关键词: 基性岩脉, 花岗岩, 壳内熔融层, 岩浆喷发带

Abstract:

Mafic dikes are found forming in different periods of the Mesozoic in Southeast China. Ages of the dikes show a spatial variation as that of the Mesozoic granites of this area, i.e. becoming younger from inland to coastal region, but the activityfastigia of mafic dikes and granites are not synchronous, and that of the former occurred relatively behind. Mafic dikes usually occurred limited in tensional cracks developed within granite bodies, seldom to perforate into the fractures in the country rocks of granite bodies. The mafic dikes generally occurred within the corresponding mafic volcanic belt that was located on the west of the intermediatedacid eruption belt of the same time, indicating that the mafic magma of eruption and intrusion should have been derived from the same source, i.e., the bottom part of the crustal magma layer or the mantle melt layer. Both reducing scales of the intermediatedacid eruption and the seaward migration of mafic eruption and intrusion belts after the Late Jurassic suggest decreasing crustal temperature of this area in the Late Mesozoic.

Key words: mafic dikes, granite, crustal melting layer, magma eruption belts