Petrotectonic Evolution of the Maksyutov Complex, Southern Urals, Russia: Implications for Ultrahigh-Pressure Metamorphism

Lennykh, V. I.; Valizer, P. M.; Beane, R. J.; Leech, M. L.; Ernst, W. G.

doi:10.1080/00206819509465420

Cited by 70 publications

(47 citation statements)

References 17 publications

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“…Most studies of the Maksyutov Complex have concentrated on three key localities ± Karayanovo, Shubino and Antingan (Figure 1) ± where ma®c eclogites and blueschists occur as layers and boudins in metasedimentary rocks of the lower unit 1. The presence of jadeite, glaucophane, phengite and garnet in the metasediments demonstrates that they experienced similar pressure±temperature (P±T) conditions as the ma®c eclogites and blueschists Lennykh et al 1995;Dobretsov et al 1996;Hetzel et al 1998).…”

Section: P±t Evolutionmentioning

confidence: 96%

“…Recently, there has been some speculation about the former presence of coesite and even diamond in the Maksyutov Complex which would indicate ultrahigh-pressure metamorphic conditions Lennykh et al 1995;Leech and Ernst 1998;Leech and Stockli 2000). As this topic is highly relevant for the interpretation of the published geochronological data (see below) and the geodynamic evolution of the arc±continent collision, we brie¯y summarize the arguments for and against ultrahigh-pressure metamorphism.…”

Section: P±t Evolutionmentioning

confidence: 97%

“…The Maksyutov Complex consists of two distinct units with different protoliths and tectonometamorphic histories (Lennykh 1977;Lennykh et al 1995). The lower unit 1 has been interpreted as subducted continental crust of the East European platform, whereas the upper unit 2 is thought to represent Palaeozoic oceanic crust and sediments (Hetzel 1999).…”

Section: P±t Evolutionmentioning

confidence: 99%

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A moderate exhumation rate for the high‐pressure Maksyutov Complex, southern Urals, Russia

Hetzel

Romer

2000

Geological Journal

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The high-pressure Maksyutov Complex in the southern Urals contains a regionally coherent crustal unit that experienced peak metamorphic conditions of $ 2 GPa ( $ 60 km) and $ 550 C at 378 AE 6 Ma. Exhumation of the high-pressure unit occurred under retrograde blueschist and middle/lower greenschist facies conditions, indicating a pronounced cooling during decompression. The rise of the high-pressure unit to a mid-crustal depth ( $ 20 km) was accommodated along retrograde ductile shear zones that formed in quartz-rich lithologies. Rb-Sr white mica ages from these quartzitic mylonites cluster at $ 360 Ma, while Ar-Ar ages are more variable, between 370 AE 7 and 344 AE 7 Ma. We interpret the Rb-Sr ages to date the mylonitic deformation in the retrograde shear zones and infer that by 360 AE 8 Ma the high-pressure Maksyutov Complex has reached mid-crustal depth. The pressure±temperature±time data suggest an average exhumation rate of 2 ( 2 / À 0.5 ) mm a À1 for the ®rst exhumation stage from 60 to 20 km. Using our Rb-Sr data and published ®ssion-track data, a slower exhumation rate of 0.3 ( AE 0.1) mm a À 1 is inferred for the rise of the high-pressure rocks from the middle to the upper crust. The moderate exhumation rate of 2 mm a À 1 is in accordance with published thermal models, which demonstrate that a relatively slow exhumation is required for high-pressure rocks to experience syn-decompressional cooling. Such syn-decompressional cooling, as inferred for the Maksyutov Complex, contrasts with isothermal decompression observed in many other regional high-pressure terrains that experienced a relatively fast exhumation. The two main factors that controlled the unusual thermal evolution of the southern Urals may be the low radiogenic heat production of the crust and the stable, $ 200 km thick lithospheric mantle beneath the orogen.

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Section: P±t Evolutionmentioning

confidence: 96%

Section: P±t Evolutionmentioning

confidence: 97%

Section: P±t Evolutionmentioning

confidence: 99%

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A moderate exhumation rate for the high‐pressure Maksyutov Complex, southern Urals, Russia

Hetzel

Romer

2000

Geological Journal

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“…There is independent geologic evidence of continental collision in the Late Precam brian, which may have resulted in eclogite formation [Gee et al, 1996;Giese et al, 1999]. In addition, there are eclogitic rocks exposed at the surface and preserved in the high-grade metamorphic Maksyutov Complex [Beane et aI., 1995;Lennykh et al, 1995Lennykh et al, , 1997Leech and Stockli, 2000]. These eclogites have been dated as Devonian in age (377-384 Ma) based on U-Pb decay ages of rutile within the mafic eclogite [Beane et aI., 1995[Beane et aI., , 1997Beane and Conelly, 2000].…”

Section: The Case For Phase-change Mohomentioning

confidence: 99%

“…Lennykh et al [1995], Hetzel et al [1998], Dobretsov et al [1996], and Beane [1997] sug gested that this complex consists of three main rock types including high-pressure eclogitc facies rocks, metasand stones (blueschist-facics), and a metamorphosed mafic ultramafic melange (grecnschist facies). The protolith and the metamorphic age of the rocks forming the Maksyutov Complex remain a subject of controversy [e.g., Zakharov and Puchkov, 1994;Hetzel, 1999;Leech and Stockli, 2000].…”

Section: Geologic Frameworkmentioning

confidence: 99%