青海尕斯库勒盐湖沉积物孢粉组合特征与铀分布关系初探

Priliminary Study of the Relationship between Pollen Assemblages and Uranium Distribution in Gasikule Salt Lake’s Sediments,Qaidam Basin

以青海省柴达木盆地西部尕斯库勒盐湖干盐滩ZK06钻孔岩芯为研究对象,结合孢粉、年代学和铀含量数据,探讨了盐湖沉积物中铀分布与古气候变化的关系。研究表明,自280ka以来,尕斯库勒盐湖经历6次成盐期和6次淡化期;植被演化趋势为疏林草原—灌丛草原—荒漠草原;气候由凉略湿逐渐变为冷干。盐湖沉积物中铀含量与孢粉总浓度、灌木浓度、蒿属浓度呈明显正相关;与草本植物浓度呈正相关。孢粉带内沉积物的铀含量比成盐期高得多,平均铀含量为成盐期的3倍。孢粉组合特征可能为研究铀及其他元素在盐湖沉积物中的影响因素提供一些古植物和古气候条件证据。

The drill core of ZK06 in Gasikule Salt Lake,which was located at the southwest of the Qaidam Basin in Qinghai Province,was selected as the research object.Based on the pollen data,geochronology and uranium concentration in sediments,this paper discussed the relationship between uranium distribution and paleo environment. The results revealed that Gasikule Salt Lake undergo 6 times of saline deposition and 6 times of detrital deposit from 280ka.Paleo vegetation changed from veld to desert steppe,and the paleo climate changed from cool and mid wet to cold and dry. Uranium concentration in sediment was significantly correlated with total sporo pollen concentration, shrubs and artemisia. The uranium concentration in pollen zone was three times compare to saline deposits.Finally,the arid and cold climate both went against the uranium enrich in sediment, but the temperate and wet climate were adversely. Pollen assemblage characteristics maybe provide paleo vegetation and paleo climate evidences for uranium and others trace elements sediment in salt lake .