The mafic intrusive Moskin and Parvaneh regions in the northwest and south of Urmia were inves-tigated for their geochemistry and petro-physical properties such as size,shape,and spatial distribution of their crystals.This type of study can be a powerful tool for analyzing the history of magma crystallization,along with geochemistry examinations.The gabbroic calc-alkaline rocks,with the Early Cenozoic is the relative age,consist of coarse pla-gioclase and amphibole with rare clinopyroxene and oli-vine in the Sanandaj-Sirjan zone at sedimentary-structural subdivisions of Iran.The depletion of HFSEs and enrich-ment of LILEs as arc-related rocks,as well as lower crust contamination(Nb/Th and K/Ce)symptoms,show that these gabbros formed at the continental arc setting from an enriched source.Considering the geographical position and relative age of the gabbros,they possibly outcropped dur-ing the Neo-Tethys subduction processes after the enrich-ment by considerably lower crust effects.The amphibole and plagioclase crystals with considerable abundance show linear crystal size distribution(CSD)patterns with a slope of(—1/Gt)-3 to—4 for amphiboles and plagioclase except for Parvaneh plagioclase which shows-16.The annealing(Ostwald ripening)caused the convex CSD on the small grains part at Parvaneh gabbro.Therefore,the ratio of nucleation to growth rates(J/G)for these minerals is 5-6 times,only for Parvaneh plagioclase is ten times which numerous nuclei were made by a significant degree of overstepping in the rocks.There is no magma mixing evidence because of the linear(one population of crystals)CSD patterns.The shape of amphibole crystals in gabbros is bladed(with S/I=0.4-0.5 and I/L=0.1-0.3)and bladed to tabular for plagioclase(S/I=0.4 and I/L=0.6-0.7).The spatial distribution patterns(SDPs)are calculated from a big R-value based on the nearest neighbor's theory for amphibole and plagioclase crystals,confirming clustered SDP for all of them.Also,the dihedral angle measurements(between amphibole and plagioclase grains)display that solid-state equilibrium is prevailing in the rocks.In this study,we tried to establish a relationship between geo-chemistry and petro-physical results and investigate the evolution of igneous rocks more accurately and all-inclu-sive.We should not neglect the importance of quantifying the texture of rocks.

Monir Modjarrad

Faculty of Science,Department of Geology,Urmia University,Urmia,Iran

地球化学学报（英文版）

[1]Monir Modjarrad-.Geochemistry and crystal shape,size and spatial distribution in arc-related gabbro,Urmia,NW Iran)[J].地球化学学报（英文版）,2022(06):1000-1018

Urmia,Moskin,Parvaneh,gioclase,oli,Sanandaj,Sirjan,outcropped,overstepping,SDPs

Geochemistry,shape,size,spatial,distribution,arc,related,NW,Iran,mafic,intrusive,regions,northwest,south,were,tigated,their,geochemistry,petro,physical,properties,such,crystals,This,type,study,powerful,tool,analyzing,history,magma,crystallization,along,examinations,gabbroic,alkaline,rocks,Early,Cenozoic,relative,age,consist,coarse,rare,clinopyroxene,vine,zone,sedimentary,structural,subdivisions,depletion,HFSEs,LILEs,well,lower,crust,contamination,Nb,symptoms,that,these,gabbros,formed,continental,setting,from,enriched,source,Considering,geographical,position,they,possibly,dur,Neo,Tethys,subduction,processes,after,by,considerably,effects,plagioclase,considerable,abundance,linear,CSD,patterns,slope,Gt,amphiboles,except,which,shows,annealing,Ostwald,ripening,caused,convex,small,grains,part,Therefore,ratio,nucleation,growth,rates,minerals,times,only,ten,numerous,nuclei,made,significant,degree,mixing,evidence,because,population,bladed,tabular,calculated,big,value,nearest,neighbor,theory,confirming,clustered,them,Also,dihedral,angle,measurements,between,display,solid,state,equilibrium,prevailing,In,this,tried,establish,relationship,results,investigate,evolution,igneous,more,accurately,inclu,We,should,not,neglect,importance,quantifying,texture

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