(Supplementary Table 1) 230Th/U results for stalagmite Cuba Grande (CG) from Pinar del Rio

We present 22 U-series ages for a stalagmite from north-western Cuba based on multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) and thermal ionisation mass spectrometry (TIMS). Our results reveal that the stalagmite continuously grew within the last ~1400a. Low uranium content of the sample and thus, extremely low 230Th concentrations limit the precision and accuracy of 230Th/U-dating by TIMS. Samples measured by MC-ICPMS show a high variability of 232Th content along the growth axis with some sections significantly affected by initial 230Th from a detrital phase. An a-priori bulk earth ratio for (238U/232Th) cannot be used to accurately account for this initial 230Th. Using an age model based on the 230Th/U ages determined on samples with low or negligible 232Th concentration, we find that the (238U/232Th) activity ratio of the detrital phase is an order of magnitude larger than the bulk earth value, indicating the importance of an accurately determined correction factor.

本研究依托多接收器电感耦合等离子体质谱（multi-collector inductively coupled plasma mass spectrometry, MC-ICPMS）与热电离质谱（thermal ionisation mass spectrometry, TIMS）两种测试技术，对古巴西北部的一根石笋获得了22组铀系测年数据。测试结果表明，该石笋在过去约1400年间持续生长发育。该样品铀含量偏低，对应的230Th浓度极低，这限制了采用TIMS开展230Th/U测年的精度与准确性。经MC-ICPMS测试的样品显示，其沿生长轴的232Th含量存在显著波动，部分区段受到碎屑相初始230Th的显著干扰。无法通过采用先验的全地球(238U/232Th)比值来准确校正该初始230Th干扰。本研究基于232Th浓度较低或可忽略的样品所获得的230Th/U测年结果构建年代模型，结果发现碎屑相的(238U/232Th)活度比值较全地球比值高出一个数量级，这凸显了精准确定校正因子的重要性。