Development of Late Miocene Delta 13C stratigraphy and assessment of changes in global ice volume and deep-water circulation (6-12 Ma, Site 1237; Leg 202)

其目标是将天文校准的海底同位素地层学扩展到中新世，并研究全球冰量和深水环流(6-12 Ma)的变化。氧同位素地层学是测定近5 Ma海相沉积层序的主要工具。最近，Tiedemann，Sturm等人。论证了已建立的海底Delta18O地层学(0-5.3 Ma)延伸到中新世受到了阻碍，因为全球分布的氧同位素记录的结构在很长一段时间内是不同的，因此不提供全球信号-缺乏扩大氧同位素地层学的主要前提条件。相反，由于6I3C的结构和旋回变化揭示了全球对气候变化的响应，我们确定底栖三角洲L3C信号是开发晚中新世天文校准地层学的替代和强大工具。我们选择了202站1237的沉积物记录作为特别合适的选择，因为它是唯一一个几乎满足所有标准的海洋地点，通过将磁性地层学和生物地层学的优秀框架整合到轨道调谐的同位素地层学中，提供了完整的新近纪参考剖面。叠加在Delta13C的轨道控制变化上的是构造时间尺度上的趋势，这将为深水循环的变化提供新的见解，包括与盆地有关的营养分布分馏。

The goal is to expand the astronomically calibrated benthic isotope stratigraphy into the Miocene and to examine changes in global ice-volume and deep-water circulation (6-12 Ma). Oxygen isotope stratigraphy is the primary tool for dating marine sedimentary sequences of the last 5 Ma. Recently, Tiedemann, Sturm, et al. (in press) demonstrated that the extension of the established benthic Delta18O stratigraphy (0-5.3 Ma) into the Miocene is hampered by the fact that the structure of globally distributed oxygen isotope records is different over long time intervals and thus provides no global signal - lacking the major precondition for expanding the oxygen isotope stratigraphy. Instead, we identified the benthic Delta l3C-signal as an alternative and a powerful tool to develop an astronomically calibrated stratigraphy for the late Miocene, as the structure and cyclic changes in 6I3C revealed a global response to climate change. We selected the sediment record from Leg 202 site 1237 as particularly suitable because it is the only marine site that meets nearly all critera of providing a complete Neogene reference section by integrating the excellent framework of both magnetostratigraphy and biostratigraphy into an orbitally tuned isotope stratigraphy. Superimposed on orbital controlled variations in Delta13C are trends on tectonic time scales that will provide new insights into changes in deep-water circulation including basin-related fractionations in nutrient distributions.