Abstract This study presents the carbon isotopic record for terrestrial plant matter (δ13CTPM) in the Jinju Formation, Gyeongsang Basin, Korea, during the middle Albian. The measured δ13CTPM provides continuous high-resolution temporal variations for reconstructing climate change during the middle Albian, which has previously been poorly understood. We found that the δ13CTPM variation mostly exceeds the isotopic variation of the contemporaneous atmospheric CO2, indicating that the variation was primarily governed by climate change rather than atmospheric source. The δ13CTPM values corrected to modern atmospheric CO2 show cyclic fluctuations (−27.8‰ to −23.3‰), reflecting a temporal variation of water availability and/or a related taxonomic turnover of plant communities in the hinterland of Jinju Lake. Based on a transfer function for estimating mean annual rainfall (MAR) from the measured δ13CTPM values, the middle Albian climate of the basin was found to vary from sub-humid to humid conditions (MAR: 500–1500 mm). This variability suggests that Albian climate change at middle latitudes occurred more frequently than previously interpreted. The temporal increase in aridity observed in the basin (35–38°N) has not been detected in the isotopic records of the Cretaceous Hokkaido section (42–45°N) in Japan. This difference implies the possibility of a periodic northward shift or expansion of the northern hemisphere subtropical high pressure belt.

中文翻译：

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陆生植物碳同位素组成记录的中阿尔比斯气候波动

摘要 本研究展示了韩国庆尚盆地晋州组中阿尔布世时期陆地植物物质 (δ13CTPM) 的碳同位素记录。测量的 δ13CTPM 为重建阿尔比斯中部气候变化提供了连续的高分辨率时间变化，此前人们对此知之甚少。我们发现 δ13CTPM 的变化大多超过同期大气 CO2 的同位素变化，表明该变化主要受气候变化而不是大气源控制。经现代大气 CO2 校正的 δ13CTPM 值显示出周期性波动（-27.8‰ 至 -23.3‰），反映了金居湖腹地植物群落可用水量和/或相关分类周转的时间变化。基于从测量的 δ13CTPM 值估计年平均降雨量 (MAR) 的传递函数，发现流域的中阿尔比斯气候从半湿润到湿润条件（MAR：500-1500 毫米）不等。这种可变性表明，中纬度地区的阿尔比气候变化比以前解释的更频繁。在日本白垩纪北海道剖面 (42-45°N) 的同位素记录中没有检测到在盆地 (35-38°N) 观测到的干旱随时间的增加。这种差异意味着北半球副热带高压带有周期性北移或扩张的可能性。这种可变性表明，中纬度地区的阿尔比气候变化比以前解释的更频繁。在日本白垩纪北海道剖面 (42-45°N) 的同位素记录中没有检测到在盆地 (35-38°N) 观测到的干旱随时间的增加。这种差异意味着北半球副热带高压带有周期性北移或扩张的可能性。这种可变性表明中纬度的阿尔比气候变化发生的频率比以前解释的要高。在日本白垩纪北海道剖面 (42-45°N) 的同位素记录中没有检测到在盆地 (35-38°N) 观测到的干旱随时间的增加。这种差异意味着北半球副热带高压带有周期性北移或扩张的可能性。