Study On Metallogenic Geological Characteristics And Metallogenic Fluid Properties Of No.273 Uranium Deposit In Northern GuangDong

The No.273 uranium deposit is a typical granite-type uranium deposit in the northern part of the Nanling metallogenic belt in South China.The deposit is mainly located in the granite body and is adjacent to the Nanxion continental red basin.The deposit formation is controlled by strong tectono-magmatic activity in the area.On the basis of detailed field geological surveys and researches,this article has collected related research samples,carried out rock ore petrology,electron probes,microscopic temperature measurement of fluid inclusions,Raman gas composition analysis,C—O,Pb.Isotopes and other research methods are used to systematically elucidate the uranium metallogenic characteristics of No.273uranium deposits,analyze and discuss the ore fluid fluid properties,sources,and genesis of the deposits.Get to know as follows:?1?The formation of the No.273 uranium deposit is affected by the strong tectonic-magmatic activities in the region.The deposit is mainly composed of three ore belts,which are 273-I,273-II,273-III ore belts,and the three ore belts correspond to each other.Controlled by structural belts I,II,and III.the output,morphology,and scale of the ore body are controlled by structural belts.The ore bodies are mainly in the form of lenticular,spindle,lenticular,etc.,and are distributed in strips.The industrial ore body develops in the regions of expansion and contraction changes.The ore body is lamellar or like lamellar,with a large quantities.?2?The wall rock alterations in No.273 uranium deposits mainly include reddening,chlorite,sericitization,silicification,and fluorsparization.Uranium mineralization is closely related to alteration types such as hematite,chlorite,fluorsparization,and silicification.The primary uranium minerals in the ore are mainly bituminous uranium minerals,followed by titanium uranium ore and uranium thorium.The types of ore include bituminous uranium ore,pyrite,microcrystalline quartz,fluorite,and bituminous uranium or hematite.?3?The homogenization temperature of fluid inclusions in the ore-forming period of the No.273 uranium deposit is 139¹94.3°C,mainly concentrated between 160¹90°C;the salinity is 0.18-1.05 wt%NaCleq,the mean value is 0.4 wt%NaCleq,and the concentration is 0.18⁰.53wt%NaCleq;Density 0.876⁰.933 g/cm³,average 0.912g/cm³;Mineralization pressure 176.99⁴30.84×10⁵Pa,average 272.56×10⁵ Pa;Mineralization depth 0.59¹.44km,average 0.91 km.The above characteristics indicate that the ore-forming fluid of the 273 uranium deposit is a hydrothermal fluid with medium-low temperature,medium-low salinity,and medium-low density.The ore-forming process is in the medium-low pressure and medium-to-light metagenesis ore-forming environments.Microscopic Raman spectroscopy shows that the gas inclusions in the ore-forming fluid contain reducing gases such as CO2,CH4,N2,and H2O,which have certain similarities with the volatile components of the mantle fluid and are also typical of eastern China.The gas composition of the inclusions in the rock is similar,suggesting that the ore-forming fluid of the No.273 uranium deposit may originate from the mantle.?4?Carbon,oxygen,and Pb isotope studies have shown that the?¹³C range of the ore-forming fluid in No.273 uranium deposit is-6.6 to-8.1‰?PDB?with an average of-7.55‰,and the?¹⁸O value ranges from-16.5 to-21.1‰?PDB?,with an average of-17.9‰,?¹⁸O_SMOWMOW values range from 9.1 to 13.8‰with an average of 12.35‰.The above characteristics indicate that the carbon in the ore-forming hydrothermal fluid of the No.273uranium deposit is mainly derived from the deep CO₂ release,which is related to the deep mantle magmatic fluid.The Pb isotope characteristics show that the ²⁰⁶Pb/²⁰⁴Pb value is between 19.692²3.764?average 21.433?and the ²⁰⁷Pb/²⁰⁴Pb values ranged from 15.742 to15.979?average 15.843?and the ²⁰⁸Pb/²⁰⁴Pb values ranged from 39.238 to 39.450?average39.342?.Similart to the properties of basal metamorphic rocks or uranium-rich granitoids,implying that the lead in ore-forming fluids originates from the upper crust and is closely related to the deep ore-forming fluids.?5?It is considered that the No.273 uranium deposit has the characteristics of typical mantle fluid metallogenesis.Mantle derived mafic magma increase and mantle metallogenic fluid uplift,activate the uranium in the granite body and the basement metamorphic rock,and dissolve and migrate with the ore-forming fluid rich in volatile matter.Along with the continuous migration of ore-forming fluidsand and contain with various degrees of degassing,the ore deposit are precipitated in the structural parts of medium-shallow depth and medium-low pressure.