汉江上游郧县庹家湾剖面光释光测年及意义

在野外考察基础上选择湖北郧县庹家湾剖面为研究对象。在对磁化率和粒度进行分析的同时，用单片再生剂量法进行了光释光测年（OSL）地层断代。OSL测年数据显示：剖面样品年龄处在55.11~13.57 ka BP，且与地层深度呈现出良好的对应关系，此剖面为黄土风化堆积形成。黏粒含量、黏粒/粉砂值以及磁化率值等气候替代性指标数值在马兰黄土层228~260 cm和294~370 cm深度明显高于典型马兰黄土（L₁），具有明显的成壤特征，通过OSL测年数据判断时间为27.26~21.59 ka BP，说明在晚更新世时期气候并非持续稳定的寒冷干旱，而是具有一定的波动，在此期间气候相对温暖湿润，而且此次气候事件在黄土高原地区其他沉积记录中也有良好记录。

OSL Dating of TJW Section in the Upper Hanjiang River Valley and Its Environmental Significance

On the basis of field investigations along the upper Hangjiang River valley, a typical loess-soil section was found at the Tuojiawan (TJW). Magnetic susceptibility and particle-size distribution were measured in laboratory. OSL ages were measured by using the quartz single aliquot regenerative-dose protocol. The OSL results show that the optical ages of these samples ranged in 55.11-13.57 ka BP, showing a good relation with the depth in the TJW profile. It indicated that the profile was formed by loess weathering and accumulation. The content of clay, clay/coarse silt ratio, magnetic susceptibility in 228-260 cm and 294-370 cm were higher than those in Malan loess. The weathering intensity of this depth was obviously higher than that of Malan loess, close to the palaeosol (S₀), belongs to the weak palaeosol (L₁-S₁ and L₁-S₂). The age range of L₁-S₁ and L₁-S₂ was 27.26-21.59 ka BP. The change of the indexes showed the climate and pedogenic environment changed since Pleistocene. It indicated there was a short time of warm and wet in the cold and arid glacial period (27.5-21.5 ka BP), and the southeast monsoon gradually intensified during the early Holocene periods with the strongest monsoon in the mid-Holocene.