Geochronology and origin of Paleoproterozoic charnockites with old crustal signature in the Haisyn block of the Ukrainian shield  

作　　者：M.Reshetnyk O.Zaiats L.Shumlyanskyy D.Starokadomsky L.Stepanyuk 

机构地区：[1]The National Museum of Natural History of the NAS of Ukraine,15,Bohdan Khmelnytsky Str.,Kyiv 01030,Ukraine [2]M.P.Semenenko Institute of Geochemistry,Mineralogy and Ore Formation of the NAS of Ukraine,34,Acad.Palladin Ave.,Kyiv 03142,Ukraine [3]School of Earth and Planetary Sciences,Curtin University,GPO Box U1987,Perth,WA 6845,Australia [4]Chuiko Institute of Surface Chemistry of the NAS of Ukraine,17,Generala Naumova Str.,Kyiv 03164,Ukraine

出　　处：《Acta Geochimica》2023年第3期393-408,共16页地球化学学报（英文）

摘　　要：Results of a geochemical and geochronological study of the Paleoproterozoic rock assemblage in the Haisyn block of the Ros-Tikych Domain of the Ukrainian Shield are reported.Within the block,the Haisyn Complex comprises granitoids,including pyroxene-bearing diorites,quartz diorites,granodiorites,amphibole-biotite and biotite granites,and aplite and pegmatite granites.Monazite U-Pb isotope age of charnockitic syenite belonging to the Haisyn Complex was defined at 2027±6 Ma.This age coeval with the time of granulite facies metamorphism and emplacement of numerous granitic intrusions in the area.The Sm–Nd apatite isochron yielded an age of 2100±150 Ma.TheεNd isochron value of-5 indicates a long crustal residence time of the crustal protolith.Geochemical data do not indicate any enrichment of the studied rocks in relation to the Eoarchean and Neoarchean charnockites developed in the same area.So,if the model of partial melting of the older crustal protolith is involved then the degree of melting must be quite high.However,deep negative anomalies of Sr,Eu,Zr,and Ti indicate that plagioclase,zircon,and Fe–Ti oxides probably remained unmelted in the source.The Haisyn block was buried in the lower crust at high temperature and pressure conditions in the Paleoproterozoic time.Such a situation resulted in partial melting of the existing crust and formation of melts,containing undigested zircon and bearing ancient Nd isotope signature.

关 键 词：PALEOPROTEROZOIC CHARNOCKITE Ukrainian Shield U–Pb dating Crustal evolution 

分 类 号：P59[天文地球—地球化学] P534.3[天文地球—地质学]