Radiometric and kinematic evidence for Middle Jurassic strike-slip faulting in southern Mexico related to the opening of the Gulf of Mexico

Abstract

One of the least-known aspects of the evolution of the Gulf of Mexico is the nature and location of shear zones along which the relevant continental fragments were displaced. The Sierra de Juárez mylonitic complex, located in southern Mexico, is a polyorogenic north-northwest-trending structure. Here we report U-Pb mylonitization dates of 165 ؎ 20 Ma for igneous zircon from the syntectonic San Felipe granite, and an integrated 40 Ar/ 39 Ar age of 169.3 ؎ 1.7 Ma from synkinematic muscovite, both of which indicate a Middle Jurassic age for the strike-slip event along the Sierra de Juárez mylonitic complex. This event therefore occurred during the opening of the Gulf of Mexico, and we propose that the shear zone was kinematically related to the southeast displacement of the Yucatan block.

La falla de Caltepec: raíces expuestas de una frontera tectónica de larga vida entre dos terrenos continentales del sur de México

“…Por ejemplo, debido a que el desplazamiento lateral derecho de la Plataforma de Yucatán, relacionada con la abertura del Golfo de México, quedó claramente registrado en la falla de Oaxaca (Alaniz-Álvarez et al, 1996), 50 km al oriente de la falla de Caltepec, es probable que ésta haya sido reactivada como falla normal o transtensiva. La presencia cercana de capas rojas del Jurásico Medio sobre el Complejo Acatlán en el área de Chazumba, Oaxaca, implica ciertamente actividad tectónica extensional durante esta epoca, pero es difi cil discriminar su fuente ya que la inmensa mayoría de los cantos son de cuarzo y cuarcita.…”

Interpretation of gravity profiles across the northern Oaxaca terrane, its boundaries and the Tehuacán Valley, southern Mexico

“…From Oaxaca City up to Teotlitl an, this Oaxaca/Ju arez terrane boundary has a complex history: (i) pre-Jurassic, east-vergent thrusting; (ii) Jurassic dextral mylonitic shearing; (iii) Late Cretaceous east-vergent thrusting; and (iv) Cenozoic normal faulting (Alaniz-Alvarez et al, 1996;Alaníz-Alvarez and Nieto-Samaniego, 1997;Nieto-Samaniego et al, 2006).…”

Tectonic correlations of pre-Mesozoic crust from the northern termination of the Colombian Andes, Caribbean region

“…Within Pangean tectonic reconstructions, northern South America and southern Mexico pre-Mesozoic terranes are juxtaposed and/or overlap (Rowley and Pindell, 1989;Dickinson and Lawton, 2001), and Permian-related orogenic events are common in both regions (Marechal, 1983;Malone et al, 2002;Weber and Cameron, 2003). From the lithostratigraphic record of the northernmost Andean massifs, terrane dispersal associated with Pangea disruption can be inferred from the possible correlation of some studied rocks with Proterozoic Oaxaquia and Socorro complex rocks, as well as the similar Jurassic thermal and magmatic record found in Mexico and Cuba (Renne et al, 1989;Alaniz-Alvarez et al, 1996;Ruiz et al, 1999;Keppie et al, 2004). Dispersal patterns related to the Meso-Cenozoic oblique migration of the Caribbean plate (Pindell, 1994) are envisaged from the presence of allocthonous domains in the Cordillera de la Costa of Venezuela (Caucagua-Tinaco belt; Ave Lallement and Sisson, 1993;Ertan et al, 1995;Seyler et al, 1998) and the Eocene conglomerates from the leeward Antilles (Priem et al, 1986).…”