Mexico dating 2015
Local-scale folds were targeted and 6–10 samples were collected per site using a portable Pomeroy EZ Core Drill.
A Brunton compass and inclinometer were used to determine the azimuth and plunge of the core samples and the orientation of the beds.
The absolute age of folds was determined by clay grain-size separation, illite polytype characterization, and Ar dating of multiple size fractions (Fitz-Díaz and van der Pluijm, 2013; Haines and van der Pluijm, 2008).
Ages of thrusting were determined for the Tolimán Sequences (83.5 ± 1.5 Ma) on the western edge of the study area, the western and eastern Zimapán Basin (82 ± 0.5 Ma and 76.5 ± 1.0 Ma, respectively), and the western and eastern Tampico-Misantla Basin (64 ± 2.0 Ma and 43.5 ± 0.5 Ma, respectively); see Figure 2 for details (Fitz-Díaz et al., 2014).
Carbonates that contain interlayered shales with radiometrically datable authigenic illite present an opportunity to directly determine the age of synfolding paleomagnetic remagnetizations.
By combining radiometric Ar/Ar dating of illitization in folds and thrusts with synfolding remagnetization, an absolute age for synfolding remagnetizations can be determined.