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<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>A.P. Pierce</dc:contributor>
  <dc:contributor>J.C. Antweiler</dc:contributor>
  <dc:contributor>K.L. Buck</dc:contributor>
  <dc:creator>R.S. Cannon Jr.</dc:creator>
  <dc:date>1961</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Searching questions about the origins of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;ore&lt;/span&gt;&lt;span&gt;&amp;nbsp;deposits have been asked for many years. Where do&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;ore&lt;/span&gt;&lt;span&gt;&amp;nbsp;fluids originate-within the crust, or deeper? Can specific sources of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;ore&lt;/span&gt;&lt;span&gt;&amp;nbsp;metals be identified? When were ores deposited? How long did mineralization continue? What was the rate and paragenesis of deposition? Which deposits are cogenetic, and what metallogenetic provinces do they define?&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Isotope&lt;/span&gt;&lt;span&gt;&amp;nbsp;analyses of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;&amp;nbsp;from rocks and ores provide a new tool for attacking such&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;problems&lt;/span&gt;&lt;span&gt;&amp;nbsp;of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;ore&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;genesis&lt;/span&gt;&lt;span&gt;. About two thousand such analyses now available from more than 20 laboratories have been compiled and studied for this purpose. The&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;data&lt;/span&gt;&lt;span&gt;&amp;nbsp;now available suggest partial answers to some questions and serve to define other, new&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;problems&lt;/span&gt;&lt;span&gt;, not previously recognized. Their greatest import, however, is to illustrate the potential future significance of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;isotope&lt;/span&gt;&lt;span&gt;&amp;nbsp;studies.&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;Ore&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;, as shown two decades ago, ranges widely in isotopic composition. Recent studies show that traces of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;&amp;nbsp;in ordinary rocks of the earth's crust exhibit apparently similar variations. All these variations are attributable primarily to mixing of old&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;&amp;nbsp;with accumulations of new radiogenic&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;&amp;nbsp;from decay of radioactive uranium and thorium. Each sample of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;&amp;nbsp;preserves in its isotopic composition a record of its own mixing history: a composite record of the time this&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;&amp;nbsp;was in different environments, its past associations with uranium and thorium, and the geochemical processes that moved it from place to place. Integrated study of all these variables will throw light on many difficult&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;problems&lt;/span&gt;&lt;span&gt;&amp;nbsp;of&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;ore&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;genesis&lt;/span&gt;&lt;span&gt;&amp;nbsp;when adequate techniques are developed. Progress will be slow, however, until more accurate&amp;nbsp;&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;lead&lt;/span&gt;&lt;span&gt;-&lt;/span&gt;&lt;span class="ScopusTermHighlight"&gt;isotope&lt;/span&gt;&lt;span&gt;&amp;nbsp;analyses can be made at lower cost and more objective criteria developed for interpreting measured isotopic compositions in terms of geologic history.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.2113/gsecongeo.56.1.1</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Society of Economic Geologists</dc:publisher>
  <dc:title>The data of lead isotope geology related to problems of Ore Genesis</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>