黄旗海岩芯烧失量分析与冰后期环境演变

重建闭流型湖泊的水位及环境变化,可以为研究冰后期及全新世以来的气候变化及季风环流演变提供不可或缺的关键信息。对HQH4岩芯烧失量与川蔓藻化石种子的研究结果显示,黄旗海湖区在全新世到来之前的气候寒冷,湖面冰封期较长,夏季温度较低,致使湖泊的有机生产率和自生碳酸盐产量比全新世低很多。黄旗海从全新世早期起进入了稳定的湖泊发展阶段后有机生产率显著上升,自生碳酸盐产量同步大幅度增长。在10 200~6 800 a BP期间,烧失量出现显著波动,很大程度上反映了气候发生暖湿-冷干-暖湿-冷湿的变化。在6 800~3 800 a BP期间,烧失量较高而且波动较小,反映了中全新世黄旗海以稳定的温暖湿润气候为主,湖水水位变化不大,有机质和碳酸盐生产力较高。从3 800 a BP起,气候逐渐变凉,间有多次冷暖干湿的剧烈变化,水位波动频繁。

Investigation on Loss-on-ignition of Lake Huangqihai Core and Post-glacial Environmental Evolution

Lake-level reconstruction for closed-basin lakes in China may provide key information for the study of Asian monsoon evolution in the Holocene.The authors investigate LOI and Ruppia macrofossil.The results indicate that Lake Huangqihai was in cold and arid climate conditions between 16~10.2 ka BP with ice cover for most of the year,which led to the organic and carbonate production much lower than that in the Holocene.An abrupt increase of seasonal inflow occurred at about 10.2 ka BP,as suggested by a layer rich in Ruppia seed,in situ dropped from the rooted aquatic plant,and by the well laminated lacustrine sediments.The data of LOI show that organic productivity increased markedly from the beginning of early Holocene.This,along with increased carbonate production,was most likely resulted from a substantial increase of summer temperature.In 10 200~6 800 a BP,distinct LOI fluctuation reflected the remarkable changes of climate and environment shifted from warm and dry,cold and wet,warm and wet,to cold and wet.In 6 800~3 800 a BP,the high and stable LOI value indicated a stable environment with warm and wet climate,high productivity of authigenic carobonate and organic matter.From circa 3 800 a BP,the lake level began to decline and the regional climate became cold.