The volcanic-subvolcanic rocks in the Luzong basin are characterized by high-K and rich in alkali, belong to typical shoshonite series. In geochemistry, these rocks exhibit obvious depletion in high-field-strong-elements (HFSE) such as Nb and Ta, enriched 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 with the enriched subcontinental lithospheric mantle of the Yangtze craton, imply that their parental magma mainly came 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. But low-pressure (< GPa) fractional crystallization and upper crustal contamination process are unconspicuous. 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. Although may being “thermal erosion” partially (such as western margin of the basin near the Tailu deep fault), we favor delamination as the main model for lithospheric thinning of the region (and the whole lower Yangtze region).