Characteristics and geological implications of the Xiajiangian (Neoproterozoic) granite porphyry in the Congjiang region, southeastern Guizhou

The Neoproterozoic granite porphyries in the Hunan-Guizhou zone are seldom reported. The acidic magmatic rocks in the lower part of the Xiajiang Group in the Congjiang region, southeastern Guizhou have long been interpreted as migmatites by the previous workers. In the present paper, the authors contend, according to the studies of lithology, geochemistry and geochronology and tectonic setting, that these rocks should be assigned to the in-situ partially remelted S-type granite porphyries and constitute the bimodal magmatic associations together with the basic rocks and basic volcanic rocks in the lower part of the Xiajiang Group, representing the important tectonic-magmatic thermal events at the onset of the Wuling post-orogenic rift basin. The recent results of research may provide new data for the refinement of the evolution of the Precambrian palaeocontinent and metallogenic responses in the study area.