EARLY YANSHANIAN TECTONIC STRESS FIELD AND ITS CONTROL OF GOLD MINERALIZATION OF THE KUANCHENG-QINGLONG-JINCHANGYU GOLD DEPOSIT-CONCENTRATED REGION OF THE EAST HEBEI PROVINCE

Strong crustal movement and tectono-magmatic activity of early Yanshanian period occurred in the Kuancheng-Qinglong-Jinchangyu gold deposit-concentrated region of east Hebei Province,and resulted in the formation of major regional compressional-shear faults and magmatic zones and more than 20 gold deposits.The early Yanshanian regional tectonic stress field played an important role in the formation and evolution of these faults and gold metallogenesis.On the basis of field investigation and palaeostress measurement,the early Yanshanian regional geodynamic condition,displacement directions and differential stresses of several locations of this gold-concentrated region were determined.Then the corresponding regional tectonic stress field of the early Yanshanian period was calculated by using the finite-element numerical modelling methods,and the relationship between regional tectonic stress field and gold mineralization was analysed.The following conclusions regarding the early Yanshanian regional tectonic stress field were obtained:(1) the maximum principal compressional stress is oriented in NW-SE direction while the minimum principal compressional stress in N E-SW direction for most units;(2) the regional differential stresses range from 2.5 to 220 M Pa;(3) the direction,magnitude and gradient of regional tectonic stress evidently controlled the distribution of gold deposits and gold mineralization.