<?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:creator>Peter W. Lipman</dc:creator>
  <dc:date>1963</dc:date>
  <dc:description>&lt;p&gt;&lt;span class="ScopusTermHighlight"&gt;Gibson&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Peak&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;pluton&lt;/span&gt;&lt;span&gt;&amp;nbsp;is the most&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;discordant&lt;/span&gt;&lt;span&gt;&amp;nbsp;of several dominantly granitic intrusions&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Trinity&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Alps&lt;/span&gt;&lt;span&gt;&amp;nbsp;of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;northern&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;California&lt;/span&gt;&lt;span&gt;. It formed during Nevadan (Late Jurassic) deformation by emplacement of at least five discrete rock units that define&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;a&lt;/span&gt;&lt;span&gt;&amp;nbsp;successively more silicic series, ranging from hypersthene gabbro to trondhjemitic tonalite. Contact features suggest that several units were incompletely crystalline when intruded by succeeding phases. Deformation of wall rocks, mainly partly serpentinized peridotite, indicates forceful&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;intrusion&lt;/span&gt;&lt;span&gt;, despite remarkable discordance of the&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;pluton&lt;/span&gt;&lt;span&gt;&amp;nbsp;to regional structures. The discordance probably was controlled by regional extension fracturing during late stages of Nevadan deformation. Chemical compositions, computed from average modes of the intrusive units, are characterized by high Fe&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O&lt;/span&gt;&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;-FeO and Na&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O-K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O ratios. Plots of normative feldspar define&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;a&lt;/span&gt;&lt;span&gt;&amp;nbsp;trend of trondhjemitic differentiation that diverges markedly from typical calc-alkaline trends. Contact metamorphism to mineral assemblages of pyroxene hornfels facies has been largely obscured by later low-grade hydration reactions, resulting&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;a&lt;/span&gt;&lt;span&gt;&amp;nbsp;net increase&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;in&lt;/span&gt;&lt;span&gt;&amp;nbsp;serpentinization of most country-rock peridotite within the contact aureole.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1130/0016-7606(1963)74[1259:GPPADC]2.0.CO;2</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Geological Society of America</dc:publisher>
  <dc:title>Gibson peak pluton: A discordant composite intrusion in the southeastern Trinity Alps, northern California</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>