晚中更新世以来武威盆地沉积特征——基于wv3钻孔的释光年代学研究  

Sedimentary characteristics of Wuwei Basin since Late Mid-Pleistocene——Based on OSL chronological study of the wv3 core

作　　者：郭力菲 潘宝林[1] 王均平[1] 程馨琳 杨勇[2] 周锐[3] 刘秀英 蔡卓昀 GUO Lifei;PAN Baolin;WANG Junping;CHENG Xinlin;YANG Yong;ZHOU Rui;LIU Xiuying;CAI Zhuoyun(College of Resource Environment and Tourism,Capital Normal University,Beijing,100048;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing,100081;Institute of Earthquake Forecasting(IEF),China Earthquake Administration(CEA),Beijing,100036;Taishan University,Taian,Shandong,271000)

机构地区：[1]首都师范大学资源环境与旅游学院,释光断代实验室,北京100048 [2]中国地质科学院地质力学研究所,北京100081 [3]中国地震局地震预测研究所,北京100036 [4]泰山学院,山东泰安271000

出　　处：《地质论评》2024年第5期1689-1708,共20页Geological Review

基　　金：北京市教委科研计划一般项目(编号:KM200910028007);国家自然科学基金资助项目(编号:41301006)的成果。

摘　　要：青藏高原东北缘河西走廊形成了一系列新生代盆地,是研究盆地沉积演化的重要区域。武威盆地位于河西走廊东部,盆地内沉积了较厚的新生代冲洪积地层。为了厘清武威盆地晚中更新世以来的沉积演化历史,笔者等在武威盆地石羊河中—上游处钻取了长207 m的wv3钻孔岩芯,获得了上部17 m岩芯的19个钾长石两步法pIR200 IR290年龄和2个多步法MET-pIRIR年龄,结合粒度资料,重建了武威盆地石羊河流域中—下游晚中更新世以来的光释光年代学框架和沉积历史。结果表明:两步法pIR200 IR290和多步法MET-pIRIR年龄在误差范围内一致。220~128 ka时期,沉积速率最小,为0.35 mm/ka,水动力条件较强,以侵蚀为主;128~108 ka(MIS 5d、MIS 5e)时期沉积速率为1.94 mm/ka,沉积物粒径由粗变细,表明此时水动力条件由强变弱;末次冰盛期到全新世早期(19~9 ka)沉积速率为2.78 mm/ka,沉积物粒径较细,表明此时水动力条件较弱,沉积速率最大,沉积为主。该地区新构造运动比较活跃,在末次间冰期至末次冰盛期期间存在逆冲活动。该研究对于揭示晚中更新世以来祁连山东北部石羊河流域沉积演化特征具有重要意义。Objectives:A series of Cenozoic basins are formed in the Hexi Corridor in the northeast of Qilian Mountains.Clarifying the sedimentary history of these Cenozoic basins is of great significance for understanding the tectonic growth process and dynamic mechanism and the sedimentary evolution history of the Wuwei Basin since the late Middle Pleistocene in the northeast margin of Qinghai—Xizang(Tibetan)plateau.Methods:This paper takes investigated the wv3 borehole core in the middle—lower reaches of Shiyang River in the Wuwei Basin,in the eastern part of Hexi Corridor.The OSL dating and grain size testing were employed for reconstructing the chronological framework and the sedimentary characteristics of sediments at the top 17 m in wv3 borehole since late Middle Pleistocene.Results and Conclusions:The results of 19 two-step PIR200IR290s and 2 multi-step MET-pIRIR dating were obtained,and the OSL dating framework of sediments at the top 17 m in wv3 borehole since late Middle Pleistocene was established.The results show that the two-step pIR200IR290 and multi-step MET-pIRIR test ages are consistent within the margin of errors.During the period of 220~128 ka,the deposition rate was the lowest,0.35 mm/ka,and the hydrodynamic conditions were strong.During the 128~108 ka(MIS 5d,MIS 5e)period,the sedimentation rate was 1.94 mm/ka,and the sediment grain size changed from coarse to fine,indicating that the hydrodynamic conditions changed from strong to weak.From the last glacial maximum to the early Holocene(19~9 ka),the deposition rate was 2.78 mm/ka,and the sediment grain size was relatively fine,indicating that the hydrodynamic conditions were weak at this time and the deposition rate was maximum.The neotectonic movement is relatively active in this area,and there are thrusting activities during the last interglacial to the last glacial maximum.This study is of great significance for revealing the sedimentary characteristics of the Shiyang River Basin on north eastern Qilian Mountains since late Middle Pleistocene.

关 键 词：晚中更新世 武威盆地 石羊河 光释光测年 沉积演化 

分 类 号：P534.631[天文地球—第四纪地质学] P512.2[天文地球—古生物学与地层学] P597.3[天文地球—地质学]