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Roman N. Pendelyak
Roman N. Pendelyak
Head of Department
AGD Diamonds JSC
Head of Department
AGD Diamonds JSC
Arkhangelsk
Russia

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Articles

Article
Geology
  • Date submitted
    2025-10-16
  • Date accepted
    2025-12-24
  • Online publication date
    2026-04-03

The problem of identifying lower crustal garnet-clinopyroxene granulites and mantle eclogites: a case study of xenoliths from the V.Grib pipe

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The article presents a comprehensive analysis of the mineralogical and geochemical features of xenoliths from the V.Grib kimberlite pipe, represented by lower crustal garnet-clinopyroxene granulites and mantle eclogites. A comparative characterization of the two xenolith types is conducted, as clear criteria for their distinction are currently lacking. The study identifies several distinctive features that unequivocally characterize mantle eclogites: elevated Cr contents (in garnets >300 ppm, in clinopyroxenes >1500 ppm), high pyrope content in garnet (>34 mol.%), and evidence of early metasomatism manifested as metasomatic garnet, spongy clinopyroxene replaced by pargasite, and phlogopite rims at garnet-clinopyroxene contacts. Evaluation of the pressure-temperature parameters of the V.Grib pipe xenoliths confirmed the mantle origin of eclogitic xenoliths formed at T = 800-1200 °C and P = 30-50 kbar, and did not refute the initial assumption of a lower crustal origin for granulitic xenoliths characterized by T = 750-800 °C and P = 14-15 kbar. To definitively resolve the issue of identifying lower crustal garnet-clinopyroxene granulites and mantle eclogites, a comprehensive comparison of the isotope-geochemical characteristics of “eclogitic” and “granulitic” zircon is proposed for future research.

How to cite: Stetskaya E.V., Salimgaraeva L.I., Berezin A.V., Ustinov V.N., Pendelyak R.N. The problem of identifying lower crustal garnet-clinopyroxene granulites and mantle eclogites: a case study of xenoliths from the V.Grib pipe // Journal of Mining Institute. 2026. Vol. 278. p. 99-114.