Geologic fingerprints of the Rodinia breakup in the western North China Craton: Constraints from the Early Neoproterozoic (ca. 825–810 Ma) mafic volcanic and intrusive rocks in the Langshan tectonic belt

Abstract

As an important component of the East Asian continental block, the North China Craton (NCC) is crucial for reconstructing Rodinia in the Neoproterozoic. However, whether the NCC is a component of the Rodinia supercontinent and records its breakup remains enigmatic. Here, we identified Langshan gabbro and mafic dikes with ages of ca. 829–826 Ma and mafic volcanic rocks with ages of 810 ± 3 Ma in the northeastern Alxa Block of the western NCC. The Langshan gabbro shows flat rare earth element (REE) patterns [(La/Yb)N = 1.3–1.5] and slight enrichment in most incompatible trace elements, similar to enriched mid-ocean ridge basalt. The mafic volcanic rocks show the geochemical features of oceanic island basalt, including high total alkaline content (7.86–8.47 wt%), enriched in light REEs (La/YbN = 8.0–9.1), and insignificant Eu anomalies. Together with contemporaneous felsic volcanic rocks identified in previous studies, the mafic volcanic rocks (ca. 810 Ma) define a bimodal association. The mafic intrusive and associated dike swarms from ca. 825–810 Ma along with the coeval Jinchuan ultramafic–mafic intrusions, followed by rifting sedimentary successions, were formed in an extensional rift setting, supporting the geologic fingerprints of the Rodinia breakup in the western NCC. The well-matched mafic magmatic barcodes, similar provenance, and sedimentary successions preserved in the Adelaide superbasin of southeastern Australia and the Langshan rift basin of the western NCC support a possible link between the NCC and Australia during the Early Neoproterozoic.