The Study Of Granite Of Paleoproterozoic Of The Lincheng In Hebei Province

Granite research in Lincheng area of Hebei Province,is a monographic study of practice base construction based on Lincheng Qishan lake.The study area is located in Lincheng County,Xingtai City,Hebei Province,adjacent to the Taihang Mountains in the South East,the tectonic position under the Zanhuang uplift,southeast margin of North China platform.According to the geology of the research methods,through field investigation and indoor test methods,the characteristics of granite rock mass distribution,petrology characteristics,rock geochemical characteristics,magmatism and tectonic evolution are discussed.Field investigation mainly for route reconnaissance and the measured profile,find out the types of granite rock,occurrence and the phase,surrounding rock type and other characteristics;Indoor research,the main elements analysis is X-ray fluorescence spectrometer(PW4400);Trace rare earth elements is plasma mass spectrometer(PE300D)analysis,and then preparing the form and the maps indoor synthetic analysis.Granite in the study area consists of orthoclase granite and monzonitic granite.Orthoclase granite with larger scale,in "A" shape distribution,is arch type in place,which separates the edge facies and intermediate facies;Monzonitic granite intrusive contact orthoclase granite and gneiss of Shijialan group,scattereing patch shaped,is middle plutonic phase,in the contact with orthoclase granite area contamination is obvious metasomatic features.Both kinds of granite for aluminum series,combining Na2 O + K2O-SiO2(TAS)diagram and silicon-potassium illustrations,belongs to calc-alkaline granite,for crust source S type granite.From the trace element characteristics,the two kinds of granite large ion lithophile elements enrichment,Cs,Rb,Ba and K high field strength elements Nb,Ta,and Ti losses,and Rb/Sr ratio and K/Rb is higher and the ratio is low,the U/Th also suggests that the magma source area for the upper crust;Nb/Ta ratio is low,show that two kinds of granite is a deep source of magmatic differentiation evolution.Orthoclase granite amount of rare earth elements to medium low,light rare earth concentration degree is high,(Ce/Yb)N is 11.46,explaining the level of magmatic differentiation is poorer,orthoclase granite crystallization cooling faster;Monzonitic granite amount of rare earth elements for medium high,light rare earth concentration degree is high,monzonitic granite is mainly formed in the late of magmatism.Comprehensive analysis of the main content,characteristics of trace rare earth elements,think that the two kinds of granite formed as crust source deep melting.Orthoclase granite in the study area w(Al2O3)/w(TiO2)ratio is more than 100,reflects its causes belong tolow temperature type when partial melting means should be in phase collision thickening;Monzonitic granite w(Al2O3)/w(TiO2)ratio is less than 100,reflects its causes,belong to the high temperature type when partial melting for the formation of orogenic reflects the adamellite since the end of the period.