贵州碳酸盐岩风化壳物源判别的新证据:石英颗粒形态、表面结构特征

利用扫描电镜分析了黔北、黔东、黔中4个剖面土样中的石英颗粒形态和表面特征,发现土样中的石英有3种类型:碳酸盐岩中的原生碎屑石英,呈次圆状或圆状,表面有被长时间、长距离水搬运的痕迹,无风成特征;燧石团块石英,具有新鲜的表面,呈不规则的尖棱状、次棱角状,表面基本无搬运痕迹;晶形较完整的次生石英,呈棱角状,晶形较完整,晶面有微生长晶体,无搬运特征。这些信息指示,3种石英均具有原位特征,前两种石英是直接对基岩的继承,第三种石英是风化壳剖面的次生产物,该结果为碳酸盐岩风化壳的物源及原位特征的确认提供了新证据。

NEW EVIDENCE TO CONSTRAIN THE ORIGIN OF WEATHERING CRUSTS OF CARBONATE ROCKS IN GUIZHOU PROVINCE: SHAPE AND SURFACE STRUCTURE CHARACTERISTICS OF QUARTZ GRAINS

Based on the study of SEM(scanning electron microscope) characteristics of quartz grains from four weathering crusts of carbonate rocks in northern and eastern and middle Guizhou Province,three kinds of quartz grains are distinguished:primary chipping quartz grains of carbonate rocks,sub-round and round in shape,with signs of being long-time and long-distance carried by water,but no sign of being wind;chert massive quartz grains on the fresh surfaces,angular and sub-angular in shape,no sign of being carried;crystal quartz grains with angular and sharp edges and better crystals have secondary micro-crystals on the surface with,no sign of being carried.The information indicates the three kinds of quartz grains all have the characteristics of carbonate bedrocks.The first and second kinds of quartz grains show inherited relationship among the carbonate bedrock insoluble residues.The third kind is the secondary quartz in red weathering crusts of carbonate rocks.This study provides new evidence to constrain the origin and inherited relationship of the weathering crusts of carbonate rocks in Guizhou Province.