青藏高原如角高温地热系统构造-热耦合成热模式

Structure-thermal coupling model of the high temperature geothermal system in Rujiao on the Xizang Plateau

【研究目的】地表热异常的形成无外乎两方面原因:异常的热源及异常的热传递方式。“厚壳”与“热壳”共存,是青藏高原高温地热系统与一般汇聚板缘型地热系统的最大差异。部分熔融(热)作为“热壳”中的异常热源,断裂系统(构造)作为“厚壳”中的对流传热通道,清晰刻画两者空间关系,探讨构造-热耦合成热模式,可能是完善“厚壳”与“热壳”共存下青藏高原特色成热理论的重要途径。【研究方法】本次研究以萨嘎县如角沸泉为例,运用大地电磁测深、音频大地电磁测深。【研究结果】探测断裂系统与部分熔融的空间关系;结合已有地球物理、地热地球化学研究,建立如角沸泉构造-热耦合成热模式;并以断裂系统的交汇处为目标体,布设两口生产井。【结论】如角式构造-热耦合成热模式具有普适性,对于完善青藏高原特色成热理论及提高地热勘查成功率具有重要意义。

This paper is the result of geothermal survey engineering.[Objective]There are two reasons for the formation of surface thermal anomaly:abnormal heat source and abnormal heat transfer mode.The coexistence of"Thick Crust"and"Hot Crust"is the biggest difference between the high temperature geothermal system on the Xizang Plateau and the common convergent plate margin geothermal system.Partial melting(Hotsource)is an abnormal heat source in the"HotCrust",and fracture system(Structure)is a convective heat transfer channel in the"Thick Crust".Clearly depicting the spatial relationship between the two and exploring the structural-thermal coupling model of heat generation may be an important approach to improving the characteristic heat generation theory of the Xizang Plateau under the coexistence of a"Thick crust"and a"Hot crust".[Methods]This study takes the Rujiao Boiling Spring in Saga County as an example,and uses magnetotelluric sounding and audio magnetotelluric sounding.[Results]To explore the spatial relationship between the fault system and partial melting;we combined with previous studies on geophysics,geochemistry and fluid dynamics,established Rujiao boiling spring structure-thermal couplingthermal model;and set up two production wells with the intersection of the fault system as the target.[Conclusion]The Rujiao tectonic-thermal coupled model of heat generation has universal applicability,which is of great significance for improving the formation theory of characteristic heat in the Xizang Plateau and enhancing the success rate of geothermal exploration.