Magnetostratigraphic study of the Continental Lower Miocene Suchilquitongo Formation, Southern Mexico
Por:
Benammi M., Urrutia-Fucugauchi J., Alva-Valdivia L.M.
Publicada:
1 ene 2003
Resumen:
New paleomagnetic data from southern Mexico provide a magnetostratigraphic framework to correlate mammal-bearing continental sections of the Suchilquitongo Formation to the Early Miocene part of the geomagnetic polarity time scale. A total of 127 paleomagnetic samples were collected from 40 horizons belonging to two sections. The sequence is characterized by a succession of cream to light pink to gray, thin- to medium-bedded tuffaceous sandstones and siltstones, partly silicified limestones, and a dominantly light green ignimbrite deposited in a fluviolacustrine environment. Remanent magnetization generally has been characterized by two components, a present-day field component with low-unblocking temperatures up to 350°C and a characteristic component with unblocking temperatures up to 580°-610°C. The characteristic component is interpreted as primarily based on antipodal populations of remanence data. Six sites at the top of the section (inclination = 40.5°, declination = 11.3°, ?95 = 1.4, and K = 471) have a mean paleomagnetic direction rotated clockwise about 17° with respect to the expected Miocene direction derived from the North American polar wander curve (inclination = 354°, declination = 30°). According to biochronologic age, the magnetostratigraphic results from the mammal-bearing sedimentary-type section in the Suchilquitongo area can be correlated with chron C5Dn-C5Cn3n at approximately 17.61-16.55 Ma. An age of about 17 Ma is proposed for the fossiliferous level, corresponding to an Early Miocene age.
Filiaciones:
Benammi M.:
Lab. de Paleomagnetismo y Geofisica, Instituto de Geofisica, Univ. Nac. Autonoma de Mexico, México 04510, Mexico
Urrutia-Fucugauchi J.:
Lab. de Paleomagnetismo y Geofisica, Instituto de Geofisica, Univ. Nac. Autonoma de Mexico, México 04510, Mexico
Alva-Valdivia L.M.:
Lab. de Paleomagnetismo y Geofisica, Instituto de Geofisica, Univ. Nac. Autonoma de Mexico, México 04510, Mexico
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