Geological Andgeochemical Characteristics Of Hydrothermal Uranium Deposit In Genduoarea,Zuogongtown,Tibet

Genduo is located in“san-jiang”region of northest Tibet sandwiched between Ban gong lake-Nu jiang river and lan cang river ancient tectonic plates.According to the uranium resources potential assessment project in Genduoarea,Zuogongtown,Tibe t province.A detailed discussion was carried out in this paper based on the previousp aper,and the petrology,metallogeny,geochemical and theory of uranium deposits,me tallogenic was combined with make system generalizations on the metallogenic envir onment and metallogenic geological characteristics.Special study of the geochemistry characteristic of Genduo deposit and system study on characteristics of major eleme nts,trace elements and rare earth elements of ore-host rock and magmatic intrusions on hydrothermal uranium deposits were analyzed,combination with ore-controlling facto rs,and genesis of genduo deposits,summed up the metallogenic factors and genetic mechanism of ore deposit.And the results are listed as follows:1)Main ore bearing strata of uranium deposit in Genduo is thick layered quartz sandstoneof Dongda village information in the upper Triassic.Uranium anomaly zonein Miduocirenpuand in xiaozalun,industrial uraniumbelt in zalungongyeand guoqingguo weredeveloped infootwallstrata of Sheila fault which obviouslycontrols the orebody.2)Through comparisoncharacteristicsof constant elements of aplitic granite and ganodiorite,there are significant differences in SiO₂,Al₂O₃,K₂O/Na₂O,DI.Content of SiO₂in granitic apliteis is higher,DI is larger in aplitic granite,butcontent of Al₂O₃in granodioritecontent is higher,K₂O/Na₂O ratio is bigger.Normal granite in Genduo area is different from Late Triassic?late Indosinian?granitoidrocks,but is similar toearly Jurassic?early Yanshanianperiod?granite,from composition characteristics ofthe trace element and Rb/Sr ratios.REE distribution patterns of granite-apliteobviously are incline right type.compared to the?Euof granite-aplite,Eu negative anomaly of granodiorite is more distinct,based on the abovedifferences,which show that two kinds of rock may not be the evolutionproduction of the same magma,deducing that granite-aplite is production of early yanshanianmagmatic activity.3)Compared with the average SiO₂content of no mineralization aplite granite in Genduo,the average SiO₂content of mineralization aplite granite and ore decreased 16.18%and the average SiO₂content increased 10.59%,which show plenty of silicon migrated in and calcium migrated out,thus reveal the close relationship between uranium mineralization and carbonatization hydrothermal alteration in Genduo deposit from one side.4)The characteristics of trace elements and its enrichment features indicate that the types of trace elements and their content of sandstone and aplite granite are nearly the same,Pb?Cu?Mo?Cd?V?Zn obviously enriched and they are all typical sulfophile element and hydrothermal metal ore-forming elements;Co?Cr obviously loss.The above characteristics show that the mineralization type in sandstone and aplite granite are the same and all belong to typical hydrothermal mineralization,and the source of hudrothermal solutions are also the same.5)The rare earth elements chondrite standardized distribution patterns of ore in Genduo uranium deposit is consistent with the pattern of upper curst and it is indicate that rare earth characteristics of rocks associated with uranium in Genduo is similar as minerals,both of them comes from crust in the continent and show that aplitic granite is a typical class of S type granite rock.6)According to comparative analysis ofnormal surroundingrock with the trace element characteristics,Cu,Pb,zinc came from the late indosinian granite classes;W may come from the formation of rocks and early yanshan granite rock;U came mainly from the late Indosinian granite diorite and early yanshan granite class,formation may also provide some of the uranium source.Through characteristics analysis of the delta Ce,the delta Eu values,the ore-forming hydrothermal was thought to be mainly formed by hot water hydrothermal precipitation cycle.7)In a preliminary summary on key factor to mineralization of Genduo,uranium metallogenic model of the"Genduo type"was established.