Research on Upper Triassic shallow marine carbonates provides information for a better understanding of the renewal of marine life after the end-Permian mass extinction. The majority of such studies were focused on Tethyan localities, while the Panthalassan counterparts remained unstudied. Goal of this study is the reconstruction of paleoenvironment and paleogeography for the Antimonio depositional system in Sonora (Mexico). Its tectonic setting at the welding line between Mexico and North America bears the potential to elucidate their paleotectonic relationship in the Upper Triassic. Through a combination of thin section analysis, geochronology on detrital zircon, and multivariate analyses, microfacies were defined and a depositional model proposed. Furthermore, comparisons with the Cordilleran terranes, including the Vizcaino terrane of the Baja California (Mexico), and the previously investigated Wallowa terrane in Oregon (USA), the Japanese Sambosan Accretionary Complex, and Laurentia were performed to gain insight into their relative paleogeographic setting inside Panthalassa.