MICRO-SCALE WEATHERING CHARACTERISTICS AND WEATHERING DEPTH OF CLIFF SANDSTONE LOCATED AT THE THOUSAND-BUDDHA GROTTO,GUANGYUAN
To assess the impact of weathering in a warm and humid environment on the cliff sandstone of the Thou-sand-Buddha Grotto in Guangyuan,we collected sandstone core samples from the site.We conducted a range of an-alyses,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-po-rosity,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 per-centage 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 un-stable 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 5 cm.
万方数据
维普
