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中文摘要：
盐类沉积韵律对研究湖泊环境及气候变迁有重要意义。对青藏高原秋里南木湖发现的芒硝、粘土和原生硼砂的韵律沉积进行了沉积速率和沉积韵律的分析。从物质来源、地貌和气候变化3个方面讨论了韵律形成的机制。在此基础上，利用矿物组成、年代、孢粉资料讨论了沉积物所反映的气候环境变化。结果表明，充足的物源和封闭的地貌环境是沉积韵律形成的物质条件，气候变化是主要外部动力。沉积韵律所反映的气候环境变化为：20．6—20．5kaBP无芒硝，植被发育，气候相对温暖湿润；20．5—11．4kaBP芒硝层很厚，植被类型过渡至以蒿为主的荒漠草原，气候干冷。其中，20．5—17．5kaBP气候极端干旱寒冷，17．5—17．1kaBP，15．9—15．2kaBP和14．1—13．4kaBP气温回升；11．4—10．1kaBP芒硝层很薄，植物种类丰富，气候显著变暖；10．1—7．5kaBP芒硝层厚度增加，木本植物花粉进一步降低，盘星藻消失，气候变冷；7．5—4．97kaBP芒硝层厚度减小，但厚薄不一，植被过渡到以蒿为主的典型草原，气候相对暖湿，但冷暖交替频繁，其中7．0—6．2kaBP蒿含量下降，湿生植物含量增加，气候冷湿，6．2—5．2kaBP耐干旱、盐碱植物增加，禾本科消失，湖水盐度增加，气候冷干。
英文摘要：
Lake sedimentary rhythm provides important information on the reconstruction of the palaeo-environment and palaeo-climate. This paper presents a rare kind of saline sedimentary rhythm composed of mirabilite, borax and clay. To identify the origin and the climatic significance of the rhythm, we used 14C and U series isotopes to get chronological data,analysed pollen compositions, studied chemistry of different water＇s and measured thicknesses of individual layers. Our study indicates that the sedimentary rhythm can be formed under the condition of enough source materials,closed morphological environment and climatic changes. During 20.6 - 20.5 ka BP. there was abundant vegetation and no mirabilite. The climate was warm and wet. Thick mirabilite layers and desert steppe suggest that from 20.5 to 11.4 ka BP the climate was dry-cold, and there were three warm pulses in 17.5 - 17.1 ka BP,15.9 - 15.2 ka BP and 14.1 - 13.4 ka BP. It became distinct warm during 11.4 - 10.1 ka BP when thin mirabilite layers and abundant vegetation were developed. From 10.1 to 7.5 ka BP, the cold climate was supported by thick mirabilite layers, decreased arboreal pollen and disappeared Pediastrum. During 7.5 -4.97 ka BP, the typical plain composed of Artemisia and the thin thickness of mirabilite layer suggest relatively wet-warm climate, and the variable thicknesses of mirabilite indicate an alternative climate from cold to warm. There was a wet-cold pulse during 7.0 - 6.2 ka BP for decreased Artemisia and increased hydrophyte. The absence of gramineous pollen and the increase in dry-salt vegetation proposes a cold-dry climate and the increased salinity of lake water from 6, 2 to 5.2 ka BP.
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Elemental composition in surface snow from the ultra-high elevation area of Mt. Qomolangma (Everest)
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