Crustal Structure and Tectonostratigraphic Evolution of the Eastern Gulf of Mexico Basin



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The crustal structure and tectonostratigraphy of the eastern Gulf of Mexico record five major tectonic events that include: 1) Late Paleozoic collision of the Florida block and its northwestward indentation along northwest-striking, right-lateral, strike- slip faults; 2) late Triassic to middle Jurassic, northwest-to-southeast, Phase 1 rifting of the Gulf of Mexico; 3) seawater filling and evaporite formation (Callovian Louann salt) within a large sag basin that overlies this area of crustal extension; 4) late Jurassic, southwest-to-northeast rifting and oceanic crust formation (Phase 2) of the eastern Gulf of Mexico related to the counterclockwise rotation of the Yucatan Peninsula; and 5) formation of passive margins. In this study, I integrated 50,000 line kilometers of 2D seismic reflection, gravity, magnetic, refraction, and wells data to better constrain the timing, structure, and fault-controlled stratigraphy of these five, main tectonic events in the eastern Gulf of Mexico. In Chapter 2, I identified the late Paleozoic, indentation-related, right-lateral, strike-slip faults that controlled 2-3-km-deep, right-stepping, pull-apart basins; these faults crosscut large areas of undeformed Paleozoic basins and are not reactivated until later Mesozoic rifting. I used regional, magnetic data to map Phase 1, Triassic, normal faults striking to the northeast that are consistent with parallel and alternating, basement highs and lows along the west Florida continental margin. I used seismic reflection data to map northwest-trending, marginal rift structures along the edges of the area of Jurassic oceanic crust that record the Phase 2 rifting between continental crust in Florida and the Yucatan basin. In Chapter 3, I used deeply-penetrating, seismic data to better define the location and geometry of Jurassic slow-spreading ridge and fracture zones. 3-D gravity modeling was used to construct a depth to Moho map that integrates the depth to the top of oceanic basement and its Moho as observed on deeply-penetrating, seismic reflection lines. Crustal thickness variations in the oceanic crust are attributed to thicker crust forming more distant from the pole of rotation. The age of stratigraphic units overlying oceanic crust was used to date the initiation (early Kimmeridgian, 156 Ma) and cessation (late Berriasian, 138 Ma) of oceanic crust formation.



Basement, Crustal structures, Eastern Gulf of Mexico