Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south–central Mongolia)

Janoušek, Vojtěch; Jiang, Yingde; Buriánek, David; Schulmann, Karel; Hanžl, Pavel; Soejono, Igor; Kröner, Alfred; Altanbaatar, Battushig; Erban, Vojtěch; Lexa, Ondrej; Ganchuluun, Turbat; Košler, Jan

doi:10.1016/j.gr.2017.10.003

Cited by 65 publications

(47 citation statements)

References 198 publications

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“…The Mongolian Collage itself consists of the accreted Mongolian Precambrian blocks overthrust by late Proterozoic ophiolites and accretionary wedge during a main Early Cambrian accretionary event (Buriánek et al, ; Jiang et al, ). The Proterozoic wedge was intruded by an ~1,800‐km‐long Cambro‐Ordovician Ikh‐Mongol arc system (e.g., Janoušek et al, ).…”

Section: Geological Settingmentioning

confidence: 99%

“…The lithological content of this unit led Xiao et al () to interpret it as a giant “Altai” accretionary wedge. Together with the Ikh‐Mongol arc system (Janoušek et al, ), it represents a huge early Paleozoic Altai accretionary system, rimming the active margin of the Precambrian Zavhan and Baydrag ribbon continents to the northeast (Figure ; Jiang et al, ; Soejono et al, ). This accretionary system developed above a long‐lasting and retreating Pacific‐type oceanic plate that produced Devonian to Carboniferous oceanic assemblages further south (Jiang et al, ; Nguyen et al, ; Xiao et al, ).…”

Section: Geological Settingmentioning

confidence: 99%

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Structural and Geochronological Constraints on Devonian Suprasubduction Tectonic Switching and Permian Collisional Dynamics in the Chinese Altai, Central Asia

et al. 2019

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Kinematic significance and time scales of geodynamic processes forming the Altai OrogenicBelt are addressed through structural and petrological analysis combined with zircon and monazite geochronology. The study area is composed of orogenic lower crust represented by a Devonian migmatite-magmatite complex and orogenic middle and upper crust formed by an amphibolite-facies Ordovician sedimentary sequence and a weakly to unmetamorphosed Devonian volcano-sedimentary cover, respectively. The orogenic lower and middle crust were first affected by moderate thickening, which formed subhorizontal Barrovian metamorphic schistosity. This fabric was reworked by deep crustal melting and intrusion of granite sheets during horizontal extension at 400-380 Ma. Soon after, this horizontal fabric was affected by NW-SE shortening generating crustal-scale upright folding associated with subvertical flow of still partially molten orogenic lower crust. During this event, the orogenic lower and middle crust were tightly juxtaposed with upper crustal sedimentary rocks. The last event was related with a NE-SW oriented convergence resulting in large-scale folding and megafold interference pattern in the Permian at 280-273 Ma. Combined with existing regional data, our results allow proposing a Devonian tectonic switching from compression to extension and back to compression, as a response to variations of subduction dynamics between slab advance and retreat in a Pacific-type suprasubduction system. The Permian folding was associated with the progressive northward exhumation of thermally softened crust. This tectonic evolution is in response to the indentation of the rigid Junggar arc domain into the weak Altai wedge.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Structural and Geochronological Constraints on Devonian Suprasubduction Tectonic Switching and Permian Collisional Dynamics in the Chinese Altai, Central Asia

et al. 2019

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“…490 Ma and a broad minor peak in the interval of 1,200–700 Ma. Such a detrital pattern was interpreted as clastic material derived mainly from the northerly Proterozoic Lake Zone and margins of Precambrian Mongolian microcontinents (e.g., Janoušek et al, 2018; Jiang et al, 2017; Soejono et al, 2018). The difference in amplitude of the ca.…”

Section: Geological Background Of the Chinese Altai And The East Junggarmentioning

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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“…Recent studies carried out in the southern part of the Lake–Mongolian Altay zone and Trans‐Altay Gobi have proposed the existence of the Ikh‐Mongol arc system (Janoušek et al, ), based on the study of Palaeozoic arc‐type granitoid magmatism (Buriánek et al, ; Hrdličková et al, ; Kröner et al, ; Soejono et al, ). It might correspond to a transition alternating from ocean crust to continental crust.…”

Section: The Geology Of the Lake And Mongolian Altay Zonesmentioning

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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Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south–central Mongolia)

Cited by 65 publications

References 198 publications

Structural and Geochronological Constraints on Devonian Suprasubduction Tectonic Switching and Permian Collisional Dynamics in the Chinese Altai, Central Asia

Structural and Geochronological Constraints on Devonian Suprasubduction Tectonic Switching and Permian Collisional Dynamics in the Chinese Altai, Central Asia

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

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