雄安新区牛驼镇凸起深部结构对浅层地热田影响——来自深地震反射剖面的约束  

Deep structure of geothermal of Niutuo Uplift:Constrained by deep seismic reflection profile in Xiong’an New Area

作　　者：刘宏凯 张杰[2] 侯贺晟[1] 李洪强[1] LIU Hongkai;ZHANG Jie;HOU Hesheng;LI Hongqiang(Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Geophysical and Geochemical Exploration,Langfang 065000,Hebei,China)

机构地区：[1]中国地质科学院,北京100037 [2]中国地质科学院地球物理与地球化学研究所,河北廊坊065000

出　　处：《地质通报》2024年第11期2015-2027,共13页Geological Bulletin of China

基　　金：中国地质调查局项目《深部地质调查》(编号:DD20230008);《松嫩地块及周缘关键区带深部地质调查》(编号:DD20190010);《白云鄂博-大兴安岭南段岩石圈结构探测与构造》(编号:DD20242875)。

摘　　要：雄安新区牛驼镇地热田是华北地区开发程度相对较高的中低温地热田之一,地热资源开发潜力巨大。为了揭示其深部结构和地热田成因,中国地质科学院于2020年采集一条近EW向、满覆盖次数为250次的40 km长深反射地震剖面,通过该剖面获得高分辨率的牛驼镇地热田地壳和上地幔结构。在精细标定和解释的基础上认为,牛驼镇浅部新生代低孔隙度近水平沉积地层直接覆于中元古界的热储层之上,对地热田起到了保温盖层作用;中元古界蓟县系、长城系是研究区的主要热储层,以孔隙度发育的碳酸盐岩为主,有利于流体的存储。牛东断裂和容东断裂向上延伸到馆陶组,向下延伸到蓟县系,与浅部断裂形成断裂系统,为流体和热运移提供通道。牛驼镇凸起16~20 km深度的壳内滑脱层起到导热和隔水作用,将深部的热通过热传导方式加热热储层;其中,地震剖面揭示的从下地壳延穿过Moho面、延伸到上地幔的透明反射区域,可能是古近纪早期软流圈上涌形成的侵入体,该侵入体极可能是该地区热异常的主要原因。浅层的沉积盖层作用、中元古代裂隙发育的碳酸岩热储层、断裂导水和导热、壳内滑脱层的隔水导热、深部的侵入岩体提供热源,共同作用使牛驼镇凸起热异常,形成地热资源的有利开发区。Niutuozhen geothermal field is located in North China,one of China's most important medium-low temperature geothermal fields.To reveal the deep structure and the origin of the geothermal field,an E-W deep reflection seismic profile which is 40 km long and 250 times folded was aquired by the Chinese Academy of Geological Sciences in 2020.The shallow strata feature in low porosity in Niutuozhen overlaid on the thermal reservoir,acts as a serviceable cap layer.Niutuozhen has a superior geothermal reservoir attributed to the evolved carbonate rocks,such as the Jixian System,and the Changcheng System,which feature high permeability.The deep-seated Niudong and Rongdong faults unequivocally extend to the basement and connect the deep thermal reservoir and shallow strata.They act as channels for the upward migration of hot water and the thermal convection process.The decollement within the crust at depths of 16 km to 20 km in the Niutuozhen Uplift serves as a thermal conductor and hydrological barrier,facilitating the conduction of heat from deeper sources to heat the reservoirs.In the seismic profile,the transparent zone revealed as intrusive bodies formed by the upwelling of the Early Paleogene asthenosphere,and the intrusive bodies extending from the lower crust below the Moho surface primarily cause the heat anomaly in the region.The shallow sedimentary cover,the Mesoproterozoic carbonatite reservoirs with well developed fracture,the conduction of water and heat through faults,the impermeable heat-conductive decollement within the crust,and the deep intrusive bodies providing a heat source,all these essential elements are combined to form the Niutuozhen geothermal field,which now has objective geothermal resources.

关 键 词：牛驼镇凸起 雄安新区 深反射地震 深层岩体 地热模型 深部断裂 

分 类 号：P314[天文地球—固体地球物理学] P54[天文地球—地球物理学] P631.4