对商丹盆地茶房村剖面210个样品进行了野外调查及粒度实验分析。结果表明:丹江一级阶地上的沉积物是55 000 a BP以来堆积的风成黄土;粒度特征主要以粉砂和粘粒为主,二者总和为86. 65%,其中粗粉砂为优势组分,在剖面中含量达46. 81%;粘粒含量为23. 94%;古土壤层的粒度组成较黄土层偏细,显示了二者风化成壤作用的差异,即古土壤层风化程度强于黄土层;茶房村剖面粒度特征的变化反映了商丹盆地自55 000 a BP以来区域气候的变化特征: 55 000 ~ 11 500 a BP时期气候寒冷干燥。全新世早期(11 500 ~ 8 500 a BP),气温有升高,降水增加。全新世中期(8 500 ~ 3 100 a BP),为大暖期,气候温暖湿润。全新世晚期(3 100 a BP至今),气温降低,降水减少。
英文摘要:
Loess-paleosol sequences have been applied to retrieve palaeoenvironment change in the study of the paleoclimatic evolution. Chafangcun(CFC)at Shangdan basin,Shaanxi provides such a loess-paleosol profile. At this profile,loess sequence's color and structure were investigated,and 210 samples were systematically collected for grain-size analysis. The results showed that: ① Chafangcun loess-paleosol sequence in the first river terrace with typical atmospheric dust sediment along the Danjiang River, has formed since 55 000 a BP. ② This loess sequence is mainly composed of silt(5 ~ 50 mum)and clay($ < 5;{