Postorogenic shoshonitic rocks and their origin by melting underplated basalts: The Miocene of Limnos, Greece

Abstract

Research Article| January 01, 2009 Postorogenic shoshonitic rocks and their origin by melting underplated basalts: The Miocene of Limnos, Greece Georgia Pe-Piper; Georgia Pe-Piper * 1Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada †E-mail: gpiper@smu.ca. Search for other works by this author on: GSW Google Scholar David J.W. Piper; David J.W. Piper 2Geological Survey of Canada (Atlantic), Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada Search for other works by this author on: GSW Google Scholar Ioannis Koukouvelas; Ioannis Koukouvelas 3Department of Geology, University of Patras, Patras 26110, Greece Search for other works by this author on: GSW Google Scholar Lila M. Dolansky; Lila M. Dolansky 4Department of Geology, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada Search for other works by this author on: GSW Google Scholar Sotiris Kokkalas Sotiris Kokkalas 5Department of Geology, University of Patras, Patras 26110, Greece Search for other works by this author on: GSW Google Scholar GSA Bulletin (2009) 121 (1-2): 39–54. https://doi.org/10.1130/B26317.1 Article history received: 23 Aug 2007 rev-recd: 06 Apr 2008 accepted: 22 Apr 2008 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 Georgia Pe-Piper, David J.W. Piper, Ioannis Koukouvelas, Lila M. Dolansky, Sotiris Kokkalas; Postorogenic shoshonitic rocks and their origin by melting underplated basalts: The Miocene of Limnos, Greece. GSA Bulletin 2009;; 121 (1-2): 39–54. doi: https://doi.org/10.1130/B26317.1 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 Potassium-rich volcanic rocks of the shoshonite suite are common features of postorogenic extensional settings inboard from subduction zones. Various petrogenetic processes and tectonic settings have been proposed for their origin. Early Miocene volcanic rocks of Limnos, part of the northeast Aegean shoshonite belt, show distinctive geochemical features that allow their petrogenesis to be well constrained. The rocks are principally trachyandesites and dacites. Very strong fractionation of light and middle rare earth elements (REEs), similar to that found in adakites, is inconsistent with a mantle source, but it can be modeled by melting of meta-basalt enriched in incompatible elements. A comparison with experimental melting of metabasaltic amphibolite requires small degrees of dehydration melting of amphibole, plagioclase, clinopyroxene, and minor garnet at a temperature >950 °C. Melting was triggered by mantle-derived magma, evidenced by repetitive zoning in clinopyroxene with Cr-rich cores. Nd and Sm isotopes suggest that some of this magma was similar to lamproite found elsewhere in this shoshonite belt and some was of asthenospheric origin. The amphibolite source is inferred to be subduction-enriched metabasalt that underplated the crust during pre-Mesozoic subduction. The regional trigger for dehydration melting was upwelling of asthenosphere as a result of slab detachment. The geochemistry and radiogenic isotopes of other shoshonitic rocks in the northeastern Aegean suggest a similar origin, but with higher degrees of partial melting of base-of-crust metabasaltic amphibolite. Similar processes appear likely for shoshonitic magmatism in some postcollisional settings elsewhere. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.