蜀南地区茅口组古岩溶地貌与缝洞系统发育关系研究

蜀南地区茅口组古岩溶地貌形态对缝洞系统的发育起着控制作用。在恢复茅口组古地貌的基础上,根据上二叠统在区域上的分布厚度、风化壳表面侵蚀特征和茅口组地层保存程度,将茅口组顶部古岩溶面划分为岩溶台地、岩溶坡地(又分为西部陡坡带和北东部缓坡带)和岩溶盆地3个二级地貌单元;研究了各地貌单元和缝洞系统发育关系。结果表明:岩溶台地岩溶水以垂向渗流为主,风化剥蚀强烈,形成垂向的溶缝、溶洞常被泥质等充填,横向连通性弱;岩溶陡坡、岩溶台地和岩溶陡坡过渡带岩溶作用最强,溶孔、溶洞发育,且充填程度低,缝洞系统最为发育,是有利的勘探区带;岩溶缓坡水流速度慢,岩溶作用周期长,溶蚀空间易受充填,不利于缝洞保存;岩溶盆地岩溶发育最弱,储集性能差,是不利的勘探区带。

Research on the relation between the ancient karst landform and the development features of fissure-cavity system in the Maokou formation in Shunan region

The ancient karst landform of the Maokou formation in Shunan region controls the facture-eavern system＇s development. According to the thickness distribution of the Maokou formation in the region, the surface erosion on weathering crust and sediment properties as well as the degree of preservation of the Maokou formation, the ancient karst landforms in the Maokou formation can be recognized as or divided into three 2nd grade landform units as karst platform, karst slope （further divided into the western steep slope and northeastern gentle slope belt） and karst basin. Then the relationship of geomorphic unit and the cave system is studied. The results show that. water in karst platform seeps mainly vertically, weathering is strong, vertical solution fissure and cave is often filled with clay~ the karstification is the strongest in the karst steep slope and the transition zone of karst steep slope to karst platform where pore and cave are devel- oped, filling rate is low, fissure-cavity system develops best, and is favorable for exploration~ the speed of water flow in karst gentle slope is slow, karst cycle is long and fissure-cavity system is easy to be filled, which does not conducive to fissure-cavity reservation; the erosional space in karst basin is less, and the res-ervoir performance is poor, which makes the area unfavorable for exploration.