摘要
根据92°经线上南北2个典型剖面的孢粉分析,结合剖面岩性特征和地层年代的测定,对库姆塔格沙漠第四纪环境进行探讨。结果表明：沙漠地层沉积特征不同,剖面孢粉种类、数量差异较大。南部ZH剖面长期受季节性洪水冲击而成,地层孢粉含量相对贫乏,只有21科属植物183粒孢粉,孢粉组成以藜科、禾本科为主,属典型的荒漠植被和草原荒漠植被类型;北部沙漠干湖盆剖面地层沉积包括了上游的冲积、洪积物和沙漠北部的风成相沉积物,地层剖面孢粉有39个科属植物孢粉1 767粒,孢粉以荒漠植被藜科占优势,并涵盖有莎草科、黑三棱属等湿生草甸类植物花粉。库姆塔格沙漠第四纪环境经历了干热、干湿交替到干旱的变化过程,代表干旱环境的藜科植物孢粉含量由南部的30.6%增至北部的50.5%,早期的ZH剖面曾出现过多次干湿交替的变化过程,表征干旱环境的麻黄属/蒿属比值在1.0%~2.0%之间变化,晚期的沙漠干湖盆剖面至少出现过一次干旱化过程,麻黄属/蒿属比值为1.80%。依次推断库姆塔格沙漠自第四纪以干旱环境为主,干旱化程度总体在加剧。
Kumtag Desert of Xinjiang,China,has complex topography,exposure strata recorded the evolution of history of desert climate,water and geographical environment.It is a blank area of ancient environmental studies.It is extremely important to extract profiles ancient environmental information for revealing the formation and evolution of Kumtag desert.The object of research is sected at the longitude line for 92°,which the ZH section lied in Haloxylon ammodendron gully in the south desert and the Basin section lied in the end of the gully in the north desert.On the basis of the pollen analysis of two sections in Kumtag desert,together with the lithology characteristics and determining of silt layer-age,the evolution of environment of the quatenary in Kumtag desert was discussed.The results showed that the sporo-pollen species composition and quantity of two sections had different due to the difference of sedimentary characteristics in desert strata.ZH section of southern desert was formed by seasonal floods from alluvial.The pollen content of ZH section was spareness relatively only with 21 species plants 183 pollen particle,dominated by poaceae plants and chenopodiaceae plants.It belonged to desert vegetation and steppe desert vegetation types and consistent with the existing vegetation types of southern desert.Meanwhile,the sediment of northern basin section included river alluvium and proluvial from the upper reaches and aeolian facies from the northern desert.The pollen species composition and quantity were abundance relatively with 1 767 pollen particle of 39 species plants,The pollen types of this section dominated by chenopodiaceae plants and included some sedge family and sparganium plants pollen and consistent with the existing vegetation types of northeast desert.There is changes process from dry-hot,alternation of drying and wetting to dry for environment of quanternary in Kumtag desert.Chenopodiaceae,as arid vegetation,the average pollen percent is increased from 30.6% in the south desert to 50.5% in the
出处
《干旱区地理》
CSCD
北大核心
2010年第3期346-352,共7页
Arid Land Geography
基金
甘肃省自然基金项目(№.0803RJZH087和0803RJZH086)
国家自然基金项目(№.40961013)
国家科技基础工作专项(№.2006FY110800)提供资助
