Characteristics and genesis of uranium mineralized lenses and its implications for deep-source uranium metallogenesis in Datian area of Panzhihua,Sichuan Province
[Objective]A very special and echelon arrangement uranium mineralized lenses group were found in the Datian area of Panzhihua,Sichuan Province,with important research value.[Methods]Through the comprehensive studies,including petrology,mineralogy petrochemistry,isotope geology and chronology,uranium occurrence state the genetic relationship between uranium mineralization and lenses.[Results]The lenses mainly consist of plagioclase with strongly sodium zoisitization,and have typical magmatic mosaic texture,with age of 821 Ma(SIMS zircon U-Pb age).They have the chemical composition characterices of high Na2O(3.95％-5.68％,average 5.09％),CaO(4.40％-7.35％,average 5.46％),low SiO2(51.52％-55.09％,average 53.34％).The analysis of trace element show that lenses have very low ΣREE content(9.96×10-6-33.63×10-6,average 22.03×10-6),positive Eu anomalies(δEu=1.59-5.51,average 2.68)and special REE distribution pattems.The results of ISr(0.7060-0.7088,average 0.7074)indicate that the raw material of lenses coming from the mantle.The mainly uranium occurrence state in lenses is the unique"U-Ti minerals aggregates".The"U-Ti minerals aggregates"are mainly composed of rutile,uranium-titanium mixture,brannerite and uranium,and the minerals in"U-Ti minerals aggregates"have the evolutionary characteristics of"rutile(Ti)→uranium-titanium mixture(Ti>U)→brannerite(Ti<U)→uranium(U)".[Conclusions]According to the relationship between uranium minerals and lenses,and the REE tracer method of uranium minerals,it is confirmed that the uranium mineralization genesis is relation to magmatism.It is speculated that the NaU4+(Ti4+)[TiO4]4+(F,Cl)is mainly complex in the deep environment with high temperature(>700℃)and high pressure(>15 kbar),and it can move and concentrate in the sodium-rich site in the lenses.The U and raw material of lenses originate from same magma,and the"U-Ti minerals aggregates"are separated from magma body in the process of isobaric cooling.The discovery of uranium mineralized lenses in Datian area of Panzhihua provides the direct geological case that uranium can be enriched in the mantle,and this discovery provides a reference for the discussion of deep-source uranium metallogenesis.
uranium mineralized lensesU-Ti minerals aggregatesanorthositemantle sourcemineral exploration engineeringDatian area of PanzhihuaSichuan
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