WEATHERING CHARACTERISTICS AND DEVELOPMENT MECHANISM OF THE DETACHMENT PATTERN IN THE SANDSTONE HERITAGE,NANKAN GROTTO
The Nankan Grotto had undergone severe weathering over long geological timescales.To elucidate the deterioration mechanisms of sandstone in the Nankan Grotto,we collected rock samples for TESCAN integrated min-eral analysis,chemical composition analysis,clay mineral composition analysis,and scanning electron microscope test.The results showed that the micro-weathering behaviors of minerals in the upper and lower sandstone strata were the same,including the dissolution of calcite,the alteration of feldspar,the expansion of clay minerals,and the oxidation of biotite.The micro-weathering processes of these minerals were the internal mechanism of detach-ment pattern in the Nankan Grotto.The higher the contents of calcite,biotite,feldspar,and clay minerals,the more likely the rock is to develop disintegration and scaling patterns.On the contrary,blistering and fragmentation patterns are more likely to develop when these contents are lower.The blistering and fragmentation patterns mainly developed in the lower light yellow sandstone,while the disintegration and scaling patterns mainly developed in the upper gray sandstone.The different deterioration in the upper and lower strata can be attributed to the higher con-tents of clay minerals and biotite in the upper gray sandstone.Our research revealed the development mechanism of detachment pattern in the Nankan Grotto from the perspective of microscopic alteration of the minerals.The research results can provide theoretical reference for the conservation of Nankan Grotto.
万方数据
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