Reconstruction and interpretation of giant mafic dyke swarms: a case study of 1.78 Ga magmatism in the North China craton

Abstract

Abstract Short-lived giant mafic dyke swarms are keys to the interpretation of continental evolution and tectonics, reconstruction of continental palaeogeographical regimes, and petrogenesis of volcanism. The 1.78 Ga Taihang–Lvliang dyke swarm, one of the most significant and best-preserved Precambrian swarms in the central part of the North China craton (NCC), is reviewed and discussed. It is interpreted to have a radiating geometry that is compatible with the Xiong'er triple-junction rift, in which the Xiong'er volcanic province is proposed to be the extrusive counterpart of this swarm. It resulted in significant extension, uplift and magmatic accretion of the NCC, and it is comparable with the Phanerozoic large igneous provinces (LIPs) in areal extent ( c. 0.3 Mkm 2 ) and estimated volume ( c. 0.3 Mkm 3 ), short lifespan (<20 Ma), and intraplate setting. This North China LIP is unique in that it comprises large volumes of both mafic and intermediate components. It could have resulted from extensive mantle–crust interaction, probably driven by a large-scale mantle upwelling. A plume tectonic model is favoured by several lines of supporting evidence (i.e. massive volcanic flows correlated over large areas and a giant fanning dyke swarm with plume-affinitive chemistry). It could responsible for massive sulphide (Pb–Zn) and gold (Au–Ag) ore deposits in the Xiong'er volcanic province. Dismembered remnants of this magmatism in other block(s), with potential candidates in South America, Australia and India, could identify other cratonic blocks that were formerly connected to the North China craton.