A reworked Lake Zone margin: Chronological and geochemical constraints from the Ordovician arc-related basement of the Hovd Zone (western Mongolia)

Soejono, Igor; Buriánek, David; Janoušek, Vojtěch; Svojtka, Martin; Čáp, Pavel; Erban, Vojtěch; Ganpurev, Nyamtsetseg

doi:10.1016/j.lithos.2017.08.014

Cited by 26 publications

(18 citation statements)

References 67 publications

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“…The comparison of published detrital zircon age spectra for the Devonian-Carboniferous metasedimentary rocks from the East Junggar (Huang et al, 2018;Long et al, 2012;Zhang et al, 2013), the Chinese and Mongol-Altai (P. Li et al, 2015;Soejono et al, 2017Soejono et al, , 2018, and the Trans-Altai Zone (Yang et al, 2019) shows that age populations from all three domains share identical basic features (Figure 4). All these age spectra contain major peaks at ca.…”

Section: 1029/2019tc006026mentioning

confidence: 99%

Revision of the Chinese Altai‐East Junggar Terrane Accretion Model Based on Geophysical and Geological Constraints

et al. 2020

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Potential field data analysis, geology, and geochemistry are used to revise the terrane accretion model of the Chinese Altai and East Junggar. Major gradients of potential field data demarcate significant crustal structures and their continuity in depth. These data demonstrate that the distribution of geophysical anomalies does not match with terranes boundaries defined previously. Instead, heterogeneously developed NE/SW-trending gravity and NW-SE magnetic anomalies in both units correlate with Devonian and Permian tectonometamorphic zones, respectively. Geophysical data also indicate a dense lower crust of the East Junggar confirmed by previous igneous petrology studies and seismic experiment. The northern tip of this dense crust coincides with the main gravity gradient beneath the Chinese Altai and a prominent magnetic high located above a NW/SE-trending zone of Permian granulites. This zone forms a boundary between north-and south-dipping gravity and magnetic anomalies that are interpreted as reflecting quasi-symmetrical extrusion of the Chinese Altai crust. In contrast, all geophysical data show the absence of a prominent deep-seated discontinuity which can be correlated with the Erqis Zone. These data are compared with corresponding data sets from southern Mongolia allowing the proposition of a new geodynamic model for the studied area. This model involves (1) accretionary stage characterized by Late Devonian joint evolution of the East Junggar and Chinese Altai characterized by N-S trending orogenic fabrics and (2) Early Permian oroclinal bending associated with underthrusting of the dense Junggar basement beneath the Chinese Altai and the development of NW-SE trending deformation zones in both units.

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Section: 1029/2019tc006026mentioning

confidence: 99%

Revision of the Chinese Altai‐East Junggar Terrane Accretion Model Based on Geophysical and Geological Constraints

et al. 2020

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“…In southern areas, the Altay intrusive magmatic area includes groups of granitoids of four different ages (Gavrilova, ). The first group (440–430 Ma) is represented by tonalite, granodiorite, adamellite, normal, and two‐mica granites (Tsagaan‐Gol complex, 440 Ma; Gavrilova, ; Tsenkher Gol complex, 430 ± 3 Ma for a monzodiorite; Soejono et al, ), and the second (398–349 Ma) is represented by numerous plutons of large and giant porphyry biotite and tourmaline‐biotite granites of the Altay complex (Chandmani massif, 340–356 Ma; Hanžl et al, ). The third group includes biotite, two‐mica, and muscovite granites of 317–263 Ma (Sagsay pluton, 309 ± 2 Ma; Burianek et al, 2016).…”

Section: The Geology Of the Lake And Mongolian Altay Zonesmentioning

confidence: 99%

“…Plutonic rocks in the area formed in three main stages associated with early Palaeozoic (E–O), middle Palaeozoic (D–C1), and Permian–Triassic (P–T) tectonomagmatic events (Buriánek et al, ; Cai et al, ; Gavrilova, ; Kovalenko et al, , ; Kozlovsky et al, ; Pavlova et al, ; Soejono et al, ).…”

Section: The Early Palaeozoic Mega‐thrusting Of the Altay–lake Zonementioning

confidence: 99%

The Early Palaeozoic mega‐thrusting of the Gondwana‐derived Altay–Lake zone in western Mongolia: Implications for the development of the Central Asian Orogenic Belt and Paleo‐Asian Ocean evolution

