A similar sharp, low-grade thermal aureole and undeformed pluton-country rock contact were observed on 41 Jurassic plutons in the SE part of the SCB. These plutons are mostly emplaced in the middle crustal with weak interaction between the tectonics and magmatism.

Integrating the regional tectonic understanding, we propose that the Jurassic LGPs in South China is derived from the partial melting of the thickened lower continental crust produced by the continental subduction of the SCB under its neighbouring blocks in the Triassic time and the deformation is mainly concentrated in the lower plate. Therefore, the SCB is trapped and thickened by multiple direction convergence. However, due to the relatively low rigidity of the SE part of the SCB with respect to its NW part, the deformation was essentially absorbed by its SE part and its crust was consequently thickened. The scarcity of Jurassic sedimentation within the SE part of SCB with respect to its surrounding areas suggests that this SE part of SCB was not only thickened but also formed a plateau-shape topography with an elevation of ~1.6 km sustained by a root of ~5.9 km estimated by the isostasy. This makes the increases of both pressure and temperature in the lower crust, and the contact surface between the mantle and the crust. Moreover, the thermal addition from the lithospheric mantle and intruded mafic materials arising from the trapped convection asthenosphere mantle during the long decompression processes of the SE part of the SCB to permit partial melting of the lower continental crust.

We concluded that the pre-magmatic tectonic events and nature of the crust are also important for the evolution of the magmatism, which seems to be the feature for the Jurassic magmatism occurred in the SE part of the SCB.