Mineralization Features And Genesis Of Taoxikeng “Basement-typed” Tungsten Deposit In Jiangxi Province

Tungsten is the significant strategic resources in our country, Nan Ling region is important tungsten ore area in our country.In recent years,a major breakthrough in deep-prospecting for Taoxikeng tungsten deposit is an important instance of ore-prospecting breakthroughs under the "five floors and basement" model, this paper is the typical tungsten ore deposit study on the basis of lots of field geological examinations and all kinds of sample processings in laboratory, through the comparative analysis of different mineralization types of mineralization.Taoxikeng tungsten deposit is located in Nanling tungsten-tin metallogenetic zone of Chongyi County of Jiangxi Province, belongs to Chongyi-Dayu-Shangyou exploring prospect of Jiulongnao ore field. Mining area tectonic is located inside of the Cathaysian plate in the Eurasia plate with Hamanishi Pacific plate subduction zone, the west side of wuyi uplift, the middle of luoxiao fold belt. “Five floors” vein of mining area mainly occurs in the sinian- Cambrian strata, and "basement" vein occurs in concealed granite in vivo of Taoxikeng tungsten deposit,which two are not well versed in both.For this thesis mainly research, the outside contact zone “five floors and the inner contact zone “basement" vein from different parts of the geological characteristics and geochemical differences in Taoxikeng tungsten deposit, reveal the connection between "five floors" and "basement".At the same time, the contrast between"basement" vein, the single vein and vein show the evolution regularity and migration direction of ore-forming fluid. Through the study, the following points are obtained:1.Compare tungsten ore body of vein type of quartz between the outside contact zone “five floors and the inner contact zone “basement" vein, found that the "basement" of tungsten ore vein features show that: pulse amplitude stability in the single pulse, the local vein appears branch vein、composite、thin out reappearance、thin out side reappearance、expand or shrink of vein、broken、compound vein structure and “vein in vein” and so on.2.“Basement "ore mineral mainly is wolframite- sulfide combination," five floors " ore mineral at the same time exists high temperature oxide phase and low temperature sulfide phase, and presents reverse zoning characteristics. "Basement" wolframite shows idiomorphic or hypidiomorphic, changes in vein enrichment wolframite"bags ". In the vein also develops give priority to with chalcopyrite sulfide, visible chalcopyrite ore bags. The gangue minerals quartz usual forms in the vein wall thick subidiomorphic crystal, it is also seen quartz geode at local position, that is shows the "basement" has sufficient ore-forming space. Ore-forming hydrothermal strength is reduced compared to the "five floors".3.Through ore mineralogy characteristics of black tungsten,it shows that the main components of black tungsten of “five floors” and “basement” is high iron and low manganese type of wolframite. The content of WO3 and Fe O or Mn O content has no obvious linear relationship, and negatively correlated with Nb2O3 relations. The content of Nb or Ta changes greatly, and higher than “five floors”.Trace elements and rare earth elements between “five floors” and “basement” have the same allocation model,along with the development of the metallogenic period of time and stages, differentiation the ore and heavy rare earth elements is more apparent, black tungsten of “basement” of this phenomenon is more obvious than that in “five floors”. In aspects of mineral assemblage characteristics, ore bearing quartz veins of "five floors" containing reverse zonation of quartz-sulfide phase and reverse zonation of quartz-sulfide phase,its suggest black tungsten of “five floors” and “basement” have the same ore sources,but they product different mineralization period of time.4.In “basement” types of fluid inclusions of quartz from the ore mainly for two-phase gas-liquid inclusions and contains a small amount of CO2 polyphase inclusions. Wide uniform temperature distribution, distribution from 170℃ to 340℃, shows a multimodal features, but the vast majority of lower than 270℃(280℃ ~ 340℃). Single inclusion laser Raman probe test shows that the inclusions in the gas phase composition is given priority to with H2 O, followed by CO2, and there were a small amount of CH4 etc. CO2 of gas phase composition plays a large role in the migration of elements of ore-forming. Uniform temperature of the high temperature range is relatively lack compared with the" five floors,which is consistent with mineral assemblage characteristics.5.Scope of the change of sulfur isotope, suggests that the source of sulfide sulfur of “basement” and “five floors” are single.They all have the characteristics of magmatic sulfur. Characteristics of hydrogen and oxygen isotopes suggest that the ore-forming fluid are the characteristics of magmatic water mixed with meteoric.Comprehensive the above view，the formation of quartz-vein type tungsten deposit of “basement” of Taoxikeng tungsten deposit is bound up with ultra fine grained biotite granite in acid of continental Crust Transformation Type at early Yanshan. It showed that the characteristics of more is sue of multistage pulse.The ore body obviously controlled by the top of processes of the concealed rock mass for the centre of NW to shear or tensile fracture fissure system. The formation of “five floors+basement” of Taoxikeng tungsten deposit is the result of many mineralization stages and periods process of evolution of the same mineralization mother rock. Taoxikeng tungsten deposit is pulsating mineralization, mineralization mainly divided into two phases. The first phase of the mineralization formed the outside contact zone of the reverse zonation vein of "five floors", this is also main metallogenic period of Taoxikeng tungsten deposit.The second stage of mineralization is the result of pulsation of main metallogenic period,weak magmatism and the effect of the shell of “immiscibility”,it formed quartz-vein type tungsten deposit of “basement” gives priority to “wolframite- sulfide” quartz-vein inside contact zone.