Effective application of multidimensional scaling for detrital zircon geochronology in the southern Miryang Subbasin, Gyeongsang Basin, Korea

Abstract

Zircon U-Pb dating was conducted using laser ablation multi-collector inductively coupled plasma mass spectrometry on samples collected from five Natural Monument fossil sites in the southern Miryang Subbasin of the Gyeongsang Basin, Korea. The resulting depositional ages and ages of fossil occurrence are approximately 117 Ma (Aptian) and 113 Ma (Aptian–Albian boundary) in the Hasandong Formation, 104 Ma (Albian) and 96 Ma (Cenomanian) in the Haman Formation, and 93 Ma (Turonian) in the Jindong Formation. By synthesizing the detrital zircon age distributions from this and previous studies, we identify distinct temporal changes in provenance that are more dynamic in the southern subbasin than in its central and northern regions. However, conventional multidimensional scaling (MDS) approaches, which rely on all concordant zircon ages, often obscure provenance signals in volcanic-arc settings due to the dominance of syndepositional volcanic zircons and widely distributed Paleoproterozoic basement rocks. To address this limitation, we applied a geologically informed filtering protocol that removes near-syndepositional volcanic ages (<145 Ma) and non-diagnostic Paleoproterozoic components (>1600 Ma), which commonly mask provenance-sensitive age populations. This refinement focuses on the 1600–145 Ma interval, enhancing the clarity and geological coherence of the resulting MDS configurations. Applying this approach to the Miryang Subbasin dataset improves the separation of samples and reveals diagnostic age patterns consistent with independent geological evidence. Our findings provide refined depositional age constraints and provenance interpretations for the southern Miryang Subbasin and demonstrate a practical framework for enhancing MDS performance in sedimentary basins influenced by syndepositional volcanism.