<html> <head> <meta http-equiv=Content-Type content="text/html; charset=unicode"> <meta name=Generator content="Microsoft Word 12 (filtered)"> <style> <!-- /* Font Definitions */ @font-face {font-family:[SO; panose-1:2 1 6 0 3 1 1 1 1 1;} @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4;} @font-face {font-family:"\@[SO"; panose-1:2 1 6 0 3 1 1 1 1 1;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {margin:0cm; margin-bottom:.0001pt; font-size:12.0pt; font-family:[SO;} h3 {mso-style-link:"h 3 Char"; margin-right:0cm; margin-left:0cm; font-size:13.5pt; font-family:[SO; font-weight:bold;} h4 {mso-style-link:"h 4 Char"; margin-right:0cm; margin-left:0cm; font-size:12.0pt; font-family:[SO; font-weight:bold;} a:link, span.MsoHyperlink {color:blue; text-decoration:underline;} a:visited, span.MsoHyperlinkFollowed {color:purple; text-decoration:underline;} p {margin-right:0cm; margin-left:0cm; font-size:12.0pt; font-family:[SO;} span.3Char {mso-style-name:"h 3 Char"; mso-style-link:"h 3"; font-family:[SO; font-weight:bold;} span.4Char {mso-style-name:"h 4 Char"; mso-style-link:"h 4"; font-family:"Cambria","serif"; font-weight:bold;} .MsoChpDefault {font-size:10.0pt;} @page WordSection1 {size:595.3pt 841.9pt; margin:72.0pt 90.0pt 72.0pt 90.0pt;} div.WordSection1 {page:WordSection1;} --> </style> <!-- --> </head> <body lang=ZH-CN link=blue vlink=purple> <div class=WordSection1> <div id=mainContent> <h3><span lang=EN-US style='font-family:"Arial","sans-serif";color:blue'>GSSP for Tortonian Stage</span></h3> <p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif"; color:red'>&nbsp;</span></p> <h4><span lang=EN-US style='font-family:"Arial","sans-serif";color:red'>Definition:</span></h4> <p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif";color:red'>The base of the Tortonian Stage is defined as the mid-point of the sapropel layer of basic cycle number 76 in the Monte dei Corvi Beach section, located on the Adriatic coast of central Italy, 5km SE of Ancona. This level has been assigned an astronomical age of 11.608 Ma. It coincides almost exactly with the Last Common Occurrences of the calcareous nannofossil <i>Discoaster kugleri</i> and the planktonic foraminifer <i>Globigerinoides subquadratus</i>, and is associated with the short normal-polarity subchron C5r.2n. This level coincides closely with oxygen isotope event Mi-5 and the associated glacio-eustatic sea-level low-stand of supercycle T3.1 and concurrent deep-sea hiatus NH4. </span></p> <table class=MsoNormalTable border=0 cellpadding=0> <tr> <td style='padding:.75pt .75pt .75pt .75pt'> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>Location:</span></h4> <p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif"'>The Monte dei Corvi Beach section is exposed in the coastal cliffs of Monte dei Corvi located 5km SE of Ancona (Italy) at a latitude of 4335'12&quot; North, and a longitude of 1334'10&quot; East. The section can be reached via the trail that starts at La Sardella some 100m east of Monte dei Corvi. </span></p> </td> <td valign=bottom style='padding:.75pt .75pt .75pt .75pt'></td> </tr> </table> <p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif"'>&nbsp;</span></p> <table class=MsoNormalTable border=0 cellpadding=0> <tr> <td style='padding:.75pt .75pt .75pt .75pt'> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>Sedimentology:</span></h4> <p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif"'>The Serravallian and lower Tortonian is exposed along the eastern slopes and in the coastal cliffs of Monte dei Corvi. This section contains the upper part of the marly Schlier Formation and consists of a cyclic alternation of greenish-grey marls, whitish marly limestones and brown colored organic-rich layers (sapropel). In addition two biotite-rich volcanic ash layers, named Respighi and Ancona, are present.