Resumen de Pedogenic uranium/thorium and thermoluminescence chronologies and evolutionary history of a coastal dunefield, Groote Eylandt, northern Australia
J. Shulmeister, S.A. Short, D. M. Price
U/Th disequilibrium dating of pedogenic ferruginous pisoliths and additional coarse fraction quartz thermoluminescense dates are used to test a TL-based chronology of the Umbakumba Dunefield, Groote Eylandt, northern Australia. These dates support the established history of the dunefield and indicate that the field is at least mid-Quaternary in age and may be much older.
Sea-level fluctuation is identified as the dominant control on dunefield accretion and destruction. The following model of sea-level control of dunefield evolution is proposed: (1) At sea-levels of less than −40 m the system is inactive. (2) From −40 to −5 m the system is accretionary. (3) At sea-levels from −5 m to +5 m the system is deflationary. (4) Above +5 m,the dunefield would be destroyed.
Modified versions of the conceptual model may be applicable to other coastlines where sediment supply is significantly altered by sea-level fluctuations.
