Tectonics of the Pliocene Loreto basin, Baja California Sur, Mexico, and evolution of the Gulf of California

Research Article| July 01, 1994 Tectonics of the Pliocene Loreto basin, Baja California Sur, Mexico, and evolution of the Gulf of California Paul J. Umhoefer; Paul J. Umhoefer 1Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011-4099 Search for other works by this author on: GSW Google Scholar Rebecca J. Dorsey; Rebecca J. Dorsey 1Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011-4099 Search for other works by this author on: GSW Google Scholar Paul Renne Paul Renne 2Institute of Human Origins, 2453 Ridge Road, Berkeley, California 94709 Search for other works by this author on: GSW Google Scholar Geology (1994) 22 (7): 649–652. https://doi.org/10.1130/0091-7613(1994)022<0649:TOTPLB>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Paul J. Umhoefer, Rebecca J. Dorsey, Paul Renne; Tectonics of the Pliocene Loreto basin, Baja California Sur, Mexico, and evolution of the Gulf of California. Geology 1994;; 22 (7): 649–652. doi: https://doi.org/10.1130/0091-7613(1994)022<0649:TOTPLB>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The Pliocene Loreto basin is a transtensional basin, exposed just north of Loreto, Baja California Sur, that consists of nonmarine to marine sedimentary rocks and interbedded tuffs. On the basis of stratigraphic study and 40Ar/39Ar dating of tuffs, the southern Loreto basin began to form at ∼3.4 Ma as an alluvial basin with moderate rates of subsidence (<0.4 mm/yr). Between 2.46 and 2.36 Ma, extremely rapid subsidence (5-10 mm/yr) of the basin was accompanied by deposition of vertically stacked Gilbert-type fan deltas. During this period, the southernmost basin began to be cut by an array of dextral-normal faults. The basin returned to a moderate rate of subsidence from ∼2.36 to ∼2.0 Ma, when volcanism increased within the northern part of the basin. The Pacific-North America boundary was first fully located within the Gulf of California beginning at ∼3.5 Ma, at which time the zone of transform-related deformation widened to initiate formation of the Loreto basin. The major change in the Loreto basin at 2.46 Ma may be coeval with the beginning of faulting in southern California on the Elsinore and San Jacinto faults. These widespread events may indicate a minor change in the plate boundary at ∼2.5 Ma. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.