An exhumation pressure–temperature path and fluid activities during metamorphism in the Tseel terrane, SW Mongolia: Constraints from aluminosilicate-bearing quartz veins and garnet zonings in metapelites

Ulziiburen, Burenjargal; Okamoto, Atsushi; Meguro, Yuichi; Tsuchiya, Noriyoshi

doi:10.1016/j.jseaes.2012.04.017

Cited by 13 publications

(26 citation statements)

References 45 publications

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“…This is the first time such a path has been reported for the Mongolian Altai Mountains. In previous studies, decompressional paths at temperatures of 580Њ-670ЊC had been identified in the Bodonch (Zorigtkhuu et al 2012) and Tseel regions (Burenjargar et al 2012), and these decompressional paths may correspond to the final process of decompression reported here. Importantly, the samples studied here also preserve the earlier history of the metamorphic process.…”

Section: Pressure-temperature Evolution Of the High-mg High-al Metamsupporting

confidence: 71%

Paleozoic Subduction-Accretion-Closure Histories in the West Mongolian Segment of the Paleo-Asian Ocean: Evidence from Pressure-Temperature-Time-Protolith Evolution of High-Mg and -Al Gneisses in the Altai Mountains

Nakano

Osanai

Satish-Kumar

et al. 2014

The Journal of Geology

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Section: Pressure-temperature Evolution Of the High-mg High-al Metamsupporting

confidence: 71%

Paleozoic Subduction-Accretion-Closure Histories in the West Mongolian Segment of the Paleo-Asian Ocean: Evidence from Pressure-Temperature-Time-Protolith Evolution of High-Mg and -Al Gneisses in the Altai Mountains

Nakano

Osanai

Satish-Kumar

et al. 2014

The Journal of Geology

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“…The Tseel terrane records widespread greenschist to amphibolite facies metamorphism (Sukhorukov, ; Burenjargal et al ., ), with granulite facies assemblages reported in migmatitic mafic gneiss from the Tsogt area (~50 km east of the Tseel area; Kozakov, ). The Tseel area, in the eastern block of the Tseel terrane (Fig.…”

Section: Geological Settingmentioning

confidence: 99%

“…Aluminosilicate‐bearing quartz veins, which contain all three aluminosilicate polymorphs, occur in the central parts of the Tseel area and have been described previously by Sukhorukov () and Burenjargal et al . (). These previous studies reported the veins to be restricted in occurrence; however, we found them to be widely distributed in the sillimanite and staurolite zones in the Tseel area (Fig.…”

Section: Aluminosilicate‐bearing Quartz Veinsmentioning

confidence: 99%

Thermal evolution of the Tseel terrane, SW Mongolia and its relation to granitoid intrusions in the Central Asian Orogenic Belt

Ulziiburen

Okamoto

Kuwatani

et al. 2014

Journal Metamorphic Geology

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The timing and thermal effects of granitoid intrusions into accreted sedimentary rocks are important for understanding the growth process of continental crust. In this study, the petrology and geochronology of pelitic gneisses in the Tseel area of the Tseel terrane, SW Mongolia, are examined to understand the relationship between igneous activity and metamorphism during crustal evolution in the Central Asian Orogenic Belt (CAOB). Four mineral zones are recognized on the basis of progressive changes in the mineral assemblages in the pelitic gneisses, namely: the garnet, staurolite, sillimanite and cordierite zones. The gneisses with high metamorphic grades (i.e. sillimanite and cordierite zones) occur in the central part of the Tseel area, where granitoids are abundant. To the north and south of these granitoids, the metamorphic grade shows a gradual decrease. The composition of garnet in the pelitic gneisses varies systematically across the mineral zones, from grossular‐rich garnet in the garnet zone to zoned garnet with grossular‐rich cores and pyrope‐rich rims in the staurolite zone, and pyrope‐rich garnet in the sillimanite and cordierite zones. Thermobarometric analyses of individual garnet crystals reveal two main stages of metamorphism: (i) a high‐P and low‐T stage (as recorded by garnet in the garnet zone and garnet cores in the staurolite zone) at 520–580 °C and 4.5–7 kbar in the kyanite stability field and (ii) a low‐P and high‐T stage (garnet rims in the staurolite zone and garnet in the sillimanite and cordierite zones) at 570–680 °C and 3.0–6.0 kbar in the sillimanite stability field. The earlier high‐P metamorphism resulted in the growth of kyanite in quartz veins within the staurolite and sillimanite zones. The U–Pb zircon ages of pelitic gneisses and granitoids reveal that (i) the protolith (igneous) age of the pelitic gneisses is c. 510 Ma; (ii) the low‐P and high‐T metamorphism occurred at 377 ± 30 Ma; and (iii) this metamorphic stage was coeval with granitoid intrusion at 385 ± 7 Ma. The age of the earlier low‐T and high‐P metamorphism is not clearly recorded in the zircon, but probably corresponds to small age peaks at 450–400 Ma. The low‐P and high‐T metamorphism continued for c. 100 Ma, which is longer than the active period of a single granitoid body. These findings indicate that an elevation of geotherm and a transition from high‐P and low‐T to low‐P and high‐T metamorphism occurred, associated with continuous emplacement of several granitoids, during the crustal evolution in the Devonian CAOB.

