Sediment source tracing using environmental magnetism: A new approach with examples from Australia

Environmental magnetism can be used for sediment source tracing in situations such as stream junctions where two catchments deliver magnetically distinguishable, well combined average source mixes to a trunk stream. Consistent mineral magnetic parameter relationships show that spatially and temporally constant magnetic mineral assemblages occur along reaches of natural streams. For most of the confluence mixing situations examined it is possible to distinguish between tributaries using magnetic parameter relationships. Using these relationships, relative tributary contributions to the resultant downstream mix can be quantified. The method can be used for tracing suspended and bedload sediments so that the principal source catchments can be determined by a sequence of measurements at stream junctions along a drainage network. There is considerable potential for using this new and easily applied method for studies of sediment delivery processes and sediment movement in fluvial environments.