Anchoring Deep Time: Process-Based Signals of Continental Growth in the Archean

Subdivision of the Archean Eon remains constrained by the fragmentary rock record, diachronous processes, and the absence of laterally continuous stratigraphic sections. Within the International Commission on Stratigraphy, Global Standard Stratigraphic Ages (GSSAs) provide a practical framework for defining time boundaries in such settings, anchored in high-precision geochronology and the preserved geological record. Recent advances in geochronology and geochemistry enable increasingly detailed reconstruction of Archean crust-forming processes. In particular, variations in continental growth mechanisms—reflected in magma generation, crustal differentiation, and the relative roles of intracrustal melting versus mantle-derived melting — offer potential markers of large-scale transitions in early Earth evolution. Within the Birth of Continents (BICO) project, these processes are investigated through integrated petrological, geochemical, and geochronological studies of Archean TTG–metabasalt systems. Emerging results indicate that systematic shifts in melting regimes and source characteristics can be resolved and linked to broader geodynamic changes. If temporally constrained and regionally consistent, such process-based signals may provide a complementary basis for defining meaningful subdivisions of the Archean.