Study On Geological Characteristics And Genesis Of Badaohezi Molybdenum Deposit, Jilin Province

Badaohezi molybdenum deposit located in Badaohezi Country,Huadian City,JilinProvince.Its tectonic location is situated in the middle of the Xiaosuihe-Hulan upliftwitch belongs to Jilin synclinorium,Jihei fold system,Tianshan-Xingmeng orogenicbelt.And it located between Dunhua-Mishan fault and Yitong-Yilan fault.InYanshannian,the activity of magmatic is very active witch is good for themineralization of this area.The main strata witch exposed in the mine area is Nanshanlou group of lowerJurassic.The other main stratas are the terrace deposits of upper Pleistocene series andthe riverbed deposit of Holocene Series of the Quaternary System.The main structureis Mentoulazi-Donggou fault(strike:NNW).It belongs to Shuang-Hua fault whichstrike is NW.And the length of the fault is3.1km.Its width is a fraction of meters todozens of meters.The fault’s property is compresso-shearing.In area,it is the mainore-bearing structure and lead ore structure.The I ore body,main body of the minearea is native to the fault.The main magmatic rock is made in Yanshanian. The mainlithology is acidity and acid.The biotite granodiorite and syengranite have closerelationship with the area’s mineralization.The main ore types is quartz-vein type.There are a little ore exists in the wallrock and the type is veinlet-disseminated.The main metallic mineral are molybdenite，pyrite.Sometimes,we can see marcasite and limonite.The ore textures include anhedraltexture, anhedral t-half form exture,cataclastic texture and so on.The ore structuresinclude Vein, the net vein structure and fine vein-disseminated structure.The wall rockalteration includes Silicide, potassium, sericitization, kaolin.In someplace wo can seeepidotization and chloritization. There are8ore bodies in Badaohezi molybdenum deposit.And6ore bodies’mineral reserve have been estimated.In all of the ore bodies，I ore body is the biggestone.Its ore reserve account for94percent of gross reserves.The length of I ore bodyis3.1km.Its width is a fraction of meters to dozens of meters.The Scale, occurrenceand form of I ore body are controlled by Mentoulazi-Donggou fault.The reserves typeof I ore body is122b.The other ore bodies Parallel or nearly parallel Ibody.Their scaleis smaller than I ore body.According to the results of metal minetal electron probe analysis,there are twomain metal minerals：molybdenite and pyrite.The pyrite’s formula is Fe（As0.01-0.043）S1.90-2.00.And pyrite have a high content of As and a low content of Mo. The contentof As is between0.57-2.59%.And the average content of Co is0.053%,this impliesthe deep-focus and hydrothermal origin of the pyrite.The molybdenite’s formula isMo0.95S2-Mo0.97S2.The content of Mo is58.59%-59.80%,average59.1%.The contentof Mo is a little lower than its theoretical value（59.94%）. The content of S is40.11%-41.53%,average40.8%,a little higher than its theoretical value.The content ofthe other element in the molybdeniteis very low.The fluid inclusion research shows that Badaohezi molybdenum deposit’s mainmetallogenic temperature range is180-240℃， main salinity range is1-5wt%NaCl,main fluid density is0.84-0.94g/cm3,and0.88g/cm3on average.And themetallogenic pressure is mainly btween9.85-19.35MPa,depth is between1.09-1.93km.Its mineralization environment is mid-low tempreture,low salinity andepithermal。The δ34S(‰) vaule of the Badaohezi metal minetal changges in the range of0.7-2.3‰,R=1.6‰.Its δ34S(‰) vaule is similar to the vaule of the magma source.Thisimplies its S comes from the upper mantle’s magma in deep source.The magmatic geochemistry shows that Badaohezi’s granite is a kind of granitewhich enriches Si, Al.It belongs to high K Calc-alkaline series rock.The contentofΣREE is （111.41~124.32）×10-6，and its average content is116.42×10-6。The vauleof LREE/HREE is between10.67~12.68.The Badaohezi granite enriches in LREEand has an Eu negative anomaly. This suite of granite rocks enrich in LILE such as Rb,Ba,K, Pb,relatively depleting in HFSE such as Nb、Ta、Ti、P,this reflects it belongsto the high grade of maturity of the island-arc granites. So we get the conclusion thatthe tetonic setting is post-Oceanic crust subduction to syn-collision stage，witch iscompression to extension transition. Its formed in early Yanshanian.The Re-Os isotopic date of the molybdenum is178.3±1.4Ma.The mainMetallogenic mode is generally vein fill.So we determine the type of the deposit tobe mesothermal hydrothermal vein deposit.