I.I. Friedman B.M. Madsen K. J. Murata 1967 <div class="panel-pane pane-highwire-panel-tabs-container article__body"><div class="pane-content"><div id="panels-ajax-tab-container-highwire_article_tabs" class="panels-ajax-tab-container" data-panels-ajax-tab-preloaded="jnl_sci_tab_art"><div class="panels-ajax-tab-wrap-jnl_sci_tab_art"><div class="panel-display panel-1col clearfix"><div class="panel-panel panel-col"><div><div class="panel-pane pane-highwire-markup"><div class="pane-content"><div class="highwire-markup"><div id="content-block-markup" data-highwire-cite-ref-tooltip-instance="highwire_reflinks_tooltip" data-highwire-glossary-tooltip-instance="highwire_reflinks_tooltip"><div class="article abstract-view "><div id="abstract-1" class="section abstract"><p id="p-1">Carbon unusually rich in C¹³(δC¹³<span>&nbsp;</span>= +5.4 to +19.0 per mil relative to the Peedee belemnite carbonate standard of the University of Chicago) is characteristic of certain diagenetic limestones and dolomites in the Miocene Monterey Shale of California and the Nye Mudstone of Oregon. This heavy carbon may have originated through low-temperature equilibration between CO₃- - and CO₂<span>&nbsp;</span>in migrating carbonated waters or between CH₄<span>&nbsp;</span>and CO₂<span>&nbsp;</span>in natural gas. Light carbon (δC¹³<span>&nbsp;</span>= -5.6 to -18.2 per mil) derived through nonequilibrium oxidation of organic matter also occurs in the carbonate of Monterey Shale in some localities, but at most places it is much less common than heavy carbon.</p></div></div><span id="related-urls"></span></div></div></div></div></div></div></div></div></div></div></div> application/pdf 10.1126/science.156.3781.1484 en Nature Carbon-13-rich diagenetic carbonates in miocene formations of California and Oregon article