Cambrian provenance transition in the southeastern North China Craton and its tectonic implications: Detrital zircon U–Pb–Hf signatures from the Xuhuai region

Abstract

The Cambrian tectonic stability and palaeogeography of the North China Craton (NCC) remain contentious. As the earliest site of Cambrian transgression, the southeastern NCC serves as an ideal location for investigating the geological evolution of the NCC. Provenance analysis through integrated field investigations, elemental geochemistry, and detrital zircon (DZ) U–Pb–Hf isotope analyses of Cambrian clastic sediments in the southeastern NCC reveals three distinct types of DZ age signatures and associated provenance changes, thereby enhancing our understanding of the Cambrian tectonics of the NCC and tracing its potential linkage to Gondwana. DZ age signatures are characterized as three types: (I) double peaks around 2510 and 1850 Ma, with mostly positive and negative ε_Hf(t) values, respectively; (II) minor peaks around 1450, 1150, and 950–750 Ma, alongside the double peaks, exhibiting predominantly positive ε_Hf(t) values; and (III) a scattered array of Mesoproterozoic to early Paleozoic zircons, with minor negative ε_Hf(t) values clustered at 476–518 and 909–1245 Ma. The contrasts between Series 2 Types I and II and the Wuliuan Type III sediments reflect a significant provenance change from the NCC Precambrian basement and/or cover to an exotic magmatic belt to the south, including the coeval Qinling arc. The comparable provenance shifts across the eastern NCC were diachronous during Stage 4 to Wuliuan, governed by transgression processes, Qinling arc-related orogeny, and paleogeographic configurations of alternating uplift and depression. The Cambrian evolution in the southeastern NCC was closely linked to an orogenic process resulting from Shangdan Ocean subduction, challenging the notion of passive tectonism in the NCC. The continental-scale DZ age signatures in the Cambrian unit support the view of the Cambrian NCC as a discrete continental block, paleogeographically separated from Gondwana-affinitive micro-continental blocks and the Gondwana landmass by the Proto-Tethys Ocean.