<?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>N.B. Keevil</dc:contributor>
  <dc:creator>Esper S. Larsen Jr.</dc:creator>
  <dc:date>1947</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Determination of radioactivity has been made on 43 rocks, carefully selected from the different mapped units of the complex Cretaceous batholith of Southern California; they range from gabbro to granite. The activity of the gabbro averages about 0.3 alphas/mg./hr., that of the tonalites, 0.8, the granodiorite 1.3, and the granites over 2.0. The activity of the average rock of the batholith is about 0.9 alphas/mg./hr. Most of the rocks have been analyzed, and modal compositions are given. The radioactivity and the percentages of K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O, SiO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and PbO are plotted on a variation diagram. The variation curve for activity nearly parallels that for K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O, and the ratio of activity to K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O is about 0.5. The radioactivities of some rocks fall far from the variation curve, and degree of activity correlates with K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O content. A less-marked correlation between activity SiO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and PbO was also noted. The K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O, SiO&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;, PbO, and radioactivity concentrate in the residual liquid during crystallization and differentiation. PbO follows K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O closely, as it is concentrated in the K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O minerals, but radioactivity is very low in the K&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;span&gt;O minerals and is greatly concentrated in the accessory minerals.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1130/0016-7606(1947)58[483:ROTROT]2.0.CO;2</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Geological Society of America</dc:publisher>
  <dc:title>Radioactivity of the rocks of the batholith of southern California</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>