Decoupling provenance similarity from depositional age in detrital zircon analysis: insights from the superbasins in Mount Isa Inlier

Quantitative comparison of detrital zircon age spectra emphasizes stratigraphic correlation and tectonic reconstruction. However, analytical workflows implicitly combine provenance similarity, depositional timing, statistical significance, and ordination structure, potentially concealing their distinct geological implications. Using the Paleoproterozoic Western Succession of the Mount Isa Inlier (Australia) as a case study, we demonstrate that provenance similarity and maximum depositional age (MDA) represent related but partially independent aspects of basin evolution. Southern Mount Guide Quartzite predate northern equivalents by >100 Myr, but they display very similar zircon age spectra and only small differences in distribution shape. A similar pattern is observed in the Warrina Park Quartzite and Moondarra Siltstone, where the units that are considered stratigraphically equivalent show different depositional ages but comparable source signatures. In contrast, some intra-formational transitions (e.g., within the Myally Subgroup) reveal abrupt shifts in provenance that are not reflected in mapped supersequence boundaries. To investigate these relationships, we combine several statistical frameworks, including measures of distribution dissimilarity (effect size), statistical testing, uncertainty assessment, grain-count sensitivity analysis, multidimensional scaling, and stratigraphy-aware change-point detection. Applied to the Mount Isa Inlier, this framework facilitates distinguishing between continuing provenance, differences in depositional timing, and structural juxtaposition of rock units. By explicitly separating dissimilarity metrics, statistical confidence, uncertainty, ordination quality, and depositional constraints, we propose a diagnostic workflow that improves interpretation of detrital zircon data. This framework refines superbasin assignment at the sample scale and provides a broadly applicable approach for detrital zircon studies in basins with complex tectono-stratigraphic evolutions.