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对青藏高原中南部纳木错长332cm的NMLC1孔湖芯研究发现,沉积物的介形类动物群计有6属15种。介形类属种生态特征和组合变化分析表明这些介形类对环境条件具有敏感性,其组合能够很好地反映过去环境变化的特征。结果表明,8.4ka以来具有三个不同的环境变化时期:早期在8400～6800 a BP,湖泊由浅向深发展,环境具有相对冷湿的特征;中期在6800～2500 a BP,湖泊深度逐渐加大,环境经历了暖湿—冷湿—冷干的变化,其中由冷湿向冷干的转化奠定了纳木错现今环境条件的基础;晚期在2500～0 a BP,湖泊深度继续增加,这个时期的较早阶段,继续保持了前一时期的冷干特点,但湖水盐度可能开始增加,较晚阶段的冷干化加剧,陆面流水的活跃性大大降低。研究发现,纳木错NMLC1钻孔介形类黑色壳体的高峰值与介形类的最大生产量相一致,并且与沉积水动力条件增强相适应,指示了这些黑壳的产生与介形类的大量繁殖处于同一阶段,并且主要为异地搬运为主。钻孔中出现大量Candona幼虫壳体,其原因可能与沉积环境的水动力条件迅速改变有关。
A study on the NMLC1 pore lake core 332 cm long in the Nam Co Wakou area in the central-southern Tibetan Plateau found that there are 6 genera and 15 species of sedimentary ostracods. The analysis of the ecological characteristics and assemblage changes of Ostracoda species shows that these Ostracoda species are sensitive to environmental conditions and their combination can well reflect the characteristics of past environmental changes. The results show that there are three different periods of environmental change since 8.4 ka: the early period is 8400-6800 a BP, the lake is developed from shallow to deep, and the environment is relatively cold and wet; in the middle period of 6800-2500 a BP, the lake depth gradually increases, The environment underwent warm-wet-cold-wet-cold-dry changes. The conversion from cold-wet to dry-cold laid the foundation for today’s environmental conditions in Nam Co. In the late period of 2500-0 a BP, the depth of the lake continued to increase, earlier in this period Stage, continue to maintain the cold and dry characteristics of the previous period, but the salinity of the lake may begin to increase, the more cold-dried later stage aggravate the activity of land surface greatly reduced. It is found that the peak value of the black shell of the NMMC1 borehole in Nam Co is consistent with the maximum output of the ostracod and is consistent with the enhanced hydrodynamic conditions of sedimentation, indicating that the generation of these black shells and the large Reproduction in the same stage, and mainly for handling different places. The large number of Candona larvae husks in the boreholes may be responsible for the rapidly changing hydrodynamic conditions in the sedimentary environment.