Re–Os and U–Pb geochronology of the El Arco porphyry copper deposit, Baja California Mexico: Implications for the Jurassic tectonic setting

New geochronologic data from the El Arco porphyry copper deposit, Baja California, Mexico, yield a Middle Jurassic crystallization U–Pb age of 164.7 ± 6.5 Ma for zircons from a granodiorite porphyry that hosts the Cu–Au–(Mo) mineralization, and four Re–Os molybdenite ages yield a weighted average age of 164.1 ± 0.4 Ma. These ages disagree with previous K–Ar age determinations that suggest a correlation of the intrusive rocks of El Arco–Calmalli area with the eastern Peninsular Ranges batholith of Cretaceous age. Instead, the volcanic–plutonic rocks of the El Arco–Calmalli area are more properly associated with the San Andres–Cedros volcanic–plutonic complex (∼166 Ma). El Arco–Calmalli block likely was part of the intraoceanic arc system described in the Vizcaino–Cedros region and accreted to the continent during the Cretaceous (98–110 Ma). The presence of a continental Jurassic magmatic arc in the mainland and the occurrence of El Arco–Calmalli (San Andres–Cedros) volcanic–plutonic complex indicate two Jurassic magmatic arcs at this latitude (continental and oceanic).