Emplacement ages and sources of kimberlites and related rocks in southern Africa: U–Pb ages and Sr–Nd isotopes of groundmass perovskite

Repeated kimberlite magmatism beneath Yakutia and its relationship to Siberian flood volcanism: Insights from in situ U–Pb and Sr–Nd perovskite isotope analysis

“…100-90 Ma, whereas plume-related mafic magmatism occurred at ca. 80 Ma in this region (Guarino et al, 2013). These observations, together with our results from combined U-Pb and Sr-Nd isotope analysis of perovskites from four kimberlite age groups of the Siberian craton, highlight that no single emplacement pattern, or geodynamic explanation, of global kimberlite magmatism appears to exist.…”

“…Although the most accurate and precise U-Pb, Rb-Sr, and SmNd isotope data of perovskites are obtained by isotope dilution methods utilizing TIMS and/or MC-ICPMS instruments (Heaman, 1989;Corfu and Dahlgren, 2008;Malarkey et al, 2010), numerous studies have demonstrated that in-situ techniques such as LA-MC-ICPMS and SIMS can approach the data quality that is obtained by isotope dilution methods (Kinny et al, 1997;Batumike et al, 2008;Li et al, 2010;Donnelly et al, 2012;Griffin et al, 2014). A clear advantage of in situ techniques is the capability of providing rapid and texturally sensitive isotope data for single perovskite grains without chemical sample treatment.…”

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

“…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] .…”

U–Pb geochronology and Sr/Nd isotope compositions of groundmass perovskite from the newly discovered Jurassic Chidliak kimberlite field, Baffin Island, Canada

“…There are two pieces of evidence that support an origin for some Group 1 kimberlites deeper than the base of the continental lithospheric mantle (∼250 km); 1) a few Group 1 South African kimberlites (e.g., Jagersfontein, Koffiefontein and Monastery) contain one or more high-pressure mineral inclusions in diamond (e.g., ringwoodite, ferropericlase, majorite garnet, silicate perovskite; see summary by Stachel, 2001) that require a deep mantle origin, implying these kimberlites transported diamond from the transition zone or deeper, and 2) most Group 1 kimberlites have depleted mantle Sr and Nd isotopic compositions (Smith, 1983), similar to the source for ocean (Heaman, 1989;Woodhead et al, 2009;Wu et al, 2010;Griffin et al, 2014) and Jurassic eastern North American kimberlites (ENA: Heaman, 1989;Zurevinski et al, 2011). Also shown are fields for Jurassic/Neoproterozoic kimberlites (Tappe et al, 2011(Tappe et al, , 2012 and Mesoproterozoic lampröites (Nelson, 1989), SW Greenland.…”

“…6 (yellow squares) together with perovskite Sr/Nd results for the Jurassic Midternaes kimberlite in SW Greenland (red circle: data reported in Table 3), reference fields for Southern African Mesozoic Group I and II kimberlites based on whole rock (Smith, 1983) and perovskite (Heaman, 1989;Woodhead et al, 2009;Wu et al, 2010;Griffin et al, 2014) analyses, reference lines for chondrite uniform reservoir (CHUR) and Bulk Earth (BE), and estimates for the composition of depleted mantle through time (150 to 2700 Ma; white squares). In addition, reference fields based on perovskite analyses for similar-age Jurassic kimberlites in eastern North America (ENA field in Fig.…”