Early Paleozoic magmatism in the Bumbat-Hairhan area of the Lake Zone in western Mongolia (geological, petrochemical, and geochronological data)

Руднев, С. Н.; Изох, А. Э.; Борисенко, А.С.; Shelepaev, R.A.; Orihashi, Yuji; Lobanov, K. V.; Vishnevskiy, A. V.

doi:10.1016/j.rgg.2012.03.004

Cited by 45 publications

(19 citation statements)

References 5 publications

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“…While ages of c. 430-440 Ma are not known from the Tseel and adjacent terranes (Tab. 1), ages of c. 510-530 Ma correspond well with those of magmatic rocks in the Lake Zone (e. g. Dijkstra et al 2006;Hrdličková et al 2010;Rudnev et al 2012Rudnev et al , 2013Jian et al 2014). Moreover, the age of ~740 Ma resembles that known from coarse-grained orthogneiss of the Zamtyn Nuruu range, also in the Lake Zone (Demoux et al 2009b;Hanžl et al 2014) Therefore, the lower-middle crust underlying the studied region seems to have an affinity to the Neoproterozoic rocks of the Lake Zone.…”

Section: Age and Character Of The Protolith To The Orthogneissessupporting

confidence: 55%

Making continental crust: origin of Devonian orthogneisses from SE Mongolian Altai

Hanžl¹,

Schulmann²,

Janoušek³

et al. 2016

Jour. Geosci.

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Orthogneiss and meta-rhyolite bodies from different crustal levels of the Tseel Terrane in the Mongolian Altai were examined using multidisciplinary approach involving structural geology, whole-rock geochemistry and U-Pb zircon geochronology. The orthogneisses form sheet-like bodies parallel with dominant sub-horizontal metamorphic fabric which was heterogeneously verticalized along localized zones of deformation at boundaries of lower and middle crustal domains. Three samples of orthogneisses yielded Late Devonian LA-ICP-MS U-Pb zircon ages of 373 ± 3, 377 ± 5 and 379 ± 2 Ma (2σ), which are interpreted as crystallization ages of felsic magmas. The meta-rhyolite displays poorly constrained, older U-Pb zircon ages of 380 ± 4 and 403 ± 5 Ma, which are also considered as intrusive. Whole-rock geochemistry, including relatively little fractionated REE patterns, as well as radiogenic whole-rock Nd and zircon Hf isotopic signatures point to a rather primitive source of the granitic protoliths. The high-K calc-alkaline chemistry and LILE over HFSE enrichments in the NMORB-normalized spider plots indicate an arc-related origin. Juvenile character of the studied rocks was confirmed by Nd and Hf crustal residence ages that are mostly 0.8-0.9 Ga. The origin of the metaigneous rocks is interpreted in terms of partial melting of Neoproterozoic to Cambrian magmatic arc-derived material, probably dominated by immature psammitic sediments (graywackes). This study brings important arguments that the orthogneisses do not represent an old crystalline basement previously assumed in the Mongolian Altai. A model is proposed suggesting formation of mature and layered continental crust by syn-orogenic melting of youthful volcanosedimentary wedge and emplacement of sub-horizontal syn-orogenic magmatic sheets at all crustal levels during crustal-scale vertical shortening. The vertical shortening was probably connected to lithospheric-scale extensional event associated with massive heat influx and emplacement of juvenile magmas at the bottom of the crust. It is suggested that this mechanism represents potentially a viable model for cratonization of accretionary systems worldwide.

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Section: Age and Character Of The Protolith To The Orthogneissessupporting

confidence: 55%

Making continental crust: origin of Devonian orthogneisses from SE Mongolian Altai

Hanžl¹,

Schulmann²,

Janoušek³

et al. 2016

Jour. Geosci.

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“…During the Late Cambrian, a new NE and/or east dipping subduction system developed along the SW and west margins of the Mongolian Precambrian blocks giving rise to the generation of widespread arc magmatism (with maximum activity at circa 510 Ma) variously intruding the Precambrian basement and the accreted Lake Zone (e.g., Izokh et al, ; Mongush et al, ; Rudnev et al, ; Yarmolyuk et al, ), exemplified by the Ikh‐Mongol arc system (see Janoušek et al, Figure ). We propose that formation of this giant arc was connected with the development of an equally giant turbidite basin to the south or west (Figure ).…”

Section: Discussionmentioning

confidence: 99%

Neoproterozoic‐Early Paleozoic Peri‐Pacific Accretionary Evolution of the Mongolian Collage System: Insights From Geochemical and U‐Pb Zircon Data From the Ordovician Sedimentary Wedge in the Mongolian Altai

et al. 2017

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Neoproterozoic to early Paleozoic accretionary processes of the Central Asian Orogenic Belt have been evaluated so far mainly using the geology of ophiolites and/or magmatic arcs. Thus, the knowledge of the nature and evolution of associated sedimentary prisms remains fragmentary. We carried out an integrated geological, geochemical, and zircon U‐Pb geochronological study on a giant Ordovician metasedimentary succession of the Mongolian Altai Mountains. This succession is characterized by dominant terrigenous components mixed with volcanogenic material. It is chemically immature, compositionally analogous to graywacke, and marked by significant input of felsic to intermediate arc components, pointing to an active continental margin depositional setting. Detrital zircon U‐Pb ages suggest a source dominated by products of early Paleozoic magmatism prevailing during the Cambrian‐Ordovician and culminating at circa 500 Ma. We propose that the Ordovician succession forms an “Altai sedimentary wedge,” the evolution of which can be linked to the geodynamics of the margins of the Mongolian Precambrian Zavhan‐Baydrag blocks. This involved subduction reversal from southward subduction of a passive continental margin (Early Cambrian) to the development of the “Ikh‐Mongol Magmatic Arc System” and the giant Altai sedimentary wedge above a north dipping subduction zone (Late Cambrian‐Ordovician). Such a dynamic process resembles the tectonic evolution of the peri‐Pacific accretionary Terra Australis Orogen. A new model reconciling the Baikalian metamorphic belt along the southern Siberian Craton with peri‐Pacific Altai accretionary systems fringing the Mongolian microcontinents is proposed to explain the Cambro‐Ordovician geodynamic evolution of the Mongolian collage system.

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“…The Lake zone of Mongolia (Figure ) is a major zone of ophiolite and arc complexes within the CAOB (Byamba, ; Kovach et al, ; Kovalenko et al, ; Kröner et al, ; Rudnev et al, ; Rudnev, Izokh, Borisenko, & Gas'kov, ; Rudnev, Izokh, Kovach, Shelepaev, & Terent'eva, ; Ruzhentsev & Burashnikov, ; Tomurtogoo, ; Yarmolyuk et al, ). The Lake zone consists mainly of Cambrian volcano‐sedimentary rocks and ophiolites (Byamba, ; Dergunov, Luvsandanzan, & Pavlenko, ; Kovalenko et al, ; Ruzhentsev & Burashnikov, ; Tomurtogoo, ; Zonenshain & Kuzmin, ).…”

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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Early Paleozoic magmatism in the Bumbat-Hairhan area of the Lake Zone in western Mongolia (geological, petrochemical, and geochronological data)

Cited by 45 publications

References 5 publications

Making continental crust: origin of Devonian orthogneisses from SE Mongolian Altai

Making continental crust: origin of Devonian orthogneisses from SE Mongolian Altai

Neoproterozoic‐Early Paleozoic Peri‐Pacific Accretionary Evolution of the Mongolian Collage System: Insights From Geochemical and U‐Pb Zircon Data From the Ordovician Sedimentary Wedge in the Mongolian Altai

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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