甘孜地区雅拉河段地热系统特征及控制因素

Characteristics of the Geothermal System and Control Factors in the Yalahe Reach,Ganzi Area

综合应用区域地质、地震、地球化学等资料,对甘孜地区雅拉河段地热系统及其主控因素进行研究。分析认为,甘孜地区地热属于典型的对流型地热系统,雅拉河断裂破碎带及板岩中发育的大量裂隙共同构成了研究区的热储体,这些热储体沿雅拉河断裂带不均匀分布。研究区充沛的大气降水以及季节性的冰雪融水为地热系统提供充足的水源。雅拉河断裂与色拉哈断裂之间大范围相对平坦的区域以及大量储水洼地为地热系统中的水源提供存储空间。该地区地表裂隙发育,利于地表水向下渗透,是地下水的主要补给通道。色拉哈断裂的强烈活动为浅层地下水在重力作用下进一步向深层运移提供重要流体通道。雅拉河断裂带的地势相对低,断裂破碎带是深层流体上涌的重要通道。在流体供给区与出露区的重力势能差以及两条走滑断裂带压力差共同作用下,流体经深部热源加热后在流体通道内形成持续的热流体循环系统。

This study is based on regional geology,earthquakes and geochemistry. The purpose is to analyze the geothermal system characteristics and main influence factors of the Yalahe reach,Ganzi area. The results indicate that the Ganzi area is a typical convection geothermal system. The Yalahe fault zone and a large number of associated fractures in slate constitute the geothermal reservoirs in the study area. These geothermal reservoirs are unevenly distributed along the Yalahe fault zone. Abundant atmospheric precipitation and seasonal meltwater provide adequate underground water for the geothermal system. The broad relatively flat area and a lot of waterholes for the geothermal system offer the water storage space between the Yalahe fault zone and the Selaha fault zone. Surface cracks in the region,in favor of surface water downward penetration,are major underground water recharge channels. Intense activity of the Selaha fautl plays a critical role in the shallow water migration toward the deep subsurface under gravity. The Yalahe fault zone is located in a relatively low-lying area,in which fractures are important channels upwelling fluids from depth. The surface elevation difference between the fluid supply area and the exposed area and the pressure difference between the two strike-slip faults generate the continuous thermal fluid circulation system,which is formed in the fluid migration pathways after the deep heat source heating.