Abstract Understanding the source‐to‐sink relationship of a large river‐marginal sea system is key to using marginal sea sediments to infer terrestrial erosion/weathering variations. The Zambezi River, the largest river in the southern African region, has been transporting large amounts of sediments to the southwestern Indian Ocean since the Cretaceous, which have been often used to infer river integration history and uplift of the southern African region. Thus, characterizing the geochemical features of different parts of the river is the key to correctly interpreting terrestrial sediment signals in the southwestern Indian Ocean drill cores. Here we present the first provenance study based on Sr‐Nd‐Hf isotopic results of river sands from mainstream and tributaries of the Zambezi River. We find that the isotopic signatures of the river sediments are largely consistent with its underlying basements of the different reaches, which suggests the local geology control of the river sedimentary provenance. This result is in line with the studies of the provenance of the Yellow and Yangtze Rivers, which suggest that sediments transported by the upper reaches of large rivers draining interior continents are primarily stored in sedimentary basins on land instead of marginal seas. This study suggests caution must be taken in using sediments of marginal seas to infer erosion history of the hinterland mountain uplift and exhumation.
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