<?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>B.P.J. Stevens</dc:contributor>
  <dc:creator>J. F. Slack</dc:creator>
  <dc:date>1994</dc:date>
  <dc:description>&lt;div id="abstracts" class="Abstracts u-font-serif text-s"&gt;&lt;div id="aep-abstract-id3" class="abstract author"&gt;&lt;div id="aep-abstract-sec-id4"&gt;&lt;p id="SP0005"&gt;Whole-rock analyses of samples of pelite, psammite, and psammopelite from the Early Proterozoic Broken Hill Group (Willyama Supergroup) in the Broken Hill Block, New South Wales, Australia, reveal distinctive geochemical signatures. Major-element data show high Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and K&lt;sub&gt;2&lt;/sub&gt;O, low MgO and Na&lt;sub&gt;2&lt;/sub&gt;O, and relatively high&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="math"&gt;&lt;span id="MathJax-Element-1-Frame" class="MathJax_SVG" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mtext&gt;Fe&lt;/mtext&gt;&lt;msub&gt;&lt;mi&gt;&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mtext&gt;O&lt;/mtext&gt;&lt;msub&gt;&lt;mi&gt;&lt;/mi&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msub&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt;&lt;mn&gt;T&lt;/mn&gt;&lt;/msup&gt;&lt;mtext&gt;MgO&lt;/mtext&gt;&lt;/math&gt;"&gt;&lt;span class="MJX_Assistive_MathML"&gt;Fe2O3TMgO&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;ratios, compared to average Early Proterozoic clastic metasediments. High field strength elements (HFSE) are especially abundant, including Nb (most 15–27 ppm), Ta (most 1.0–2.2 ppm), Th (17–36 ppm), Hf (4–15 ppm), and Zr (most 170–400 ppm); Y (33–74 ppm) is also high. Concentrations of ferromagnesian elements are generally low (&lt;i&gt;Sc&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= &amp;lt; 20 ppm,&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Ni&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= ≤ 62 ppm,&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Co&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= &amp;lt;26 ppm;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;Cr&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= most &amp;lt; 100 ppm). Data for rare earth elements (REEs) show high abundances of light REEs (&lt;i&gt;La&lt;/i&gt;&lt;sub&gt;&lt;i&gt;CN&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 116–250 × chondrite;&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;La&lt;/i&gt;&lt;sub&gt;&lt;i&gt;CN&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 437 in one sample), high&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;span class="math"&gt;&lt;span id="MathJax-Element-2-Frame" class="MathJax_SVG" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mtext&gt;La&lt;/mtext&gt;&lt;msub&gt;&lt;mi&gt;&lt;/mi&gt;&lt;mn&gt;CN&lt;/mn&gt;&lt;/msub&gt;&lt;mtext&gt;Yb&lt;/mtext&gt;&lt;msub&gt;&lt;mi&gt;&lt;/mi&gt;&lt;mn&gt;CN&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;"&gt;&lt;span class="MJX_Assistive_MathML"&gt;LaCNYbCN&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;ratios (5.6–13.9), and large negative Eu anomalies (&lt;span class="math"&gt;&lt;span id="MathJax-Element-3-Frame" class="MathJax_SVG" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mtext&gt;Eu&lt;/mtext&gt;&lt;mtext&gt;Eu&lt;/mtext&gt;&lt;msup&gt;&lt;mi&gt;&lt;/mi&gt;&lt;mn&gt;&amp;amp;#x2217;&lt;/mn&gt;&lt;/msup&gt;&lt;mtext&gt;= 0.32&amp;amp;#x2013;0.57&lt;/mtext&gt;&lt;/math&gt;"&gt;&lt;span class="MJX_Assistive_MathML"&gt;EuEu∗= 0.32–0.57&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;).&lt;/p&gt;&lt;p id="SP0010"&gt;The geochemical data indicate derivation of the metasedimentary rocks of the Broken Hill Group by the erosion mainly of felsic igneous (or meta-igneous) rocks. High concentrations of HFSE, Y, and REEs in the metasediments suggest a provenance dominanted by anorogenic granites and(or) rhyolites, including those with A-type chemistry. Likely sources of the metasediments were the rhyolitic to rhyodacitic protoliths of local quartz + feldspar ± biotite ± garnet gneisses (e.g., Potosi-type gneiss) that occur within the lower part of the Willyama Supergroup, or chemically similar basement rocks in the region; alternative sources may have included Early Proterozoic anorogenic granites and(or) rhyolites in the Mount Isa and(or) Pine Creek Blocks of northern Australia, or in the Gawler craton of South Australia.&lt;/p&gt;&lt;p id="SP0015"&gt;Metallogenic considerations suggest that the metasediments of the Broken Hill Block formed enriched source rocks during the generation of pegmatite-hosted deposits and concentrations of La, Ce, Nb, Ta, Th, and Sn in the region. Li, Be, B, W, and U in pegmatite minerals of the district may have been acquired during granulite-facies metamorphism of the local metasediments.&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>10.1016/0016-7037(94)90155-4</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>Clastic metasediments of the Early Proterozoic Broken Hill Group, New South Wales, Australia: Geochemistry, provenance, and metallogenic significance</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>