The volcanic-subvolcanic rocks in the Luzong Basin are characterized by high-K and rich in alkali, belonging to typical shoshonite series. These rocks is obvious depletion in high-field-strong-elements (HFSE)such as Nb and Ta, and rich in strong incompatible elements such as Rb, Th, U and K as well as light rare earth elements (LREE). Nd and Sr isotope compositions of the rocks are similar roughly to those of the enriched subcontinental lithospheric mantle in the Yangtze craton, implying that their parental magma came mainly from partial melting of the enriched subcontinental lithospheric mantle. Geochemical variations of the volcanic-subvolcanic rocks show that the shoshonitic original magma had undergone high-pressure (higher than the stabilization pressure of plagioclase, > 1.5 GPa) fractional crystallization, dominant Cpx and Ti-Fe oxide fractionation. These rocks are partially similarly the shoshonite series in intra-oceanic island arcs in geochemistry (such as Ce/Yb), possibly because lithospheric thinning has allowed upwelling of asthenospheric mantle to relatively shallow depths where a greater proportion of spinel-facies melting can contribute to magma generation.
