Crustal contamination in the petrogenesis of a calc-alkalic rock series: Josephine Mountain intrusion, California

Abstract

Research Article| February 01, 1995 Crustal contamination in the petrogenesis of a calc-alkalic rock series: Josephine Mountain intrusion, California Andrew P. Barth; Andrew P. Barth 1Department of Geology, Indiana/Purdue University, Indianapolis, Indiana 46202 Search for other works by this author on: GSW Google Scholar J. L. Wooden; J. L. Wooden 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar R. M. Tosdal; R. M. Tosdal 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar J. Morrison J. Morrison 3Department of Geological Sciences, University of Southern California, Los Angeles, California 90089 Search for other works by this author on: GSW Google Scholar Author and Article Information Andrew P. Barth 1Department of Geology, Indiana/Purdue University, Indianapolis, Indiana 46202 J. L. Wooden 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 R. M. Tosdal 2U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 J. Morrison 3Department of Geological Sciences, University of Southern California, Los Angeles, California 90089 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1995) 107 (2): 201–212. https://doi.org/10.1130/0016-7606(1995)107<0201:CCITPO>2.3.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 Andrew P. Barth, J. L. Wooden, R. M. Tosdal, J. Morrison; Crustal contamination in the petrogenesis of a calc-alkalic rock series: Josephine Mountain intrusion, California. GSA Bulletin 1995;; 107 (2): 201–212. doi: https://doi.org/10.1130/0016-7606(1995)107<0201:CCITPO>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 SocietyGSA Bulletin Search Advanced Search Abstract The Josephine Mountain intrusion is a Cretaceous calc-alkalictonalite-granite pluton emplaced at 22 km depth in a continental margin arc. Variable uplift of adjacent terranes in southern California since mid-Cretaceous time allows us to reconstruct the local crustal column and evaluate its role as a contaminant of mantle-derived arc magmas in this region. The parental magma of the intrusion was high-alumina basalt whose isotopic signature (87Sr/86Sr = 0.7087; δ18O = 7.5; ϵNd = −10) cannot have been generated by intracrustal assimilation of known or inferred rock types in the middle or lower crust. Such a signature could have resulted from high-pressure fractionation of primary low-alumina basalt coupled with assimilation of felsic/pelitic lower crust, partial melting of enriched subcontinental mantle followed by high-pressure fractionation, or a combination of these processes. Tonalite of the intrusion was formed by fractionation of the parent magma coupled with assimilation of local felsic wall rocks or by crustal melts similar to slightly younger granite. Assessment of the magnitude of crustal contamination is hampered by uncertainty regarding the existence and role of partial melting of previously enriched subcontinental mantle in generating the parental basaltic magma, leading to concomitant uncertainty in the fraction of new continental crust created by such arc plutonism. 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.