U–Pb Age of Kimberlite Zircon Grains from Commercial Placers and Placer Occurrences of Diamonds in the Northeastern Siberian Platform

The results of the study of zircon grains recovered from ancient and modern diamond placers of the Lena–Anabar subprovince of the Siberian Diamondiferous Province are presented. The study includes U–Pb dating and quantification of trace and rare earth elements using a SHRIMP-IIе ion microprobe. The research has covered all commercial diamond placers of the Anabar, Kuonamka, and Prilensky regions, along with placer occurrences in the Lower and Middle Olenek, Muna–Tyung, and Primorsky diamondiferous regions. Kimberlite zircon grains associated with diamonds yielded Jurassic, Triassic, Late Devonian–Early Carboniferous, and Silurian–Early Devonian ages. These dates correspond well with the known ages of primary sources. The analysis of both balance and mined-out placers indicates that 75% of the placer diamond deposits originated from Triassic primary sources.