Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6436480 | Chemical Geology | 2014 | 9 Pages |
â¢The ε53Cr for the Bon Accord oxide body is 0.00 epsilon units.â¢The precursor of the Bon Accord oxide body was probably not a meteorite.â¢The Bon Accord body is surrounded by both komatiite and depleted peridotite.â¢A deep mantle source is compatible with the geochemistry of the Bon Accord body.
An unusual oxide body, enriched in Ni and the platinum-group elements, was found in the north-western part of the Barberton greenstone belt, South Africa, in the 1920s. With mineralogy and geochemistry which are extremely anomalous, and do not conform to that of any other Ni-rich crustal rocks, it has been interpreted as either an Archaean paleo-meteorite or of terrestrial deep-mantle origin. Cr isotopic ratios were used to evaluate the merits of these two possibilities. Isotopic analyses returned values for ε(53) of 0.00 epsilon units, within a 2 s error, relative to a terrestrial standard. We interpret this information, together with trace element data from the surrounding peridotites, as pointing to a terrestrial origin for the body, and conclude that the current dataset is not inconsistent with a deep-mantle origin, as a remnant of core formation, with subsequent transport to and emplacement in the lithosphere by a mantle plume.