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Granites of the batholiths of California: Products of local assimilation and regional-scale crustal contamination

1987; Geological Society of America; Volume: 15; Issue: 1 Linguagem: Inglês

10.1130/0091-7613(1987)15 2.0.co;2

1943-2682

Jay J. Ague, George H. Brimhall,

Geological and Geochemical Analysis

Research Article| January 01, 1987 Granites of the batholiths of California: Products of local assimilation and regional-scale crustal contamination Jay J. Ague; Jay J. Ague 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar George H. Brimhall George H. Brimhall 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Search for other works by this author on: GSW Google Scholar Author and Article Information Jay J. Ague 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 George H. Brimhall 1Department of Geology and Geophysics, University of California, Berkeley, California 94720 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1987) 15 (1): 63–66. https://doi.org/10.1130/0091-7613(1987)15 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 Email Permissions Search Site Citation Jay J. Ague, George H. Brimhall; Granites of the batholiths of California: Products of local assimilation and regional-scale crustal contamination. Geology 1987;; 15 (1): 63–66. doi: https://doi.org/10.1130/0091-7613(1987)15 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 SocietyGeology Search Advanced Search Abstract We address on a regional scale the controversial problem of determining the source materials involved in the formation of the granites of southwestern North America. Compositional data on plutonic biotites, whole-rock chemistry, and mineral assemblages in rocks collected as part of sampling traverses across die batholiths of central and southern California are assessed for this purpose. We conclude that two distinct types of granites occur in California. One type, largely overlooked in the past and which we term I-SCR (strongly contaminated and reduced I type), is confined to narrow northwest-striking belts in the western Sierra Nevada and Peninsular Ranges batholiths in prebatholithic continental margin terrenes containing reduced pelitic roof pendants. We interpret the I-SCR magmas to have arisen from local-scale contamination of I-type magmas that intruded reducing pelitic material in sedimentary roof pendant terrenes. We conclude that cordierite-bearing S types are absent from the California batholiths, although sedimentary materials were required to produce the I-SCR plutons. The second type of granite, which we refer to as I-SC (strongly contaminated but not reduced I type), occurs on the eastern side of the California batholiths as part of a well-known regional west-to-east progression from quartz diorites to granites. These granites are the eastern variant of a sequence that is, from west to east, I-WC (weakly contaminated), I-MC (moderately contaminated), and I-SC This eastward progression is not controlled by pendant occurrence and probably reflects increasing contamination on a regional scale of mantle I-type magmas with F-rich igneous and metamorphic rocks, or their sedimentary derivatives, of the Precambrian continental craton. We demonstrate that the nature of prebatholithic terranes can strongly influence the composition and regional distribution of granitic rocks developed in an active continental margin. 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.