U-Pb isotopic dating of detrital zircons from a conglomeratic barite sandstone in the Sonora allochthon and a calciclastic sandstone in the Mina México foredeep of the Minas de Barita area reveals two main age groups in the Upper Devonian part of the Los Pozos Formation, 1.73–1.65 Ga and 1.44–1.42 Ga; and three main age groups in the Lower Permian part of the Mina México Formation, 1.93–1.91 Ga, 1.45–1.42 Ga, and 1.1–1.0 Ga. Small numbers of zircons with ages of 2.72–2.65 Ga, 1.30–1.24 Ga, ca. 2.46 Ga, ca. 1.83 Ga, and ca. 0.53 Ga are also present in the Los Pozos...