长白山仙人桥温泉断裂岩溶复合型地热成因模式

Faults and Karsts Controlled Geothermal Genesis Model of Xianrenqiao Hot Spring in Changbai Mountain

长白山仙人桥温泉是我国著名的矿泉水疗养旅游胜地,阐明其成因模式对于温泉区的进一步开发和热水资源的可持续利用具有一定的指导意义。笔者采用地质学、水文地质学和地球物理学结合的方法对其进行了系统研究。结果表明,该区属中低温对流型地热系统,地热成因模式为断裂岩溶复合型。热储层主要为古生界寒武系和奥陶系灰岩,灰岩本身的孔渗条件较差,但后期发育的构造裂缝和溶蚀裂缝却极大地改善了热储层的储集性能;盖层主要为中生界侏罗系安山岩和安山质火山碎屑岩,封闭性较好。长白山一带的大气降水沿侧向断裂和溶蚀裂缝渗入热储层中成为地下水;然后经正常大地热流加热成为地热水,热储温度为89~118℃,循环深度为2 853~3 820m;最终地热水在区内NE向与NW向断裂交汇处富集并沿导水断裂上涌形成温泉。因此,该区断裂交汇和岩溶发育的部位是地热勘探的有利部位。该结论为该区类似地热资源的勘探提供了理论依据。

Xianrenqiao hot spring is a great sparesort of China.We conducted a systematic study to explore the genesis mechanism through the methods of geology,hydrogeology and geophysics,for the purpose of further exploration and sustainable development of geothermal resources.Results show that this area belongs to a low-medium temperature geothermal system of convective type,with a composite geothermal genesis model of faults and karsts.The thermal reservoir was originally Paleozoic Cambrian and Ordovician limestone with poor porosity and permeability,but the reservoir property wasgreatly improved by the structural and dissolved fractures that formed in later period.The cap rocks are mainly Mesozoic Jurassic andesite and andesitic volcaniclastic rocks with strong sealing capability.The hot spring area origins mainly from the rainfall recharged in the area of Changbai Mountain,seeps into the underground thermal reservoir along the lateral faults and karst fractures;Then the groundwater is gradually heated by the normal heat flow during circulating,forming the geothermal water.The thermal reservoir temperature has been estimated to be 89-118 ℃,with a water circulation depth of 2 853-3 820m;Finally the geothermal water flows upward in the intersection zones of the NE-and NWstriking faults,forming the Xianrenqiao hot spring.In a word,the area that has intersecting faults and abundant karsts is a favorable and prospective area for the exploration of geothermal water.This conclusion provides a theoretical reference for the exploration of similar geothermal resources.