High resolution Sr-isotope stratigraphy of Early Cretaceous belemnites - an approach for correlating Boreal and Tethyan events

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A fundamental pre-requisite for understanding the causes underiying global oceanic, climatic and bioevolutionary changes in the marine realm is a reliable high-resolution chronostratigraphic scheme. Only synchronous events can be interpreted in a global contexl. The various established stratigraphie schemes for the marine Eariy Cretaceous still lack reliability and precession due to a) imprecise definition of the relevant index taxa, b) inadequate correlation of global oceanographic events and biostratigraphy, c) diachronous appearance of index taxa, d) a biogeographic provincialism resulting in two different floral and faunal settings, the Boreal and the Tethyan Realm, e) a correlation of Borealand Tethyan successions, which is based in many cases on a "rule of thumb" chronostratigraphy.This project aims at overcoming some of these problems by using an integrated bio- and chcmostratigraphic approach. We intend to study the carbon and strontium isotopic composition of stratigraphically well-dated and taxonomically clearly defined belemnites from Valanginian to Albian sections both from the Boreal Realm and the Tethys. Our goal is a) to refine and to improve the validity of current Boreal-Tethyan zonation schemes, b) to better date oceanographic events, c) to add a Boreal perspective on the discussion for potential causes of oceanographic changes.