Diagenetic And Metallogenic Geochronology Of Uranium-bearing Boron Iron Deposit In Wengquangou Area,Fengcheng,Liaoning Province

In the Paleoproterozoic strata of eastern Liaoning region,the Lieryu formation at the bottom of the Liaohe Group was obviously enriched with boron elements and formed a number of boron-riched formations.Those boron-riced formations,which could be divided into a unified boron bearing rock series by previous researches,produced the boron deposits from the west to the East in the Liaodong-Jilin region.It has formed a world-famous boron ore belt and also constitutes an important boron mineral area in China.The boron deposit in Weng Quan Gou area of Fengcheng City,Liaoning province,belongs to the boron ore belt.It is a super large uranium bearing iron boron deposit.Chronology of wall rocks such as granulite and serpentine olivine basalts have been investigated,and the initial age of boron mineralization is basically determined to be 2.24-2.13Ga.In order to explore the relationship between uranium mineralization and borosineralization in temporal and spatial scales,chronology of uraninite and related geological bodies was carefully investigated to demonstrate the age of uranium formation.Finally,the genetic mechanism and the evolution process of the deposit is established according to the evolution of geotectonic background.The study of metallogenic chronology is based on the comprehensive analysis of U-Pb isotopic dating?TIMS?,in-situ LA-ICP-MS U-Pb isotope dating of uraninite and⁴⁰Ar/³⁹Ar isotope dating of muscovite.It is concluded that the age of uranium mineralization in Weng Quan Gou deposit is 1806 Ma.The chronological study of diagenesis uses the different geological bodies around the orebodies:the zircon LA-ICP-MS U-Pb isotope dating of the granite,the granulite,and the Pegmatite.The 2100Ma result of granite indicate an age of formation.The other ages are 1989±13Ma,1868±33Ma and 1865±57Ma,respectively,indicating the age of metamorphism.These geological bodies undergo the same metamorphism of 1840Ma¹900Ma,which could be attributed to the 1900Ma's regional metamorphism.Through the chronological study of uranium mineralization and the wall rocks,this paper demonstrates the correlation between uranium mineralization and iron&boron mineralization in temporal and spatial scales.Combining with the major tectonic,magma and metamorphic activities in the region,the genesis model of"four phase plus three stage model type"is proved,that is:?I?the volcanic sedimentary formation formed by the volcanic eruption period;?II?ore bodies experienced the formation period of magnesia bearing rocks,which features the emplacement of a large number of ultrabasic-basic volcanic rocks and deposition of marine facies;?III?regional metamorphism and mixed rock formation period,which could be divided into?a?hydrothermal metasomatic phase,?b?hydrothermal decomposition mineralization phase,and?c?post phase hydrothermal transformation phase.Above mentioned three stage model illustrate the complete process of iron boron uranium mineralization.Finally,the orebody experienced different degrees of structural transformation period?IV?to produce the ore body.