High-Alumina Pyroxenite Xenoliths from Quaternary Basalt of Spitsbergen Island: Evidence for Continental Crust Delamination.

Марина Юрьевна Корешкова, Ю.Б. Марин, Лариса Петровна Никитина, Хилари Даунс, Айжан Токушева, Алексей Георгиевич Гончаров

Research output

Abstract

Abstract: The origin of spinel–garnet pyroxenite from xenoliths in Quaternary basaltoids of Spitsbergen Island (Svalbard Archipelago) is discussed. The rocks have a high concentration of Al 2O 3 and MgO and low Cr. The primary magmatic association Spl–Opx–Cpx and the high Al content in pyroxenes provide evidence for the formation of these rocks as cumulates of hydrous basaltic melts in the lower crust at a pressure of ~1.2 GPa. Transformation of the texture from the magmatic hypidiomorphic to the metamorphic granoblastic and growth of garnet at the expense of spinel and high-alumina pyroxenes indicate transport of rocks to a depth below the spinel/garnet phase transition boundary in the Cr 2O 3-free CaO–MgO–Al 2O 3–SiO 2 system. The parameters of the Grt–Opx equilibrium range within 1060–1120°C and 2.2–2.6 GPa. Thus, magmatic pyroxenite was transported to a great depth into the mantle, which provides evidence for delamination in the region of the lower continental crust containing ultramafic cumulates.

Original languageEnglish
Pages (from-to)413-417
Number of pages5
JournalDoklady Earth Sciences
Volume485
Issue number2
DOIs
Publication statusPublished - 1 Apr 2019

Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Earth and Planetary Sciences(all)

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