Abstract:

 Lots of information concerning granite genesis can be obtained from the geological sections of Xilingang granite body in Guangdong Province. The sections indicate that the Baihedong Formation (K1bh) formed in the Early Cretaceous acted as a residual cap over the Xilingang granite body with abrupt contact in between. The granite underlying the contact contains numerous red bed clastics that reduce gradually with increasing depth in the rock body. The results of geochemical and mineralogical analysis suggested that materials of granite were from the insitu rockstrata including part of the red bed of Baihedong Formation. Differentiation during the meltingcrystallizing process led different elements to be enriched in different depths of the rock body. Growth of quartz crystals of granite is found in a stable environment and during crystallization of quartz, SiO2 supersaturation of magma gradually decreases. All the above data indicate that the Xilingang granite was formed by insitu melting of the crustal rocks, not the intrusion from a depth source.

Key words: Xilingang, Lower Cretaceous, red bed, granite genesis, insitu melting