f Integrated Model for the Tectonic Development of Southern Mexico/Central America and the Chiapas-Campeche Basin: Plate Motions, Geochronology, Thermochronology, Paleomagnetism, Structural Geology and Depositional Source to Sink Models

We integrate refined analyses of plate motions, geochronology, thermochronology, paleomagnetism, structural geology and depositional source to sink models to define the primary and inter-related aspects of the geological evolution of Southern Mexico and Central America. The model is the result of a 10-year research program conducted mainly by Tectonic Analysis Ltd. and UNAM Querétaro, funded largely by industry. Primary Late Cretaceous to Recent evolutionary events are: 1) collision and emplacement of the Greater Antilles Arc (Nicaragua Rise–Jamaica portion) along southern Yucatan (Chiapas to Belize) and east of the continental core of the Chortis Block, in the Maastrichtian; 2) dislocation of the continental core of the Chortis Block from the Oaxaca coastline in the late Maastrichtian, probably due to flat slab Laramide subduction and associated plate-interface traction; 3) Paleocene-Recent eastward migration of the composite Chortis–Nicaragua Rise–Jamaica belt, as part of the Caribbean Plate since the late? Eocene, with strong transpression in the Paleogene which emplaced the Chontal/Chivela nappes onto the former south-facing Pacific margin of Tehuantepec and southern Yucatán; 4) progressively eastward inception of subduction along Southern Mexico in the wake of the migrating Chortis Block, causing uplift and erosion of the Xolapa (Eocene-early Miocene), Guichicovi (Oligocene), and eventually Chiapas Massif (Miocene). The Chiapas Massif rotated clockwise by about 20° in the middle Miocene as shortening ensued in the Chiapas Foldbelt, but the main period of uplift of the massif has been since 10 Ma (Late Miocene), due to the progressive flattening of subduction beneath it. Beginning at about 11 Ma, the northern flank of the Chiapas Foldbelt (Akal High) gravitationally broke away to the NNW from the onshore foldbelt to create the Macuspana Basin, detaching on autochthonous (Bajocian) salt. At about 4 Ma, the same occurred in the Comalcalco Basin; this updip extension manifests itself as downdip compression in more northerly portions of the offshore Campeche Salt Basin. For Paleocene-middle Miocene time, clastic sediment was able to pass from plate boundary source areas to the southern Veracruz and Gulf of Mexico basin, without topographic impedance by the Chiapas Massif. The Nanchital conglomerate of the western Chiapas Foldbelt is the coarsest terrigenous clastic depositional Cenozoic unit of the region, probably comprising more proximal sections of hydrocarbon-rich slope-fan reservoirs found in the more distal Sureste Basin of the southern Gulf of Mexico fringe. Traditionally, the felsic igneous and metamorphic components of this conglomerate were assumed to derive from the Permian basement of the nearby Chiapas Massif. However, zircon U–Pb dating of five Nanchital conglomerate clasts from the Chiapas Foldbelt and also igneous exposures in SW Tehuantepec indicates that the Nanchital conglomerate’s catchment area included the western Isthmus of Tehuantepec up to the end of middle Miocene time, after which the more proximal Chiapas Massif and Chiapas Foldbelt likely became the dominant clastic source areas. We propose a temporal framework for viewing Neogene and Quaternary clastic supply to the southern Gulf of Mexico.