Sedimentación turbidítica y asociaciones de foraminíferos bentónicos en el margen continental de la Gran Barrera de Arrecifes, NE Australia

Abstract

A micropaleontologic study has been performed in order to test the viability of the use of benthic foraminifera assemblages to determine the source area of turbidites on the mixed carbonate-siliciclastic continental margin of north-eastern Australia. Turbidites drilled in the uppermost 10 m of the ODP Leg 133 Site 823A are bioclastic carbonate-dominated, and only a few of them show high terrigenous content. The principal component analysis of benthic foraminifera assemblages suggests a main source area corresponding to sediments deposited between 0 and 40 m water depth. The relationship between the timing of turbidite deposition and relative sea level changes indicates that turbidites were emplaced preferentially during periods when sea level was below 75 m with respect to its present-day position. The results obtained in this study are not fully consistent with conventional models of sediment transfer to deep-water settings, but they support and extend the turbidite depositional model in the study region from 60 ka, to at least, 200 ka.