近2600年来内蒙古居延海湖泊沉积物的色素含量及环境意义

Sedimentary Pigment and Its Environmental Signification of East Juyanhai in Inner Mongolia since the Past 2600 Years

通过分析东居延海S1探坑剖面色素含量 ,结合碳酸盐、介形类化石、腐殖酸、磁化率及化学元素等多环境指标分析结果 ,探讨该区近 2 6 0 0年来环境气候波动特点。研究区气候变化大致经历几个阶段 :温暖湿润(2 6 5 0～ 2 5 6 0aB .P .)→湖泊菱缩 ,气候偏干暖 (2 5 6 0～ 2 36 0aB .P .)→暖湿气候背景下湖泊的扩张 (2 36 0～2 1 2 0aB .P .)→冷湿向冷干转换 ,湖泊由大湖开始菱缩 (2 1 2 0～ 1 6 0 0aB .P .)→气候暖湿 ,湖泊再次扩张 ,(1 6 0 0～ 6 5 0aB .P .)→湖泊由扩张到菱缩 ,气候由冷湿向暖干变化 (6 5 0aB .P .—至今 )。同时尝试把色素与其它指标的结合作为指示湖泊古初始生产力的有效性 。

Organic carbon content in lake sediment is often used to indicate the lake paleoprimary productivity.The main sources of organic carbon include autochthonous lake organism and allochthonous terrestrial plant,and there is complex degradation after deposition.Therefore the total organic carbon in lake sediments only can offer rough information about lake paleoprimary productivity. Compared with organic carbon, pigments are more table and have close relationship with lake temperature,water depth,salinity,trophic status.Recently pigments are used as an effective environment index in the study of lake environmental evolution. According to the contents and assemblages of pigments and other environmental multiproxy from the sediments core of S 1 Core in East Juyanhai in Inner Mongolia, this paper mainly deals with the climatic and environmental changes during the past 2 600 years of this area.The characteristics of climate assemblages have the feature with the process of warm wet(2 540～2 650 aB.P.)→lake shrink, warm dry (2 360～2 540 aB.P.)→warm wet,lake expand(2 150～2 360 aB.P.)→cold wet to cold dry,lake shrink(1 630～2 150 aB.P.)→warm wet,lake expand(600～1 630 aB.P.)→cold wet to warm dry(600 aB.P.～present).In the meantime, the authors also try to contribute the pigment and other environmental index to evaluate the paleoprimary productivity,and to distinguish the human activities in lake records.The natural climate change played an important role in the process of environmental evolution in the area of Juyanhai Lake during the past 2 600 years, and human activities affected the lake environment greatly only in a special period.