Biomarkers in the rock outcrop of the Kazusa Group reveal palaeoenvironments of the Kuroshio region
Biomarkers in the rock outcrop of the Kazusa Group reveal palaeoenvironments of the Kuroshio region
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DOI：
10.1038/s43247-021-00154-2
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发表时间：
2020-09
影响因子：
7.9
通讯作者：
Hiroto Kajita;A. Maeda;M. Utsunomiya;T. Yoshimura;N. Ohkouchi;A. Suzuki;H. Kawahata
中科院分区：
文献类型：
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作者：
Hiroto Kajita;A. Maeda;M. Utsunomiya;T. Yoshimura;N. Ohkouchi;A. Suzuki;H. Kawahata
海洋和湖泊沉积物岩心中保存的长链烯烃和正构烷烃被广泛用于重建古环境。然而，由于有机生物标志物的成岩蚀变，将该技术应用于暴露的沉积岩序列相对具有挑战性。在这里，我们从日本中部Kazusa群的一个暴露的露头中提取了长链烯烃和正烷烃，这是世界上最连续的沉积序列之一，几乎覆盖了整个更新世。烷烃不饱和比和烷烃平均链长分别反映了冰期-间冰期海洋表面温度和陆地气候的变化。基于烯酮的110万至100万年前的海洋表面温度与基于有孔虫的Mg/ ca温度估计一致，可能反映了黑潮的入侵。我们认为，这些生物标记物在Kazusa群的保存表明了其提供详细的古环境记录的潜力。
Long-chain alkenones andn-alkanes preserved in marine and lake sediment cores are widely used to reconstruct palaeoenvironments. However, applying this technique to exposed sedimentary rock sequences is relatively challenging due to the potential for the diagenetic alteration of organic biomarkers. Here, we extract long-chain alkenones andn-alkanes from an exposed outcrop of the Kazusa Group in central Japan, one of the most continuous sedimentary successions in the world, covering almost the entire Pleistocene. We find that the alkenone unsaturation ratio and average chain length ofn-alkanes appears to reflect the glacial-interglacial changes in sea surface temperature and terrestrial climate, respectively. Alkenone-based sea surface temperatures between 1.1 and 1.0 million years ago concur with foraminiferal Mg/Ca-based temperature estimates and may reflect an intrusion of the Kuroshio Current. We suggest that the preservation of these biomarkers in the Kazusa Group demonstrates its potential to provide a detailed palaeoenvironmental record.