断裂和不整合面对古岩溶的控制作用

Role of Fractures and Unconformities in Paleo-karst

在古岩溶的形成演化过程中,断裂和不整合面对它起着十分重要的控制作用。这两种构造并不相互独立,在构造比较活跃的地区,它们通常相互并存,对古岩溶的控制作用可相互叠加,而且互为促进。断裂带的非封闭性、构造应力以及热能等因素从不同的角度影响古岩溶的发育。断裂的非封闭性越强,大气淡水越畅通,对断裂带及其两侧的岩溶作用越强烈。在流体运移的过程中,断裂的垂向运移作用和不整合面的侧向运移作用相结合,使大气淡水、深部热液流体等在碳酸盐岩地层中形成环流体系,从而组成良好的岩溶系统,使岩溶分布具有垂向分带、侧向连片的特征。一般情况下,越靠近断裂或不整合面附近的区域,岩溶体系越发育,储层的孔隙度和渗透率越高。

karst is natural structure of carbonate rock aissolved by at- mospheric water near the earth surface,Structures play an im- portant role during formation and evolvement of karst.Not both faults and unconformable planes are entirely separated struc- tural systems from each other.Where there is an active tecton- ic movement,they always coexist and interact.During process of fluid migration,faults made the fluid move vertically and un- conformable planes led to it lateral.Combination of the both movements constitutes a circumfluent system of atmospheric water and deep thermal fluid in the carbonate rock layer,which forms a good karst system.The system is characterized by distribution as a belt in vertical and as a joined sheet in lateral as well.In general,the nearer to the area where faults and un- conformable planes exist it is,the more developed the karst system is,the higher the porosity and permeability of the res- ervoirs are.