Los sedimentos del límite Cretácico/Terciario en El Tecolote (México): evidencias de aloctonía

Abstract

Sediments from the Cretaceous-Tertiary interval were studied at the El Tecolote area (northeastern México). The composite section consists of Maastrichtian marls belonging to the Méndez Formation, and a clastic unit with a spherulidc layer (considered as impact ejecta) toward its basal part. The uppermost Méndez Formation, as well as the spherulidc layer, were affected by slumping processes at El Tecolote. Benthic forarninifera found into the K/T sediments allowed us to infer the paleobathymetry of these deposits, and indicate that spherules and marls from outer shelf or upper slope environments slided toward middle slope environments (700 m depth). The clastic unit, containing shallow forarninifera from the platform, formed a gravity flow and was deposited in middle slope depths.

Sedimentologic features of the K/T deposits at El Tecolote are consistent with a meteoritic impact that caused destabilization of the continental margin around the Culf of México just at the K/T boundary