Post-depositional reddening of late Quaternary coastal dune sands, north-eastern Australia

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Abstract
Summary: Deeply weathered quartz sand dunes of late Quaternary age occur at Cape Bedford and Cape Flattery on the seasonally humid tropical east coast of North Queensland, Australia. Many dunes have deep podzolic profiles with reddened B horizons up to 8 m thick. The red colour is produced by iron oxides and hydroxides which, together with kaolinite and minor gibbsite, form interstitial matrix and cutans on quartz grains. The red sands are generally uncemented, but nodular ironstone layers are present in some sections. Radiocarbon dating has shown that one red podzol profile near Cape Flattery has formed in the last 7500 C-14 years. Progressive podzolization has removed much of the iron pigment from the oldest dunes in the area, which are >48 000 C-14 years old. These dunes are degraded and contain subsurface horizons which are cemented by humate.