辽东郑屯地区基于广域电磁法的深孔验证  

Deep-hole verification of wide-field electromagnetic method-derived results in the Zhengtun area of the Liaodong region

作　　者：梁维天[1] 李帝铨[2,3] 孙新胜[1] 王东波[1] 冯家新 李浩 樊金虎[1] LIANG Wei-Tian;LI Di-Quan;SUN Xin-Sheng;WANG Dong-Bo;FENG Jia-Xin;LI Hao;FAN Jin-Hu(Liaoning Fifth Geological Brigade Co.,Ltd.,Yingkou 115100,China;Key Laboratory of Metallogenic Prediction of Non-Ferrous Metals and Geological Environment Monitoring,Ministry of Education,Central South University,Changsha 410083,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,China)

机构地区：[1]辽宁省第五地质大队有限责任公司,辽宁营口115100 [2]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083 [3]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《物探与化探》2024年第3期675-683,共9页Geophysical and Geochemical Exploration

基　　金：辽宁省2020年财政出资项目(JH20-210000-05760)。

摘　　要：辽东金矿床的发育被认为受变质核杂岩体系叠加拆离断层带控制,传统观点判定永宁盆地永宁组盖层厚度达到几千米以上,阻碍含矿流体的运移的同时,不利于形成大规模金属矿床。辽东地区矿床深部探测投入少、研究程度低,勘查探测深度长期局限于1 km以内。本文在郑屯地区采用广域电磁法获得了3 km以浅的电阻率分布特征,厘清了辽东盖层厚度为千米左右,突破了对永宁组巨厚盖层的传统认识;进一步施工2 km深钻开展验证,在孔深1 345 m处发现永宁组地层与下伏太古宙基底呈不整合接触关系,界面附近未见明显的构造拆离迹象。本研究证实永宁盆地盖层厚度仅为千米左右,结合区内多期活动断裂构造和密集分布的浅成岩脉群,初步判定永宁盆地的成矿地质背景类似胶东金矿集区,推测存在华北克拉通破坏时期含矿变质流体或岩浆热液运移至界面上部成矿的可能。辽东地区具有实现多金属找矿突破的潜力,广域电磁法勘探为深地成矿预测指明了方向。The development of gold deposits in the Liaodong region is considered to be controlled by the superimposed detachment fault zone of the metamorphic core complex system.The traditional view holds that the thickness of the cap rocks of the Yongning Formation in the Yongning Basin can exceed thousands of meters,thus hindering the migration of ore-bearing fluids and the formation of large-scale metal deposits.The exploration of deposits in the Liaodong region has remained within a depth of 1 km due to limited exploration efforts and insufficient research.This study obtained the resistivity distribution characteristics within a depth of 3 km in the Zhengtun area using the wide-field electromagnetic method(WFEM),ascertaining that the thickness of the cap rocks in the Liaodong region is around 1 km,in sharp contrast to the extremely thick cap rocks in the Yongning Formation.As verified by the 2 km deep drilling,an unconformable contact between the Yongning Formation and the underlying Archean basement was observed at a hole depth of 1345 m,without significant structural detachment near the boundary.This study demonstrates that the thickness of the cap rocks in the Yongning Basin is merely around 1 km.Considering multistage active fault structures and densely distributed hypabyssal rock vein swarms in the area,it is preliminarily determined that the geological setting for mineralization in the Yongning Basin is akin to that of the Jiaodong gold ore concentration area.The ore-bearing metamorphic fluids or magmatic-hydrothermal fluids might have migrated to the upper part of the boundary for mineralization during the destruction of the North China craton.Overall,the Liaodong region has the potential to achieve breakthroughs in polymetallic prospecting,and the WFEM pinpoints the deep mineralization prediction.

关 键 词：华北克拉通 辽东 盖层 广域电磁法 深钻 

分 类 号：P631[天文地球—地质矿产勘探]