| As a comprehensive and multi-phases orogenic belt,Qinling has been concerned by geologists for very long time,and the study on this region was started many years ago and large numbers of conclusions has been acquired.It is generally accepted that Qinlin was formed under the collision of the Yangtze Block and the North China Block which caused a series of mineralization in this area.South Qinling Mountains tectonic belt is the largest unit as well as main part of Qinling orogenic.There is so much mine resource in South Qinling area,especially plentiful gold resource,and consequently it is helpful to explore more resource by further research South Qinling.Ore-filed is designed as the region contains several ore-beds which formed under the analogous space,time,structure and reason.Geologists can effectively ascertain the characteristics as well as formation regularity of those ore-beds through ore-field geology study,and this is significant for mine resource exploration.North Hanyin gold ore-field of South Qinling with the length of about 50 km in EW direction and the width of 10~20 km in NS direction,is located in the mid of South Qinling Mountains tectonic belt.These years tens of gold ore-beds with different scales have been detected.However,mine exploration is faced with difficulty today,and consequently it is emergent to make clear the control structure,ore-formation regularity and pattern of gold beds in this area.This study based on research project ?Shannxi Shiquan-Xunyang gold exploration region special mapping and technology application”,aimed at gold ore-field of North Hanyin.After collecting,analyzing and study existing results made by other people,this study found the characteristics of rocks,styles of structure deformation,geological feature of ore-beds,and information of mineralization,and these process was finished by large scale geological mapping,measuring section and mine well.Secondly,through massive comprehensive research and making map,structural characteristics of ore-field and ore-control factors were acquired.Farther more,through picking up large numbers of rock samples which were analyzed in laboratory,much information on gold mineralization was made clear.After these processes above,the regularity and pattern of gold ore-field was acquired.The achievements of this study are shown below.(1)It can be divided five large brittle ductile shear zones distributing in near EW and NW directions,and they formed in early Jurassic when Ankang and Ninshan large faults started large-scale strike slip shear movement and the mid plate moved towards east under compressing.(2)These five brittle ductile shear zones controlled space positions of gold ore-beds and secondary faults controlled gold ore-bodies.(3)Structural foliation of this area can be divided into three phases and S2 phase dominated,and the S2 phase foliation which was structure of metallogenic time,control gold mineralization.(4)Magmatic rockzirconU-Pbisotope indicated that the magmatic rock of Guan yinhe formed about 180.2±3.6 Ma,and that of Liuken formed about 176.0±1.9 Ma,and this proved that the time of magmatism was early Yanshan period in which the S2 phase foliation formed.(5)Analysis of fluid inclusions in quartz vein shown that the gold of this region formed in 190~300?,20.61~100.77 Mpa and 0.76~3.74 km environment.(6)The time of gold ore-formation was in Yanshan period,the ore-source came from original stratum,the metallogenic time was earlyYanshan period,and magmatic water took part in mineralization,and it probably brought gold element.(7)The metallogenic types of the gold deposits in this gold ore-fieldis the ductile shear altered rock typeand superimposed magmatic(later)hydrothermal fluid.And the metallogenic pattern is eventually established.The results of this study can provide valuable and important guide for gold exploration in North Hanyin area and other surrounding places,and it is helpful to acquire more gold resource. |
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