Vice Professor PENG Peng and his team present new geochemical and isotopic age data on several generations of 2200-1880 Ma dykes/sills, and propose that they occur in a Paleoproterozoic intracontinental rift within a newly-defined coeval magmatic belt. This new information should help in understanding and unraveling the complex framework and evolution of this classic craton.

The 2200–1880 Ma igneous rocks in the central and eastern parts of the North China Craton (NCC) constitute a new Hengling magmatic belt (HMB), which includes the ~2147 Ma Hengling mafic sill/dyke swarm, the ~2060 Ma Yixingzhai mafic dyke swarm, and the ~1973 Ma Xiwangshan mafic dyke swarm. The 2200–1880 Ma igneous rocks in the central and eastern parts of the North China Craton (NCC) constitute a new Hengling magmatic belt (HMB), which includes the ~2147 Ma Hengling mafic sill/dyke swarm, the ~2060 Ma Yixingzhai mafic dyke swarm, and the ~1973 Ma Xiwangshan mafic dyke swarm. The progressive changing compositions of the three swarms are interpreted in terms of their source regions at different depths, i.e., shallower and shallower through time. And the decrease in scale and size of the intrusions and their magma volumes indicate the progressive weakening of magmatism in this rift.

Fig. 1. Distribution of 2200–1880 Ma igneous rocks in the North China Craton. (Image by PENG)

Fig. 2. Cartoons showing the proposed geological scenario and tectonic model of the North China Craton. (Image by PENG)

Peng et al. Genesis of the Hengling magmatic belt in the North China Craton: Implications for Paleoproterozoic tectonics. Lithos. 2012, 148: 27-44（DownloadHere）