田洋玛珥湖中更新世以来磁化率特征及其环境意义

 对雷州半岛东南部的田洋玛珥湖TYC孔前40 m岩芯进行了研究，结果表明，磁化率与孢粉有很好的对应关系，因而磁化率值的高低变化能够作为该区气候环境变化的替代指标。沉积物磁化率与气候变化的关系为：磁化率的低值与气候暖湿对应；磁化率的高值则与气候寒冷或温凉相对应。中更新世以来，田洋玛珥湖气候环境演化经历了9个不同的阶段：346~301.4 kaBP，气候相对暖湿。301.4~248.8 kaBP，气候寒冷干燥。248.8~188.8 kaBP，气候相对暖湿。188.8~125.2 kaBP，气候寒冷干燥。125.2~69.3 kaBP，气候较为暖湿。69.3~40.43 kaBP，气候偏凉。40.43~25.5 kaBP，气候偏凉但较上阶段温度低，此时玛珥湖呈现出沼泽化过渡阶段。25.5~10.8 kaBP，气候寒冷干燥，玛珥湖干枯成为干玛珥湖。10.8 kaBP以来，由于后期人类活动对玛珥湖的改造，致使磁化率值不断升高。

Characteristics and Environmental Significance of Magnetic Susceptibility of the Tianyang Maar Lake since Middle Pleistocene

The Tianyang Maar Lake is situated in the southeastern Leizhou Peninsula,the transitional climate zone between tropical and subtropical region of China.In this paper,a study was carried out on the upper 40 meters of core TYC collected from the Tianyang Maar Lake.The results suggest that magnetic susceptibility(MS) correlates well with pollen records.Thus,variations of MS can be used as an indicator for climate and environmental changes in the Tianyang Maar Lake.Generally,a low MS indicates a warm and humid environmental condition,while a high MS suggests a cold or cool environment.Results of the MS analysis suggest that the environmental history of the Tianyang Maar lake area since the Middle Pleistocene can be divided into 9 stages: 346~301.4 ka BP,the climate was relatively warm and humid.301.4~248.8 ka BP,the climate became relatively cool and dry.248.8~188.8 ka BP,the climate was warm and humid.188.8~125.2 ka BP,it was cold and dry.125.2~69.3 ka BP,the climate was relatively warm and humid.69.3~40.43 ka BP,the climate was cool.40.43~25.5 ka BP,the climate was cool and the temperature was lower than the former stage,with a swamping transitional environment in Tianyang Maar Lake.25.5 ~ 10.8 ka BP,the climate got even colder and drier,the water of Tianyang Maar Lake almost dried up.During the last 10.8 ka BP,the existence of human activities has probably resulted in high MS values.