Facies and sand‐body geometry of the Queen City (Eocene) tide‐dominated delta‐margin embayment, NW Gulf of Mexico Basin

Abstract

ABSTRACTThe Queen City Formation (Eocene) displays an array of tide‐dominated coastal facies in the Tyler Basin of the northern Gulf of Mexico. This facies assemblage, which is atypical of the microtidal, wave‐dominated, coastal depositional complexes that characterize the Cenozoic Gulf basin, reflects tidal amplification in a generally protected embayment on the east flank of a strongly prograded delta system. The shallow embayment was confined to the east by contemporaneous uplift and shoaling across the Sabine Uplift. Fluvial, barrier (including ebb tidal delta), heterolithic tidal, estuary‐fill, and tidal point‐bar facies are all found at outcrop. These facies were projected into the three‐dimensional geometry of the tide‐dominated depositional complex. Inlet, estuary, and distributary‐fill sand bodies, which are linear and diporientated, dominate lithofacies maps.The Queen City facies assemblage in the Tyler Basin records a mixture of mesotidal to macrotidal environments that were interspersed in time and space with fluvial‐dominated lobes, which periodically prograded eastward from the deltaic depocentre into the flanking embayment. Queen City deposition terminated with regional marine flooding and deposition of glauconitic, fossiliferous shelf sands and muds of the Weches Formation. Transgression is marked by a prominent ravinement surface that truncates underlying facies of the tide‐dominated shore zone.