Oxygen isotopic compositions of zircons from pyroxenite (-145 Ma) of Daoshichong, Dabieshan have been measured by an ion microprobe. Both within the single grain and among different grains, oxygen isotopic ratios are ...Oxygen isotopic compositions of zircons from pyroxenite (-145 Ma) of Daoshichong, Dabieshan have been measured by an ion microprobe. Both within the single grain and among different grains, oxygen isotopic ratios are homogeneous, σ18O = (7.66‰±0.46)‰(1 SD, 1σ=0.10, n = 22). High σ18O values indicate that the mantle-derived parent magma of Daoshichong pyroxenite have undergone interaction with crustal materials. Combing with other geo-chemical constraints, the way of crust-mantle interaction is suggested to be source mixing other than crustal contamination. The time interval between crust-mantle interaction and formation of the parent magma of Daoshichong pyroxenite is less than several million years. The crustal component involving in crust-mantle interaction is mafic lower crust, and the parent magma of pyroxenite possibly contain large proportion (】37%) of such lower crust.展开更多
基金This work was supported by the Chinese Academy of Sciences (CAS) (Grant No. KZCX2-107)the CAS-CNRS cooperation project.
文摘Oxygen isotopic compositions of zircons from pyroxenite (-145 Ma) of Daoshichong, Dabieshan have been measured by an ion microprobe. Both within the single grain and among different grains, oxygen isotopic ratios are homogeneous, σ18O = (7.66‰±0.46)‰(1 SD, 1σ=0.10, n = 22). High σ18O values indicate that the mantle-derived parent magma of Daoshichong pyroxenite have undergone interaction with crustal materials. Combing with other geo-chemical constraints, the way of crust-mantle interaction is suggested to be source mixing other than crustal contamination. The time interval between crust-mantle interaction and formation of the parent magma of Daoshichong pyroxenite is less than several million years. The crustal component involving in crust-mantle interaction is mafic lower crust, and the parent magma of pyroxenite possibly contain large proportion (】37%) of such lower crust.
