太原盆地区碳酸盐岩中-低温地热系统演化

Evolution of Middle-Low Temperature Carbonate Geothermal System in Taiyuan,Northern China

针对太原盆地区碳酸盐岩中-低温地热系统与边山岩溶水系统的相互作用关系这一难点问题,以地质构造分析为背景,以岩溶水的水化学、同位素组成特征为线索,重塑了太原盆地区碳酸盐岩中-低温地热系统地质演化过程.获得了如下3方面的认识:(1)该系统经历了自燕山运动以来的5个阶段的地质演化过程.在晚第三纪至早更新世阶段的稳定沉降期,该系统与边山岩溶水系统开始分离,并各自演化.(2)该系统的岩溶作用来自于2个方面:①中更新世晚期-晚更新世早期的大气降雨沿汾河等断裂带下渗,经与石炭-二叠煤系地层中的金属硫化物作用,形成富含硫酸的地下水,补给碳酸盐岩热储层,并与其中存留的更古老的岩溶水混合,促进了碳酸盐岩溶解;②受中更新世晚期-晚更新世早期盆地基底岩浆的烘烤,碳酸盐岩发生热解.(3)该系统中的岩溶热水形成于中更新世晚期-晚更新世早期,由于上覆盖层良好的保温作用而封存至今.其分布范围受地质构造的控制,东西向分别以东山、西山断裂为界,南以田庄断裂为界,北以亲贤地垒北边界为界.

To study the complicated issue of interactions between carbonate geothermal system with mid-low temperature existing in Taiyuan basin and its surrounding karst system existing in mountains,the geological evolution processes of the carbonate geothermal system were remodeled based on the analysis of geological structure and characterization of hydrochemistry and isotopic compositions of the karst water.We come to the following conclusions：（1） The carbonate geothermal system with mid-low temperature has experienced five stages of geological evolution since Yanshan Movement.and it separated from its surrounding karst system in mountains during the stable sedimentation period of Neogene to the Early Pleistocene,and then they evolved respectively;（2） The karstification of the carbonate geothermal system with mid-low temperature were due to the following two factors：① rainfall of the late Middle Pleistocene and the early Late Pleistocene infiltrated along the fault zone（e.g.Fenhe fault）,reacted with the metal sulfide in C-P coal measure strata and formed the groundwater rich in sulfuric acid.The groundwater was recharged to the carbonated geothermal reservoir and mixed with the older karst water stored in it,which facilitated the dissolution of carbonate rock;② the pyrolyzation of carbonated rock occurred by the baking of magma from the basin basement in the late Middle Pleistocene and the early Late Pleistocene;（3） The karst water in the geothermal system formed in the late Middle Pleistocene and the early Late Pleistocene,and sealed up to now because of the good insulation of its overlying strata.Mainly controlled by the geological structure,its east-west boundaries were Dongshan fault and Xishan fault respectively and its south-north boundaries were Tianzhuang fault and north boundary of Qinxian horst respectively.