40-year long monthly-resolved Sr/Ca record from 2.35 ka Bonaire coral, sample BON-6-A

We present a 40-year long monthly resolved Sr/Ca record from a fossil Diploria strigosa coral from Bonaire (Southern Caribbean Sea) dated with U/Th at 2.35 ka before present (BP). Secondary modifiers of this sea surface temperature (SST) proxy in annually-banded corals such as diagenetic alteration of the skeleton and skeletal growth-rate are investigated. Extensive diagenetic investigations reveal that this fossil coral skeleton is pristine which is further supported by clear annual cycles in the coral Sr/Ca record. No significant correlation between annual growth rate and Sr/Ca is observed, suggesting that the Sr/Ca record is not affected by coral growth. Therefore, we conclude that the observed interannual Sr/Ca variability was influenced by ambient SST variability. Spectral analysis of the annual mean Sr/Ca record reveals a dominant frequency centred at 6–7 years that is not associated with changes of the annual growth rate. […]

本项研究揭示了源自南加勒比海博奈尔岛（Bonaire）化石珊瑚 Diploria strigosa 的 40 年月度 Sr/Ca 记录，该记录采用 U/Th 定年法测得，距今约 2.35 ka（公元前 2350 年）。对年轮珊瑚海水表面温度（SST）替代指标进行的研究涵盖了骨骼的成岩变化和骨骼生长速率等次级修饰因素。广泛的成岩调查揭示，该化石珊瑚骨骼原始状态良好，此结论得到珊瑚 Sr/Ca 记录中清晰年度周期的进一步证实。观察到年度生长速率与 Sr/Ca 之间不存在显著相关性，表明 Sr/Ca 记录未受珊瑚生长的影响。因此，我们得出结论，所观测到的年际 Sr/Ca 变异性受环境 SST 变异性影响。对年度平均 Sr/Ca 记录的频谱分析显示，主导频率集中在 6-7 年，这一频率与年度生长速率的变化无关。