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“…Štípská et al ., ; Skrzypek et al ., ). Despite a large effort during the last decade, the petrological studies carried out in both the Chinese and Mongolian Altai are concentrated mostly on the estimation of peak P–T conditions, retrograde P–T trajectories or geochronology attempting to date paroxysmal stages of metamorphism (Kröner et al ., ; Burenjargal et al ., , ). However, the complexity of the metamorphic and structural evolution of this area (Economos et al ., ; Hrdličková et al ., ; Lehmann et al ., ; Buriánek et al ., ) calls for integrated structural, metamorphic petrology and geochronological studies that may provide information about tectonic history and time‐scales of thermal evolution of the Altai orogeny as well as about mechanisms responsible for exhumation of the high‐grade rocks.…”

Section: Introductionmentioning

confidence: 99%

P–T–t–D record of crustal‐scale horizontal flow and magma‐assisted doming in the SW Mongolian Altai

Broussolle

Štípská

Lehmann

et al. 2015

Journal Metamorphic Geology

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The Chandman massif, a typical structure of the Mongolian Altai, consists of a migmatitemagmatite core rimmed by a lower-grade metamorphic envelope of andalusite and cordieritebearing schists. The oldest structure in the migmatite-magmatite core is a sub-horizontal migmatitic foliation S1 parallel to rare granitoid sills. This fabric is folded by upright folds F2 and transposed into a vertical migmatitic foliation S2 that is syn-tectonic, with up to several tens of metres thick granitoid sills. Sillimanite-ilmenite-magnetite S1 inclusion trails in garnet constrain the depth of equilibration during the S1 fabric to 6-7 kbar at 710-780°C. Reorientation of sillimanite into the S2 fabric indicates that the S1-S2 fabric transition Accepted ArticleThis article is protected by copyright. All rights reserved. occurred in the sillimanite stability field. The presence of cordierite, and garnet rim chemistry point to decompression to 3-4 kbar and 680-750°C during development of the S2 steep fabric, and postectonic andalusite indicates further decompression to 2-3 kbar and 600-650°C. Widespread crystallization of post-tectonic muscovite is explained by the release of H 2 O from crystallizing partial melt. In the metamorphic envelope the subhorizontal metamorphic schistosity S1 is heterogeneously affected by upright F2 folds and axial planar subvertical cleavage S2. In the north, the inclusion trails in garnet are parallel to the S1 foliation, and the garnet zoning indicates nearly isobaric heating from 2.5-3 kbar and 500-530°C. Cordierite contains crenulated S1 inclusion trails and has pressure shadows related to the formation of the S2 fabric. The switch from the S1 to the S2 foliation occurred near 2.5-3 kbar and 530-570°C; replacement of cordierite by fine-grained muscovite and chlorite indicates further retrogression and cooling. In the south, andalusite containing crenulated inclusion trails of ilmenite and magnetite indicates heating during the D2 deformation at 3-4 kbar and 540-620°C. Monazite from a migmatite analyzed by LASS yielded elevated HREE concentrations. The grain with the best-developed oscillatory zoning is 356±1. Pb), considered to date the crystallization from melt in the cordierite stability around 680°C and 3.5 kbar, whereas the patchy BSE-dark domains give a date of 347±4.2 [±7] Ma interpreted as recrystallization at subsolidus conditions. The earliest subhorizontal fabric is associated with the onset of magmatism and peak of P-T conditions in the deep crust, indicating important heat input associated with lower crustal horizontal flow. The paroxysmal metamorphic conditions are connected with collapse of the metamorphic structure, an extrusion of the hot lower crustal rocks associated with vertical magma transfer and a juxtaposition of the hot magmatite-migmatite core with supracrustal rocks. This study provides information about tectono-thermal history and time scales of horizontal flow and vertical mass and heat transfer in the Altai orogen. It is shown that, similar to collisional orogens, ...

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An exhumation pressure–temperature path and fluid activities during metamorphism in the Tseel terrane, SW Mongolia: Constraints from aluminosilicate-bearing quartz veins and garnet zonings in metapelites

Cited by 13 publications

References 45 publications

Paleozoic Subduction-Accretion-Closure Histories in the West Mongolian Segment of the Paleo-Asian Ocean: Evidence from Pressure-Temperature-Time-Protolith Evolution of High-Mg and -Al Gneisses in the Altai Mountains

Paleozoic Subduction-Accretion-Closure Histories in the West Mongolian Segment of the Paleo-Asian Ocean: Evidence from Pressure-Temperature-Time-Protolith Evolution of High-Mg and -Al Gneisses in the Altai Mountains

Thermal evolution of the Tseel terrane, SW Mongolia and its relation to granitoid intrusions in the Central Asian Orogenic Belt

P–T–t–D record of crustal‐scale horizontal flow and magma‐assisted doming in the SW Mongolian Altai

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