Biostratigraphic and sequence stratigraphic analysis of the Yegua Formation, Houston Salt Embayment, northern Gulf of Mexico

The Yegua Formation is a unique unit in the Paleogene of the Gulf Coast in its progradation during an overall marine transgression of the Eocene. A comprehensive analysis, including a detailed quantitative biostratigraphic and biofacies study, high-resolution stratigraphic analysis and genetic sequence stratigraphic study, reveals its depositional history.; The quantitative methods used for analyzing foraminiferal data include ranking, graphic correlation, cluster analysis and factor analysis. The Yegua Formation is assigned to biochron zone P15 and chronostratigraphic age ranging from 37.4–35.6 Ma in the late Middle and the early Late Eocene. Eleven biofacies are recognized from marginal marine to middle bathyal environments.; The Yegua Formation was deposited in a variety of depositional environments, including fluvial, shore-zone, deltaic, shelf and slope fan systems in water-depth ranging from 0 to over 500m. Starting in strike-oriented shore-zone systems and ending in transgressive barrier island systems, the Yegua was dominated by stacked fluvial-dominated deltaic systems during its deposition. Frequent fluctuations of sea level created complex patterns of progradational and retrogradational deposition of the Yegua.; Four genetic sequences, bounded by maximum flooding surfaces, are recognized on the evidence of faunal and depositional changes. Erosional surfaces are also recognized in the Yegua Formation. The erosional surfaces include the fluvial entrenchment surface, regressive ravinement surface, transgressive erosional surface and slope entrenchment surface.; A major sea-level fall occurred in the late Yegua and was accompanied by incised valleys cutting across the shelf and shelf margin slumps. Three prominent shelf-margin delta systems developed within the accommodation space provided by slumps and were reworked along strike.