Mexico dating 2015
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.
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).
Local-scale folds were targeted and 6–10 samples were collected per site using a portable Pomeroy EZ Core Drill.