Khukhuudei

Kusky

Otgonbayar³

et al. 2020

Geological Journal

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The position of structures of Mongolia during Rodinia break‐up and Paleo‐Asian Ocean opening is debatable, and reconstructions between them are poorly known. In this paper, we apply an integrated approach to the not widely known yet distinctive structure (ribbon‐like) of the Lake and Mongolian Altay zones in western Mongolia, relating these with the surrounding Tuva–Mongolian and central Mongolian microcontinents (CMMs) development within the Central Asian Orogenic Belt (CAOB) and Paleo‐Asian Ocean evolution. We present a summary of the Neoproterozoic–early Palaeozoic tectonic development of western Mongolia and the CAOB and suggest a new comprehensive model for its evolution. The Lake zone of Mongolia is a major zone of ophiolite and arc complexes within the CAOB. The main sections of ophiolites are located along the west margin, bordering with Precambrian crystalline basement of the CMM. The ophiolites are distributed from north to south and have been dated to have similar ages. A classic oceanic plate stratigraphy section is preserved in the Lake zone. Serpentinite mélange and other volcanogenic‐terrigenous assemblages from the Lake zone are characterized by a system of nappe sheets thrust over the Dzavkhan block of the CMM. The ribbon‐like structure that the southern part of the Altay–Lake zone preserves at present provides an explanation for the development between the Gondwana‐derived microcontinent and Paleo‐Asian Ocean. During the pre‐Neoproterozoic, convergence accretion between Siberia and the CMM formed the Tuva–Mongolian belt, which later converted to the Altay–Lake collision zone associated with the thrusting of its eastern margin. All well‐known ophiolites of western Mongolia (Agardag, Khantayshir, and Dariv) as well as ophiolites of the Erdene Uul area mostly correspond to an “open‐ocean” phase with drifting microcontinents between 655 and 540 Ma or Neoproterozoic. In the early Neoproterozoic, the Altay peninsula‐like ribbon microcontinent after rifting of East Gondwana gradually drifted to Siberia. In this time, the east margin of the Paleo‐Asian Ocean was developed as a passive margin with the Dzavkhan Block. The Paleo‐Asian ocean plate simultaneously drifted to the CMM, whereas the Altay microcontinent moved into Siberia‐CMM. In middle‐upper Neoproterozoic times, the eastern part of the Paleo‐Asian ocean plate was thrusted over the CMM, obducting ophiolites (e.g., Tas Khairkhan), in the early Cambrian time, an oceanic spreading centre (?) of the Paleo‐Asian Ocean reached the CMM and stopped obduction. In the Neoproterozoic, the west margin of the Paleo‐Asian Ocean was developed as an active continental margin, with subduction under the Gondwana‐derived microcontinent. In the early Cambrian, there was significant subduction rollback and accretion of seamounts (Turgen). Later, in middle Cambrian–early Ordovician times, a large turbidite sequence was deposited in Altay. During the Devonian to Carboniferous, the Paleo‐Asian Ocean was preserved as a remnant ocean or big sea (Lake zone), accumulating ...

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“…Syn-rift igneous activity resulted in the emplacement of the Numrug granite (442.10 ± 0.19 Ma), which lies in the Khasagt Khairkhan range of the Zavkhan autochthon (Bold et al 2016). Rift-related igneous activity has also been reported in the adjacent Lake zone (Yarmolyuk et al, 2011;Soejono et al, 2017). Rifting is thought to have lasted until at least the early Silurian (~440 Ma), so it is also unlikely that the Urgamal eclogite formed in relation to this event.…”

Section: Discussionmentioning

confidence: 98%

Geochronology and tectonic implications of the Urgamal eclogite, Western Mongolia

Naemura

Erdenejargal

Javkhlan

et al. 2020

Journal of Mineralogical and Petrological Sciences

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The Urgamal eclogite in western Mongolia, described here for the first time, occurs in the Altai allochthon (also known as the Urgamal subzone) in the Zavkhan terrane of the Central Asian Orogenic belt. The eclogite consists of garnet, omphacite, white mica, quartz, epidote, rutile, and barroisite. We measured zircon U-Th-Pb ages in a barroisite-rich sample of the eclogite using an electron probe microanalyzer, which yielded an age of 1113 +31/ −52 Ma. This suggests that the eclogite protolith is slightly older than the recorded metamorphic and igneous activity in the Zavkhan autochthon (880-780 Ma). To constrain the timing of eclogite facies metamorphism, K-Ar geochronology was applied to white mica separates, yielding an age of 395 ± 7.9 Ma. This Devonian age is much younger than the time at which the Lake terrane and the Zavkhan terrane collided (545-525 Ma). After the collisional event, the Zavkhan terrane was subjected to extensional tectonics, resulting in alkaline volcanism until the beginning of the Silurian (440 Ma). The Urgamal eclogite records a subduction or collision event at 440-395 Ma, which has not been recognized before. This convergent tectonic environment may have been the result of collision between the Zavkhan terrane and the eastern Tarvagatai terrane. During collision, part of the Altai allochthon may have been subducted beneath the Zavkhan autochthon, thereby forming the Urgamal eclogite.

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A reworked Lake Zone margin: Chronological and geochemical constraints from the Ordovician arc-related basement of the Hovd Zone (western Mongolia)

Cited by 26 publications

References 67 publications

Revision of the Chinese Altai‐East Junggar Terrane Accretion Model Based on Geophysical and Geological Constraints

Revision of the Chinese Altai‐East Junggar Terrane Accretion Model Based on Geophysical and Geological Constraints

The Early Palaeozoic mega‐thrusting of the Gondwana‐derived Altay–Lake zone in western Mongolia: Implications for the development of the Central Asian Orogenic Belt and Paleo‐Asian Ocean evolution

Geochronology and tectonic implications of the Urgamal eclogite, Western Mongolia

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