TY - JOUR

T1 - Metamorphic history of the Precambrian lower cratonic crust from U-Pb dating of granulite xenoliths (Anabar province, Siberia)

AU - Корешкова, Марина Юрьевна

AU - Акимова, Екатерина Юрьевна

AU - Сергеев, Сергей Андреевич

AU - Downes, Hilary

AU - Peytcheva, Irena

AU - Macheva, Lyubomirka

AU - Стифеева, М. В.

AU - САЛЬНИКОВА, Е.С.

AU - Плоткина, Юлия

PY - 2024/6/27

Y1 - 2024/6/27

N2 - Garnet granulite xenoliths from the Nurbinskaya diatreme in the central part of the Archean Anabar province in Siberiaare fragments of the local lower crust that experienced multiple metamorphic events in the Paleoproterozoic and reheatingevents in the Mesoproterozoic and later. This study addresses the timing of metamorphic transformations, and constrainsthe cooling rate and the time of stabilization of the lower crust. The observed metamorphic mineral assemblage of garnet,clinopyroxene, plagioclase, amphibole, rutile and ilmenite was formed at ~ 800 °C, 1.1–1.2 GPa under water-undersaturatedconditions at ~ 1.88 Ga. However, the mineral assemblage is not well equilibrated and retains evidence of earlierand subsequent metamorphic stages. Late titanite formed in response to hydrous fluid influx according to phase equilibriamodeling. U-Pb dating shows two events of titanite formation at 1850 ± 5 Ma and at 1788 ± 2 Ma. After deformation,which led to the porphyroclastic rock textures, the granulites underwent near-isobaric cooling. The cooling rate was higherthan ~ 6 °C/Myr, to retain the garnet compositional zoning. Rutile ages are discordant, with 207Pb/206Pb dates rangingfrom 1.43 to 1.53 Ga. However, rutile may have responded to earlier thermal pulses, and was also reset later, so it doesnot record the stabilization of the crust. Crustal stabilization after Paleoproterozoic orogenic events may have occurredshortly after titanite formation.

AB - Garnet granulite xenoliths from the Nurbinskaya diatreme in the central part of the Archean Anabar province in Siberiaare fragments of the local lower crust that experienced multiple metamorphic events in the Paleoproterozoic and reheatingevents in the Mesoproterozoic and later. This study addresses the timing of metamorphic transformations, and constrainsthe cooling rate and the time of stabilization of the lower crust. The observed metamorphic mineral assemblage of garnet,clinopyroxene, plagioclase, amphibole, rutile and ilmenite was formed at ~ 800 °C, 1.1–1.2 GPa under water-undersaturatedconditions at ~ 1.88 Ga. However, the mineral assemblage is not well equilibrated and retains evidence of earlierand subsequent metamorphic stages. Late titanite formed in response to hydrous fluid influx according to phase equilibriamodeling. U-Pb dating shows two events of titanite formation at 1850 ± 5 Ma and at 1788 ± 2 Ma. After deformation,which led to the porphyroclastic rock textures, the granulites underwent near-isobaric cooling. The cooling rate was higherthan ~ 6 °C/Myr, to retain the garnet compositional zoning. Rutile ages are discordant, with 207Pb/206Pb dates rangingfrom 1.43 to 1.53 Ga. However, rutile may have responded to earlier thermal pulses, and was also reset later, so it doesnot record the stabilization of the crust. Crustal stabilization after Paleoproterozoic orogenic events may have occurredshortly after titanite formation.

U2 - 10.1007/s00410-024-02156-7

DO - 10.1007/s00410-024-02156-7

M3 - Article

VL - 179

JO - Contributions to Mineralogy and Petrology

JF - Contributions to Mineralogy and Petrology

SN - 0010-7999

M1 - 74

ER -