坝上高原安固里淖全新世沉积地球化学特征与环境变化

湖泊沉积物是记录过去气候变迁的自然档案，分析湖泊沉积物的地球化学特征可以恢复湖区的古环境。在安固里淖湖心区钻取一沉积剖面，并以1cm为间隔分样，测得剖面各段的化学元素组成。根据岩心化学元素组成的变化和元素比值指标的变化，结合岩心纹层年代，获得湖区全新世以来的环境变化信息： 8507～7543a BP气候略干冷,但向暖湿方向发展；7453～4617a BP以湿润气候为主，但是存在相对干旱的时段(5137～4617a BP);4617～574a BP以干冷气候为主，在4617a BP和2494～1924a BP期间出现强干冷气候突变事件；574a BP以来，前期气候向湿润方向发展，但是在383a BP以后又转为干旱。安固里淖湖区全新世的环境变化状况与我国北方同期的气候状况具有很好的可比性。

GEOCHEMICAI CHARACTERS AND ENVIRONMENTAL CHANGES OF HOLOCENE SEDIMENTS OF ANGULINAO LAKE IN BASHANG PLATEAU

Lacustrine sediments can record environmental changes,therefore analyzing their geochemical characters can reconstruct palaeoenvironment around lake basin. This paper makes in detail a geochemical analysis of lacustrine sediments from a core profile collected in the lacuster of Angulinao Lake, Bashang Plateau, North China. The environmental changes are confirmed by variations in concentrations of chemical elements such as Mg, Ca, Fe et al. and variations of Mg/Ca, Ca/K, Fe/Al et al.. combining with the varve chronology, Holocene environmental changes around Angulinao Lake can be speculated. In 8 507-7 453 a BP, the climate was a little dry and cold, but turned to warm and humid; In 7 453-4 617 a BP, the climate was warm and humid, but the short stage of arid existed(5 137-4 617 a BP); In 4 617-574 a BP, the climate was cold and dry, but the stronger cold and dry climates arose at 4 617a BP and in 1 924-2 494 a BP. Since 574 a BP, climate drived to humid in the earlier stage, but turned to dry since 383a BP. The climate changes around Angulinao Lake coincided with the other areas in North China at the same time.