Partitioned Pathways, Unified Sibumasu Depocenter: Gondwanan Tectono-Climatic Rerouting From West Malaya's Detrital Record

Peripheral terranes are often assumed to mirror adjacent continental detrital zircon sources. However, the peri-Gondwanan Sibumasu terrane exhibits two distinct zircon signatures—traditionally interpreted as separate basins fed by different sedimentary pathways (Australia or India). This conceptual shortcut bypasses the labyrinthine reality of source-sink relationships, necessitating refined sediment dispersal reconstructions. Crucially, West Malaya—strategically located in the middle of Sibumasu terrane—provides key insights into resolving this structural conundrum. Two Cambrian samples in West Malaya reveal coeval detrital contributions from India and Australia. But by mid-Paleozoic, Northwestern domain strata are dominated by 1.0–0.7 Ga Indian zircons, contrasting with the Southeastern domain 1.3–1.0 Ga Australian sources. Volcaniclastic sediments with Early Ordovician (480–460 Ma) zircon population demarcate these provenance shifts. The distinct source of these diverging transport pathways mid-Paleozoic are further corroborated by dissimilar T_DM2 (Hf) model ages (2.1 vs. 1.8 Ga) and dissimilar normalized α-dose values (Ectasian to Stenian and Ediacaran to Cambrian age populations) between the Northwestern and Southeastern domains. The abrupt mid-Paleozoic provenance disparity following Cambrian mixing suggests an absence of local structural or geomorphic controls within Sibumasu and implies a single, cohesive sink region. Rather than fragmentation into sub-basins, these shifts record evolving Gondwanan tectonic dynamics and paleoclimate that progressively redirected two distinct sediment dispersal systems from their continental sources (India and Australia) into a unified depocenter.