宁夏火石寨岩石岩性特征及其对丹霞地貌形成的影响

Lithologic characteristics in Huoshi Village,Ningxia Province and the influence on the formation of Danxia landform

宁夏火石寨丹霞地貌是西北地区发育最典型的丹霞景观之一,该地区岩石岩性特征的量化研究对分析西北干旱地区丹霞地貌成因具有重要意义。对岩石岩性标本进行干湿抗压、冻融后抗压、薄片鉴定、氧化物含量等分析测试,结果表明:雨水浸润和冻融作用会导致岩石抗压、抗风化能力降低;岩石岩性和结构构造的差异是导致丹霞岩层差异风化和崩塌的主要原因;水平凹槽中的砂岩和砾岩样品CaO含量高于陡崖的砾岩,CaO含量较高易导致溶蚀作用的发生,使抗压强度和抗风化能力下降,引发岩石的破碎和崩塌,是火石寨丹霞地貌一系列水平凹槽形成的影响因素之一。

The Danxia landform of Huoshi Village in Ningxia is one of the most typical Danxia landscapes developed in northwest China,and a quantitative study of the lithology characteristics of the rock in this area is of great significance in analyzing the causes of Danxia landform in the arid northwest region.After analyzing and testing the lithology samples of rocks,such as uniaxial compression strength of dry and saturated rocks,compressive resistance of freezing-thawing test,slice identification,and oxide content determination,it is found that,firstly,rainwater infiltration and freezing-thawing would reduce the compressive and weathering resistance of rocks.Secondly,the difference in lithology and structural structure of the rock is an important factor accouting for the differential weathering and collapse of the Danxia rock layer.Thirdly,the CaO content of sandstone and conglomerate samples in the horizontal groove is higher than that of the conglomerate of the steep cliff,and the higher CaO content is easy to lead to the occurrence of dissolution,which reduces the compressive strength and weathering resistance,causes the fragmentation and collapse of the rock,and is regarded as one of the influencing factors of a series of horizontal grooves in the Danxia landform of Huoshi Village.