Deep-hole verification of wide-field electromagnetic method-derived results in the Zhengtun area of the Liaodong region
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 a-round 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 1 345 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 a-chieve breakthroughs in polymetallic prospecting,and the WFEM pinpoints the deep mineralization prediction.
North China cratonLiaodongcap rockwide-field electromagnetic method(WFEM)deep drilling
国家科技期刊平台
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