水盐冻融条件下莫高窟砂砾岩晶相蚀变特征研究  

Study on the characteristics of crystal phase alteration of gravel from Mogao Grottoes in the brine solution under freeze-thaw conditions

作　　者：钱玲[1] 吴玉琪[1] 吕功煊[1] 陈港泉[2] QIAN Ling;WU Yuqi;LYU Gongxuan;CHEN Gangquan(State Key Laboratory for Oxo Synthesis and Selective Oxidation(Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences),Lanzhou 730000,China;Dunhuang Academy,Jiuquan 736200,China)

机构地区：[1]羰基合成与选择氧化国家重点实验室(中国科学院兰州化学物理研究所),甘肃兰州730000 [2]敦煌研究院,甘肃酒泉736200

出　　处：《文物保护与考古科学》2025年第1期110-121,共12页Sciences of Conservation and Archaeology

基　　金：国家自然科学基金重点项目(51732008)资助;甘肃省自然科学基金(20JR5RA565)资助。

摘　　要：盐害引起的硅酸盐质文化遗产劣化是文物保护工作面临的难题,尤其水盐侵蚀作用导致的砂砾岩蚀变行为与岩石微观结构变化之间的关系研究更是难点。通过对采集于莫高窟崖体的砂砾岩块进行矿物自动定量分析(TIMA)、X射线衍射(XRD)、X射线荧光(XRF)等表征,发现试验岩块在含盐水溶液中进行冻融循环后,岩块中的钠、钾长石类组分发生了向高岭石类物相蚀变的行为,同时伴随着岩块本身碎裂。离子盐溶和水环境引发的交代作用是水盐冻融循环过程中砂砾岩矿物组分发生蚀变的主要原因。方解石、白云石和绿泥石等矿物的蚀变表现为晶相溶蚀和重构,石英发生部分晶格畸变。这种砂砾岩矿物组分受外界环境变化引发自身晶相转变、重构的行为使岩体微观结构发生变化,导致崖体在力学性能上产生劣化,引发崖体裂隙扩大、失稳等,也是遗址基体底部掏蚀,坍塌的主要原因。The deterioration of silicate cultural heritage caused by the salt damage is a difficult problem for cultural heritage conservation.It is more difficult to study the relationship between rock alteration behavior due to brine solution erosion and rock microstructural change.Mineral automatic quantitative analysis(TIMA),X-ray diffraction(XRD)and X-ray fluorescence(XRF)spectrometry were carried out on sand and gravel blocks collected from the cliff of Mogao Grottoes.It was found that the sodium and potassium feldspar components in the tested rock block underwent phase alteration to kaolinite after the freeze-thaw cycle in the brine solution,with the rock block fractured.The ion exchange and substitution in brine solutions were the main causes of rock alteration in the process of freeze-thaw cycle.The alterations of calcite,dolomite and chlorite were manifested as phase dissolution and reconstruction,and quartz had partial lattice distortion.The mineral composition of conglomerate is transformed and reconstructed by the change of external environment.Moreover,the change of cliff microstructure leads to the deterioration of its mechanical properties,resulting in cliff instability and cracks,which are the main reasons for the bottom cutting and collapse of site base.

关 键 词：砂砾岩 晶相蚀变 水盐运移 盐害 石窟 

分 类 号：K878[历史地理—考古学及博物馆学]