Geological Characteristics And Genesis Of Dongzigou Polymetallic Ore Deposit In Xinglong Area,hebei Province

The Dongzigou silver(copper) deposit is located in the town of Xinglong County of Hebei Province, tectonically belongs to the northern part of the North China platform of Yanshan fold belt.It located at the center of the Yan Liao Late Proterozoic aulacogen and NE to the aulacogen intersection trigeminal rift divergent. Based on the study of the investigation and detailed reserch.This paper combined the results of the analysis with metallogenic geological characteristics.On the basis of the following study,Dongzigou silver copper mineralization, ore controlling factors, and the genesis of the deposit is discussed:(1) The research on the geological survey and rock alteration types indicates that Changzhougou group sandstone have closely relationship with the genesis of the deposit.Research shows that, it not only as the wall rock of the deposit,it also mineral source layer which providing some mineral deposits in this area. Changzhougou formation sandstone can be used as an important prospecting signs.The wall rock alteration types mark of the deposit are silicification, pyritization and chloritization. Chloritization,silicification, pyritization can be used as the important prospecting marks.(2) The main fault in this area is the Huangyaguan The others secondary faults and interlayer ore structure mainly the faults which on both sides of the major faults. The main structure of the area is a broad anticline fold which belongs to the part of the Ma Lan Valley westward plunging anticline. According to this research, the fold structure have closely relationship to the formation of the Dongzigou deposit.(3) The study area has the characteristics of the ore bodies along the output layer. The veins showed local wear layer phenomenon and veins branching composite phenomenon and the same characteristics showed in performance the grade and thickness of ore body in the tunnel.The ore is mainly composed of tetrahedrite, galena, sphalerite, pyrite,composition. Through the analysis of existing test, tetrahedrite, silver copper rich,tetrahedrite, the higher the content of silver, copper grade, the rich. The ore structures are mainly metasomatic texture, metasomatic relict texture, edge structure; structure are mainly banded structure, massive structure, brecciated structure(4) Based on the systematic observation of field geological survey, hand specimen andlight sheet and study on the geochemical characteristics of rocks, The author thinks that the genesis of the deposit have closely relationship with igneous rocks which is the Dahongyu period of igneous rocks, the rock types are mainly alkaline basic rocks, the rock series is the potassic basalt It has the characteristic of potassium and alkali rich.(5) On the study of metallogenic temperature, this paper mainly based on the results of previous research of sulfides and quartz in ore fluid inclusion homogenization temperature and crack method, The temperature test shows that the Dongzigou deposit formed in the low temperature environment.(6) On the study of mineralization age of the deposits,the Dongzigou silver copper Single stage mode lead at an average age of(1635~1721) Ma. In order to more accurately defing the mineralization age, this study combines the predecessors of the ore host rock of Changzhougou formation age results(1800) Ma, with the age of vein rock cutting each other’s(1521±4) Ma. Ultimately the mineralization age of the deposit is determined in the Mesoproterozoic:Dahongyu period.(7) On the study of ore genesis,this reserch makes full use of the ore lead isotopic characteristics of possible source of minerals in the ore, the result has showed the characteristics of that metallogenic substance coming from the deep area. The test of the sulfur isotope of sulfide deposits within the mining area also describes the characteristics of deep source of metallogenic substance. Based on the above research work, the genetic type of Dongzigou deposit is superimposed reworked deposit.which have the characteristics of sedimentary layer controlled properties.