| The Fankou lead-zinc deposit is a famous large-extra large scale lead-zinc deposit where located in Shaoguan of Guangdong Province, China. The tectonic located at the north of Quren in North Guangdong. It is play an extremely vital role in the mineral resources.Over the years, many scholars researched the deposit, using different methods and different angles, and accumulated a wealth of basic information, and proposed form the mineralization and ore-controlling conditions of the deposit, but its sources of minerals, deposit genesis mechanism research remains unclear. Based on study of minerals deposit, stratabound ore deposits, geochemical and other modern metallogenic theory as the instruction, on the basis of field geological observation, focused research from geochemistry, and probes into the source of ore-forming materials, ore-controlling factors, genesis of deposit and mineralization process, comprehensive metallogenic model is established finally.A large number of basic geological information show that, Stratums of Cambrian, Devonian, Carboniferous and Permian developed in the ground in Fankou mining area. Fankou mining area included NWW, NW, NNE and NE fault belts. After the formation of the sedimentary strata, loss of part or all of the stratums in between C2ht and D3ta, lack of them formed several to dozens of meters fragmentation mud or cleavage of strata, which is named as "The broken layers", and it is the upper boundary in Fankou deposit. The northern range is generally NWW to lack of stratum; then NW trending fault zone (former NW trending fault zone is referred to as F203) formation, NW trending fault zone may be in the south area of the mine activities associated with the NWW trending fault zone compound, Fracture F203composed of NWW and NW trending fault zone. The NW fault belt is a lower boundary of mining area, between the formation of ore bodies should be two.F203development NNE to the secondary fracture zone, there was F1～F10fault, the fault is the main ore-bearing structure of ore. NE fault zone as a NNE fault zone more secondary structures, including F100, F101, F102, F104fault, the fault and NNE trending fault zone interchange is an ideal place for the formation of ore bodies.Trace and rare earth elements of rock and ore shows that, the element of Fe mainly come from carbonate of mining area. The stratums of Fankou mining area of alteration in different degree due to late hydrothermal, affected the values of trace and rare earth elements, Similar characteristics of the different stratums indicated layers of Fankou mining area are affactd by same properties hydrothermal.Stable isotope showed that, the813C value is-6.5‰and δ18O value is14.9%o with Ordovician, it is the lowest of all and mainly affected by terrigenous detrital materials. The δ13C value is2.17‰and δ18O value is21.9%o with Carboniferous, it is greater than other stratums and affected by lithology. Devonian as the main metallogenic formation, From deep to shallow, the values of carbon, oxygen and strontium are decreased along with hydrothermal alteration weaken, its in addition to the impacts of lithology and marine sedimentary cycle, mainly affected by the late hydrothermal process.The lead isotopes in ores are mainly originated from ancient crustal material. The lead isotopes are the mixture of multiple sources, Surrouding rocks similar with the source. The sulfur of the ore came from sulfates in the seawater, and experienced the reduction of organic matter. The relative abundance of pyrite, sphalerite, and galena is:δ34S value of pyrite> δ34S value of sphalerite>δ34S value of galena.The ore-forming fluid temperature concentrated in110～150℃and160～210℃, Fluid inclusions of light brown sphalerite, homogenization temperature is109℃in average, and usually low salinity(<4wt%NaCl). The main content of the fluid is H2O (liquid)-H2O (gaseous), NaCl-H2O, not found Sodium chloride crystal, and organic matter such as CH4, HCl, CO, a few of organic matters involved in mineralizationg.The formation of Fankou lead-zinc deposit is closely related to the regional dolomitization. The time of ore-forming is basically during86.8～90.7Ma, it corresponds to the period which red bed basin was widely developed in Southern China. Further, and the ore-bearing stratums are dolomitized, which is also correspond to the large scale dolomitization in this region.This study suggests that Fankou lead-zinc deposit is mainly formed during a period of hydrothermal mineralization. There are three metallogenic stages:early, main and late metallogenic stage. Early stage is mainly the formation of pyrite ore body and nearly absent of lead-zinc, main stage is the formation of lead-zinc ore body with pyrite, late stage is marked by the presence of coarse grained bright yellow colored pyrite, produced by the effect of hydrotherm of late mineralization period. Two main categories of ore-forming fluid in Fankou lead-zinc deposit:the first is the deep fluid at the bottom of the mining area, which is possibly originated from the basin brine of regional Cretaceous red strata. The second is the original formation water in carbonate rocks in upper part of the mining area, mainly from atmospheric water. The two types of fluid meet at specific condition at proper place, the metallic elements of two fluids were responsed, caused aggregation and concentrate. Finally, they formed giant ore body.Fankou lead-zinc deposit and MVT deposit have many similarities,but the differences are higher temperature, lesser organic matter, fewer collapse breccia, fewer colloidal from texture than MVT deposit. But geological and geochemical characteristics, ore-forming fluid transport, sulphides deposition are similar with MVT deposit, Fankou lead-zinc deposit as a whole belongs to this model of MVT deposit. |
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