Global sea-level fall triggered Ediacaran–Cambrian unconformity in North China craton

Abstract

The Great Unconformity that separates the Cambrian and the underlying Proterozoic strata has been interpreted as recording a composite of multiple diachronous unconformities, among which the Ediacaran–Cambrian unconformity represents the last stage of these erosional processes. Whilst the major denudational episode of the Great Unconformity was strictly restricted to happen before or during the Cryogenian and considered to be associated with the Rodinia supercontinent cycle and “Snowball Earth” event, the cause(s) for the relatively temporary exhumation in late Neoproterozoic remains elusive. Here we present a synthetic geochronological study for the late Ediacaran to early Cambrian strata on the southern North China craton (NCC), where the Ediacaran–Cambrian unconformity occurs. The absence of the latest Ediacaran to earliest Cambrian age zircons of these strata may suggest a significant tectonic quiescence in NCC. A similar phenomenon can also be recognized in other blocks isolated from the Gondwanaland during the late Neoproterozoic–early Cambrian interval. This world-wide Ediacaran–Cambrian unconformity thus was more likely caused by a global sea-level fall, possibly associated with the assembly of the Gondwana supercontinent during the Precambrian–Cambrian transitional period.