PERMIAN MAGMATIC ARC RELATED TO THE OUACHITA SUTURE ZONE IN CHIHUAHUA, MEXICO

The Ouachita system extends southwest from where it joins the Appalachian orogeny near the Black Warrior Basin in Alabama, westward through Mississippi, Arkansas, and southwest Oklahoma, and continues through the Llano Uplift and Big Bend regions of Texas. In Mexico outcrops attributable to the Ouachita are found in Coahuila, Chihuahua, and Sonora.

The Ouachita orogeny, since the Silurian, evolved first as a result of the approach of Gondwana to Laurentia as the Rheic oceanic plate was subducted beneath both continental plates, followed by volcanic arc emplacement in Mississippian time, and finally the collision of the continental plates in the Pennsylvanian. Thus, a tectonic evolution trend from east to west is apparent. As a consequence, igneous volcanic and intrusive rocks of presumed Permian age were emplaced on and within turbidity-sequence rocks that crop out in the Benavides, Chorreras, Carrizalillo, Plomosas, Placer de Guadalupe, Aldama, Magistral, Moris and El Pilar regions of Chihuahua.

According to Arvizu et al. (2009), the Permian-Triassic magmatic arc, which extends from California-Nevada to central and southern Mexico, is the result of eastward subduction during the Ouachita orogeny from late Carboniferous to early Permian times. The Gondwana plate approached Laurentia plate from Silurian to Permian times, and the intervening Rheic oceanic plate experienced type-B subduction under one or both continental plates.