广元千佛崖石窟本体砂岩微观风化特征及风化深度研究  

MICRO-SCALE WEATHERING CHARACTERISTICS AND WEATHERING DEPTH OF CLIFF SANDSTONE LOCATED AT THE THOUSAND-BUDDHA GROTTO,GUANGYUAN

作　　者：施紫越 向芳[2,3] 郝嘉欣 赵希 谢振斌[5] 王剑平 SHI Ziyue;XIANG Fang;HAO Jiaxin;ZHAO Xi;XIE Zhenbin;WANG Jianping(College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;Center for Scientific and Technological Archaeology,Chengdu University of Technology,Chengdu 610059,China;Guangyuan Grottoes Research Institute,Guangyuan 628000,China;Sichuan Provincial Cultural Relics and Archaeology Research Institute,Chengdu 610041,China)

机构地区：[1]成都理工大学地球与行星科学学院,成都610059 [2]成都理工大学沉积地质研究院,成都610059 [3]成都理工大学科技考古研究中心,成都610059 [4]广元石窟研究所,广元628000 [5]四川省文物考古研究院,成都610041

出　　处：《工程地质学报》2024年第6期1973-1987,共15页Journal of Engineering Geology

基　　金：广元市科技计划项目(资助号:22ZDYF0002);四川省科技计划项目(资助号:2020YFS0391)。

摘　　要：为研究温暖潮湿环境下风化作用对广元千佛崖石窟本体的影响,以现场选取的石窟本体砂岩岩芯为对象,通过铸体薄片鉴定、粒度统计、磁化率测试、色度测试、以及黏土矿物测试,分析砂岩微观风化特征,讨论各项测试指标随深度的变化规律。研究表明:砂岩风化表层与基岩的颗粒含量、微观孔隙、磁化率和色度特征存在明显差异。越靠近本体砂岩表层,风化程度越高,石英、不稳定岩屑、黑云母的含量,以及磁化率、红度/黄度、明度值逐渐降低,粒间溶孔、铸模孔与缝的面积百分含量逐渐升高。砂岩风化表层发育的粒缘缝和裂缝,体现出温差造成了较为明显的物理破坏。此外,风化作用溶蚀的颗粒主要为不稳定岩屑和黑云母,同时造成了石英、自生石英等硅质成分的减少,并出现以伊利石和绿泥石为主的黏土矿物,表明风化作用形成于碱性孔隙水环境中。综合各项测试结果,石窟本体砂岩的风化深度应在5 cm以内。To assess the impact of weathering in a warm and humid environment on the cliff sandstone of the Thousand-Buddha Grotto in Guangyuan,we collected sandstone core samples from the site.We conducted a range of analyses,including cast thin section identification,grain size statistics,magnetization testing,chromaticity testing,and clay mineral testing,to examine the micro-scale weathering characteristics of the sandstone and to investigate how these indicators vary with depth.Our findings revealed notable distinctions in particle composition,micro-porosity,magnetization,and chromaticity between the weathered surface and the underlying bedrock of the sandstone.Proximity to the surface correlated with heightened weathering,evidenced by reductions in the content of quartz,unstable rock fragments,and biotite,as well as decreases in magnetization,a^(*),b^(*),and L^(*).Conversely,the percentage area content of intergranular dissolution pores,cast mold pores,and fissures exhibited gradual increments as approaching the surface.The presence of grain boundary fissures and cracks on the sandstone surface indicated substantial physical damage resulting from temperature variations.In addition,weathering predominantly erodes unstable rock fragments and biotite,leading to a decrease in silica components,including quartz and authigenic quartz.The prevalence of clay minerals such as illite and chlorite indicates that weathering occurred in an alkaline environment.The weathering depth of the grotto-hosting sandstone should be within 5cm.

关 键 词：千佛崖石窟 微观风化特征 风化深度 碱性风化条件 温差影响 

分 类 号：P585[天文地球—岩石学] TU458[天文地球—地质学]