细粒松散沉积地层中垂直循环带岩溶划分

A STUDY ON KARST IN VERTICAL CIRCULATION ZONES IN FINE AND LOOSE SEDIMENTS

根据细粒松散沉积中ＣａＣＯ３含量及ｐＨ值测定资料所指示的岩溶作用差异，将前人确定的垂直循环带划分为３个亚带。第一亚带为上部的非饱和循环强溶蚀带，第二亚带为中部的过饱和循环沉淀带，第三亚带为下部的不稳定循环弱溶蚀－弱沉淀带。这３个亚带对ＣＯ２在垂向上的循环有重要指示作用。第一亚带底界是来自大气降水及土壤中ＣＯ２对岩溶作用强烈影响的下界，第二亚带指示到达该带的岩溶水的ＣＯ２基本消耗完毕。

On the basis of the difference of the karst processes showed by CaCO 3 and pH values determined in fine and loose sediments,the circulation zone ascertained by predecessors can be divided into three subzones, that is, the upper first subzone, characterised by unsaturated water solution and strong dissolution processes, the middle second subzone, characterised by supersaturated water solution and sedimentation, and the lower third subzone, characterised by unstable water solution and weak sedimentation or weak dissolution.The subzones can indicate the vertical CO 2 cycle. The bottom of the first subzone is the lowerlimit strongly influenced by CO 2 from rainfall and soil. In the second subzone, the CO 2 in karst water is almost exhausted.And the third subzone shows that if karst processes under the subzone take place, there should be other CO 2 sources besides the vertical cycle CO 2.