“…In addition, this paper also examines the results of magnetic modelling of total magnetic intensity (TMI) anomalies interpreted as being produced by diatremes. These diatremes have been interpreted by Gardam et al (2008) to be the source of the Arumpo bentonite deposits. The Arumpo bentonite deposits, situated in the Murray Basin sediments, are typically 5 m thick, covered by 5-20 m of clay and sand overburden, are derived from volcanic ash, and were deposited at about 3 Ma.…”