Geological Signature and Possible Position of the North China Block in the Supercontinent Rodinia

Abstract

Recent studies suggest that the South China Block (SCB) was located at a central position in the Neoproterozoic supercontinent Rodinia between ca. 1000 Ma and 800 Ma, but fewer studies dealt with the North China Block (NCB) in the reconstruction of Rodinia. The NCB was suggested, in general, to be in a stable cratonic setting from ca. 1650 Ma to ca. 160-140 Ma. Our recent study suggests that there were two metamorphic-magmatic events at ∼1300-1000 Ma and ∼800-650 Ma in the NCB. Although these events were weak, they have been regarded as marking the assembly (Grenville-age orogenic event) and breakup (Neoproterozoic mafic dyke swarm and granitoid intrusive) of the supercontinent Rodinia. A possible Grenvillian ophiolite or convergent margin complex in the NCB exists only in the North Qinling end-Mesoproterozoic orogenic belt. The major meta-volcanic-sedimentary rocks in this complex belong to the Kuanping Group and are associated with gabbros and serpentinized peridotites. Collisional and post-collisional granites have been recognized along the North Qinling belt. Volcanic and sedimentary rocks along northern margin of the NCB indicate possible continent rift or continental margin environment. The main rock associations of ca. ∼800-650 Ma are mafic dyke swarms with e Nd(t) values of enriched mantle. Therefore, this paper suggests that the mafic dykes were possibly related to the breakup of the Rodinian supercontinent. The tectonostratigraphic constraints and palaeomagnetic reconstruction show that the Proterozoic NCB was different from the SCB, but somewhat similar to Siberia. The above features possibly suggest that the NCB, as part of the supercontinent Rodinia, was possibly located in a marginal location not directly connected to the SCB, but likely adjacent to the Siberian Craton.