Luminescence dating of the Yellow River terraces in the Hukou area, China

Abstract

In order to understand the evolution of the Yellow River, China, the chronology of the terraces along the river should be established. In this study, the terrace deposits including fluvial sediments and overlying loess from the Hukou area were dated using optically stimulated luminescence (OSL) techniques on coarse (or medium) and fine quartz grains. The medium-grained and fine-grained quartz OSL ages of the loess samples are statistically consistent, but this is not the case for the coarse-grained and fine-grained quartz fractions of two fluvial samples. The coarse-grained quartz OSL ages are believed to be more reliable for the fluvial samples compared to the fine-grained quartz ages. The dating results show that the ages of the strath terraces are >130ka for the TH terrace, 93.5±5.1ka for the T3-B terrace (above the Hukou Waterfall), 116.1±7.5ka for the T3-C terrace (below the Hukou Waterfall) and ∼75ka for the T2 terrace, respectively. Based on the heights of strath above the modern Yellow River level and the strath ages, the mean incision rates between different terrace levels were calculated to be 0.89mm/yr for the period between ∼95 and ∼75ka, 0.35mm/yr between ∼75 and ∼30ka, 0.31mm/yr between ∼30ka and present, respectively. The river incision rates may reflect the uplift rate of the Ordos block (or Ordos Plateau). The terrace formation was influenced by joint effect of tectonic uplift and climatic transition.