利用δ^18O和δ^34S示踪重庆都市圈地下热水循环过程

Using δ^(18)O and δ^(34)S isotopic techniques to trace the recycling process of hot springs in Chongqing metropolitan

重庆市地下热水储存量大约有1亿m3,其中75%分布在都市圈内。通过对重庆市都市圈13个温泉群,20个泉点的温泉水的δD、δ18 O和δ34S调查,结合水化学指标进行分析表明:重庆市都市圈温泉水类型为SO42-Ca或者SO24-Ca Mg型,水的来源为大气降水。δ18 O值为-7.41‰～-9.48‰,研究认为地下热水的补给来源于海拔672～1 503m研究区域背斜核部岩溶出露区和背斜北端的岩溶出露区。热水中主要离子SO24-和Ca2+、Mg2+均存在很好的正相关性,且δ34S值为31.46‰～34.32‰,正好处于下三叠统嘉陵江组二段硬石膏δ34S值异常段,由此表明雨水和地表径流沿岩溶裂隙等进入深部的含有硬石膏的嘉陵江组,由此认为重庆都市圈温泉水储水层可能为下三叠统嘉陵江组二段。

There is about 100 million m^3 underground thermal resource storage in Chongqing, of which 75% are stockpiled in metropolitan area. 20 samples from 13 hot springs in Chongqing metropolitan area are collected and analyzed for chemistry and isotopes of heavy hydrogen, oxygen and sulfur. The results shows that these hot springs are SO^2-4-Ca andSO^2-4-Ca-Mg, and the water sources is precipitation. The value of δ^18O is between -7. 41‰～-9. 48‰, which can ascertain that the recharge area of these hot springs are the karst area in these anticlines and the karst area at the north of these anticlines with the altitude of 672～1 503 m. There is a good positive correlation between SO^2-4- and Ca^2＋ , Mg^2＋. The δ^34S value of the samples is between 31.46‰～34.32‰, precisely the same with the δ^34S value in gypsum at the second phase of Jialingjiang formation in Early Trias. Both of them shows that rainflow and surface flow along the karstfissures infiltrate into the Jialingjiang Formation which have gypsum, and it also shows that the hot springs storage formation may Be the second phase of Jialingjiang formation in Early Trias.