地质通报2025，Vol.44Issue(9)：1722-1735,14.DOI:10.12097/gbc.2024.05.054
世界地质公园粤北丹霞山地区河流阶地光释光测年及其气候演变
OSL dating of the river terraces and climatic evolution in the Danxiashan Global Geopark,Northern Guangdong,China
摘要
Abstract
[Objective]In the Danxia landform area,numerous river terraces have developed,yet research on them has been relatively limited,particularly concerning their dating.River terraces serve as valuable records of the incision processes of rivers and associated environmental changes.Investigating the chronostratigraphy of these terraces enhances our understanding of Danxia landform evolution,reconstructs river history,and explores responses to climate change.[Methods]In the Danxiashan area of northern Guangdong,the river terrace profiles of the Jinjing River and Lingxi River(intermountain streams)exhibit sedimentary characteristics of a river"dual structure".[Results]Optically stimulated luminescence(OSL)dating reveals deposition ages for the T0 floodplain,T1 and T2 terraces of Jinjing River,as well as the T1 terrace of Lingxi River,at 0.4±0.1 ka,70.1±6.1 ka,300.6±14.7 ka,and 18.3±3.2 ka,respectively.The sedimentation periods for the T1 and T2 terraces of Jinjing River align with transition phases of deep-sea oxygen isotope stages 5 to 4(MIS5-MIS4)and 9 to 8(MIS9-MIS8),respectively.This suggests that during the shift from warmer to cooler periods,the sediment flux of the Jinjing River exceeded its transport capacity,resulting in ongoing terrace deposition.Subsequent climatic shifts led to valley incision,forming terraces from earlier floodplain deposits and the underlying broad valley surface.The T1 terrace of Lingxi River emerged during MIS2,during which the intermountain stream carried a significant amount of sediment.By analyzing the relationship between the gravel layers of the terraces,their heights,and their ages,we estimated the minimum incision rates for the Jinjing River during two periods:300 ka to 70 ka and 70 ka to the present,at 0.05±0.002 mm/a and 0.22±0.02 mm/a,respectively.[Conclusions]The notable increase in incision rate may be attributed to three primary factors:first,the alternation between river erosion and sediment accumulation,leading to a generally low long-term average incision rate;second,the rate of river cutting through alluvial deposits surpassing that through bedrock;and third,the increased climate variability since the last glacial period,which has amplified river erosion rates.These incision rate data provide crucial insights for reconstructing the evolution of Danxia landforms.关键词
丹霞山/河流阶地/光释光/锦江/下切速率Key words
Danxiashan/river terraces/OSL dating/Jinjiang River/incision rates分类
天文与地球科学引用本文复制引用
罗明,郭福生,龚志军,陈留勤,周万蓬,彭花明,蒋晓鸿..世界地质公园粤北丹霞山地区河流阶地光释光测年及其气候演变[J].地质通报,2025,44(9):1722-1735,14.基金项目
广东国家公园建设专项资金项目《丹霞盆地地质条件对丹霞地貌形成的制约》(编号:2021GJGY026)、东华理工大学科研发展基金项目《丹霞山地貌与断裂遥感解译》(编号:FZJJ20231220)和中央专项彩票公益金支持未成年人校外教育教育项目《地震灾害科学研究与科学普及项目》(编号:G20200002) Special fund project for the construction of Guangdong National Park(No.2021GJGY026)and Scientific research development fund projects of East China University of Technology(No.FZJJ20231220)and Scientific research and popularization of earthquake disasters(No.G20200002) （编号:2021GJGY026）
