Mantle sources of Cenozoic volcanic activities around the South China Sea revealed by geochemical and isotopic data using the principal component analysis (PCA)

Principal component analysis (PCA) was conducted to analyze geochemical and isotopic data and interpret the characteristics and types of mantle sources of Cenozoic volcanic activities around the South China Sea (SCS). Fifteen trace element indicators and five isotopic indicators were surveyed from 623 volcanic rock samples obtained from the SCS, Hainan Island, Fujian–Zhejiang, Taiwan, Vietnam, and Thailand to characterize the geochemical properties of the volcanic rocks, determine the types of mantle sources, and assess the influence degree of each mantle source. Two principal components (PCs) were extracted by PCA based on trace elements and Sr–Nd–Pb isotopic ratios, which are an enriched oceanic island basalt-type mantle plume and a depleted mid-ocean ridge basalt-type spreading ridge. In the Southeast Asian region, the influence of Hainan mantle plume on younger volcanic activities ( 13 Ma) in the same location. PCA was used to verify the mantle plume–ridge interaction model of volcanic activities beneath the expansion center of the SCS and refute the hypothesis that the tension in the SCS is triggered by the Hainan plume. The results of this study demonstrate the efficiency and applicability of PCA to the discussion of mantle sources of volcanic activities and provide a new method with which to analyze geochemical data.