MESOZOIC INTEGRATED BIOSTRATIGRAPHIC AND SEQUENCE STRATIGRAPHIC FRAMEWORK, NORTHERN GULF OF MEXICO

Establishment of a chronostratigraphic framework based on an integrated biostratigraphic and sequence stratigraphic approach is fundamental to intrabasin and interbasin stratal correlation and to the reconstruction of the geohistory of a sedimentary basin. Microfossil and macrofossil biozones and stratigraphic sequences are recognized in Mesozoic strata of the northern Gulf of Mexico. Sequence recognition is based on stratal geometries, nature of sequence boundaries, facies stacking patterns, and large-scale shifts in major facies belts as observed from the study of physical surfaces and facies changes in outcrop and from the study of well log signature patterns and seismic reflector configurations and terminations in the subsurface. Transgressive-regressive sequences are composed of aggrading and backstepping intervals of a transgressive phase (upward deepening section) and an infilling interval of a regressive phase (upward shallowing section), which are separated by a surface of maximum transgression. The aggrading interval marks the change from base-level fall and erosion to base-level rise and sediment accumulation. Transgressive events of the backstepping interval are widespread and provide regional correlation datums. Progradational events associated with the infilling interval represent major influxes of siliciclastic sediments and result in a loss of accommodation space. An integrated biostratigraphic and sequence stratigraphic approach provides for the correlation of stratigraphic sequences across the northern Gulf of Mexico and for the opportunity to show correspondance between sequences recognized in strata of the Gulf of Mexico to comparable stratigraphic sequences reported from Western Europe.