中国东北依兰盆地始新世气候演化及湿度降低对冷却事件的指示

Paleoclimate evolution during Eocene in Yilan Basin,NE China and its indication of humidity reduction on cooling event

利用时频时序分析对依兰盆地始新世连续沉积物的烧失量数据进行旋回划分,再利用皮尔逊相关分析、降噪滤波和统计学方法分析有机质和碳酸盐的含量特征和变化规律。在依兰盆地始新世中识别出湿热、半湿较热、半干较热、干冷、半干较冷和半湿较冷6种气候状态。认为其温度湿度的中长期变化趋势是先升高,在巴顿阶末期温度湿度达到整个始新世最高,之后逐渐降低,在晚始新世早期达到最低,之后回升,又小幅下降。在短期气候变化过程中,温度湿度从同步平衡态向下一个同步平衡态过渡的过程中,温度保持不变,湿度持续下降,是冷却即将出现的重要标志。依兰盆地始新世中长期温度变化与东北地区一致,滞后于深海同位素揭示的温度变化。

The time-frequency and time series analysis were used for the cycle division of the original loss of ignition(LOI)data obtained from the Eocene continous sediments within the Yilan Basin,NE China.The dynamic characteristics of the organic and carbonate contents indicated by these LOI data were then analyzed using the Pearson correlation analysis,noise reduction filtering and statistical methods.Six climate types were identified:humid and hot,semi-humid and hot,semi-dry and hot,dry-cold,semi-dry and cold,and semi-humid and cold.As for the temperature and humidity changes during the mid-long term climate cycle,both factors firstly increased to the highest of the entire Eocene at the end of the Early Eocene,then gradually decreased to the lowest in the early of the Late Eocene,and laterly rebounded and decreased slightly.During the short-term climate cycle of the temperature and humidity transition,the authors found the temperature remained unchanged while the humidity decreased continually during the changes from an early synchronous equilibrium state to an adjacent late state.This is an important mark to find whether the climate is about to turn cold.The comparisons with other researches show that,the mid-long term temperature changes in the Eocene of Yilan Basin were consistent with other regions in Northeast China,but lagged behind the temperature changes revealed by the deep-sea isotopes.