Implicaciones de los datos paleomagneticos sobre la edad de la Sierra de Chichinautzin, Cuenca de Mexico

Abstract

The dominant normal geomagnetic polarity observed for the Chichinautzin Group in the southern Basin of Mexico correlates with the Brunhes Chron, implying an age for the volcanic units younger than about 0.78-0.79 Ma. However, to estimate the age for the onset of the activity and its spatial-temporal distribution, further detailed studies of radiometric dating and volcanic stratigraphy are needed. Preliminary results from a section towards Cuernavaca Valley yield reverse polarity, suggesting that activity began earlier than 0.78-0.79 Ma. The paleomagnetic data do not provide firm constraints on the discrete character of the activity. Results for the Ajusco volcanic complex yield reverse and normal/reverse polarities, indicating that the activity spanned a transitional period probably during the Brunhes Chron. -from English summary