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Petrology and retrograde P‐T path for eclogites of the Maksyutov Complex, Southern Ural Mountains, Russia
Author(s) -
Beane R. J.,
Liou J. G.,
Coleman R. G.,
Leech M. L.
Publication year - 1995
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/j.1440-1738.1995.tb00148.x
Subject(s) - eclogite , geology , metamorphism , coesite , lawsonite , phengite , pseudomorph , glaucophane , omphacite , geochemistry , schist , epidote , metamorphic rock , petrology , chlorite , quartz , subduction , seismology , paleontology , tectonics
The Maksyutov Complex, situated in the southern Ural Mountains of Russia, is the first location where quartz aggregates within garnets exhibiting radial fractures were identified as coesite pseudomorphs (Chesnokov & Popov 1965). The complex consists of two tectonic units: a structurally lower eclogite‐bearing schist unit and an overlying meta‐ophiolite unit. Both units show evidence for multiple stages of metamorphism and deformation. The high‐pressure metamorphism of the eclogite‐bearing schist unit, discussed in this report, is suspected to be related to a collision between the Russian platform and a fragment of the Siberian continent during the early Cambrian. At least three stages of metamorphism (M 1‐3 ) and two stages of deformation (S 1 and S 2 ) were observed in thin sections: M 1 ) garnet (Alm 55‐60 , Prp 22‐28 , Grs 16‐20 ) + omphacite (Jd 46‐56 ) + phengite (Si ≅ 3.5) + rutile; M 2 ) garnet + glaucophane ± lawsonite + white mica; and M 3 ) epidote + chlorite ± albite ± actinolite + white mica. Observed mineral parageneses define a retrograde P‐T path for the eclogite. Mineral assemblages within the most representative eclogite from the lower unit of the Maksyutov Complex indicate minimum peak pressures of 15 kbar at temperatures of approximately 600°C. If the presence of coesite pseudomorph is confirmed, the peak ultrahigh‐pressure metamorphism may be as high as 27 kbar at 615°C.