东北哈尼泥炭沉积物磁化率特征及古气候意义

东北哈尼泥炭沼泽位于长白山西麓和龙岗山脉中段,沉积连续,受人为干扰较小,记录了东北地区全新世以来的古气候、古环境演变信息。本研究采用AMS ¹⁴C测年技术建立了哈尼泥炭剖面年代学框架,并对泥炭柱心磁化率进行测定,分析其古气候意义,结合相关气候代用指标,重建了东北地区14 ka B.P.以来的古气候与环境演化历史。结果表明,哈尼泥炭磁化率总体偏低,说明在全新世的大部分时间内哈尼泥炭中的磁性矿物颗粒富集程度较低。哈尼泥炭磁化率记录了区域环境温度和湿度变化信息,较高的磁化率表明气候温暖湿润,较低的磁化率表明气候干燥寒冷。磁化率参数变化响应了全新世多次气候干冷事件,如0.4~0.6 ka B.P.(小冰期)、2.8 ka B.P.、4.3 ka B.P.和8.2 ka B.P.等气候突变事件。哈尼泥炭磁化率不仅反映了东北地区全新世以来的气候变化,而且呼应了全新世的多起气候突变事件。

Magnetic Susceptibility of Hani Peat Sediments in Northeast China and Its Paleoclimate Significance

The Hani peat bog is located in the western Changbaishan of Jilin province, Northeast China. The peat records paleoclimate and paleoenvironment change. The record is benefited from the continuous deposition, high deposition rate, and low anthropological influence. In this study, AMS ¹⁴C dating was used to determine the age of peat samples, and the magnetic susceptibility was measured to determine its paleoclimatic significance and reconstruct the paleoclimatic evolution since 14 ka B.P.. The results show that magnetic susceptibility of Hani peat is low overall, which indicates that the concentration of magnetic mineral particles in Hani peat is low during most of the Holocene.The magnetic susceptibility of Hani peat records the change of ambient temperature and humidity. Higher magnetic susceptibility indicates warm and humid climate, whereas lower magnetic susceptibility indicates dry and cold climate. The magnetic susceptibility responds strongly to many dry-cold climatic events during the Holocene, including the 0.4-0.6 ka B.P.event ( Little Ice Age), and the events at 2.8 ka B.P., 4.3 ka B.P. and 8.2 ka B.P. Thus, magnetic susceptibility of the Hani peat not only records the climate change since the Holocene, but also responds well to the global climate change.