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Further constraints for Permo-Carboniferous magnetostratigraphy: case study of the sedimentary sequence from San Salvador–Patlanoaya (Mexico)De nouvelles contraintes pour la magnétostratigraphie du Permo-Carbonifères : cas d'étude de la séquence sédimentaire de San Salvador–Patlanoaya (Mexique)
Authors:Luis M Alva-Valdivia  Avto Goguitchaichvili  Manuel Grajales  Antonio Flores de Dios  Jaime Urrutia-Fucugauchi  Carmen Rosales  Juan Morales
Affiliation:1. Lab. Paleomagnetismo, Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico, D.F., Mexico;2. Subdireccion de Exploracion y Produccion Geociencias, Instituto Mexicano del Petroleo, 07730 Mexico, D.F., Mexico;3. Instituto de Geologia, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico, D.F., Mexico
Abstract:We report rock-magnetic and magnetostratigraphic results from one of the best exposed Permo-Carboniferous outcrops in Mexico, in order to determine some decisive magnetostratigraphy constraints. Some spinels, most probably titanomagnetites, seem to be responsible for aimantation, although greigite may also exist judging from thermal desaimantation of isothermal remanence. Remanence analyses indicate that only one remanent component could be recognized with minor secondary overprint, which were easily removed applying 100–180 °C. Six normal and four reverse magnetozones were recognized from bottom to top in Patlanoya section between 340 and 280 Myr. Both normal and reverse polarity rocks were found in Carboniferous time around 340 Myr, in agreement with previous paleomagnetic works. Our record revealed two normal subchrons within PCRS (Kiaman), the dominantly reverse superchron, at 305 and 280 Myr, respectively. These, which may be speculatively correlated to normal aimantation, occasionally occurred during PCRS interval. More detailed studies are needed in order to establish a more precise magnetostratigraphy for Permo-Carboniferous time. To cite this article: L.M. Alva-Valdivia et al., C. R. Geoscience 334 (2002) 811–817.
Keywords:magnetostratigraphy  Permo-Carboniferous  central Mexico  magnétostratigraphie  Permo-Carbonifère  Mexique central
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