Study On The Characterisitics Of Ore-controlling Structures In The Hadamengou Mining Area,Inner Mongolia

The tectonic positon of the Hadamengou gold deposit is in the southern margin of the Yinshan uplift zone(?),northern margin of the North China craton(?),North China Plate(?).The host rocks are the Wulashan Group metamorphic rocks,Neoarchean Erathem.The quartz veins type,gold-bearing quartz-potassium feldspar veins type and potassium alteration rocks type are the main types of the gold mineralization.The metallogenic type of the Hadamengou golden deposit can be summed in two categories: metamorphic hydrothermal genesis and magmatic hydrothermal genesis.By analyzing the initial source rock,the wallrock alteration and the conditions such as temperature and pressure,magmatic hydrothermal genesis might prevail.Based on the isotopic age and the cutting relationship between gold vein and wall rock,this article argues that there were multi-stage mineralizations in the formation of Hadamenggou golden field.The tectonic deformation in the study area is complex,which includes main folification structure with gneissicosity,linear structure with stretching lineation,boudinage,etc.Fold structure can be identified by three phases: the first phase is when the plastic rheid folds were formed due to the shear slip fault of layers,such as rootless hook-like folds,ptygmatic folds and flowage folds;the second phase is when buckle folds,with gneissosity as the key bed,were formed due to the horizontal compression;the third phase is when the superimposed folds,originated from the folds in the second phase,were formed.Apparently,the formation of the Hadamengou golden field is dependent on the structures.The forming scale of the deposit is totally controlled by Linhe-Jining fault and Hohhot-Baotou fault,and the gold veins are mainly reserved in the secondary faults with ductile-brittle superposition properties that are derived from the regional faults;the approximate equidistance between the adjacent veins at the south-north line indicates that the distribution of the gold veins is restricted by the ductile shear zone.