%0 Journal Article
%T Upper Pliensbachian ¨C Toarcian (Jurassic) palaeoenvironmental perturbations in a temporal and regional context: an extended 87Sr/86Sr, ¦Ä13C and ¦Ä18O belemnite isotope study from Bulgaria
%A L. S. Metodiev
%A I. P. Savov
%A D. R. Gr£¿cke
%A P. B. Wignall
%J Solid Earth Discussions
%D 2012
%I Copernicus Publications
%R 10.5194/sed-4-315-2012
%X The Upper Pliensbachian¨CToarcian (Jurassic) sedimentological, palaeontological and geochemical (belemnite 87Sr/86Sr, ¦Ä13C and ¦Ä18O) record is examined in two Eastern Tethyan (Bulgarian) locations. This interval contains the well-known Early Toarcian ocean anoxic event (T-OAE) and its manifestation and temporal context is examined in Bulgaria. Many of the features characteristic for the SW European sections were identified: collapse of carbonate platform productivity at the Pliensbachian/Toarcian boundary, the T-OAE (a short pulse of anoxic deposition in the Falciferum ammonite Zone), an Early Toarcian rapid warming event seen in the belemnite ¦Ä18O record that peaked around the Falciferum/Bifrons ammonite zonal boundary. The long-recognized positive ¦Ä13C excursion in the late Falciferum ammonite Zone is also seen but a precursor, sharp ¦Ä13C negative excursion seen around the Tenuicostatum/Falciferum ammonite zonal boundary in many organic carbon records is not evident in the belemnite data, a curious absence noted from other belemnite records. Subsequent fluctuations of the 87Sr/86Sr, ¦Ä13C and ¦Ä18O suggest there may be a further perturbation of the global isotopic systems. On the other hand, belemnite Sr isotope values from Bulgaria are in accord with those seen in Western Europe and hence its value for chronostratigraphy.
%U http://www.solid-earth-discuss.net/4/315/2012/sed-4-315-2012.pdf