Abstract:

Three different types of structural basins, i.e. downwarping, faulting and faultingblock basins were developed in the Mesozoic in Southeast China. The first type formed from the Late Triassic to the Early Jurassic with coalbearing strata; the second formed from the Middle Jurassic to the Early Cretaceous with volcanic strata; and the last from the Cretaceous to the Paleogene time with continental redbed. The formation of the three types of basins was closely related to the evolution of the Mesozoic intracrustal magma layer of this area. Subduction of the paleoPacific plate initiated at the Late Paleozoic increased the intrinsic energy of the lithosphere of this area, caused the formation and thickening of the intracrustal magma layer, brought on bendingdeformation of the cover over the magma layer, and thus resulted in the formation of numerous downwarping basins in the earlier Mesozoic. Multicrustal movements from the Indosinian to the Early Yanshanian period broke the crust and formed lots of faults that provided conduits for magma eruption and thus formed a series of volcanic basins controlled by faults in the eastern coastal area where the MI (Melting Interface understood as the upper face of the intracrustal magma layer) was imbeded relatively shallow. Decreasing intrinsic energy of the crustal melting system started at the end of the Late Jurassic and made the crust cool down and shrink, which resulted in faultblock movements under gravitation and thus produced lots of faultblock basins in the Late Mesozoic and the Early Cenozoic.

Key words: Southeast China, Mesozoic, intracrustal magma layer, structural basin