Reconstruction of the early Late Cretaceous paleogeography of the southern Korean Peninsula and its tectonic implications

We traced the early Late Cretaceous compression in the Korean Peninsula through integrated analysis of the Jindong and Goseong formations, Gyeongsang Basin. High-resolution facies analysis, quantitative petrography, cathodoluminescence (CL) characterization of quartz grains, and zircon geochronology provide constraints on basin evolution and paleogeographic reconstruction. The Jindong Formation comprises shallow lacustrine sediments deposited under semi-arid climatic conditions. The sandstones of this formation are dominated by volcanic lithic fragments (L = 70%–84%, F = 15%–25%, Q = 1%–5%) and contain abundant Cretaceous zircons. Quartz CL textures suggest volcanic origin, indicating primary sediment derivation from volcanic terrains (Gyeongsang Volcanic Arc) with minimal basement contribution. The unconformably overlying Goseong Formation is composed of channel conglomerates and sandstones interbedded with floodplain deposits formed also under arid to semi-arid climatic conditions. The sandstones of the Goseong Formation exhibit bimodal composition: Group I (n = 6) is dominated by lithic fragments (L = 48%, F = 35%, Q = 17%) and volcanic quartz with predominant Cretaceous zircon populations displaying systematic younger-upward trends. On the other hand, Group II (n = 8) exhibits characteristics of those sourced from basement (Q > 40%, L = 38%, F = 15%) and contains large amounts of plutonic and metamorphic quartz together with pre-Cretaceous zircons. These compositional records suggest the establishment of dual drainage networks during deposition of the Goseong Formation (ca. 97 Ma–90 Ma): one sourced from the Gyeongsang Volcanic Arc and another from the basement (Yeongnam Massif and/or Okcheon Belt), as a result of a basinward advance of drainage systems from the basin margin. Given stable climatic conditions, this drainage reorganization and facies transitions across the unconformity reflect regional uplift driven by NW–SE compression along the eastern Eurasian margin. This study provides the first stratigraphic evidence for the early Late Cretaceous compression in the Korean Peninsula, establishing critical constraints for paleogeographic reconstruction during this tectonic phase. • Highlights for "Reconstruction of the early Late Cretaceous paleogeography of southern Korean Peninsula and its tectonic implications " • First stratigraphic documentation of early Late Cretaceous (97-90 Ma) compression in the Korean Peninsula through integrated stratigraphic analysis. • Documentation of systematic drainage network reorganization through multiple, independent indicators (facies analysis, framework grain populations, quartz CL characteristics, detrital zircon geochronology). • Facies and provenance analysis reveals transition from volcanic-dominated lacustrine (Jindong Formation) to dual-sourced fluvial systems (Goseong Formation). • Establishment of dual sediment routing systems during compression, recording regional uplift response. • This comprehensive analytical framework establishes robust evidence of sedimentary response to early Late Cretaceous compression, addressing a significant gap in understanding regional tectonic evolution.