Detrital zircon geochronology and whole-rock geochemistry of the 1.8–1.7 Ga Xiong’er volcanic-sedimentary succession in the southern North China craton and their implications for basin evolution

Abstract

The Xiong’er volcanic-sedimentary succession in the southern North China Craton (NCC) documents crucial data regarding the geological evolution of the supercontinent Columbia (Nuna). Previous researches largely focused on the volcanic rocks in the Xiong’er succession, while the paleo-tectonic significance of its sedimentary rocks has not been explored. LA-ICP-MS detrital zircon U-Pb dating and whole-rock geochemistry of the interlayered sedimentary units within the succession are conducted to ascertain the provenance and tectonic driver of the basin infill. New chronological constraint suggests the deposition of the succession persisted until ca. 1710 Ma, temporally aligned with the initial deposition of the overlying Ruyang Group. Normalized rare earth elements (REE) and classification diagrams indicate derivation predominantly from felsic sources with supplementary input from mafic sources. Detrital zircon U-Pb ages indicate a major 2.5 Ga provenance from the proximal latest Archean and Paleoproterozoic metamorphic complexes and a subordinate ca. 2.3 ∼ 1.8 Ga provenance from adjacent regions. Notably, an elevated ca. 1.8 ∼ 1.7 Ga detrital zircon peak in the uppermost section of the succession implies contributions from coeval granites and volcanogenic rocks. Integrating these observations with the stratigraphic progression, the Xiong’er succession is interpreted as a magma-rich syn-rift basin infill and we hypothesize the existence of a “breakup unconformity” separating the syn-rift Xiong’er Group from the overlying post-rift Ruyang Group.