A high-resolution relative time scale for the Vise´ an Stage (Carboniferous) of the Kulm Basin (Rhenish Mountains, Germany) DIETER KORN 1 * and BERND KAUFMANN 2 1 Museum fu¨ r Naturkunde der Humboldt-Universita¨ t zu Berlin, Berlin, Germany 2 O ¨ sterreichische Akademie der Wissenschaften, Kommission fu¨ r die pala¨ ontologische und stratigraphische Erforschung O ¨ sterreichs, c/o Institut fu¨ r Erdwissenschaften (Geologie und Pala¨ ontologie), Karl-Franzens- Universita¨ t Graz, Graz, Austria The Vise´an (Carboniferous) sedimentary succession of the basinal Kulm facies (Rhenish Mountains) was investigated in detail in order to achieve a high-resolution stratigraphic subdivision and correlation. Additionally, the ranges of fossil index taxa (ammonoids), fossil marker beds, volcaniclastic horizons and sedimentary features (e.g. colour changes) were integrated in the correlation. As a result, a comprehensive database was compiled, which contains 190 stratigraphic events of the Vise´an interval of this area. Several sections are almost completely composed of shales, which are regarded to represent a slow but constant basinal background sedimentation of the Kulm facies. The thickness of lithological homogeneous sections thus indicates an approximately linear record of time and the average thicknesses of biozones and positions of stratigraphic events can easily be calculated from the compiled database. The result is an approximately time-linear biostratigraphic scale for the Vise´an Stage of the Kulm Basin. Given a numerical length of the Vise´an Stage of ca. 19 Ma, 190 stratigraphic events give a mean resolution of 100 000 years. This is unique in Palaeozoic stratigraphy. Copyright # 2008 John Wiley & Sons, Ltd. Received 29 May 2008; accepted 29 October 2008 KEY WORDS Carboniferous; chronostratigraphy; index horizons; volcaniclastics; ammonoids; time scale 1. INTRODUCTION The Vise´an is the longest stage of the Carboniferous period with an absolute length of ca. 19 Ma (Davydov et al. 2004; Menning et al. 2006). However, there is great uncertainty about the relative lengths and proportions of Vise´an substages and biozones. Recently, the Vise´an sedimentary rocks of the type area in Belgium have been subdivided into the three local stages Moliniacian, Livian, and Warnantian (late Chadian to Brigantian of the British local stages) or the seven foraminiferal zones MFZ9-MFZ15 (Hance et al. 2006). Foraminifers, however, are best applicable in the palaeogeographic realm of the shallow-water ‘Kohlenkalk’ shelf, but they have only rarely been used in the basinal Kulm facies, as present in the Rhenish and Harz Mountains (Germany), Devon and Cornwall (SW England), and South Portugal (Conil and Paproth 1968; Herbig 2006). In these regions, ammonoids (goniatites) are the best index fossils that allowed the development of a very detailed stratigraphic scheme (Schmidt 1925; Ruprecht 1937; Kulick 1960; Nicolaus 1963; Korn 1996, 2006; Korn and Horn K 1997; Stoppel et al. 2006). Correlation of the Kohlenkalk and the Kulm realms is difficult and has mainly been achieved by conodonts (Voges 1960; Witten 1979) and to a certain degree by smaller calcareous foraminifers (Herbig 2006). The conodont Pseudognathodus homopunctatus (Ziegler) is a marker species for the base of the Vise´an stage (Devuyst et al. 2003) in both realms. According to GEOLOGICAL JOURNAL Geol. J. 44: 306–321 (2009) Published online 30 December 2008 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/gj.1143 * Correspondence to: D. Korn, Museum fu¨r Naturkunde der Humboldt-Universita¨t zu Berlin, Invalidenstraße 43, 10115 Berlin, Germany. E-mail: dieter.korn@museum.hu-berlin.de Copyright # 2008 John Wiley & Sons, Ltd.