Zircon trace element characteristics and ages in granulite xenoliths: a key to understanding the age and origin of the lower crust, Arkhangelsk kimberlite province, Russia

M.Y. Koreshkova, H. Downes, V.A. Glebovitsky, N.V. Rodionov, A.V. Antonov, S.A. Sergeev

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Garnet granulite and pyroxenite xenoliths from the Grib kimberlite pipe (Arkhangelsk, NW Russia) represent the lower crust beneath Russian platform in close vicinity to the cratonic region of the north-eastern Baltic (Fennoscandian) Shield. Many of the xenoliths have experienced strong interaction with the kimberlite host, but in others some primary granulite-facies minerals are preserved. Calculated bulk compositions for the granulites suggest that their protoliths were basic to intermediate igneous rocks; pyroxenites were ultrabasic to basic cumulates. A few samples are probably metasedimentary in origin. Zircons are abundant in the xenoliths; they exhibit complex zoning in cathodoluminescence with relic cores and various metamorphic rims. Cores include oscillatory zircon crystallized in magmatic protoliths, and metamorphic and magmatic sector-zoned zircons. Recrystallization of older zircons led to the formation of bright homogeneous rims. In some samples, homogeneous shells are surrounded by darker convol
Original languageEnglish
Article number973
Number of pages22
JournalContributions of Mineralogy and Petrology
Volume167
Issue number2
DOIs
StatePublished - 2014

Keywords

  • Lower crust
  • xenoliths
  • zircon geochronology
  • zircon trace element composition
  • garnet granulites
  • garnet pyroxenites

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