Paleomagnetic secular variation study of Ar-Ar dated lavas flows from Tacambaro area (Central Mexico): Possible evidence of Intra-Jaramillo geomagnetic excursion in volcanic rocks
Por:
Pena, RM, Goguitchaichvili A., Guilbaud, MN, Martinez, VCR, Rathert M.C., Siebe C., Reyes B.A., Morales J.
Publicada:
1 abr 2014
Resumen:
More than 350 oriented paleomagnetic cores were obtained for rock-magnetic and paleomagnetic analysis from radiometrically dated (40Ar-39Ar) magmatic rocks occurring in the southern segment (Jorullo and Tacámbaro areas) of the Michoacán-Guanajuato Volcanic Field in the Trans-Mexican Volcanic Belt. Most of the lavas (37) stem from monogenetic volcanoes dated at less than 4Ma. Two additional sites were sampled from the plutonic basement dated at 33-30Ma. Primary remanences carried by low-Ti titanomagnetites allowed to determining 34 reliable site-mean directions of mostly normal (27) but also reversed (7) polarities. The mean directions of these two populations are antipodal, and suggest neither major vertical-axis rotations with respect to the North America craton nor tilting in the region for the last 4Ma (rotation and flattening of the inclination parameters being less than -5.9±3.8 and 0.1±3.9, respectively). The corresponding paleomagnetic pole obtained for Pliocene-Pleistocene times is PLAT=83.4°, PLON=2.4° (N=32, A95=2.7°). Virtual geomagnetic poles also contribute to the time averaged field global database and to the paleosecular variation (PSV) investigations at low latitudes from lavas for the last 5Ma, showing a geomagnetic dispersion value that is in agreement with available PSV models. When comparing the magnetic polarities and corresponding radiometric ages of the studied sites with the Cenozoic geomagnetic polarity time scale (GPTS), a good correlation is observable. This finding underscores the suitability of data obtained on lavas in Central Mexico for contributing to the GPTS. Furthermore, the detection of short-lived geomagnetic features seems possible, since the possible evidence of Intra-Jaramillo geomagnetic excursion could be documented for the first time in these volcanic rocks. © 2014 Elsevier B.V.
Filiaciones:
Goguitchaichvili A.:
Univ Nacl Autonoma Mexico, Lab Interinst Magnetismo Nat, Inst Geofis Sede Michoacan, Mexico City 04510, DF, Mexico
Laboratorio Interinstitucional de Magnetismo Natural, Instituto de Geofísica - Sede Michoacán, Universidad Nacional Autónoma de México, Campus Morelia, Mexico
Guilbaud, MN:
Univ Nacl Autonoma Mexico, Inst Geofis, Dept Vulcanol, Mexico City 04510, DF, Mexico
Rathert M.C.:
Departamento de Física, Escuela Politécnica Superior, Universidad de Burgos, E-09001 Burgos, Spain
Siebe C.:
Univ Nacl Autonoma Mexico, Inst Geofis, Dept Vulcanol, Mexico City 04510, DF, Mexico
Departamento de Vulcanología, Instituto de Geofísica, Universidad Nacional Autónoma de México, 04510 México DF, Mexico
Reyes B.A.:
Univ Nacl Autonoma Mexico, Lab Interinst Magnetismo Nat, Inst Geofis Sede Michoacan, Mexico City 04510, DF, Mexico
Laboratorio Interinstitucional de Magnetismo Natural, Instituto de Geofísica - Sede Michoacán, Universidad Nacional Autónoma de México, Campus Morelia, Mexico
Morales J.:
Univ Nacl Autonoma Mexico, Lab Interinst Magnetismo Nat, Inst Geofis Sede Michoacan, Mexico City 04510, DF, Mexico
Laboratorio Interinstitucional de Magnetismo Natural, Instituto de Geofísica - Sede Michoacán, Universidad Nacional Autónoma de México, Campus Morelia, Mexico
Laboratorio Interinstitucional de Magnetismo Natural, Sede Tacámbaro, Instituto Tecnológico Superior de Tacámbaro, Michoacán, Mexico
Departamento de Física de la Tierra, Astronomía y Astrofísica I, Universidad Complutense de Madrid, Madrid, Spain
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