Chronostratigraphic framework and depositional environments in the organic rich Eagle Ford Group

Since the beginning of the century, several authors have hypothesized and documented the presence of bottom currents during the deposition of mudstones, including mudstones rich in organic matter, challenging the assumption that persistent low-energy conditions are necessary prerequisites for deposition of such sediments. More processes responsible for transport and deposition of mudstones means also more processes acting contemporaneously in different parts of a basin.

Without a precise and robust chronostratigraphic framework, however, it is not possible to characterize these differences. The new data reported here provide a profoundly different understanding of the controls on sedimentation in distal continental shelf platforms. To enhance the understanding of the different coeval environments of deposition coexisting in a muddy system, the Upper Cretaceous Eagle Ford Group, deposited on the Comanche carbonate platform, has been investigated by integrating sedimentology, mineralogy, geochemistry and palaeoecology and creating age models in different physiographic sectors using biostratigraphy and geochronology.