Tying catchment to basin in a giant sediment routing system: a source-to-sink study of the Neogene–Recent Amur River and its delta in the North Sakhalin Basin

This paper uses an extensive dataset from more than 200 samples to provide a comprehensive source-to-sink analysis of the Amur River and its delta in the Russian Far East. The majority of sand-sized sediment in the Amur River and its former delta comes from upstream of the Lesser Khingan Ridge, shown by uniformity of sediment composition in the lower 1700 km of the river. Stable mineral ratios, U–Pb age spectra and garnet geochemistry show little stratigraphic provenance-specific variation in the Neogene delta. This renders Miocene–Pliocene drainage capture models unlikely. The onset of uplift in the delta is marked by a decrease in the apatite–tourmaline index (ATi) in Upper Pliocene offshore well samples, caused by dissolution of apatite as sediments were uplifted and eroded onshore Sakhalin. These wells also show variable ATi and garnet–zircon index (GZi) values in Lower Miocene samples, which could potentially be used for stratigraphic correlation. A positive correlation between GZi values and distance from the river mouth is attributed to hydrodynamic sorting across the delta system. This has negative implications for the use of this stable mineral index and others of a similar hydraulic equivalence as regional correlation tools on a basin scale (>100 km).