<?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>G. Brent Dalrymple</dc:contributor>
  <dc:creator>M. A. Lanphere</dc:creator>
  <dc:date>1976</dc:date>
  <dc:description>&lt;div id="abstracts" class="Abstracts u-font-serif"&gt;&lt;div id="ab1" class="abstract author" lang="en"&gt;&lt;div id="aep-abstract-sec-id4"&gt;&lt;p&gt;&lt;sup&gt;40&lt;/sup&gt;Ar/&lt;sup&gt;39&lt;/sup&gt;Ar incremental heating experiments on igneous plagioclase, biotite, and pyroxene that contain known amounts of excess&lt;sup&gt;40&lt;/sup&gt;Ar indicate that saddle-shaped age spectra are diagnostic of excess&lt;sup&gt;40&lt;/sup&gt;Ar in igneous minerals as well as in igneous rocks. The minima in the age spectra approach but do not reach the crystallization age. Neither the age spectrum diagram nor the&lt;sup&gt;40&lt;/sup&gt;Ar/&lt;sup&gt;36&lt;/sup&gt;Ar versus&lt;sup&gt;39&lt;/sup&gt;Ar/&lt;sup&gt;36&lt;/sup&gt;Ar isochron diagram reliably reveal the crystallization age in such samples.&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;ul id="issue-navigation" class="issue-navigation u-margin-s-bottom u-bg-grey1"&gt;&lt;/ul&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/0012-821X(76)90052-2</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>Identification of excess 40Ar by the  40Ar 39Ar, age spectrum technique</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>