An Experimental Study of Tectonic Overpressure in Franciscan Rocks

Abstract

Research Article| May 01, 1970 An Experimental Study of Tectonic Overpressure in Franciscan Rocks WILLIAM F BRACE; WILLIAM F BRACE Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Search for other works by this author on: GSW Google Scholar W. G ERNST; W. G ERNST Department of Geology and Institute of Geophysics, University of California, Los Angeles, California 90024 Search for other works by this author on: GSW Google Scholar RAZEL WITTELS KALLBERG RAZEL WITTELS KALLBERG Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Search for other works by this author on: GSW Google Scholar Author and Article Information WILLIAM F BRACE Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 W. G ERNST Department of Geology and Institute of Geophysics, University of California, Los Angeles, California 90024 RAZEL WITTELS KALLBERG Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Publisher: Geological Society of America Received: 30 Dec 1969 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1970) 81 (5): 1325–1338. https://doi.org/10.1130/0016-7606(1970)81[1325:AESOTO]2.0.CO;2 Article history Received: 30 Dec 1969 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation WILLIAM F BRACE, W. G ERNST, RAZEL WITTELS KALLBERG; An Experimental Study of Tectonic Overpressure in Franciscan Rocks. GSA Bulletin 1970;; 81 (5): 1325–1338. doi: https://doi.org/10.1130/0016-7606(1970)81[1325:AESOTO]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 Approximately 4 kb tectonic overpressure was required, according to one theory, for the formation of jadeite-aragonite-bearing rocks of the Franciscan. Strength of two common Franciscan rocks—massive graywacke, and thin-bedded shale and graywacke—was determined to see if this tectonic overpressure could have been generated under the conditions of metamorphism; that is, 4 kb confining pressure, 200 to 300° C, in the presence of aqueous pore fluid. The strength was found to depend markedly on both pore and total pressures. The required tectonic overpressure could only have been generated in massive graywacke, and only when pore pressure was less than hydrostatic. With even moderate amounts of interbedded shale, tectonic overpressure could not have exceeded 1 kb. 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.