煤田地质与勘探2024，Vol.52Issue(1)：70-82,13.DOI:10.12363/issn.1001-1986.23.10.0631
湖南省热水圩地热田干热岩形成的热源机制与成因模式
Heat source-related mechanisms and genetic modes for the formation of hot dry rocks in the Reshuiwei geothermal field,Hunan Province
摘要
Abstract
Hot springs with temperatures exceeding 90℃ indicate that the Reshuiwei geothermal field in Hunan Province enjoys sound geothermal geological conditions,making this geothermal field a potential favorable area for hot dry rock(HDR)exploration.To carry out a reasonable evaluation of the geothermal reservoir and prospects for explora-tion and exploitation of HDRs in the Reshuiwei geothermal field in the Rucheng area,this study comprehensively ana-lyzed the deep geological structures,geochemical characteristics,geophysical characteristics including gravity,magnet-ic,electrical,and seismic properties,and geothermal field characteristics of the geothermal field.Furthermore,it re-vealed the deep thermal structures of the geothermal field from deep to shallow and explored the heat source-related mechanisms and geodynamic process for the formation of HDRs in the geothermal field.Primary results are as follows.(1)The Reshuiwei geothermal field exhibits deep reservoir temperatures ranging from 79.4 to 143.9℃ ,as estimated us-ing a silica geothermometer.(2)The Zhongpeng and Yuwang granite plutons near the Reshuiwei area display average heat production rates between 7.07 and 8.44 μW/m3,which are significantly higher than the average heat production rates of the crust in the major geological units in Chinese continent.(3)The gravity and magnetic characteristics reveal relatively thin lithosphere in the Reshuiwei area.Furthermore,the interpretations of the magnetotelluric sounding and seismic wave velocities reveal that the crust hosts geobodies with high conductivity and low velocity,which coincide with deep-seated fault zones.This indicates that these faults might serve as pathways for the upward intrusion of deep thermal materials.Based on these results,this study summarized the genesis mode of HDRs in the Reshuiwei geotherm-al field.Specifically,the subduction and retreat of the Pacific Plate led to intensive thermal disturbances to the plate front,further resulting in the uplift of the asthenosphere and the intrusion of mantle-derived thermal materials.As a res-ult,a relatively highly located mantle-derived heat source was formed.Granite plutons with high heat production rates and uranium deposits featuring radioactive heat production form a favorable crustal heat source.Furthermore,deep-seated faults serve as pathways for the upward intrusion of deep thermal materials while supplying heat sources for the formation of shallow HDRs.The favorable thermal source conditions and the upward intrusion of deep thermal materi-als along deep-seated faults jointly lead to the formation of a favorable HDR target area represented by plutons around Reshuiwei in southeastern Hunan.As inferred from the comprehensively determined geothermal gradients,the con-cealed and tight granite plutons with scarce fractures and burial depths ranging from 4 000-6 000 m in the Reshuiwei geothermal field exhibit temperatures reaching 176.8-256.6℃,serving as favorable HDRs to be explored and exploited in the near future.关键词
干热岩/地球化学/重磁电震联合/热源机制/成因模式/湖南热水圩Key words
hot dry rock/geochemistry/gravity,magnetic,electricity and seismic combination/heat source-related mechanism/genesis mode/Reshuiwei in Hunan分类
天文与地球科学引用本文复制引用
杜江,蔡宁波,张保建,王克营,何立宏,廖凤初..湖南省热水圩地热田干热岩形成的热源机制与成因模式[J].煤田地质与勘探,2024,52(1):70-82,13.基金项目
湖南省地质院科研项目(HNGSTP-202102,HNGSTP-202330) （HNGSTP-202102,HNGSTP-202330）
