含天青石、石膏白云岩混合溶蚀特征研究

Study on the Characteristics of Mixed Dissolution of Dolomitewith Celestine and Gypsum

以亚洲第一长白云岩洞穴——贵州省遵义市绥阳双河洞地区的白云岩为研究对象,根据白云岩中石膏(或硬石膏)的存在可加速白云石溶解的理论,考虑双河洞洞穴中同时存在天青石(SrSO 4)与石膏(CaSO 4)岩层,溶解后形成混合溶液,可能会加速白云岩的溶蚀。白云岩在自然条件下常混有杂质,为了实验的准确性,直接采用白云石进行实验。在静态条件下进行白云石在含天青石和石膏的不同含量溶液中混合溶蚀的模拟实验,研究在常温酸性和中性条件下,双河洞地区的地下水以及地表水对白云岩溶蚀过程的影响。结果表明,根据地下水以及地表水中Ca/Sr比例不同以及pH值的不同,在离子强度以及同离子效应的影响下,Ca/Sr比例直接影响白云石的溶蚀率,且生成的过多沉淀吸附在白云石的溶蚀孔隙中,会导致实验反应减缓。该研究为解释绥阳双河洞白云岩洞穴的成因具有一定的指导意义。

The Shuanghe cave,the first long dolomite cave in Asia,is the research theory.The dolomite in Shuanghe cave area is gypsum bearing dolomite.According to the theory that the existence of gypsum(or anhydrite)in dolomite can accelerate the dissolution of dolomite.At the same time,there is a mixed solution formed by celestine (SrSO 4)and dissolved gypsum(CaSO 4),which may accelerate the dissolution of dolomite.Under natural conditions,impurities are often mixed in dolomite,so in order to study accurately,dolomite is directly used in this experiment.In this paper,based on the different contents of the two substances in the groundwater and surface water of Shuanghedong,the simulation experiment of dolomite dissolution in the solution containing different contents of celestine and gypsum was carried out under the static condition.The influence of the groundwater and surface water on the dissolution process of dolomite in the area of Shuanghedong under the acidic and neutral conditions under the normal temperature was studied.The results show that according to the different ratio of Ca/Sr and pH value in groundwater and surface water,the ratio of Ca/Sr directly affects the dissolution rate of dolomite under the influence of ionic strength and the same ion effect,and the excessive precipitate adsorbed in the dissolution pore of dolomite will lead to the slowing down of experimental reaction.The study has certain significance for explaining the genesis of shuang he cave in Suiyang.