关键词: 福建龙岩, 混合发育模式, 硫酸水作用, 龙石空洞, 碳酸水作用

Abstract: The Longkong Cave, including the underground river and dry passages decorated by the solutional features and carbonate speleothems, is one of the well known show caves in Southeastern China. It developes in the Lower Permian Qixia limestone with siliceous layers and concretions. The Qixia limestone is contacted by faults with Lower Permian Tongzhiyan sandstone and shale with coal mines, Wenbishan sandtone and shales and Devonian silicarenite and conglomerate rock. The surface valleys developed along the faults. The Qixia limestone was metamorphosed by the Late Yanshan granite intrusion. Topograpgically, The sandstone and shale with coal and the granite on the mountain and the Qixia limestone on the lower slope. The surface water and groundwater from the sandstone and shale with coal and othe noncarbonates terrains flows into or down to the limestone. A part of limestone has been exposed as the noncarbonate rocks,which have been removed away. The fissure spring water discharging from the Tongzhiyan formation is with pH values in the range from 3.78 to 4.73, 240 mg/l of SO_4 -2 anions; the water with pH of 6.78～7.25 and lower contents of Ca 2+ and HCO_3 - sources from other noncarbonate rock terrains. These exotic waters, expecially with sulphuric acid aqueous,strongly dissolve the limestone to form the Longkong cave system. The endogenetic water penetrates into soil covering on the limestone from the rainwater and dissolves the CO_2 produced by vegetation roots breath, organism decomposion and biofunction of soil fauna and mcrobe to form the carbonatic acid aqueous. When the water flows into the limestone,it dissolves the limestone to enlarge the fissures and passages. The Longkong Cave is the typical genetic model for cave development by the sulphuric and carbonatic acid aqueous from the exotic and endogenetic waters.

Key words: carbonatic acid solution, Fujiang Longyan, longkong cave, mixed karstic genesis model, sulphuric solution