鄂西地区氯化钠型岩溶热储地热资源成因模式研究

Study on Genetic Model of Geothermal Resources of Sodium ChlorideType Karst Heat Reservoir in Western Hubei

鄂西地区氯化钠型岩溶热储地热资源分布广泛,其形成与区域构造、地层岩性关系密切。为进一步研究其成因模式,在区域地热地质条件的基础上,结合水化学微量元素、氢氧硫同位素等水文地球化学特征,建立了鄂西地区氯化钠型岩溶热储地热资源成因模式。研究表明,鄂西地区岩溶地热系统的热储主要为寒武系—奥陶系的碳酸盐岩,碳酸盐岩裂隙岩溶系统是区内地下热水的主要储存与运移场所;热源主要为自然梯度增温;盖层主要为志留系的(含)泥质岩类;碳酸盐岩深大断裂及裂隙岩溶为区内地下热水的导水通道,岩溶发育程度主要受NE、NW向断裂的控制;高含量的氯化钠地热流体来源于覃家庙组的泥质白云岩,含有石盐和石膏假晶。地下水在径流中穿过了该地层,因而形成了高含量的氯化钠水。

The geothermal resources of sodium chloride type karst geothermal reservoir in western Hubei are widely distributed,and its formation is closely related to regional structure and stratigraphic lithology.In order to further study the genetic model of sodium chloride type geothermal resources in western Hubei,based on the regional geothermal geological conditions,combined with hydrogeochemical characteristics of hydrochemical trace elements and hydrogen,oxygen and sulfur isotopes,the genetic model of sodium chloride type karst geothermal resources in western Hubei is established.This study shows that the thermal reservoirs of karst geothermal system in western Hubei are mainly Cambrian-Ordovician carbonate rocks,and the carbonate fractured karst system is the main storage and migration place of underground hot water in the area.The heat source is mainly natural gradient warming;cap rock,mainly Silurian argillaceous,argillaceous rocks;the deep fault and fissure karst of carbonate rock is the water channel of underground hot water in the area,and the degree of karst development is mainly controlled by NE and NW faults.The high content of sodium chloride geothermal fluid comes from argillaceous dolomite of Qinjiamiao Formation,containing halite and gypsum pseudocrystal.Groundwater flows through the stratum,thus forming a high content of sodium chloride water.