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摘要
The heterogeneous mantle sources are generally caused by involvements of crustal recycling material into lithospheric mantle. The mafic magmatic rocks derived from heterogeneous mantle sources can provide important information for revealing mantle evolution and crust-mantle interaction. In this paper, we conducted new LA-ICP-MS dating of zircon in mafic rocks from the Feidong area of the southern section of the Zhangbaling uplift of the Tan-Lu fault zone, and obtained ages concentrated in the range of 127 Ma to 122 Ma. These samples show SiO2 contents of 51.33% to 54.01% and Mg# values of 52.6 to 70.0, with Na-rich and alkali-rich（σ = 2.46 to 4.22）, belonging to the subalkaline and high-K cal-alkaline series. These mafic rocks are enriched in large-ionic lithophile elements（LILEs, such as Ba, Pb, and K）and relatively depleted in high-field strength elements（HFSEs, including Nb, Ta, Ti, etc.）, exhibiting arc-like geochemical characteristics. Zircon Hf-O isotopic compositions show extremely negative εHf （t）values（-23.4 to -21.2）and slightly higher δ18O values（5.49‰ to 6.01‰）, showing a consistent evolutionary trend and similar distribution characteristics with the isotopic composition of the Neoproterozoic plagioclase amphibolite. Therefore, the enriched isotopic characteristics of these mafic dykes in the Early Cretaceous were mainly inherited from the lithospheric mantle in the Neoproterozoic（～800 Ma）, caused by the decompression melting of the ancient lithospheric mantle during the extension of Tan-Lu fault zone. ? 2023 Science Press.
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