Miocene to recent dust record from the Southwest Pacific Ocean

Bulk mass accumulation rates (MAR) are calculated at ~10 mg/cm2/kyr over the last 4 Myr, consistent with previously estimated Quaternary eolian flux rates to this part of the Pacific. Nd, Pb and Sr radiogenic isotopic compositions of the detrital mineral extract (<38 µm) show no trends with age, while 40Ar/39Ar ages show an upcore younging trend (~180 Ma to ~150 Ma), in concert with a slight coarsening of eolian grain-size distributions.

These ages likely reflect mixing of Mesozoic illite-dominated clay from at least two continental source areas: southeastern Australia (Murray-Darling Basin/Lake Eyre Basin) and New Zealand (South Island). The data indicate remarkable constancy of continental eolian sources exposed to weathering and dispersal at this latitude during the Neogene.