Geology and structure of the Tastiota-Himalaya region, eastern margin of the Gulf of California rift, coastal Sonora, Mexico

This work reports a new 1:50,000-scale geologic map of a portion of the Gulf of California rift along the central Sonoran coast in northwestern Mexico. Six chronostratigraphic units established by regional lithologic correlations are (1) Paleozoic (?) calcareous and clastic sedimentary and metasedimentary successions that represent isolated, rare roof pendants intruded by (2) Cretaceous granodiorite bodies. These pre-Neogene rocks are overlain by an extensive Miocene volcanic cover categorized into (3) Lower-Middle Miocene (21–15 Ma) porphyritic intermediate lavas; (4) a widespread distributed Upper Miocene (11–10 Ma) succession of felsic pyroclastic deposits, dikes, and lavas showing vertical and lateral lithofacies variations; (5) Upper Miocene (10–8.5 Ma) mafic volcanic lava flows; and (6) Pliocene to Recent colluvial and alluvial deposits. The structural architecture consists of a complex network of normal, oblique-normal, and strike-slip faults active during the Late Miocene and related to the early Gulf of California rift history.