汝城盆地深部构造及地热资源赋存潜力——基于重力与AMT探测的认识  

Gravity survey and audio magnetotellurics-based insights into the deep structures and geothermal resource potential of the Rucheng Basin

作　　者：赵宝峰 汪启年[1,2,3] 郭信 官大维[1,2,3] 陈同刚 方雯 ZHAO Bao-Feng;WANG Qi-Nian;GUO Xin;GUAN Da-Wei;CHEN Tong-Gang;FANG Wen(Geological Exploration Technology Institute of Anhui Province,Hefei230031,China;Anhui Provincial Key Laboratory of Electrical Prospecting,Hefei230031,China;Technology Innovation Center of Coverage Area Deep Resource Exploration Engineering,MNR,Hefei230001,China)

机构地区：[1]安徽省勘查技术院,安徽合肥230031 [2]安徽省电法勘探重点实验室,安徽合肥230031 [3]自然资源部覆盖区深部资源勘查工程技术创新中心,安徽合肥230001

出　　处：《物探与化探》2023年第5期1147-1156,共10页Geophysical and Geochemical Exploration

基　　金：国家重点研发计划项目课题(2018YFC0603606);安徽省重点研究与开发计划(2020n07020003)。

摘　　要：地热是重要的清洁能源和旅游矿产,汝城盆地是湘东南山区内的碳酸盐岩盆地,具有形成对流型地热的有利条件,由于盆地三面受诸广山巨型岩体夹持,基底遭受岩体侵入破坏,地层变形严重,断裂纵横,东西构造差异显著,导热、导水通道与深部热储构造发育不清,制约了对该盆地地热赋存潜力的认识。针对以上问题,利用重力与AMT对盆地深部构造进行了探测,取得以下认识:①汝城盆地东西分异呈双向对冲的结构,东部复向斜受燕山期岩体围绕侵位发生挤压和顺时针旋转,核心区岩石破碎,边界走滑断裂岩石破碎带发育,断裂垂向切割深度超过4 km,宽度300-600 m,倾角80°-90°。②盆地内沿基底背斜轴部NWW向发育有多个隐覆岩体,直径3-4 km,埋深0.5-1.5 km,温泉产出在过隐伏岩体边界的断裂破碎带中。③盆地内具有形成对流型地热的良好条件,褶皱、断裂带和隐覆岩体等相互匹配形成统一的控热要素空间组合关系,构成东西双向补给、中间排泄的聚热特征,东部深部热储更发育,盆地地热资源潜力大。Geothermal resources are significant clean energy and tourism mineral resources.The Rucheng Basin,a carbonate basin in the southeastern mountainous area of Hunan Province,possesses favorable conditions for the formation of convective geothermal energy.However,the basin is enclosed on three sides by the giant Zhuguangshan rock mass,and its basement is subjected to the intrusion and destruction by the rock mass,resulting in severely deformed formations,crisscrossing faults,and significantly different eastern and western structures.The understanding of the basin's water-and heat-conducting pathways and deep reservoir structures remains elusive,thus restricting the investigation of the basin's geothermal potential.Hence,this study probed the basin's deep structures through gravi-ty survey and audio magnetotellurics(AMT),obtaining the following insights:(1)The Rucheng Basin has developed into a bidirec-tional ramp structure due to east-west differentiation.The synclinorium in the east experienced compression and clockwise rotation due to the emplacement of the Yanshanian rock mass,rocks were fragmented in the core zone,and strike-slip fracture zones were found at the boundary.The faults have vertical cutting depths exceeding 4 km,widths ranging from 300-600 m,and dip angles between 80°-90°.(2)The basin's basement anticlinal axis hosts several NWW-directed concealed rock masses,with diameters from 3-4 km and buried depths from 0.5-1.5 km.Hot springs reside in the fracture zones crossing the boundaries of the concealed rock masses.(3)The basin boasts favorable conditions for the formation of convective geothermal energy.Folds,fault zones,and concealed rock masses match each other to form a unified spatial combination of heat-controlling elements,manifesting heat accumulation characterized by east-west recharge and intermediate discharge.With more thriving deep geothermal reservoirs in the east,the basin has high potential for geothermal resources.

关 键 词：汝城盆地 深部结构 地热资源 重力与AMT 

分 类 号：P631[天文地球—地质矿产勘探]