Evolution of beach placer shorelines and heavy-mineral deposition in the eastern Eucla Basin, South Australia


*Correspondence: hou.baohong@saugov.sa.gov.au


The eastern Eucla Basin of South Australia has potential as a world-class heavy-mineral sand province. Heavy-mineral sampling has provided a vector to such deposits, but there is debate about the distribution and evolution of heavy-mineral deposits. Several cycles of marine transgression have left generations of beach placer concentrations buried beneath the present landscape of the eastern Eucla Basin. Evidence from boreholes, compilation of stratigraphic records and analysis of the palaeogeographical evolution assist in defining a number of Tertiary shorelines. Concentrations of detrital rutile, zircon, ilmenite, and minor leucoxene and monazite occur as beach placers in highstand barriers and dunes of Tertiary age along these shorelines. The most prospective strata are the barrier and associated sandstones of Tertiary shorelines that were buried by voluminous sand dunes at over 40 Ma. The geographical and stratigraphic distributions of heavy-mineral-bearing sandstone in Tertiary sediments suggest contemporaneous transport through palaeovalleys predominantly from Precambrian cratons.