河流阶地是研究河流演化、构造运动的良好载体,虽然北京地区第四纪地质研究程度较高,但北京东部地区对河流阶地的相关研究资料较少.笔者等以北京平谷燕山山前发育的泃河、黄松峪石河、将军关石河为研究对象,通过野外地质调查、光释光测年技术(OSL)详细划分了上述河流阶地的发育序列,在此基础上讨论了部分河流阶地的形成时代、阶地成因及河流阶地对燕山隆升的响应等地质问题,认为泃河南岸发育有3级阶地,北岸发育2级阶地;黄松峪石河最多发育有6级阶地;将军关石河发育有5级阶地.将军关石河至晚形成于中更新世晚期(161.7±7.7 ka BP),黄松峪石河至晚形成于晚更新世早期(121.2±5.4～100.3±4.1 ka BP),泃河至晚形成于晚更新世中期(79.4±3.3～70.8±3.4 ka BP).泃河、黄松峪石河、将军关石河各级阶地的形成受到了古气候变化和燕山隆升的双重影响,平谷地区燕山在中更新世晚期以来,一直处于隆升的状态,晚更新世早期时隆升速率达到最大,可达0.24～0.34 mm/a,晚更新世中期时隆升速率降低,0.18～0.24 mm/a.以上成果对研究北京东部河流阶地发育特征、形成时代具有重要参考价值,也为中更新世晚期以来燕山的隆升提供了新的证据.
Development sequence,formation age and geological significance of Piedmont River terrace in Pinggu,Beijing
Objectives:River terrace is good carrier for the study of river evolution and tectonic movement.Although the Quaternary geology in Beijing area is highly studied,there are few relevant research data on river terrace in the east of Beijing.In this paper,the Juhe River,Huangsongyushi River and Jiangjunguanshi River developed in front of Yanshan Mountains,are taken as the research objects in Pinggu area,Beijing.Methods:The development sequence of the above-mentioned river terraces is divided in detail.On this basis,the formation times,terrace genesis and the response of river terraces to the uplift of the Yanshan Mountains are discussed by field geological survey and opto-luminescence dating (OSL).Results:It is considered that the Juhe River developed three terraces on the south bank and developed two terraces on the north bank.The Huangsongyushi River developed 6 terraces.The Jiangjunguanshi River developed 5 terraces.The Jiangjunguanshi River was formed no later than the late Middle Pleistocene (161.7±7.7 ka BP) and the Huangsongyushi River was formed no later than the early Late Pleistocene (121.2±5.4 ka BP～100.3±4.1 ka BP).The Juhe River was formed no later than the middle of the Late Pleistocene (79.4±3.3 ka BP～70.8±3.4 ka BP).The formation of the terraces of the Juhe River,Huangsongyu River and Junjiangguanshi River is influenced by paleoclimate change and the Yanshan Mountains uplift.The Yanshan Mountains in Pinggu area has been in a state of uplift since the late Middle Pleistocene,and the uplift rate reached the maximum in the early Late Pleistocene,up to 0.24 mm/a～0.34 mm/a,and decreased in the middle of the Late Pleistocene,to 0.18 mm/a～0.24 mm/a.Conclusions:The above results have important reference value for the study of the development characteristics and formation times of river terraces in eastern Beijing,and also provide new evidences for the uplift of the Yanshan Mountains since the late Middle Pleistocene.
万方数据
维普
