岩溶作用季节性变化对洞穴沉积物沉积速率的影响研究——以重庆雪玉洞地下河系统为例  

Impact of Seasonal Karstfication on the Precipitation Rate of Cave Sediments:A Case Study of the Underground River System of the Xueyu Cave,Chongqing

作　　者：徐尚全[1] 殷建军[1] 王晓晓[1] 杨平恒[1] 毛海红[1] 沈立成[1] 

机构地区：[1]西南大学地理科学学院,三峡库区生态环境教育部重点实验室,重庆400715

出　　处：《热带地理》2012年第5期481-486,共6页Tropical Geography

基　　金：国家自然科学基金项目(41072192;41103068);中国地质调查局项目(1212011087119);重庆市科委院士专项(编号:CSTS;2010BC7004);重庆市国土房管局科技项目;西南大学博士基金项目(SWU111009)

摘　　要：以重庆雪玉洞地下河系统为例,通过对2007年2月―2011年9月的水化学结果进行分析,结合近年来对洞穴沉积物沉积速率和洞穴CO2浓度的监测,发现雪玉洞地下河水化学成分受围岩的岩溶作用控制,地下河水中的3HCO、Ca2+分别占总离子的84.2%～94.4%,水化学类型为Ca2+-3HCO型。与西南其他岩溶研究区相比,该研究区域由于上覆植被好、枯枝落叶多、土质松软、岩石裂隙发育等因素,促使雨季岩溶作用较旱季异常强烈,雨季地下水中的3HCO、Ca2+和电导率较旱季分别高出20.1%、29.9%和16.5%。洞穴滴水在滴落过程中释放出CO2,导致洞穴CO2浓度升高,但由于雨季水源较旱季更为充裕(洞内表现为滴水增多),因而雨季的洞穴沉积速率较旱季高82.5%。雪玉洞内温度稳定、水汽饱和以及CO2浓度较高,使得岩溶沉积不易风化、色白如玉。The cave sediment is a product of karstification. The seasonal variation of karstification has greatly impacted on the precipitation rate and feature of sediment. Selected hydrochemical indictors in the groundwater, the precipitation rate of the cave sediment and carbon dioxide concentration in the case of Xueyu Cave, Chongqing were monitored during Feb. 2007 to Sep. 2011. Results show that the bicarbonate and calcium concentrations are the main components of the total ions in the groundwater with a ratio of 84.2 %-94.4 %. It demonstrates the chemical components are controlled by karstfication of the covered bedrock of the carbonate, and the hydrochemical faces are Ca2＋- HCO3- Compared to other karst areas in SW China, the better overlaying vegetation, more dead branches and leaves, soft ground and developed rock crack in the study area enable the karstification to be stronger in rainy season than that in dry season. The conductivity and concentrations of calcium and bicarbonate in rainy season were 20.1%, 29.9% and 16.5 % higher than that observed in dry season, respectively. In additional, due to the abundant water source during the rainy season in the performance of increase in drip water, the precipitation rate in rainy season is 82.5% higher than that in dry season. The sediments can not be easily weathered and their color remains white like jade, which is caused by stable temperature, saturated humidity and high carbon dioxide concentration in the cave causes.

关 键 词：岩溶作用 季节变化 地下水化学 洞穴沉积物 沉积速率 雪玉洞 

分 类 号：P641.25[天文地球—地质矿产勘探]