Abrupt Climate Change During the Last Interglacial: Testing a New Approach to U-Series Coral Dating and Sea-Level Reconstruction

末次间冰期气候突变：检验u系列珊瑚定年和海平面重建的新方法。摘要本项目的目的有两个：首先，我们将测试一种有前途的U/Th珊瑚测年和海平面重建的新方法。其次，我们将检验一个新出现的假设，即最后一次间冰期的海平面变化很大。在对较老的珊瑚化石进行U/Th定年时，最紧迫的问题是对用于定年的U系列同位素有充分记录的干扰，从而造成可供分析的标本缺乏。珊瑚U/Th测年的最新进展表明，有可能纠正这些干扰，从而产生连贯和可重复的结果。使用校正年龄进行的海平面重建表明，末次间冰期海平面比以前认为的变化更大。如果这些隐含的海平面振荡实际上是真实的，那么它对我们当前气候的稳定性有严重的影响，并且需要重新考虑提出的快速气候变化的机制。在本项目中，我们将对巴巴多斯、巴哈马和西澳大利亚的末次间冰期化石礁的露头进行高分辨率采样，以分析样本内部和样本之间珊瑚的年龄可重复性。地层中年龄的一致性将为其准确性提供强有力的支持，而差异将有助于确定该方法的限制和精度。个别记录内部和之间的差异将指导未来的海平面重建工作。如果这种新方法被证明是可靠的，它将导致对过去60万年海平面年表的重大改进，并将为未来对快速气候变化的机制和冰盖响应的研究提供更完整的数据库。该项目将资助一名新的PI，并将包括来自俄亥俄州史密斯学院和伍斯特学院的本科生进行采样和测绘实地工作。

Abrupt Climate change during the Last Interglacial: Testing a new approach to U-series coral dating and sea level reconstruction.AbstractThe objectives of this project are twofold: First, we will test a promising new approach to U/Th coral dating and sea level reconstruction. Second, we will test an emerging hypothesis that sea level during the last interglacial was quite variable. The most pressing problem in U/Th dating of older fossil corals is a well-documented disturbance of the U-series isotopes that are used for dating, thereby creating a paucity of specimens for analysis. Recent advances in U/Th dating of corals suggest that it is possible to correct for these disturbances, thereby producing coherent and reproducible results. Sea level reconstructions using corrected ages suggest that last interglacial sea level was more variable that previously thought. If these implied sea-level oscillations are in fact real, it has serious implications regarding the stability of our present climate and requires a rethinking of proposed mechanisms for rapid climate change. In this proposal, we will conduct high-resolution sampling of outcrops of last interglacial fossil reefs at Barbados, the Bahamas, and Western Australia in order to analyze the age reproducibility of corals within and between samples. Agreement of ages within stratigraphic layers will provide strong support for their accuracy and differences will help define the limits and precision of the method. Discrepancies within and between individual records will guide future efforts in sea-level reconstruction. If this new approach proves robust, it will lead to significant improvements in sea level chronologies for the past 600,000 years and will provide a more complete database for future research on the mechanisms and ice sheet response to rapid climate change. This project will fund a new PI and will involve undergraduates from Smith College and Wooster College of Ohio in sampling and mapping fieldwork.