Carboniferous–permian Stratigraphy of the Taebaeksan Basin, Korea: A Current Synthesis

The Taebaeksan Basin in the central-eastern Korean Peninsula preserves scattered Carboniferous–Permian paralic to nonmarine successions, collectively referred to as the Pyeongan Supergroup, overlying Cambrian–Ordovician marine strata. Although the tectonic affinities of the Korean Peninsula with the North and South China blocks remain debated, the lithostratigraphy of the Pyeongan Supergroup exhibits several features closely comparable to coeval successions in North China (the Benxi–Taiyuan–Shanxi–Lower Shihezi–Upper Shihezi–Sunjiagou formations). These successions consistently overlie a regional unconformity spanning the Late Ordovician to Mississippian. The lower Pennsylvanian interval comprises heterolithic sandstone–mudstone of variable color, including characteristic purple shale. From the upper Pennsylvanian to lower Cisuralian, gray to black coal-bearing sequences are developed, with limestone intercalations common up to the Asselian but absent in younger intervals. Since the upper Cisuralian, the succession is dominated by multicolored sandstone–shale alternations indicative of predominantly nonmarine environments. Conodont and fusuline biostratigraphy have provided the principal basis for regional and global correlation of the limestone-bearing lower part of the Pyeongan Supergroup, while smaller foraminifera, brachiopods, and rugose corals have also been documented. However, as most studies were conducted in the 1980s and 1990s, the previously proposed absence of Kasimovian–Gzhelian strata are under scrunity. Post-Sakmarian biostratigraphy relies largely on plant macrofossils, resulting in relatively low temporal resolution. Moreover, recent proposed revisions to the age assignments of Permian strata in North China call for a reassessment of their applicability to the Korean Peninsula. The Pyeongan Supergroup in the Taebaeksan Basin is inferred to have experienced burial and metamorphic temperatures of ~250°C, locally exceeding 500°C, limiting the applicability of palynology, while magnetostratigraphic and chemostratigraphic approaches remain sparsely applied. Recent advances in zircon U–Pb geochronology provide new age constraints, although issues related to the interpretation of maximum depositional ages and potential Pb-loss persist. Future progress will depend on the integration of high-precision geochronology (e.g., CA-ID-TIMS) with efforts to identify datable tuff layers, alongside expanded biostratigraphic studies, to achieve a more refined stratigraphic framework.