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

要了解全球海洋、气候和海洋领域生物进化变化的根本原因，一个基本的先决条件是可靠的高分辨率年代地层方案。只有同步事件才能在全局上下文中解释。由于a)相关指数分类群的定义不精确，b)全球海洋事件与生物地层学的相关性不足，c)指数分类群的出现是跨时的，d)生物地理的地方性导致两种不同的植物和动物设置，北方和特提斯王国，e)北方和特提斯演代的相关性，因此各种已建立的海洋早白垩世地层学方案仍然缺乏可靠性和进动性。这在很多情况下是基于“经验法则”的年代地层学。本项目旨在通过综合生物地层学和化学地层学的方法来克服这些问题。我们打算研究来自北方地区和特提斯地区的瓦兰吉尼亚至阿尔比安剖面上地层年代准确、分类明确的菱铁矿的碳和锶同位素组成。我们的目标是：a)完善和提高目前北方-特提斯分区方案的有效性；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北方的视角。

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.