Fingerprinting subducted oceanic crust and Hainan Plume in the melt sources of Cenozoic Basalts from the South China Sea Region. (21st July 2020)

• Record Type: Journal Article
• Authors: Tian, Zhi‐Xian; Yan, Yi; Huang, Chi‐Yue; Dilek, Yildirim; Yu, Meng‐Ming; Liu, Hai‐Quan; Zhang, Xin‐Chang; Zhang, Yong
• Is Part Of: Terra nova. Volume 33:Number 1(2021)
• Page Start: 21
• Page End: 29
• Publication Date: 2020-07-21
• Subjects: Earth sciences -- Periodicals; Geology -- Periodicals; 550
• DOI: 10.1111/ter.12486
• Languages: English
• ISSNs: 0954-4879

Abstract

Abstract: Geochemical data compilation of Cenozoic basalts recovered from the South China Sea tectonic domain shows westward weakening of the influence of a focal zone‐like component in Nd–Hf, Nd–Pb and Sr–Pb, but not in Pb–Pb isotope spaces because the Pb isotopes are dominantly controlled by the high U/Pb component derived from the subducted Pacific oceanic slab. Low Th/U melt generated by recycling of marine carbonates, rather than the subduction‐related enriched mantle (EM2), signals the emplacement of the Hainan Plume at ~25 Ma. Radiogenic Hf in the pre‐existing ancient sub‐continental lithospheric mantle beneath the Cathaysia Block was greatly depleted by early‐stage magmatism influenced by the high U/Pb component. Hence, late Cenozoic basalts associated with the carbonatitic melts display contrasting Nd–Hf isotope covariations, with the Red River–Zhongnan Fault System as a dividing line, implying that the East and Southwest sub‐basins have been developed on the Cathaysia and Indochina Blocks respectively.