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

要了解全球海洋、气候和海洋生物进化变化的原因，一个基本的先决条件是可靠的高分辨率年代地层方案。在全局上下文中只能解释同步事件。早白垩世海相地层的各种已建立的地层方案仍然缺乏可靠性和岁差，原因是：a）相关指标分类群的定义不精确，B）全球海洋事件和生物地层学的相关性不足，c）指标分类群的历时出现，d）导致两种不同植物群和动物群背景的地理区域性，即北方区和特提斯区，e）北方和特提斯层序的对比，在许多情况下是以“经验法则”年代地层学为基础的。本项目旨在通过使用综合生物和化学地层学方法克服其中一些问题。我们打算研究的碳和锶同位素组成的地层学良好的日期和分类学上明确界定的从Valanginian阿尔比安节从北方域和特提斯。我们的目标是：a）改进和提高目前的北半球-特提斯分带方案的有效性，B）更好地确定海洋事件的日期，c）在讨论海洋变化的潜在原因时增加一个北半球的观点。

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.