TY - JOUR
T1 - Multistage melt/fluid-peridotite interactions in the refertilized lithospheric mantle beneath the North China Craton
T2 - Constraints from the Li-Sr-Nd isotopic disequilibrium between minerals of peridotite xenoliths
AU - Tang, Yan Jie
AU - Zhang, Hong Fu
AU - Nakamura, Eizo
AU - Ying, Ji Feng
N1 - Funding Information:
Acknowledgments We are very grateful to Moriguti Takuya, Kobayashi Katsura and Akio Makishima for their help in clean lab works to Chie Sakaguchi and Hiroshi Kitagawa for their assistance for Sr–Nd isotopic analysis. We acknowledge the valuable comments by Paul Tomascak, Horst Marschall, Sonja Aulbach, Bjorn Mysen, Ralf Halama and an anonymous reviewer and editorial suggestions of Timothy L. Grove, which helped to improve the different versions of the manuscript. Inspiring discussions with Horst Marschall, Feng Guo and Wei Yang were highly appreciated. This research was financially supported by the Natural Science Foundation of China (90714008, 40773026 and 40534022), the State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, CAS (0808), and the program of COE-21 designated to the Institute for Study of the Earth’s Interior, Okayama University, Japan.
PY - 2011/6
Y1 - 2011/6
N2 - Elemental and Li-Sr-Nd isotopic data of minerals in spinel hosted by Cenozoic basalts allow us to refine the existing models for Li isotopic fractionation in mantle and constrain the melt/fluid-peridotite interaction in the lithospheric mantle beneath the North China Craton.Highly elevated Li concentrations in cpx(upto 24pp)relative to coexisting opx and olivine(< 4 ppm)that the experienced metasomatism by mafic silicate meltsanor fluids.The mineral δ7Li vary greatly, with olivine(+0.7 to +5.4‰) being isotopically heavier than coexisting opx (-4.4 to -25.9‰) and cpx (-33 to -21.4‰) in most samples. The δ7Li in pyroxenes are considerably lower than the normal mantle values and show negative correlation with their Li abundances,likely due to recent Li ingress attended by diffusive fractionation of Li isotopes. Two exceptional samples have olivine δ7Li of -3.0 and -7.9‰,indicating the existence oflow δ7Li domains in the mantle,which could be transient and generated by meter-scale diffusion of Li during melt/fluid-peridotite interaction.The 143Nd/144Nd (0.5123-0.5139) and 87Sr/86Sr (0.7018-0.7062) in the pyroxenes also show a large variation, in which the cpx are apparently lower in 87Sr/86Sr and slightly higher in 143Nd/144Nd than coexisting opx, implying an intermineral Sr-Nd isotopic disequilibrium.This is observed more apparently in having low 87Sr/86Sr and high 143Nd/144Nd ratios than in those with high 87Sr/86Sr and low 143Nd/144Nd,suggesting that a relatively recent interaction existed between an ancient metasomatized lithospheric mantle and asthenospheric melt, which transformed the refractory with highly radiogenic Sr and unradiogenic Nd isotopic compositions to the fertile lherzolites with unradiogenic Sr and radiogenic Nd isotopic compositions.Therefore,we argue that the lithospheric mantle represented by the has been heterogeneously refertilized by multistage melt/fluid-peridotite interactions.
AB - Elemental and Li-Sr-Nd isotopic data of minerals in spinel hosted by Cenozoic basalts allow us to refine the existing models for Li isotopic fractionation in mantle and constrain the melt/fluid-peridotite interaction in the lithospheric mantle beneath the North China Craton.Highly elevated Li concentrations in cpx(upto 24pp)relative to coexisting opx and olivine(< 4 ppm)that the experienced metasomatism by mafic silicate meltsanor fluids.The mineral δ7Li vary greatly, with olivine(+0.7 to +5.4‰) being isotopically heavier than coexisting opx (-4.4 to -25.9‰) and cpx (-33 to -21.4‰) in most samples. The δ7Li in pyroxenes are considerably lower than the normal mantle values and show negative correlation with their Li abundances,likely due to recent Li ingress attended by diffusive fractionation of Li isotopes. Two exceptional samples have olivine δ7Li of -3.0 and -7.9‰,indicating the existence oflow δ7Li domains in the mantle,which could be transient and generated by meter-scale diffusion of Li during melt/fluid-peridotite interaction.The 143Nd/144Nd (0.5123-0.5139) and 87Sr/86Sr (0.7018-0.7062) in the pyroxenes also show a large variation, in which the cpx are apparently lower in 87Sr/86Sr and slightly higher in 143Nd/144Nd than coexisting opx, implying an intermineral Sr-Nd isotopic disequilibrium.This is observed more apparently in having low 87Sr/86Sr and high 143Nd/144Nd ratios than in those with high 87Sr/86Sr and low 143Nd/144Nd,suggesting that a relatively recent interaction existed between an ancient metasomatized lithospheric mantle and asthenospheric melt, which transformed the refractory with highly radiogenic Sr and unradiogenic Nd isotopic compositions to the fertile lherzolites with unradiogenic Sr and radiogenic Nd isotopic compositions.Therefore,we argue that the lithospheric mantle represented by the has been heterogeneously refertilized by multistage melt/fluid-peridotite interactions.
KW - Lithium isotope
KW - Lithospheric mantle
KW - Melt/fluid-peridotite interaction
KW - North China Craton
KW - Peridotite xenoliths
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U2 - 10.1007/s00410-010-0568-1
DO - 10.1007/s00410-010-0568-1
M3 - Article
AN - SCOPUS:79955867551
VL - 161
SP - 845
EP - 861
JO - Contributions of Mineralogy and Petrology
JF - Contributions of Mineralogy and Petrology
SN - 0010-7999
IS - 6
ER -