Correlating the arperos basin from Guanajuato, central Mexico, to Santo Tomás, southern Mexico: Implications for the paleogeography and origin of the Guerrero terrane

Abstract

The Guerrero terrane has been interpretedeither as a Mesozoic Pacific multi-arc systemaccreted to North America, or as a detachedslice of the North American continental margin, which was rifted during backarc spreadingand subsequently accreted back to thecontinental mainland. In order to test thesetwo scenarios, we present here a petrologicstudy of metasandstones from the SantoTomás area, southern Mexico. Our datadocument that the Guerrero terrane suturebelt contains the remnants of the Tithonian-Cenomanian Arperos Basin. This basin displaysa marked provenance asymmetry. Itseastern margin is composed of metasedimentaryrocks derived from sources in the NorthAmerican continental mainland, whereasits western margin consists of a metasedimentarysuccession derived from volcanicsources of the Guerrero terrane. Sedimentationin the Arperos Basin was coeval withthe emplacement of Tithonian-Barremianfelsic dikes and lava flows with volcanogenicmassive sulfide deposits and Aptian-Cenomanianintraplate-like and mid-ocean ridgebasalts. This suggests that the Arperos Basinevolved progressively from continentally tooceanic floored during the Early Cretaceousand that a mature oceanic crust was generatedonly ca. 15 Ma before the accretionof the Guerrero terrane, which took placein the late Cenomanian. On the basis of thisevidence, we favor a North American originfor the Guerrero terrane, which is thenconsidered to represent a west-facing NorthAmerican arc that was rifted from the continentalmainland during backarc spreadingand subsequently accreted back to nuclearMexico.