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：测试U系列珊瑚测年和海平面重建的新方法。该项目的目标有两个：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，我们将检验一个新的假设，即上一次间冰期的海平面变化很大。在对较老的化石珊瑚进行U/Th测年中，最紧迫的问题是有充分证据证明，用于测年的U系列同位素受到了干扰，从而造成了可供分析的标本的匮乏。珊瑚U/Th测年的最新进展表明，有可能对这些干扰进行校正，从而产生连贯和可重复性的结果。使用修正的年龄重建海平面表明，上一次间冰期海平面的变化比之前认为的要多得多。如果这些隐含的海平面波动实际上是真实的，它对我们目前气候的稳定性具有严重影响，需要重新考虑拟议的快速气候变化机制。在这项建议中，我们将对巴巴多斯、巴哈马和西澳大利亚最后一次间冰期化石礁露头进行高分辨率采样，以分析样品内和样品之间珊瑚的年龄再现性。地层内年龄的一致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度和精度。个别记录内部和之间的差异将指导今后的海平面重建工作。如果这一新方法被证明是可靠的，它将显著改善过去60万年的海平面年表，并将为未来对快速气候变化的机制和冰盖反应的研究提供一个更完整的数据库。该项目将资助一个新的PI，并将让来自俄亥俄州史密斯学院和伍斯特学院的本科生参与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.