LAM-ICPMS U–Pb dating of kimberlitic perovskite: Eocene–Oligocene kimberlites from the Kundelungu Plateau, D.R. Congo

Did diamond-bearing orangeites originate from MARID-veined peridotites in the lithospheric mantle?

“…Thus, mantle xenoliths entrained by the Bultfontein kimberlite can be considered representative of the same mantle lithosphere that produced the Barkly West-Boshof orangeites. Our study reveals that MARID minerals contain carbonate-rich primary inclusions and have Hf 28,38 and U-Pb perovskite geochronology 30 (Fig. 2).…”

“…1). The Kimberley area is unique because it hosts kimberlites (B81-95 Myr ago 16,[28][29][30] ) that were emplaced after the orangeites of the Barkly West-Boshof district (115-128 Myr ago 29,31 ; Fig. 2), and the Kimberley kimberlites host a variety of metasomatized mantle xenoliths, which have been extensively studied 11,12,18,19,[32][33][34][35][36][37] .…”

Uranium-Lead, Rubidium-Strontium, Kimberlite

“…U-Pb dating of perovskite was pioneered in the 1980s (Kramers and Smith 1983;Smith et al 1989;Heaman 1989) and since that time there have been more than 1,000 U-Pb perovskite dates reported for kimberlites utilizing all the U-Pb dating techniques (e.g., Heaman 1989;Smith et al 1989;Kinny et al 1997;Batumike et al 2008;Yang et al 2009;Li et al 2010). There are three main challenges in dating perovskite: (1) the small grain size (often <50 mm), making it difficult to extract from the whole rock using conventional mineral separation techniques and difficult to analyze by ion beam U-Pb techniques (e.g., LA-ICPMS requires a 30-40 mm diameter spot for a precise analysis); (2) it contains a significant amount of common Pb (10-30 % of the total Pb), so any age calculation is sensitive to the common Pb correction; and (3) it can be easy to confuse with Encyclopedia of Scientific Dating Methods DOI 10.1007/978-94-007-6326-5_235-5 # Springer Science+Business Media Dordrecht 2013 other minerals (e.g., spinel, slightly tarnished sulfide) in a concentrate using a binocular microscope at the highest magnification.…”

“…There are a number of analytical techniques that have been used to determine U-Pb dates of kimberlites including isotope dilution thermal ionization mass spectrometry (IDTIMS; e.g., Heaman 1989;Smith et al 1989;Heaman and Kjarsgaard 2000), laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS; e.g., Cox and Wilton 2006;Simonetti et al 2008;Batumike et al 2008;Yang et al 2009;Wu et al 2010), and secondary ion mass spectrometry Kinny et al 1997;Li et al 2010;Chalapathi Rao et al 2013;Wu et al 2013). For IDTIMS analyses the sample material is dissolved in acids, U and Pb purified using anion exchange chromatography, and their isotopic compositions determined using a thermal ionization mass spectrometer (Heaman 1989 (Fig.…”

The discovery of kimberlites in Antarctica extends the vast Gondwanan Cretaceous province

“…The analytical technique was described in ref. 37. Ablation occurs in He, permitting efficient sample transport, signal stability and reproducibility of U/Pb fractionation.…”