Open AccessP–T CONDITIONS, U/Pb AND 40Ar/39Ar ISOTOPIC AGES OF UHT GRANULITES FROM CAPE KALTYGEI, WESTERN BAIKAL REGION
Author(s) -
Н. И. Волкова,
Е. И. Михеев,
А. В. Травин,
А. Г. Владимиров,
А. С. Мехоношин,
В. В. Хлестов
Publication year - 2021
Publication title -
geodinamika i tektonofizika
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.336
H-Index - 8
ISSN - 2078-502X
DOI - 10.5800/gt-2021-12-2-0526
Subject(s) - granulite , zircon , metamorphism , metamorphic rock , geology , geochemistry , protolith , quartz , mineral , monazite , paleontology , chemistry , facies , organic chemistry , structural basin
The study is focused on metapelitic granulites of Cape Kaltygei (Western Baikal region) that contain a diagnostic mineral assemblage of ultrahigh temperature (UHT) metamorphic rocks (orthopyroxene+sillimanite+quartz). The pseudosection-based thermobarometry yields peak metamorphic temperature and pressure values (T=950 °C, P=~9 kbar) and suggests near-isobaric cooling (IBC) conditions during the retrograde evolution of the granulites. The U/Pb zircon age estimates for metamorphism (~1.87 Ga) support the data published by other researchers. The SHRIMP-II U-Pb dating of zircon cores yields a minimum protolith age of 1.94–1.91 Ga. Biotites and amphiboles from granulites of Cape Kaltygei show the 40 Ar/ 39 Ar isotopic ages that are close to the Early Paleozoic accretion-collision system of the Western Baikal region.