砾石钙膜显微纹层定年方法及黄河黑山峡高阶地形成年代厘定

DATING METHOD OF CALICHE MICRO-LAMINATION AND DATING OF HIGH-TERRACES IN HEISHAXIA OF THE YELLOW RIVER

砾石钙膜是一种在干旱—半干旱环境中形成,反映环境和气候变化的沉积物,保留了比较完整的环境和气候信息,可用来分析古气候和测定形成年代.本文通过砾石钙膜的沉积原理讨论,认为钙膜中的显微明暗纹层变化反映了气候变化过程,其明暗度变化曲线可与其它测年方法(深海岩芯氧同位素曲线、黄土剖面粒度曲线、古地磁变化、构造事件等)作对比,得到其形成年代的信息.而砾石钙膜形成年代可代表所在地貌面的年龄.本文以此方法对黄河黑山峡高阶地的形成时代进行了厘定.

Caliche is the sediment which formed on surface of gravel in drought and semidrought environment and reflecting environment and climate change. It contains more integral environment and climate information, can be used to analyze palaeoclimate and dating the forming age. In this paper, it is considered that the shades of caliche microlamination record the process of climate change through the discussion of sedimental mechanism of the caliche, and it can be compaired with other dating methods, such as bathy-oxygen-isotope curve, loesspalaeosol sequence, loessgrain curve, palaeomagnetic curve and tectonic events etc., therefore its forming age can be determined. The age of the caliche represents the age of landform surface where the caliche locates on. By using this method the ages of the high terraces in Heishanxia, Yellow River, are redetermined.