Appendix B.1 - Relative sea level

Paleo relative sea-level (RSL) indicators formed during the Marine Isotope Stage (MIS) 5e have been reported by a large number of studies worldwide. Despite this, three main aspects are seldom reported: (1) use of high-precision survey techniques applied to MIS 5e RSL indicators; (2) application of modern analogs to understand the indicative meaning of MIS 5e RSL indicators; (3) estimates of the effects of glacial isostatic adjustment (GIA) on the MIS 5e records. In this study, we show how the three points above have been addressed in a focused study on Last Interglacial outcrops on the island of Mallorca. We measured the elevation of several RSL indicators with high-accuracy differential GPS (vertical accuracies down to 0.1 m) and we established the relationship between each RSL indicator and the paleo sea level through calculation of the indicative meaning for each RSL indicator. In particular, we present a novel technique to calculate the indicative meaning of fossil beach deposits with a phase-averaged morphodynamic model (CSHORE). We show how this approach helps overcoming difficulties with the survey of the modern analogs for these indicators. Our results show that two paleo RSLs are imprinted in Mallorca at + 2.9 ± 0.8 m and + 11.3 ± 1.0 m. We then compare our field-based results with modelled paleo RSL, calculated from the predictions of the ice-earth coupled ANICE-SELEN model, using few different ice-sheet melting scenarios during MIS 5e. We conclude that indicative ranges can be derived from relatively simple morphodynamic models and that the comparison of field-derived and modelled RSL values is a good method to validate possible scenarios of MIS 5e sea-level variability, especially in absence of precise dating.全球已有大量研究报道了形成于海洋同位素阶段（Marine Isotope Stage, MIS）5e的古相对海平面（Relative Sea-Level, RSL）标志物。尽管已有诸多相关研究，但以下三个核心方面仍鲜有涉及：（1）针对MIS 5e期RSL标志物的高精度测绘技术应用；（2）借助现代类比物解析MIS 5e期RSL标志物指示意义的研究；（3）冰川均衡调整（Glacial Isostatic Adjustment, GIA）对MIS 5e期海平面记录影响的估算。本研究以马略卡岛末次间冰期露头为研究对象，系统探讨了上述三个方面的解决方案。研究团队采用高精度差分GPS（垂直精度可达0.1米）测定了多件RSL标志物的高程，并通过计算每件标志物的指示意义，建立了其与古海平面之间的对应关系。尤为关键的是，本研究提出了一种基于相平均地貌动力模型（phase-averaged morphodynamic model, CSHORE）计算古海滩沉积指示意义的全新方法，该方法可有效解决该类标志物现代类比物测绘的难题。研究结果显示，马略卡岛留存有两处古RSL信号，分别为+2.9±0.8米与+11.3±1.0米。随后，研究团队结合MIS 5e期多种冰盖消融情景下冰-地球耦合ANICE-SELEN模型的预测结果，将野外实测的古RSL数据与模拟得到的古海平面数据进行了对比。最终得出结论：通过相对简单的地貌动力模型即可推导得到指示范围，而野外实测与模拟得到的RSL值对比方法，可有效验证MIS 5e期海平面变化的相关情景，尤其在缺乏精确定年数据的情况下优势显著。