<br> The depositional environment remained (hemi)pelagic throughout the succession. Bottom water conditions changed cyclically between oxic (marls) and anoxic or dysoxic (sapropel layers). </span></p> </td> <td valign=bottom style='padding:.75pt .75pt .75pt .75pt'></td> </tr> </table> <p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif"'>&nbsp;</span></p> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>Primary Markers:</span></h4> <p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif"'>The Monte dei Corvi Beach section is composed of a cyclic alternation of marls, marly limestones and organic-rich beds (Montanari et al., 1997). The basic small-scale cycle is a couplet (between 0.3 and 1.0 m thick) which consists of an indurated whitish marly limestone and a softer grey to greenish-grey marl. Brownish to blackish colored organic-rich beds termed sapropels are frequently but not always intercalated in the limestones. <br> Larger-scale cycles can be distinguished in addition and comprise both small-scale and large-scale sapropel clusters. Small-scale clusters contain 2 to 4 sapropels (and 5-6 basic cycles); large-scale clusters contain several small-scale clusters (and up to 20 basic cycles). Finally a cycle of intermediate-scale is recognized by repetitive sapropel patterns in every other basic cycle. Previous studies of marine sections of Late Miocene to Pleistocene age in the Mediterranean (Hilgen, 1991; Hilgen et al., 1995; Lourens et al., 1996) showed that similar sapropel patterns reflect the astronomical cycles of precession (basic cycle), obliquity (intermediate cycle) and eccentricity (larger-scale cycles). Using the same phase relations as established for the younger sapropels, the sedimentary cycles in the Monte dei Corvi Beach section were tuned to the precession and insolation time series of the La93 solution (Laskar, 1990; Laskar et al., 1993). This tuning provides astronomical ages for all the sedimentary cycles, calcareous plankton bioevents, magnetic reversals and ash beds recorded in the section. It shows that the entire beach section ranges from 13.4 to 8.5 Ma and that the Tortonian GSSP has an astronomical age of 11.608 Ma (Hilgen et al., 2003). </span></p> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>Secondary Markers:</span></h4> <p class=MsoNormal style='margin-bottom:12.0pt'><b><span lang=EN-US style='font-family:"Arial","sans-serif"'>Foraminifera:</span></b><span lang=EN-US style='font-family:"Arial","sans-serif"'><br> The GSSP is close to the Last Common Occurrence of <i>Globigerinoides subquadratus</i>. The GSSP falls within the <i>Paragloborotalia siakensis</i> Zone of Iaccarino (1985).<br> <b>Nannoplankton:</b><br> The GSSP closely coincides with the Last Common Occurrence of <i>Discoaster kugleri</i>. <br> <b>Paleomagnetics:</b><br> The GSSP is closely associated with the base of the short normal subchron C5r.2n. </span></p> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>Correlation Events:</span></h4> <p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif"'>Calcareous nannofossil last common occurrence of <i>Discoaster kugleri</i> </span></p> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>Other Locations around the World:</span></h4> <p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif"'>An auxiliary boundary stratotype section was designated along the southern slopes of Monte Gibliscemi, Sicily (Italy). This section has been correlated bed by bed to the Monte dei Corvi section. The Last Common Occurrence of <i>Discoaster kugleri</i> and <i>Globigerinoides subquadratus</i> appear to be synchronous between the Mediterranean and the low-latitude open ocean. The GSSP further coincides almost exactly with the Barstovian-Clarendonian Mammal Age boundary in North America. </span></p> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>Notes on Derivation of Age:</span></h4> <p class=MsoNormal style='margin-bottom:12.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif"'>Astronomical cycles in sediments </span></p> <h4><span lang=EN-US style='font-family:"Arial","sans-serif"'>References:</span></h4> <p style='margin-left:36.0pt;text-indent:-36.0pt'><span lang=EN-US style='font-family:"Arial","sans-serif"'><a href="Tortonian.pdf">Hilgen, F. J., Abdul Aziz, H., Bice, D., Iaccarino, S., Krijgsman, W., Kuiper, K., Montanari, A., Raffi, I., Turco, E., Zachariasse, W. J., 2005. The Global Boundary Stratotype Section and Point (GSSP) of the Tortonian Stage (Upper Miocene) at Monte dei Corvi. Episodes, 28/1, p. 6 - 17.</a></span></p> <p class=MsoNormal><span lang=EN-US><br> <br> <a href="index.html">Back to GSSP Table</a></span></p> </div> </div> <!-- --> </body> </html>