The Geological And Geochemical Characteristics And The Discussion On The Genesis Of The Daxigou Gold Deposit, Fengning Hebei Province

The geological structure in our country is very complex, and there are abundant noble metal such as gold and silver in china .There are also many gold deposits in the northern part of Huabei plate and it has become an important base of mine product in our country.The gold , silver , polymetallic deposits is mostly formed in two historic era, namely former Cambrian and Mesozoic Yanshan epoch . The main ore-forming processes in the north Hebei province and west Liaoning province was that the former aged stratum was activated by Mesozoic magma process .Fluid has an important role in the ore-forming processes , it is also the main medium which activate, carry and enrich the ore-forming substance . The movement of fluid is also advantageous for the enlarge of the space for ore formation .The fluid inclusion can be the ancient fluid sample which formed rock or ore body, and the data drown from fluid inclusion can explain the contemporary ore-forming environment ,so the fluid inclusion is more and more used in the study of ore depositsThe Daxigou gold deposit which is studied this time is located in the north Hebei &west Liaoning district in the northern part of the Huabei plate , and its ore-forming condition is representative in this district .There are few studies on this mine ,so the data which is drown from this study is the first data.Through the observation outdoors and all kinds of work indoors including checkup of the rock, the analysis of the rare elements , isotope and the fluid inclusion ,now we have a basic knowledge of this deposit including the stratum, structure , the shape of the ore body ,the type of the alteration ,the characteristics of the ore body and the wall rocks ,the mineralogical characteristics of the ore ,rare elements characteristics in all kinds of rocks and the characteristics of the fluid inclusion ,also we have a primary understand of the type and the genesis of the deposit.The primary conclusions are as follows : 1. The alteration type of the Daxigou gold deposit is simple ,it is mainly pyrite which carrys most of the gold ,so the pyrite can be a symbol for exploration;2. The ore-forming processes of the Daxigou gold deposit occurred in late Jurassic, and has much to do with the porphyry which was formed in the sane time;3. The ore body is located in the small structure which is in the porphyritic magmatite , the attitude of the ore body is strictly controlled by the fructure;4. The deposition of the ore-forming substitute in the fluid has much to do with the alteration which occurred between fluid and the wall rock and the change of the fluid property which is caused by the mixture of the fluid which maybe came from the porphyry around and the rain water;5. The type of the Daxigou gold deposit islow to moderate temperature and low to moderate salinity hydro-thermal gold deposit which is related to continental sub-volcanism.