Highly heterogeneous Late Mesozoic lithospheric mantle beneath the North China Craton: evidence from Sr-Nd-Pb isotopic systematics of mafic igneous rocks
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Zhang, HF
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机构:Chinese Acad Sci, Inst Geol & Geophys, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
Zhang, HF
Sun, M
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机构:Chinese Acad Sci, Inst Geol & Geophys, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
Sun, M
Zhou, MF
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机构:Chinese Acad Sci, Inst Geol & Geophys, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
Zhou, MF
Fan, WM
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机构:Chinese Acad Sci, Inst Geol & Geophys, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
Fan, WM
Zhou, XH
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机构:Chinese Acad Sci, Inst Geol & Geophys, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
Zhou, XH
Zhai, MG
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机构:Chinese Acad Sci, Inst Geol & Geophys, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
Zhai, MG
机构:
[1] Chinese Acad Sci, Inst Geol & Geophys, Lab Lithosphere Tecton Evolut, Beijing 100029, Peoples R China
[2] Univ Hong Kong, Dept Earth Sci, Hong Kong, Hong Kong, Peoples R China
The lithospheric mantle beneath the North China Craton changed dramatically in its geophysical and geochemical characteristics from Palaeozoic to Cenozoic times. This study uses samples of Mesozoic basalts and mafic intrusions from the North China Craton to investigate the nature of this mantle in Mesozoic times. Sr-Nd-Pb isotopic data demonstrate that the Late Mesozoic lithospheric mantle was extremely heterogeneous. In the central craton or the Luzhong region, it is slightly Sr-Nd isotopically enriched, beneath the Taihangshan region it has an EM1 character (Sr-87/(86)Sri = 0.7050-0.7066; epsilon(Nd(t)) = -17- -10), and beneath the Luxi-haodong region, it possesses EM2-like characteristics (Sr-87/(86)Sri up to 0.7114). Compositional variation with time is also apparent in the Mesozoic lithospheric mantle. Our data suggest that the old lithospheric mantle was modified during Mesozoic times by a silicic melt, where beneath the Luxi-Jiaodong region it was severely modified, but in the Luzhong and Taihangshan regions the effects were much less marked. The silicic melt may have been the product of partial melting of crustal materials brought into the mantle by the subducted slab during the formation of circum-cratonic orogenic belts. This Mesozoic mantle did not survive for a long time, and was replaced by a Cenozoic mantle with depleted geochemical characteristics.