with a 5% quadrupole. The VGP scatter of this group of sites (12.3\deg, with lower and upper 95% confidence limits of 11.4\deg and 13.3\deg) is close to the value expected from Model G (13.5\deg).
DE: 1522 Paleomagnetic secular variation
DE: 1560 Time variations--secular and long term
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting