Recycled Franciscan Material in Franciscan Mélange West of Paso Robles, California

Research Article| August 01, 1975 Recycled Franciscan Material in Franciscan Mélange West of Paso Robles, California DARREL S. COWAN; DARREL S. COWAN 1Department of Geological Sciences, University of Washington, Seattle, Washington 98195 Search for other works by this author on: GSW Google Scholar BENJAMIN M. PAGE BENJAMIN M. PAGE 2Department of Geology, Stanford University, Stanford, California 94305 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1975) 86 (8): 1089–1095. https://doi.org/10.1130/0016-7606(1975)86<1089:RFMIFM>2.0.CO;2 Article history first online: 01 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 DARREL S. COWAN, BENJAMIN M. PAGE; Recycled Franciscan Material in Franciscan Mélange West of Paso Robles, California. GSA Bulletin 1975;; 86 (8): 1089–1095. doi: https://doi.org/10.1130/0016-7606(1975)86<1089:RFMIFM>2.0.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 SocietyGSA Bulletin Search Advanced Search Abstract Recycled Franciscan detritus has been confirmed in the Franciscan Complex west of the Salinian block in the California Coast Ranges. A mass of Late Cretaceous sandstone and conglomerate-breccia, the Las Tablas unit, locally contains blocky clasts of Franciscan greenstone, chert, ultramafic rocks, glaucophane-lawsonite schist, and graywacke, together with larger amounts of non-Franciscan material. The Las Tablas unit is enveloped in a Franciscan tectonic mélange, and it contains metamorphic pumpellyite, suggesting the probable onset of blueschist-facies metamorphism.The Franciscan clasts in the Las Tablas unit represent former components of an early mélange related to subduction. The heterogeneous mélange accumulated as an elongate pile of "scrapings" along the inner wall of a trench. During Late Cretaceous time, submarine debris flows of Franciscan mélange material were shed from the pile into the trench, arc-trench gap, or smaller intervening basins to form the Las Tablas conglomerate-breccia. Eventually the Las Tablas unit was "cannibalized" by continued subduction. The unit was technically engulfed in a Late Cretaceous or early Tertiary neo-Franciscan mélange and was carried to a depth sufficient to induce the development of pumpellyite. 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.