<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>J.B. Gill</dc:contributor>
  <dc:contributor>M. Kusakabe</dc:contributor>
  <dc:contributor>S. Newman</dc:contributor>
  <dc:contributor>M. Pringle</dc:contributor>
  <dc:contributor>B. Taylor</dc:contributor>
  <dc:contributor>P. Fryer</dc:contributor>
  <dc:creator>A.G. Hochstaedter</dc:creator>
  <dc:date>1990</dc:date>
  <dc:description>&lt;p&gt;A bimodal volcanic suite with K&lt;img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif" alt="single bond" data-mce-src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif"&gt;Ar ages of 0.05–1.40 Ma was collected from the Sumisu Rift using&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="small-caps"&gt;alvin&lt;/span&gt;. These rocks are contemporaneous with island arc tholeiite lavas of the Izu-Ogasawara arc 20 km to the east, and provide a present day example of volcanism associated with arc rifting and back-arc basin initiation. Major element geochemistry of the basalts is most similar to that of basalts found in other, more mature back-arc basins, which indicates that back-arc basins need not begin their magmatic evolution with lavas bearing strong arc signatures.&lt;/p&gt;&lt;p&gt;Volatile concentrations distinguish Sumisu Rift basalts from island arc basalts and MORB. H&lt;sub&gt;2&lt;/sub&gt;O contents, which are at least four times greater than in MORB, suppress plagioclase crystallization. This suppression results in a more mafic fractionating assemblage, which prevents Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;depletion and delays the initiation of Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;sup&gt;(tot)&lt;/sup&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and TiO&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;enrichment. However, unlike arc basalts,Fe&lt;sup&gt;3+/&lt;/sup&gt;ΣFe ratios are only slightly higher than in MORB and are insufficient to cause magnetite saturation early enough to suppress Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;sup&gt;(tot)&lt;/sup&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and TiO&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;enrichment. Thus, major element trends are more similar to those of MORB than arcs.&lt;/p&gt;&lt;p&gt;H&lt;sub&gt;2&lt;/sub&gt;O, CO&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and S are undersaturated relative to pure phase solubility curves, indicating exsolution of an H&lt;sub&gt;2&lt;/sub&gt;O-rich mixed gas phase. HighH&lt;sub&gt;2&lt;/sub&gt;O/S, highδD, and low (MORB-like)δ&lt;sup&gt;34&lt;/sup&gt;S ratios are considered primary and distinctive of the back-arc basin setting.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/0012-821X(90)90184-Y</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>Volcanism in the Sumisu Rift, I. Major element, volatile, and stable isotope geochemistry</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>