黄土中蜗牛壳Mn^(2+)的EPR研究及其古气候意义  

An EPR Study on Mollusk Shells from Loess-Paleosol Sequences in the Loess Plateau, Central China

作　　者：盛雪芬[1] 陈骏[1] 季峻峰[1] 眭云霞[2] 

机构地区：[1]南京大学地球科学系表生地球化学研究所和成矿作用国家重点实验室,江苏南京210093 [2]南京大学现代分析中心,江苏南京210093

出　　处：《高校地质学报》2002年第1期40-45,共6页Geological Journal of China Universities

基　　金：国家重点基础研究发展规划项目 (G19990 434 0 0 ) ;国家杰出青年基金 (4 972 5 30 7)

摘　　要：对黄土高原陕西省洛川和甘肃省西峰剖面中黄土 -古土壤层中的蜗牛壳进行了EPR波谱分析 ,同时对洛川地区的现代蜗牛壳也进行了测定。结果显示 :(1)不同种类的蜗牛壳具有相近的EPR信号强度 ,表明不同种类的蜗牛对Mn2 + 的吸收没有差异性。 (2 )黄土层中蜗牛壳的EPR信号强度远大于古土壤中的 ,即黄土中蜗牛壳所含的Mn2 + 远大于古土壤中的蜗牛壳的Mn2 + 的含量 ,说明前者生活在比较还原的条件下 ,后者形成环境的氧化性较高。因此本文认为蜗牛壳中Mn2 + 的含量可反映其生长环境中Mn2 + 的含量和氧化还原条件 。Electron paramagnetic resonance (EPR) spectrum was induced to decipher the paleoclimatic change information in the mollusk shells from the Luochuan and Xifeng sections in the Loess Plateau, central China. The EPR analysis results showed the presence of trace amount of Mn 2+ in the mollusk shells carbonate and no obvious tribal discrepancy of the EPR spectrum intensities among different species of modern mollusks. The EPR intensities of the mollusk shells from the loess are significantly different from those in the paleosols. The EPR signals of Mn 2+ in the mollusk shells from the loess, which were formed under cold conditions, are stronger than those from the paleosols which were developed under warmer conditions. Therefore, the Mn 2+ content in the mollusk shells from the loess is higher than that from the paleosols. It is concluded that during the glacial period, mollusks lived in more reducing environment. On the contrary, during the interglacial period, the environment was more oxidizing. Thus the content of Mn 2+ in the mollusk shells reflects the redox conditions of the environment. The EPR signals of Mn 2+ in the mollusk shells from loess and paleosols provide a new approach to reveal important information of environment changes.

关 键 词：EPR波谱 蜗牛壳 黄土 氧化-还原条件 古气候 锰离子 

分 类 号：P642.131[天文地球—工程地质学] P532[天文地球—地质矿产勘探]