Conodont and graptolite biostratigraphy and the Ordovician (Early Chatfieldian, Middle Caradocian) d13C excursion in North America and Baltoscandia: implications for the interpretation of the relations between the Millbrig and Kinnekulle K–bentonites

• Matthew R. Saltzman ^[1] ; Stig M. Bergström ^[1] ; Warren D. Huff ^[2] ; Dennis R. Kolata ^[3]
  1. [1] Ohio State University

     Ohio State University

     City of Columbus, Estados Unidos

     
  2. [2] University of Cincinnati

     University of Cincinnati

     City of Cincinnati, Estados Unidos

     
  3. [3] Illinois State Geological Survey

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• Localización: Serie correlación geológica, ISSN-e 1666-9479, ISSN 1514-4186, Vol. 17, Nº. 1, 2003
• Idioma: inglés
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• Resumen

  • Two significant Carbon isotope excursions are currently recognized in the Upper Ordovician Global Series, one in the Hirnantian (Gamachian) Stage, and one in the early Chatfieldian North American Stage. Whereas the former excursion, known as the Hirnantian excursion, has received a substantial amount of recent study (see, e.g., Kaljo et al., 2001; Brenchley et al., 2003), relatively little has been published on the latter excursion (see, e.g., Ainsaar et al., 1999), which is now commonly referred to as the Guttenberg Isotope Carbon Excursion or GICE. During the past few years, we have studied the GICE in eastern and central North America and in Sweden. One aspect of our studies has been to explore the geographic and stratigraphic ranges of the GICE and its potential as a chronostratigraphic tool for assessment of local and regional stratigraphic relations. In the present paper, we will first briefly review the currently known distribution of the GICE and its relations to conodont and graptolite biostratigraphy. In a later part of the paper, we will discuss trans–Atlantic biostratigraphic relations and their bearing on relations between the North American Millbrig and the Baltoscandic Kinnekulle K–bentonites.