The Research Of Geochemistry,Geochronology And Petrogenesis Of DaHeNan Rock Mass In Hebei Province

DaHeNan Rock Mass belongs to the eastern edge of Shanxi fault uplift of the North China plate,with the northern section of the Taihang uplift,located NNE-trending Taihang tectonic-magmatic-metallogenic belt.To study the material composition and petrogenesis of DaHeNan Rock Mass,this paper uses field geological survey,interior sheet identification,CT scanning,the main and trace element testing,Sr-Nd-Pb isotope trace and LA-ICP-MS zircon U-Pb geochronology and other research methods.We obtain the following results:(1)The study area is mainly exposed diorite,monzodiorite,quartz monzonite diorite,quartz monzonite,monzonite granite and syenogranite.Overall magmatic rocks are Calc-alkaline-K calc-alkaline series,as well as quasi-Aluminum-weakly peraluminous series category.(2)Through the study about the rare earth elements,it reveals that fractionation of light and heavy rare earth in DaHeNan rock mass is significant.All samples show a right-wing-type REE distribution patterns,LREE enrichment,HREE loss.? Ce is less than 1.Diorite and monzonite reveal no Eu anomaly;quartz monzonite diorite,quartz monzonite,monzonite granite and syenogranite reveal weak negative Eu anomaly.Syenogranite has obvious negative Eu anomaly.In trace elements From diorite to syenogranite,the content of Co,Ni,Cr is declining,while the trend of other elements is not obvious.(3)Sr-Nd-Pb isotopes indicate that magma of DaHeNan Rock Mass may come from a mixed crust-mantle source region.(4)The results of U-Pb zircon age reveal that the emplacement time of the DaHeNan rock mass is 127-147.4 Ma.The age of quartz monzonite is 146.8 Ma and 133.7 Ma.The age of monzonite granite is 134.2 Ma.The age of syenogranite is134.0 Ma and 135.2 Ma.So,the emplacement time of DaHeNan Rock Mass belongs to the Late Mesozoic Jurassic-Early Cretaceous.(5)Comprehensive studies show that different rock types of DaHeNan Rock Mass is not the product of magmatic differentiation in the same period,may be the result of homologous lava pulsating intrusion of multi-stage.