Stratigraphy of Earliest Mesozoic Sediments in Southeastern Mexico and Western Guatemala

Abstract

Earliest Mesozoic sediments in southeastern Mexico and western Guatemala consist of clastics of the Late Jurassic Todos Santos and Late Jurassic-Early Cretaceous San Ricardo Formations. The Todos Santos is a redbed sequence which averages about 850 meters in thickness, but varies significantly from area to area. The San Ricardo, formally defined here for the first time, is about 400 meters thick and is composed of limestone and clastics of marginal marine origin. Stratigraphic sections and detailed lithologic descriptions are presented to define these two formations.