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

测试等时性、估计速率并跟踪晚白垩世早期海平面变化的节拍：一种综合的板间方法。

基本信息

批准号：
162632737
负责人：
Privatdozent Dr. Markus Wilmsen
金额：
--
依托单位：
Senckenberg Naturhistorische Sammlungen Dresden
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2013-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/162632737?language=en
关键词：
Testing isochrony estimating rates tracking

项目摘要

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.

温暖的晚白垩世早期温室时代的特点是普遍上升或高海平面的立场反复打断了大而迅速的海平面下降，其原因仍然知之甚少。一些海平面福尔斯的下降被推测为冰川-海平面变化的驱动，这是通过ODP腿中或多或少成岩未改变的有孔虫方解石中的正δ 18 O位移实现的。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相互关联。另一方面，陆上层序在晚白垩世早期海平面变化模式方面具有更全面的信息，并具有很大的潜力。不整合面在陆上有很好的表现，可以通过综合方法，特别是高分辨率的宏体化石生物地层学、碳稳定同位素和旋回地层学进行地层标定。沿着（生物）相和地层结构的分析，如在层序边界的上/下超几何形状或切口，海平面变化的幅度和速率的一个相当精确的评估是可能的。为了检验晚白垩世早期海平面变化的等时性，建议对不同构造板块（欧洲、北方非洲、中东）上的Cenomanian-Turonian（~ 1亿~ 9千万年）海平面事件进行板间层序地层学研究。此外，海平面变化的周期性和米兰科维奇带（<500 kyr）中的高频轨道强迫相对于这些振荡的低频调制（> 100万年）的作用将被估计。这项研究将是一个关键的测试重建的基础上同位素代理，并承担中生代温室气候和未来海平面变化的评估具有重要意义。