Magnetostratigraphy of the lower Cretaceous strata in Tlay úa Quarry, Tepexi de Rodriguez, State of Puebla, Mexico

Abstract

A stratigraphic sequence of magnetic polarity reversals consisting of nine magnetozones is recognized in Early Cretaceous sedimentary strata in the Tlay úa Quarry of Tepexi de Rodriguez, state of Puebla. Combined with biostratigraphic age assignments using ammonites that apparently belonging to the Albian, the geomagnetic polarity sequence can be correlated with the middle part of chron C34n (C34n.1n-C34n.2n chrons, with an age of 100-105 Myr), the Cretaceous long normal interval. The magnetic properties and characteristic remanence of magnetization are dominated by soft and hard coercivity magnetic minerals. Rock-magnetic properties and a positive reversal test suggest that remanence is primary. The section displays both reverse and normal polarities with mean directions: D=344.9°, I =32.4°, k=21, a95=4.2° and D=149.4°, I=-36.6°, k=17, a95=8.7°, respectively. Comparison with the North American apparent polar wander path indicates tectonic stability of the region since the Cretaceous. © 2006, The Seismological Society of Japan, Society of Geomagnetism and Earth, Planetary and Space Sciences, The Volcanological Society of Japan, The Geodetic Society of Japan, The Japanese Society for Planetary Sciences. All rights reserved.