Abstract The Long-chain Diol Index (LDI) is a palaeotemperature proxy applied to marine sediments up to Miocene in age. Recent studies have revealed that the LDI-inferred temperature yields significant errors in waters >27 °C. This necessitates further assessment of the performance of the LDI proxy in high-temperature marine regimes. For this purpose, we collected 58 surface sediment samples from the tropical South China Sea (SCS), where annual sea surface temperature (SST) ranges from 24 °C to 29 °C. The original LDI calibration yields temperatures 4 °C) as SST increases. This ΔT, or mis-calibration, is significantly correlated with the measured SST as the temperature increases above 27 °C. This relationship also exists in sediment trap data. We therefore re-calibrated the LDI-inferred temperature to generate a new relationship that can be applied to environments with SST >27 °C, which is beyond the range of the original LDI proxy. Both the recalibrated LDI and, for comparison, archaeal lipid temperature proxies were applied in the high-temperature SCS; the improved correlation shows the LDI recalibration could be applied to palaeo-records from tropical oceans.

中文翻译：

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评估长链二醇 (LDI) 温度代理在高温南海的适用性

摘要 长链二醇指数 (LDI) 是一种古温度替代指标，适用于直到中新世的海洋沉积物。最近的研究表明，LDI 推断的温度在 >27 °C 的水域中会产生显着的误差。这需要进一步评估 LDI 代理在高温海洋环境中的性能。为此，我们从热带南海 (SCS) 收集了 58 个表层沉积物样本，那里的年海表温度 (SST) 范围为 24 °C 至 29 °C。随着 SST 的增加，原始 LDI 校准产生的温度为 4 °C)。当温度升高到 27 °C 以上时，该 ΔT 或错误校准与测量的 SST 显着相关。这种关系也存在于沉积物圈闭数据中。因此，我们重新校准了 LDI 推断温度以生成一种新关系，该关系可应用于 SST > 27 °C 的环境，这超出了原始 LDI 代理的范围。重新校准的 LDI 和作为比较的古菌脂质温度代理均应用于高温 SCS；改进的相关性表明 LDI 重新校准可以应用于热带海洋的古记录。