Magmatic development of an intra-oceanic arc: High-precision U-Pb zircon and whole-rock isotopic analyses from the accreted Talkeetna arc, south-central Alaska

Abstract

Research Article| September 01, 2007 Magmatic development of an intra-oceanic arc: High-precision U-Pb zircon and whole-rock isotopic analyses from the accreted Talkeetna arc, south-central Alaska Matthew Rioux; Matthew Rioux 1Department of Earth Science, University of California, Santa Barbara, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar Bradley Hacker; Bradley Hacker 1Department of Earth Science, University of California, Santa Barbara, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar James Mattinson; James Mattinson 1Department of Earth Science, University of California, Santa Barbara, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar Peter Kelemen; Peter Kelemen 2Lamont Doherty Earth Observatory, Columbia University, 58 Geochemistry Building, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar Jurek Blusztajn; Jurek Blusztajn 3Department of Geology and Geophysics, Woods Hole Oceanographic Institute, Woods Hole, Massachusetts 02543, USA Search for other works by this author on: GSW Google Scholar George Gehrels George Gehrels 4Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2007) 119 (9-10): 1168–1184. https://doi.org/10.1130/B25964.1 Article history received: 09 Jan 2006 rev-recd: 22 Nov 2006 accepted: 31 Jan 2007 first online: 08 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 Matthew Rioux, Bradley Hacker, James Mattinson, Peter Kelemen, Jurek Blusztajn, George Gehrels; Magmatic development of an intra-oceanic arc: High-precision U-Pb zircon and whole-rock isotopic analyses from the accreted Talkeetna arc, south-central Alaska. GSA Bulletin 2007;; 119 (9-10): 1168–1184. doi: https://doi.org/10.1130/B25964.1 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 accreted Talkeetna arc, south-central Alaska, is an archetypal example of an intra-oceanic arc crustal section. Arc-related units include all levels of a lithospheric column, from residual mantle harzburgites to sub-aerial volcanic rocks, and provide a rare opportunity to study intrusive arc processes directly. We present the first high-precision U-Pb zircon ages and an extensive new data set of 143Nd/144Nd and 87Sr/86Sr isotopic analyses from Talkeetna arc plutonic rocks. These data provide new insight into the timing and extent of Talkeetna arc magmatism, the tectonic development of the arc, and the role of preexisting crustal material in the generation of arc magmas. New analyses from the exposed arc crustal section in the Chugach Mountains indicate that the Talkeetna arc began to develop as a juvenile [ϵNd(t) = 6.0–7.8 and 87Sr/86Srint = 0.703379–0.703951] intra-oceanic arc between 202.1 and 181.4 Ma. This initial arc plutonism was followed ca. 180 Ma by a northward shift in the arc magmatic axis and generation of a large plutonic suite in the Talkeetna Mountains. Plutons from the eastern Talkeetna Mountains yield U-Pb zircon ages of 177.5–168.9 Ma and are isotopically similar to the Chugach Mountains intrusions [ϵNd(t) = 5.6–7.2 and 87Sr/86Srint = 0.703383–0.703624]. However, plutons from the western Talkeetna Mountains batholith have more evolved initial isotopic ratios [ϵNd(t) = 4.0–5.5 and 87Sr/86Srint = 0.703656–0.706252] and contain inherited xenocrystic Carboniferous–Triassic zircons. These data are interpreted to represent assimilation of adjacent Wrangellia crust into arc magmas and require amalgamation of the Talkeetna arc with the Wrangellia terrane by ca. 153 Ma. As a whole, the combined U-Pb zircon and isotopic data from the Chugach and Talkeetna Mountains indicate that the main volume of Talkeetna arc magmas formed with little or no involvement of preexisting crustal material. These observations justify the use of the Talkeetna arc as a type section for intrusive intra-oceanic arc crust. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.