Fig. 3
Comparison of the Sr-isotope ratios measured on rhynchonellids from the western Swiss Jura with the ammonite-calibrated 87Sr/86Sr curve obtained from belemnites from the Vocontian Trough after Godet et al. (2011, Fig. 6, modified) red dots from Schootbrugge (2001), black dots from Bodin et al. (2009), red circles from McArthur et al. (2007). Absolute ages on the vertical axis (Y) are from McArthur et al. (2004, 2007). There are two numerical ages for the “Urgonien jaune” in Godet et al. (2011): redrawn after their figure and another one centered on the value given in their text. Regarding the Sr-isotope ratios, the first three digits after the decimal point are 707, the next three digits are displayed on the horizontal axis (X). The discrete arrows indicate when the curve is intercepted sporadically, the joined arrows indicate larger intervals of interception (spanning several ammonite zones). The last two columns present ranges identified by Godet et al. (2011) and an alternative reading derived from the same data set (this discussion). From base to top MBH, Marnes bleues de Hauterive (blue), MU, Marnes d’Uttins (black), UG, Urgonien Jaune (orange), MR, Marnes de la Russille (red), UB, Urgonien Blanc (green)