Testing the isochrony, estimating the rates and tracking the beat of early Late Cretaceous sea-level changes: an integrated interplate approach.

晚白垩世早期温暖的温室时代的特点是海平面普遍上升或较高，其间反复出现海平面大而迅速的下降，其原因至今尚不清楚。一些海平面的下降被推测为冰川静力驱动的方式，其驱动方式是δ腿中或多或少未经成岩作用改变的有孔虫方解石的18O正移位。然而，同位素证据往往是模棱两可的，海上岩心测井和陆上层序仍然很难进行对比。另一方面，陆上层序承载了更全面的信息，对揭示晚白垩世早期海平面变化的格局具有重要的潜力。陆上的不整合面很好地表达出来，可以通过综合方法，特别是高分辨率宏观化石生物地层学、碳稳定同位素和旋回地层学的方法，在地层学上进行标定。随着对(生物)相和地层结构的分析，如层序界面上/下的几何形状或切割，对海平面变化的幅度和速度进行相当精确的评估是可能的。为了验证晚白垩世早期海平面变化的等时性，对不同构造板块(欧洲、北非、中东)的Cenomian-Turonian(~100-90 MYR)海平面事件进行了板间层序地层学研究。此外，将估计海平面变化的周期和米兰科维奇频带(&lt；500KYR)的高频轨道强迫与这些振荡的低频调制(&gt；1 MYR)的作用。这项研究将是对仅基于同位素替代物的重建的关键检验，对于中生代温室气候和未来海平面变化的评估都具有重要的意义。

The warm early Late Cretaceous greenhouse epoch was characterized by generally rising or high sea-level stands repeatedly punctuated by large and rapid sea-level drops, the reasons of which are still poorly understood. Some of the sea-level falls have been speculated as glacio-eustatically driven by means of positive δ18O shifts in more-or-less diagenetically unaltered foraminiferal calcite from ODP legs. However, the isotopic evidence is often ambiguous and offshore core logs and onshore sequences are still difficult to correlate. On the other hand, onshore sequences bear much more comprehensive information on, and have significant potential for unravelling the pattern of early Late Cretaceous sea-level change. Unconformities are well expressed onshore and they can be stratigraphically calibrated by means of integrated approaches, especially high-resolution macrofossil biostratigraphy, carbon stable isotopes and cyclostratigraphy. Along with analyses of (bio-)facies and stratal architectures such as on-/offlap geometries or incision at sequence boundaries, a fairly precise assessment of the magnitudes and rates of sea-level change is possible. In order to test the isochrony of early Late Cretaceous sea-level change, an interplate sequence stratigraphic study of selected Cenomanian-Turonian (~100-90 myr) sea-level events on different tectonic plates (Europe, northern Africa, Middle East) is proposed. Furthermore, the periodicities of the sea-level changes and the role of highfrequency orbital forcing in the Milankovitch Band (<500 kyr) versus low-frequency modulation of these oszillations (>1 myr) will be estimated. This study will be a crucial test for reconstructions based on isotope proxies only, and bears important implications for both Mesozoic greenhouse climates and the evaluation of future sea-level change.