Sedimentary evidence for the early Paleoproterozoic tectono-magmatic lull: Detrital zircon provenance of the 2.47–2.17 Ga Langzishan Formation, Liaohe Group, Eastern Block of the North China Craton

Abstract

As one of the most ancient cratons in Asia, the North China Craton (NCC) provides an opportunity to examine the evolution of the early earth. However, it is poorly known about the tectonic setting of the Eastern Block of the NCC at 2.47–2.17 Ga. In this study, zircon U-Pb dating was conducted to constrain the provenance, depositional age, and depositional environment of the Langzishan Formation in the Liaodong peninsula, to investigate the tectonic setting of the Eastern Block during the earliest Paleoproterozoic. Provenance analysis suggests that the basal sandstones (protolith of quartzite) in the Langzishan Formation were sourced from 3.8 to 2.5 Ga continental crust, while the overlying sandstone and pelite units were sourced exclusively from 2.5 Ga continental crust. The distribution of detrital zircon ages shows that the basal sandstones of the Langzishan Formation were deposited at 2.47–2.2 Ga, during which the tectonic setting changed from an early collisional setting (2.47–2.35 Ga) to a stable continental margin (2.35–2.2 Ga), whereas pelites in the upper layer of the Langzihsan Formation were deposited at 2.2–2.17 Ga, and also experienced a transition in tectonic setting from a passive continental margin to an active continental margin. The Langzishan Formation is believed to be the lowest sedimentary unit in the Eastern Block. The transition of tectonic setting of this formation shows that the Eastern Block probably has undergone the same transition at 2.47–2.17 Ga, from a collisional setting to a passive continental margin, and then to an active continental margin, possibly related to both onset of the 2.3–2.2 Ga Paleoproterozoic tectono-magmatic lull (TML) and its cessation.