Journal
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
Volume 125, Issue 7, Pages -Publisher
AMER GEOPHYSICAL UNION
DOI: 10.1029/2019JB019260
Keywords
Yangtze Block; late Paleoproterozoic to early Mesoproterozoic; mafic magmatism; mantle plume; supercontinent breakup; Nuna
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Funding
- National Natural Scientific Foundation of China [NSFC41972242]
- Fundamental Research Funds for the Central Universities [CUGCJ1709]
- MOST Special Fund from the SKLGPMR [MSFGMR 01-1]
- Fundamental Research Funds for National Universities, China University of Geosciences (Wuhan)
- Australian Endeavor Fellowship [6272-2018]
- Australian Research Council [FL160100168]
- government of the Government Council on Grants, Russian Federation [14.Y26.31.0012]
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Numerous late Paleoproterozoic to early Mesoproterozoic mafic magmatic rocks are exposed in the southwestern Yangtze Block, corresponding to early breakup of the Nuna supercontinent. Geochronological data reveal three episodes of mafic magmatism at similar to 1,740, 1,700, and 1,500 Ma. The two older generations have MORB-like Nb/Ta ratios and superchondritic Nd-Hf isotopes, indicating that they were likely derived from partial melting of asthenospheric mantle. In contrast, the similar to 1,500 Ma mafic rocks possess OIB-like Nb/Ta (16.7-19.1) and Zr/Hf (41.0-45.1) ratios, epsilon(Nd) (t) values (-0.8 to +0.1), and epsilon(Hf) (t) values (-3.3 to +8.4), suggesting that they originated from a mantle plume. These three pulses of mafic magmatic activity in the Yangtze Block have geochemical features (such as TiO2 contents, Nb/Y, and La/Yb values), similar to coeval mafic rocks in Siberia and Laurentia, consistent with detrital zircon provenance studies, which show a spatial linkage of the Yangtze Block with northern Laurentia in the Nuna configuration. Taking all synchronous mafic magmatism into account, a mantle plume beneath southern Siberia was considered to be initiated at similar to 1,750 Ma forming a broad region of mafic magmatism that extended into the Yangtze Block as well as beneath northern Laurentia and resulted in lithospheric extension. The Yangtze Block was possibly the nearest neighbor to northwestern Siberia at similar to 1,500 Ma and subsequently drifted from the Nuna supercontinent induced by the similar to 1,500 Ma Kuonamka mantle plume, heralding a period of limited magmatic activity and tectonic quiescence in the Yangtze Block that extended throughout the remainder of the Mesoproterozoic.
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