J. D. King J.L. Clayton 1987 <p><span>GC-MS analyses were performed on core samples collected from a shale outcrop of the Permian Phosphoria Formation in Utah, U.S.A., to study effects of weathering on selected biological marker and aromatic (phenanthrene) hydrocarbon compounds. Among the biological markers, the most important weathering effects are a decrease in the&nbsp;</span><span class="math"><span id="MathJax-Element-1-Frame" class="MathJax_SVG" data-mathml="<math xmlns=&quot;http://www.w3.org/1998/Math/MathML&quot;><mtext>20S</mtext><mtext>20R</mtext></math>"><span class="MJX_Assistive_MathML">20S20R</span></span></span><span>&nbsp;diastereomer ratio of the C</span>₂₉<span>&nbsp;steranes and loss of low molecular weight triaromatic steroids. A decrease in the C</span>₁₉<span>&nbsp;through C</span>₂₂<span>&nbsp;tricylcic terpanes occurs relative to the total C</span>₁₉<span>-C</span>₂₆<span>&nbsp;tricyclic fraction. Pronounced loss of methyl-substituted phenanthrenes occurs relative to phenanthrene. No major effect on the overall distribution of pentacyclic terpanes is evident.</span></p> application/pdf 10.1016/0016-7037(87)90264-X en Elsevier Effects of weathering on biological marker and aromatic hydrocarbon composition of organic matter in Phosphoria shale outcrop article