The distribution and characteristics of turbidites in the Solander Trough, south of New Zealand

Abstract

The Solander Trough (ST) is a complex depositional environment. The study of the sedimentology of turbidites allows for the predictions of sediment origin, flow processes and flow pathways of transported sediment within deep marine basins such as this one. This study aims to characterise and discuss the sedimentology of turbidites to produce a depositional model for sediment within the ST. The study utilised core samples and bathymetry data to conduct sedimentological, paleontological, geochemical and watershed delineation analyses. The sedimentological data, which includes; visual; grainsize; magnetic; and carbonate content, presents a set of cores consisting of interbedded homogeneous muds and normally graded sands. Through some cores, an increase in carbonate content can be observed through the sand beds, which isn’t observed in others. The paleontological cluster analysis of benthic foraminifera shows that the sand beds comprise of shelf and/or bathyal foraminifera, while the geochemical shows a range in composition from entirely calcite to all igneous regimes to high and low grade metamorphic environments. The analysis of bathymetry data produced a channel network for the ST, characterising the different potential pathways for flow, highlighting a single trunk channel, while minor channels connect to it from the north, east and west. From this a depositional model was derived displaying a multisource and multi-fan complex with terrigenous sediment originating from the South and Stewart Islands and carbonate sediment being derived from the flanking Macquarie Ridge Complex and Campbell Plateaus.