Typomorphic characteristics and geological significance of fluorite in Mianhuakeng uranium deposit,north Guangdong
Uranium mineralization of Mianhuakeng uranium deposit in northern Guangdong is closely related to fluorite.To explore the evolution characteristics of the ore-forming fluid in the deposit,X-ray powder diffraction analysis,chemical analysis,and other methods were used to study the typomorphic characteristics of fluorite in ores at different depths and stages of mineralization.The results showed that from green fluorite in the early stage of mineralization to purple black fluorite in the later stage of mineralization,the Eu loss of purple black fluorite in the early stage of mineralization was more significant than the green fluorite in the early stage and purple fluorite in the late stage of mineralization,but the Eu loss of purple fluorite was slightly stronger than that of green fluorite;fluorite at each stage mostly shows weak negative Ce anomalies,a small portion shows weak positive Ce anomalies;in the Y/Ho-La/Ho diagram,fluorite samples in each stage are roughly projected in a horizontal straight line and Y/Ho is relatively uniform;at the same stage,the a0 value of fluorite shows a phenomenon of first increasing,then decreasing and then increasing with depth.The a0 value of fluorite formed in the early stage of the same middle stage is larger than that in the late stage.After comprehensive research,it was believed that the ore-forming fluid with fluorite formed under an environmental evolution from relative reduction to oxidation,and from a relatively closed hydrothermal system to an open system;the ore-forming fluids were isogenous.The purple fluorite stage may originate from the re migration and reformation of fluorite in the first two stages;The REE content and a0 value indicate that the ore-forming fluid in this area has the characteristic of alternating acid-base solutions.The cells parameters of deep fluorite crystal are still relatively large,indicating that the ore body is not deeply eroded and the depth has good mineralization prospects.
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