摘要
内蒙古黄旗海湖泊沉积物剖面层次结构清晰完整,通过对该剖面全样、77!m￣20"m和小于20#m三个不同粒级Rb、Sr含量和磁化率的系统测定,结果表明,湖泊沉积物中小于20$m粒级成分的Rb、Sr含量和Rb/Sr值变化阶段明显,Rb/Sr值与磁化率分布曲线十分吻合,因此,小于20%m粒级成分的Rb/Sr值与磁化率包含更加真实的古气候环境信息。Rb/Sr值反映了风化的强度,因而可以作为指示夏季风环流强度的代用指标。黄旗海湖泊沉积物的地球化学Rb、Sr元素含量和Rb/Sr值以及磁化率值波动特征具有深刻的环境演变背景,由此揭示的环境特征在一定程度上反映了全新世气候千百年尺度的波动变化,与全球气候波动有关。
The Huangqihai Lake, a small enclosed lake in Inner Mongolia of China, lies at the northern boundary of Eastern Asian Summer Monsoon and in the central part of Asian Winter Monsoon. Thus, its lacustrine sediment sensitively recorded the climate change of the above two monsoon systems. Based on the geochemical elements Rb and Sr of three different grain size fractions sediment from profile H3 on the northern lacustrine bottomland 13 m above the Huangqihai Lake surface in 1986, this paper investigates the record of palaeolake stand state, sedimentary environment evolution, and winter monsoon change. First, these samples are divided into three different grain size fractions, i.e., total sediments, 77-20 μm and 〈 20 μm. Second, the chemical elements, Rb and Sr of the grain size separation, are tested and analyzed systematically in this paper. Then these elements compositions of these samples are measured using VP-320 mode fluorescence spectrum instrument, respectively. The magnetic susceptibilities of these samples are measured using Kappabridge KLY-3 mode instrument made in Czech AGICO Company. The results showed the elements of Rb and Sr and the ratios of Rb/Sr vary regularly with the grain size. But the ratios of Rb/Sr in the sediments with 〈 20 μm correlate positively with the magnetic susceptibility of these samples. Therefore, the ratios of Rb/Sr in the fraction 〈 20 μm from the lake sediments reflect the weathering intensity in the deposition sites. It is a good indicator of the summer monsoon-induced weathering and pedogentic fluctuations and can be used to reconstruct the conditions of the paleoclimate and paleoenvironment.
出处
《地理学报》
EI
CSCD
北大核心
2006年第11期1208-1217,共10页
Acta Geographica Sinica
基金
国家自然科学基金项目(No.40401006)~~
关键词
内蒙古
黄旗海
全新世
不同粒级
湖泊沉积物
Rb/Sr比值
气候变化
Inner Mongolia
Huangqihai Lake
Holocene
different grain size fractions
lake sediment
ratio of Rb/Sr
climate change
