Zircon U-Pb age,whole rock geochemical and zircon Hf isotopic data are presented for Late Paleozoic granodiorites from the Taerqi region,central Daxing'anling to constrain its petrogenesis and tectonic implication...Zircon U-Pb age,whole rock geochemical and zircon Hf isotopic data are presented for Late Paleozoic granodiorites from the Taerqi region,central Daxing'anling to constrain its petrogenesis and tectonic implication.LA-ICP-MS zircon U-Pb age data indicates that the Late Paleozoic granodiorites were emplaced with age of333.4 ± 2.2 Ma(Early Carboniferous).Geochemically,the granodiorite samples have Si O2= 60.54%-71.40%,Na2 O = 4.04%--4.66%,K2 O = 1.65%--4.27% and Mg O = 0.96%--3.53%,belonging to medium-K to high-K calc-alkaline I-type granites.They are slightly enriched in large ion lithophile elements(e.g.Rb,Th,U and K) and light rare earth elements,and depleted in high field strength elements(e.g.Nb,Ta and Ti),with εHf(t) values of 8.0--11.8 and Hf two-stage model ages of 586-829 Ma.All these geochemical features suggest that the primary magma was derived from partial melting of Neoproterozoic to Phanerozoic newly accreted lower crust.According to the geochemical data and regional geological investigations,the Early Carboniferous granodiorites formed in an island arc setting linked to the subduction of the Paleo-Asian Oceanic Plate beneath the Xing'an Terrane.This also implies that the Xing'an and Songliao terranes have not amalgamated before the Early Carboniferous.展开更多
基金supported by the China Geological Survey (Grants 201301009018)
文摘Zircon U-Pb age,whole rock geochemical and zircon Hf isotopic data are presented for Late Paleozoic granodiorites from the Taerqi region,central Daxing'anling to constrain its petrogenesis and tectonic implication.LA-ICP-MS zircon U-Pb age data indicates that the Late Paleozoic granodiorites were emplaced with age of333.4 ± 2.2 Ma(Early Carboniferous).Geochemically,the granodiorite samples have Si O2= 60.54%-71.40%,Na2 O = 4.04%--4.66%,K2 O = 1.65%--4.27% and Mg O = 0.96%--3.53%,belonging to medium-K to high-K calc-alkaline I-type granites.They are slightly enriched in large ion lithophile elements(e.g.Rb,Th,U and K) and light rare earth elements,and depleted in high field strength elements(e.g.Nb,Ta and Ti),with εHf(t) values of 8.0--11.8 and Hf two-stage model ages of 586-829 Ma.All these geochemical features suggest that the primary magma was derived from partial melting of Neoproterozoic to Phanerozoic newly accreted lower crust.According to the geochemical data and regional geological investigations,the Early Carboniferous granodiorites formed in an island arc setting linked to the subduction of the Paleo-Asian Oceanic Plate beneath the Xing'an Terrane.This also implies that the Xing'an and Songliao terranes have not amalgamated before the Early Carboniferous.