TECTONIC SETTING OF THE SENO MEXICANO (SOUTH TEXAS AND BURGOS BASIN): EXTENSION, FOLDING, TILTING, GROWTH FAULTING AND SOME SALT

The broad basin of the Seno Mexicano (South Texas and northeastern Mexico) is built on poorly known, highly extended continental crust related to Jurassic formation of the Gulf of Mexico, at its junction with complex Mexican Cordillera extension and strike-slip. Salt was deposited across the area, although few salt diapirs penetrate the Cenozoic sediments. The area lay in deep water east of the Jurassic and Cretaceous shelf margins, accumulating deep-water limestone, organic deposits, and clay. Laramide (Hidalgoan) folding on NW-SE axes affected the southern part of the basin into Middle Eocene time.

Regional west-up tilting began in Paleocene time, forming the Lobo gravity slide complex and rafting the Mesozoic sediments eastward above Jurassic salt, creating the deep Rosita trough. This trough was then filled by Lower to Middle Eocene shelf-margin clastic sediments expanded across growth faults. Rosita rafting is cognate to a Miocene event (Macuspana) in southeastern Mexico. Later tilting is indicated by the Vicksburg gravity slide (Lower Oligocene), as deltaic margins prograded eastward. Upper Oligocene and Lower Miocene sediments prograded with growth faulting into a second trough, initiating a salt canopy and/or rafting sediments to form the abyssal Perdido fold belt. Strong Miocene tilting placed Goliad (Late Miocene-Pliocene) sediments atop rocks as old as Eocene; later tilting uplifted Goliad sediments to form the high cuesta of the Bordas Escarpment.