摘要
本文利用采自中国南方地区重庆市金佛洞的一支长228 mm石笋J119,通过9个高精度^230Th测年数据和3241个灰度值数据,建立了该洞穴方解石石笋全新世灰度序列,并结合相邻地区黑风洞的石笋灰度数据,研究分析发现:石笋灰度高值对应于石笋表面颜色偏浅部分,杂质含量多,为不纯的方解石,透光性差;石笋灰度低值对应于石笋表面颜色较深部分,为致密且纯净的方解石,属石笋透明层段.石笋J119灰度值序列与其δ13C序列存在着相似的变化趋势,显示它们响应相同的驱动因素,主要反映的是洞穴上方土壤植被和水岩作用情况,间接反映当地季风降水和温度变化.黑风洞与金佛洞石笋灰度记录对比显示,石笋灰度在轨道时间尺度上存在着不同的变化趋势,但是对千年尺度气候突变事件具有相似响应,表明石笋灰度指示的是短时间、区域性的气候环境信息.
In order to make up for the deficiency of theδ^18O index of stalagmite,the research on multiple climate indexes of stalagmite has become a trend.Subsequently,stalagmite grayscale is attracting more and more attention from paleoclimatologists because of its convenient data acquisition and high resolution.However,the climatic environment significance of stalagmite grayscale is still on discuss.Therefore,based on precise 9^230Th data and 3241 grayscale values of the stalagmite J119 from Jinfo cave(28°50'~29°20'N,107°0'~107°20'E)in Chongqing,China,this paper establishes the grayscale sequence of calcite stalagmites during the Holocene in Southern China to discuss about the significance of climate indicated by grayscale values of stalagmite.The stalagmite J119 is 228 mm in length and the sedimentary period of the whole stalagmite is 9.6~1.6 ka B.P.The stalagmite profile was drilled with a 1 mm diameter dental drill parallel to the growth layer for dating.We polished the stalagmite profile and scrubbed it with alcohol and ultrapure water.After scanning the profile under the condition of darkness,we captured the image near the growth axis without holes and cracks.Finally,we used ImageJ software to extract its RGB values,and yielded 3241 grayscale values through calculation by formula.Through a series of analysis,we find that the peak of grayscale value indicates that the color of stalagmite surface is lighter and impure calcite is deposited.In contrast,the bottom value of grayscale corresponds to the stalagmite with darker color and pure calcite deposits.Besides,the grayscale andδ13C sequences of stalagmite J119 have similar trends,indicating that they respond to the same driving factors.Therefore,stalagmite grayscale mainly reflects the soil vegetation,biomass and water-rock interaction above the cave,and implies the local monsoon precipitation and temperature changes indirectly.In comparison of the stalagmite grayscale sequences from Heifeng cave and Jinfo cave,we infer that stalagmite grayscale has different re
作者
张日萍
杨勋林
张瑞
鄢应燃
刘睿恺
Zhang Riping;Yang Xunlin;Zhang Rui;Yan Yingran;Liu Ruikai(Chongqing Key Laboratory of Karst Environment,School of Geographical Sciences,Southwest University,Chongqing 400715;Field Scientific Observation&Research Base of Karst Eco-Environments at Nanchuan in Chongqing,Ministry of Natural Resources of the People's Republic of China,Chongqing 408435)
出处
《第四纪研究》
CAS
CSCD
北大核心
2020年第4期936-944,共9页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:41971109和41572158)
国家重点基础研究发展计划项目(批准号:2016YFC0502301)共同资助。
关键词
石笋
灰度
气候意义
千年尺度
金佛洞
stalagmite
gray scale
climatic significance
millennium scale
Jinfo Cave
