Tracing sediment pathways across an active continental margin: Detrital zircon geochronology and mineralogical evidence from the Magdalena and La Aguja submarine canyons in northern Colombia

Submarine canyons serve as conduits linking fluvial sediment sources to deep-sea depocenters. This study investigates sediment pathways within and between two contrasting canyon systems along the Colombian Caribbean margin: the Magdalena Canyons System (MCS), supplied by the Magdalena River, and La Aguja Canyon (LAC), which receives limited sediment from the Sierra Nevada de Santa Marta (SNSM), together with offshore distal (OD) sites located beyond LAC within the Magdalena Submarine Fan. Ten surface sediment samples (~30–4000 m water depth) recovered by box and gravity cores across these domains (MCS, LAC, and OD) were analyzed in terms of grain-size distribution, X-ray diffraction, and detrital zircon U-Pb geochronology. Bulk and clay mineralogy reveal two provenance signatures: a quartz-rich, compositionally mature Andean signal in the MCS and a plagioclase-amphibole-rich, immature assemblage in LAC. OD sites incorporate compositional signatures of both, consistent with the convergence of multiple sediment-routing pathways. A total of ~1000 detrital zircon ages further support this interpretation. The MCS samples display a multimodal Andean signal including Neogene (<8 Ma), Jurassic–Cretaceous (80–150 Ma), Permian–Triassic (~240–270 Ma), and Neoproterozoic (~990 Ma) peaks. The LAC samples show Paleogene (~50 Ma) and Jurassic (~180 Ma) peaks characteristic of the SNSM, while OD sites combine both age populations. The presence of <1 Ma zircons in deep-marine MCS sediments, sourced from volcanic centers located >600 km inland, may reflect unusually rapid erosion and continent-to-basin sediment transfer, although contributions from currently undocumented volcanic sources cannot be excluded. These results suggest that sediment transfer along the margin is characterized by persistent Andean supply, structural confinement, multiple canyon pathways, and episodic slope reactivation and reworking. The Magdalena Submarine Fan therefore represents an illustrative natural example of provenance mixing and sediment-routing efficiency in tectonically active canyon–fan systems.