江西峨嵋洞石笋微层特征及其形成机制  

CHARACTERISTICS AND FORMATION MECHANISM OF STALAGMITE LAMINAE IN E’MEI CAVE,JIANGXI PROVINCE,CHINA

作　　者：张海伟 包艳艳[1] 张瑞 孟秉霖[1] 蔡演军 程海[1,2,3] ZHANG Haiwei;BAO Yanyan;ZHANG Rui;MENG Binglin;CAI Yanjun;CHENG Hai(Institute of Global Environmental Change,Xi'an Jiaotong University,Xi'an 710049,Shaanxi;Key Laboratory of Karst Dynamics,Ministry of Natural Resources&Guangxi,Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin 541004,Guangxi;State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi'an 710061,Shaanxi)

机构地区：[1]西安交通大学全球环境变化研究院,陕西西安710049 [2]中国地质科学院岩溶地质研究所,自然资源部/广西岩溶动力学重点实验室,广西桂林541004 [3]中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,陕西西安710061

出　　处：《第四纪研究》2022年第4期1148-1158,共11页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41888101、41972186、41731174和41502166);中国地质科学院岩溶地质研究所自然资源部/广西岩溶动力学重点实验室开放基金项目(批准号:KDL201502)共同资助。

摘　　要：生长快速、具有年纹层的洞穴石笋是研究过去季节-年际尺度气候变化的重要地质载体之一。本研究对江西峨嵋洞长度为60 mm的现代石笋EM1进行微层分析、高分辨率的氧、碳同位素测试分析,研究了石笋微层特征及其形成机制。研究表明峨嵋洞石笋微层具有典型的“南方型”微层特征:肉眼可见的暗褐色致密亚层,在透射光下为透光层,在紫外光下为不发光层;肉眼可见的乳白色疏松亚层,在透射光下为不透光层,在紫外光下为发荧光层。暗褐色致密亚层的方解石δ^(18)O值由年内最小变为最大而δ^(13)C值为年内偏正峰值,乳白色疏松亚层的方解石δ^(18)O值由年内最大变为最小而δ^(13)C值为年内偏负峰值。月-季节分辨率的δ^(18)O和δ^(13)C记录为反相关关系,δ^(18)O滞后于δ^(13)C变化约3~4个月。研究认为峨嵋洞石笋微层的形成可能主要与春季-早夏较多降水和有机质淋滤(形成乳白色疏松亚层)以及盛夏高温干旱(形成暗褐色致密亚层)的配置有关。部分乳白色疏松亚层内还发育有极细的荧光层,被证实为年内层(伪年层),其成因很可能与春季至早夏多次强降水造成的数次有机质脉冲沉积有关。The fast-growing stalagmite with annual laminae is one of the important geological carriers for the study of past seasonal-interannual climate changes.In this paper,the laminae analysis and high-resolution oxygen and carbon isotope analysis of a modern stalagmite EM1(ca.60 mm length)in E'mei cave(29°33'18″N,115°29'44″E;53 m a.s.l.),Jiangxi Province were carried out,and the characteristics of the stalagmite laminae and its formation mechanism were studied.Uranium series dating and stable isotope analysis were carried out,and mineral and laminar features were observed and photographed under transmitted light and UV light using Zeiss polarizing microscope at Isotope laboratory,Xi'an Jiaotong University,respectively.Scanning and laminar counts of stalagmite EM1 were performed using confocal laser fluorescence microscopy(CLFM)at state key laboratory for manufacturing system engineering,Xi'an Jiaotong University.The^(230) Th dates,laminar counts andδ^(18)O circles of EM1 are consistent within the error,which confirms that the laminae is an annual layer,with a grow period of 1810~2009 A.D.,a total of 200 years.Studies have shown that the E'mei cave stalagmite laminae has the typical characteristics of“southern China type”stalagmite laminae:a dark dense sublayer visible to the naked eye,corresponding to a transparent sublayer under transmitted light and a non-luminescent sublayer under fluorescence;a milky white loose sublayer visible to the naked eye,corresponding to an opaque sublayer under transmitted light and a luminescent sublayer under fluorescent light.The calcite δ^(18)O value of the dark dense sublayer changed from the minimum to the maximum during the year,while the δ^(13)C value was a positive peak value during the year.The calcite δ^(18)O value in the milky white loose sublayer changed from the maximum to the minimum during the year,while the δ^(13)C value was at a negative peak during the year.Monthly-seasonal resolution δ^(18)O and δ^(13)C records were inversely correlated,with δ^(18)O la

关 键 词：石笋 年纹层 伪年层 季节分辨率 碳、氧稳定同位素 

分 类 号：P597.2[天文地球—地球化学] P534.63[天文地球—地质学] P532