Thomas E. Ewing1,2
1Bureau of Economic Geology, University of Texas at Austin, 10100 Burnet Rd,, Austin, Texas 78758
2Frontera Exploration Consultants, 19240 Redland Rd., Ste. 250, San Antonio, Texas 78259
Insights from the Texas through Time Project
Onshore Gulf of Mexico Exploration I (GRBCC, Assembly Area B)
Tuesday, September 22, 2015, 11:10 am
As part of the forthcoming Texas through Time book on the geology of Texas for general audiences, I needed to give a coherent account of the beginnings of the Gulf of Mexico and the Gulf Coast Basin, based on current thinking and models of crustal development under extension. That model is presented here for discussion, with Figures 1–7.
The opening of the Gulf of Mexico from a Triassic closed configuration may best be described as a two-stage process, after Pindell and Kennan (2009): an early “Tethyan” distributed southeasterly extension, followed by rotational sea-floor spreading behind Yucatan influenced by proto-Pacific subduction.
In Phase I (Norian-Callovian, ca. 225 to 162 Ma), blocks surrounded by extended crust moved southeast from North America up to 200 km as part of the general northwestward drift of North America and northern Europe out of Pangea. Northwest-oriented linear features in Mexico allowed for substantial translation of blocks on the Pacific margin (Ewing, 2011). Other large northwest-oriented features lie along the old Paleozoic Alabama-Oklahoma lineament and farther southwest; southwest of the Sabine Uplift, the “Brazos linear” (Hudec and others, 2013), and the Frio River zone among others. This stretching left thick crustal blocks as “arches” separating deeper basins with highly extended crust.