Petrography and Stable Isotope Geochemistry of the Cretaceous El Abra Limestones (Actopan), Mexico: Implication on Diagenesis

Abstract

Petrography and stable isotopes (carbon and oxygen) geochemistry of limestones from the El Abra Formation, Actopan, were studied to identify their digenetic environments. The major petrographic types identified are mudstone, wackestone, grainstone, and boundstone. Most of the studied samples show positive d13C values, except two samples (2 and 28), which are slightly negative values (-0.27‰ and -0.02‰). The organic remains identified in foraminiferal wackestone type can be responsible for the negative d13C values. The d18O values range from -12.41‰ to -4.02‰ and indicate meteoric diagenesis.