依兰盆地始新世沉积碎屑约束的古气候演化

Eocene paleoclimate evolution constrained by sedimentary debris in Yilan Basin

为补充和印证其他气候代用指标揭示的东北地区始新世古气候的变化规律和变化细节,利用时频、时序分析以及降噪滤波等方法分析依兰始新世沉积碎屑组分中长石/石英和单晶石英/多晶石英的旋回性及细节特征揭示其气候变化过程。结果表明:依兰地区始新世存在暖湿、较暖湿、较干冷和干冷4种气候状态;伊普利斯期气候由初期的干冷逐渐变得暖湿,在卢泰特期开始达到始新世最暖湿的状态,卢泰特期晚期向干冷变化,到巴顿期早期达到最干冷状态,之后气候波动回暖;长石/石英和单晶石英/多晶石英所指示的结果与其他气候代用指标推断的变化趋势存在较好的一致性;长石/石英和单晶石英/多晶石英整体呈镜像关系,镜像程度越高,推断结果越同步,则推断结果越可信;其中长石/石英整体上对暖湿过程敏感,单晶石英/多晶石英对干冷过程敏感。

To complement and verify the Eocene paleoclimate patterns and regularities revealed by other climate proxies in NE China,the cyclicity and details of feldspar/quartz and monocrystalline quartz/polycrystalline quartz in the Eocene sedimentary debris of Yilan were analyzed by time-frequency,time-series analysis and noise reduction filtering to reveal their climate change processes.The results show that the Eocene climate in the Yilan region were warm-wet,relatively warm-wet,relatively dry-cold,and dry-cold.During the Eocene,the paleoclimate in the Ypresian stage gradually changed from initial dry-cold to warm-wet,which reached the most warm-wet pattern at the early Lutetian stage,then changed to dry-cold at the late Lutetian stage,and reached the most dry-cold state at the early Bartonian stage,after which the climate fluctuated and warmed up.The results indicated by feldspar/quartz and monocrystalline quartz/polycrystalline quartz are in good agreement with the trends inferred from other climate proxies.Feldspar/quartz and monocrystalline quartz/polycrystalline quartz have an overall mirror relationship,and the higher the mirror degree,the more synchronous the inferred results are,and the inferred results are more reliable.Feldspar/quartz is sensitive to warm-wet processes on the whole,while monocrystalline quartz/polycrystalline quartz is sensitive to dry-cold processes.