S. R. Shee

TL;DR: In this article, the isotopic composition of Hf has been measured in 124 mantle-derived zircon megacrysts from African, Siberian and Australian kimberlites, using a laser-ablation microprobe (LAM) and a multi-collector ICPMS.

TL;DR: Whitaker et al. as mentioned in this paper integrated U-Pb dating, Hf-isotope analysis and trace-element analysis to detrital zircon populations offers a rapid means of assessing the geochronology and crustal evolution history of different terranes within a composite craton.

TL;DR: Garnets from phlogopite harzburgite xenoliths from the Wesselton kimberlite show zoning from low-Ca harzbergitic cores to rims with lherzolitic Ca-Cr relations.

Abstract: Two populations of kimberlitic zircon are present in the Timber Creek kimberlites, Northern Territory. Laser ablation ICP MS U—Pb dating yields an age of 1483 ± 15 (2σ) Ma for the main group and an age of 179 ± 2 Ma for the other group. This distinction of two age groups is strongly supported by Hf isotope data on the same zircons. Although the trace element patterns of both populations are typical of mantle derived zircons, the ‘young’ population has slightly higher concentrations of most trace elements, but has lower Hf, Nb, Ta and Pb contents. The distinct differences in trace element contents and Hf isotopic composition of the two zircon populations indicate that they were derived from different magma sources. The dating results indicate that the emplacement age of the Timber Creek kimberlites cannot be older than the age of the ‘young’ zircon population (i.e. 179 ± 2 Ma). This clarifies the inconsistency between the previously reported SHRIMP age of the Timber Creek zircons (1462 ± 53 Ma) and the muc...

TL;DR: In this article, the authors carried out in situ LAM-ICPMS U-Pb dating of groundmass perovskite in two kimberlitic pipes (Kambeli and Msipashi) in Kundelungu Plateau (SE Congo).