To better understand how the evolution of Cenozoic deep-water circulation related to changes in global climate and ocean basin configuration, we generated Nd isotope records from Ocean Drilling Program sites in the southeastern Atlantic to track deep water mass composition through time. We used fossil fish debris from ODP Sites 1262-1264 (Leg 208), spanning present-day water depths of 2500-4750 m, to reconstruct the isotopic signature of deep waters over the past ~53 Ma. The data indicate an initial transition from relatively non-radiogenic values (??Nd=~-10) at 53 Ma to more radiogenic values (~-8.5) at ~32 Ma. From ~32 Ma to 3.85 Ma, the Nd signal becomes more nonradiogenic, ~-12.3 at the top of the record. Comparison of our data with Nd isotopic records derived from a North Atlantic Fe-Mn crust show similar non-radiogenic values (~-10.5) in the 53??32 Ma interval and a trend toward more non-radiogenic values beginning at ~20 Ma. The data likely reflect an overall shift from a Southern Ocean deep water source to the ultimate incursion of deep waters from the North Atlantic. The non-radiogenic values at the base of the record reflect a Southern Ocean source of deep water. The shift toward more radiogenic values indicates an increased contribution of Pacific waters to the Southern Ocean source as the tectonic gateways changed after ~35-33 Ma. The subsequent trend toward more non-radiogenic Nd isotope values is approximately concurrent with the increase of benthic foraminiferal ??18O values, based on comparison with a compilation of global data. Thus, changes in oceanic gateway configuration in addition to overall cooling and the build-up of continental ice on Antarctica may have altered the Nd isotope character of Southern Ocean deep waters during the early Oligocene.

>Magister Scientiae - MSc / The Platreef, is a contact-type pyroxenitic reef in the Northern Limb of the Bushveld Complex, enriched in platinum group elements (PGE) and base metal sulfides (BMS). Relatively subdued mining in the Platreef, compared to RLS, has been attributed to limited knowledge regarding irregular distribution, complex style and genesis of PGE mineralisation in the Platreef. This study was, therefore, aimed at investigating the petrogenesis of the Platreef, particularly to evaluate whether the formation of the ore reefs resulted from a single or multiple sill-like magma intrusions. The study also sought to unveil the interplay of fractional crystallisation, hydrothermal fluid activities, floor rock and crustal contamination on the formation of Platreef types, PGE mineralisation and the magma source.