Research Article| May 01, 1988 Shoshonitic magmas in nascent arcs: New evidence from submarine volcanoes in the northern Marianas Robert J. Stern; Robert J. Stern 1Programs in Geosciences, University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083-0688 Search for other works by this author on: GSW Google Scholar Sherman H. Bloomer; Sherman H. Bloomer 2Department of Geology, Duke University, Durham, North Carolina 27701 Search for other works by this author on: GSW Google Scholar Ping-Nan Lin; Ping-Nan Lin 1Programs in Geosciences, University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083-0688 Search for other works by this author on: GSW Google Scholar Emi Ito; Emi Ito 3Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive, Minneapolis, Minnesota 55455 Search for other works by this author on: GSW Google Scholar Julie Morris Julie Morris 4Department of Terrestrial Magnetism, Carnegie Institute of Washington, 5241 Broad Branch Road NW, Washington, D.C. 20015 Search for other works by this author on: GSW Google Scholar Author and Article Information Robert J. Stern 1Programs in Geosciences, University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083-0688 Sherman H. Bloomer 2Department of Geology, Duke University, Durham, North Carolina 27701 Ping-Nan Lin 1Programs in Geosciences, University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083-0688 Emi Ito 3Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive, Minneapolis, Minnesota 55455 Julie Morris 4Department of Terrestrial Magnetism, Carnegie Institute of Washington, 5241 Broad Branch Road NW, Washington, D.C. 20015 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1988) 16 (5): 426–430. https://doi.org/10.1130/0091-7613(1988)016<0426:SMINAN>2.3.CO;2 Article history First Online: 02 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 Robert J. Stern, Sherman H. Bloomer, Ping-Nan Lin, Emi Ito, Julie Morris; Shoshonitic magmas in nascent arcs: New evidence from submarine volcanoes in the northern Marianas. Geology 1988;; 16 (5): 426–430. doi: https://doi.org/10.1130/0091-7613(1988)016<0426:SMINAN>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 SocietyGeology Search Advanced Search Abstract Volcanoes in the northern Mariana arc between Uracas (lat 20°N) and Minami Iwo Jima (24°N) are very active yet entirely submarine. In contrast to the predominantly low-K basaltic magmas of the central Mariana arc, the northern Mariana arc is dominated by more siliceous melts in the south and by shoshonites in the north. The northern arc melts have enrichments in Ba (<800 ppm), Rb (<70 ppm), Sr (<1000 ppm), Ce (<50 ppm), and (Ce/Yb)n (<24) which increase to the north as far as Iwo Jima. Lavas from volcanoes north of Iwo Jima lack these enrichments and are indistinguishable from those of the central Maranas. The shoshonites are unusual in occurring along the magmatic front of a primitive, intra-oceanic arc. We hypothesize that they represent the reconstruction of a magmatic arc following melting of enriched mantle due to the propagation of the Mariana Trough spreading center northward through the Volcano arc. Shoshonites thus may characterize the initial stages of arc construction after an episode of back-arc rifting and need not be restricted to the mature stages of arc evolution. This situation contrasts with subduction-zone initiation, where first melts may be boninites or low-K tholeiites. These differing initial melts converge toward tholeiitic and calc-alkaline compositions as arcs evolve. 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.