【摘要】 秦岭地区阶地黄土广泛分布,揭示着秦岭的环境演变过程;发源于秦岭的嘉陵江,上游阶地堆积黄土,其可靠的地层年代序列能够为嘉陵江上游古环境研究提供时间标尺。本文以嘉陵江上游灵官峡段一级阶地黄土剖面为研究对象,利用光释光单片再生剂量法测定等效剂量。由于大部分样品晒褪不彻底,因此以CW-OSL曲线拆分法分离出快速组分,最终确定等效剂量值,以此确定了嘉陵江上游灵官峡段一级阶地的形成时间在58.99 ka左右;并结合地层沉积特征和粒度分析,建立了自末次冰期以来嘉陵江上游灵官峡段气候演变的年代序列:底部黄土堆积于干冷的末次冰期(58.99～21.47 ka);21.47 ka以后直至2.42 ka,缺乏黄土沉积记录;古土壤发育于温暖湿润的晚全新世(2.42 ka～0.35 ka);0.35 ka以后气候转为干冷,再次堆积黄土。更多还原

【Abstract】 Loess is widely distributed on river terraces in Qinling Mountains, which reveals the climate changes of Qinling Mountains.The Jialing River is originated from Southern Qinling Mountains. There is loess accumulation on the upper stream terraces.The reliable stratigraphic chronology can provide time scale for researching palaeoenvironment process in the upper reaches of Jialing River.In this article,Lingguanxia(LGX)loess profile is taken as the research object which located on the first terrace of the upper reaches of Jialing River.Single-aliquot regenerative-dose(SAR) Optically Stimulated Luminescence(OSL) dating protocol is used to determine the equivalent dose in order to get the stratum age.Because most of the samples’ OSL signal are not completely faded before the last deposition,the equivalent dose value is determined by the fast components which are separated by CW-OSL raw curve splitting method.The formation time of the first terrace of LGX section is about 58.99 ka.Combining with the stratigraphic sedimentary characteristics and grain size analysis,the chronological sequence of climatic evolution in LGX section since the last glacial period has been established. Loess deposited at the bottom during the last dry-cold glacial period from 58.99 ka to 21.47 ka.After 21.47 ka until 2.42 ka,there was no loess saved; paleosoils developed in the warm and humid in the late Holocene between 2.42 ka and 0.35 ka;after 0.35 ka,the climate changed to dry and cold, and loess accumulated again.更多还原