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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>K.R. Johnson</dc:contributor>
  <dc:creator>Douglas J. Nichols</dc:creator>
  <dc:date>2002</dc:date>
  <dc:description>&lt;p&gt;Palynology&lt;span&gt;&amp;nbsp;is used to bracket or pinpoint the&amp;nbsp;&lt;/span&gt;Cretaceous&lt;span&gt;-&lt;/span&gt;Tertiary&lt;span&gt;&amp;nbsp;(K-T)&amp;nbsp;&lt;/span&gt;boundary&lt;span&gt;&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;17 measured&amp;nbsp;&lt;/span&gt;sections&lt;span&gt;&amp;nbsp;near the contact of the Hell Creek Formation and the Ludlow Member of the Fort Union Formation&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;&lt;/span&gt;southwestern&lt;span&gt;&amp;nbsp;&lt;/span&gt;North&lt;span&gt;&amp;nbsp;&lt;/span&gt;Dakota&lt;span&gt;. Palynostratigraphy is the most reliable method for locating the K-T extinction horizon - which defines the K-T&amp;nbsp;&lt;/span&gt;boundary&lt;span&gt;&amp;nbsp;-&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;nonmarine rocks. The palynological database includes 110 taxa for which relative abundance or presence or absence data were recorded&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;more than 350 samples based on surveys of more than 700 000 specimens. These data from laterally extensive outcrops&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;the badlands along the Little Missouri River provide a temporal framework for concurrent studies&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;the area on megafossil paleobotany, vertebrate paleontology, lithostratigraphy, magnetostratigraphy, and chemostratigraphy.&amp;nbsp;&lt;/span&gt;Palynology&lt;span&gt;&amp;nbsp;demonstrates extinction of 30% or more of the Maastrichtian palynoflora, including characteristic Maastrichtian taxa ("K taxa"), at the K-T&amp;nbsp;&lt;/span&gt;boundary&lt;span&gt;. Most of the palynomorph taxa discussed probably represent higher-level plant taxa (botanical genera or families). The K-T&amp;nbsp;&lt;/span&gt;boundary&lt;span&gt;&amp;nbsp;is shown to be coincident with the Hell Creek-Fort Union formational contact at only two localities; it is as much as 2.7mabove the base of the Fort Union Formation at others. Thus, a distinctive interval of Fort Union strata of&amp;nbsp;&lt;/span&gt;Cretaceous&lt;span&gt;&amp;nbsp;age is recognized that is characterized by occurrences of numerous K taxa, usually&amp;nbsp;&lt;/span&gt;in&lt;span&gt;&amp;nbsp;low percentage abundance, up to the K-T&amp;nbsp;&lt;/span&gt;boundary&lt;span&gt;. This interval documents a regional paleoenvironmental change that is independent of the extinction event and that is important to understanding the K-T transition throughout western&amp;nbsp;&lt;/span&gt;North&lt;span&gt;&amp;nbsp;America.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1130/0-8137-2361-2.95</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Geological Society of America</dc:publisher>
  <dc:title>Palynology and microstratigraphy of Cretaceous-Tertiary boundary sections in southwestern North Dakota</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>