川西鲜水河、安宁河和龙门山断裂带地热水的水文地球化学特征及成因模式的讨论

吕国森; 章旭; 张云辉; SAFONOVAInna; 黄豪擎; 余中友; 代倩

doi:10.12029/gc20230309001

川西鲜水河、安宁河和龙门山断裂带地热水的水文地球化学特征及成因模式的讨论

Discussion on hydrogeochemical characteristics and genetic model of geothermal waters in Xianshuihe, Anninghe and Longmenshan fault zones in western Sichuan, China

摘要

摘要:
研究目的 研究川西鲜水河断裂带、安宁河断裂带和龙门山断裂带地热水的水化学特征及成因模式，可为川西地热水资源的合理开发利用提供重要参考依据。
研究方法 本文运用水文地球化学、热储温度计算、氢氧同位素等方法分析了分布在3条断裂带上的48处典型温泉（地热井）的水化学组分、水化学过程、热储温度和深度、热水补给来源等特征，并探讨了其形成模式。
研究结果 结果显示：（1）鲜水河断裂带热水水化学类型以HCO₃−Na型为主；龙门山断裂带主要为SO₄−Na和Cl−Na型；安宁河断裂带包括HCO₃·Cl−Na、HCO₃·SO₄−Ca·Mg和Cl·SO₄−Na型等。（2）3条断裂带地热水组分主要受硅酸盐矿物溶解和离子交换作用控制。（3）鲜水河断裂带热储温度为129.6~210.6℃，深度为2532~4184 m，冷水混入比为66%~82%；安宁河断裂带热储温度为81~121.9℃，深度为2155~3519 m，冷水混入比为52%~95%；龙门山断裂带热储温度为108.2~153℃，深度为3573~5654 m，冷水混入比为68%~89%。（4）3条断裂带的地热水接受大气降雨补给，补给高程分别为鲜水河断裂带2493~5034 m、安宁河断裂带3235~3839 m和龙门山断裂带1628~4574 m。（5）鲜水河断裂带地热水的“δ¹⁸O漂移”程度强于安宁河断裂带，龙门山断裂带部分地热水出现“δ¹⁸O漂移”和“负向漂移”特征。
结论基于本次研究得到的3条断裂带地热水成因模式，鲜水河断裂带地热水的开发潜力优于安宁河断裂带、龙门山断裂带，是四川省中高温地热资源开发利用的优势靶区。

Abstract:
This paper is the result of geothermal geological survey engineering.
Objective In order to develop and use geothermal water resources in western Sichuan rationally, it is important to study hydrochemical characteristics and genetic models of the geothermal waters spatially linked with the Xianshuihe (XFZ), Anninghe (AFZ), and Longmenshan (LFZ) fault zones.
Methods The methods of hydrogeochemistry, reservoir temperature calculation, hydrogen and oxygen isotopes were used to estimate hydrochemical types, hydrochemical processes, reservoir temperatures and depths, and recharge sources of 48 typical localities of geothermal waters (or geothermal springs or drilling holes) located around these three fault zones, and reconstruct the mode of their formation.
Results (1) Hydrochemically the geothermal waters are dominated by HCO₃−Na type in the XFZ, SO₄−Na and Cl−Na types in the LFZ and HCO₃·Cl−Na, HCO₃·SO₄−Ca·Mg and Cl·SO₄−Na types in the AFZ. (2) The composition of geothermal waters of the three fault zones are mainly controlled by the dissolution of silicate minerals and ion exchange process. (3) The temperatures of the reservoirs, their depths and the cold water mixing ratio are, respectively, 129.6−210.6℃, 2532−4184 meters, and 66%−82% for the XFZ, 81−121.9℃, 2155−3519 meters, and 52%−95% for the AFZ and 108.2−153℃, 3573−5654 meters, and 68%−89% for the LFZ. (4) The geothermal waters in the three fault zones are recharged by meteoric waters derived from elevations at 2493 to 5034 meters in the XFZ, 3235 to 3839 meters in the AFZ, and 1628 to 4574 meters in the LFZ. (5) The degree of the “δ¹⁸O drift” of geothermal waters in the XFZ is higher than that in the AFZ, and the geothermal waters in the LFZ exhibit characteristics of “δ¹⁸O drift” and “negative drift”.
Conclusions Our results show that among the three perspective areas of the Sichuan Province, the Xianshuihe Fault Zone possesses a higher commercial potential for the exploration and utilization of medium-high temperature geothermal resources compared to the Anninghe and Longmenshan fault zones.

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