Abstrak

Exposed in the Southeast Arm of Sulawesi, Indonesia, the Meluhu Formation represents continental fragments derived from northern Australia, formerly part of Gondwana. This study integrates sedimentological relationships, petrography, and geochemistry of the Meluhu sandstones to constrain their provenance, tectonic setting, source area weathering, palaeoclimate, depositional history, and palaeogeographic evolution during the Mesozoic. Facies analysis identifies five facies associations representing depositional system: Fluvial, Delta Plain, Delta Front, Prodelta, and Marine. Petrographic analysis classifies the sandstones into arenites (quartz arenite, litharenite, and sublitharenite) and wackes (arkosic wacke, lithic wacke, and quartz wacke). QFL ternary diagram analysis indicates a recycled orogenic provenance, with contributions from cratonic interior and mixed fields. Petrographic and geochemical analyses reveal that the sandstones are primarily derived from felsic igneous sources and gneiss as well as recycled sedimentary quartz, indicating multiple-cycle sedimentation. Detrital framework analysis and major element ratios (CIA, CIW, PIA, and ICV) suggest moderate-severe chemical weathering under warm and humid conditions, consistent with multiple-cycle sedimentation. Chondrite-normalized rare earth element (REE) patterns exhibit enriched light REEs and relatively flat heavy REE distributions with negative Eu anomalies. These geochemical characteristics resemble Upper Continental Crust (UCC) and Post-Archaean Australian Shale (PAAS) patterns, suggesting deposition in a passive margin setting. Additionally, major and trace element data suggest that deposition indicate passive margin (PM), intermittently influenced by an active continental margin (ACM). Hence, the deposition of the Meluhu Formation was influenced by two distinct tectonic phases. Based on geochemical and provenance indicators, the primary sediment sources are interpreted North Australian Craton and the Tasman Line Orogen, with possible additional input from South West Borneo (SWB), as well as the Sula Spur and Bird’s Head terranes. These findings illuminate the depositional history of the Meluhu Formation and help reconstruct the palaeogeography and geodynamic evolution of Eastern Indonesia.