Are the Chinese Altai “terranes” the result of juxtaposition of different crustal levels during Late Devonian and Permian orogenesis?

Broussolle, Arnaud; Sun, Min; Schulmann, Karel; Alfonso, Guy; Aguilar, Carmen; Štípská, Pavla; Jiang, Yingde; Yang, Yu; Xiao, Wenjiao

doi:10.1016/j.gr.2018.11.003

Cited by 62 publications

(57 citation statements)

References 116 publications

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“…In the Chinese Altay, three types of deformation and metamorphism have been described in correlated rocks: the first is MP–MT Barrovian metamorphism formed during moderate thickening, the second is LP–HT Buchan‐type metamorphism related to intrusions of syn‐subduction granitoids in an extensional setting and, subsequently, affected by the NW‐SE late Devonian–early Carboniferous shortening. Third or finally, the Permian collision between the Chinese Altai orogenic belt and the Junggar arc system provoked a NE‐SW shortening event resulting in a crustal scale upright folding and an extrusion of ultrahigh temperature–high‐temperature granulites and migmatites (Broussolle 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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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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“…Red circles show the location of geochronological points. ( c ) The age distributions of regional magmatism, metamorphism and shear activities in the Chinese Altai, n = number of ages from 14,15,22–26 .…”

Section: Resultsmentioning

confidence: 99%

“…The 420–360 Ma metamorphic events are interpreted by a transformation from middle-temperature/middle-pressure Barrovian type to low-pressure/high-temperature Buchan type metamorphism during tectonic switching from northwest to southeast shortening events. In the early-middle Permian (290~270 Ma), another high-temperature Buchan type metamorphic event occurred during northeast-southwest shortening of the Chinese Altai Orogen 19,26 . After 270 Ma, no regional metamorphic event occurred.…”

Section: Discussionmentioning

confidence: 99%

“…Previous Ar-Ar dates of biotite in marble from a plateau age of 221 ± 3 Ma suggest a thermal event relating to strike-slip fault movements 23 . U-Pb dating of hydrothermal zircon from skarn (250 ± 2 Ma) 11 and Re-Os dating of a molybdenite-bearing quartz vein (261 ± 7 Ma) 23 reveal that the hydrothermal fluid deposits in Mengku occurred in the late Permian to Triassic, which is younger than both the regional magmatic activity (450–270 Ma) and local granites in the mining area (400–378 Ma) 14,15,22–26 . Based on geological, chronological, and isotopic observations, we propose that meteoric water circulating in a shear zone triggered the Mengku iron mineralization 11 .…”

Section: Introductionmentioning

confidence: 99%

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Garnet U-Pb and O isotopic determinations reveal a shear-zone induced hydrothermal system

Zang

Dong

Liu

et al. 2019

Sci Rep

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The absolute crystallization ages of minerals from hydrothermal fluids measured in situ can unravel the timing of key events leading to the formation of, for instance, ore deposits and hydrothermally derived geological terrains. In this study, a skarn iron deposit from northwest (NW) China is shown to have U-Pb garnet and U-Pb zircon ages of 254.2 ± 1.7 Ma and 255.5 ± 1.0 Ma, respectively, which are both significantly younger than magmatism and metamorphism of the region. This skarn age instead correlates with the occurrence of strike-slip and thrust faulting in the region. The water/rock mass ratio of 0.065~0.115 suggests the δ 18 O garnet composition is ~1‰ at temperatures ranging from 250–450 °C. The low oxygen isotopic composition indicates the role of meteoric water in the garnet formation. These measurements can be interpreted as the shear along faults circulating meteoric water ~10 km below the hanging wall of meta-volcanic sedimentary rock. Meteoric water in this hydrothermal system would leach cations from the meta-volcano-sedimentary rocks necessary for mineralization. Silica-rich hydrothermal fluid reacts with calcic-rich materials in the meta-volcano-sedimentary rocks, depositing the garnet and magnetite. Our work suggests that the shear zone is rich in ores, rendering this deposit for NW China a prospective source for future mineral resource exploration.

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“…Small-scale geological maps are one of the most important bases for mutual correlation of geological units forming these zones and to better understand their assembly during the accretion and subsequent collisional reworking (e.g. Broussolle et al, 2019;Kröner et al, 2010;Lehmann et al, 2010). For this purpose, we produced a 1:500,000 scale map sheet L-47-V covering c. 53 000 km 2 in the Bayankhongor and Gobi Altai provinces of SW Mongolia.…”

Section: Introductionmentioning

confidence: 99%

Geology of the Gobi and Mongol Altai junction enhanced by gravity analysis: a key for understanding of the Mongolian Altaides

Hanžl

Alfonso

Altanbaatar³

et al. 2019

Journal of Maps

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The geological map L-47-V at a scale 1:500,000 covers part of Mongolian Altaids with ophiolite fragments in southern Central Asian Orogenic Belt in SW Mongolia. This region has a basin and range topography with Neoproterozoic and Palaeozoic units exposed at NW-SE trending ranges rising along major intracontinental faults and with intermontane basins filled by Mesozoic and Cenozoic sediments in between. The map shows clear N-S tectonic zonation featuring the northerly Precambrian Baidrag microcontinent, the lower Palaeozoic Lake Zone in the centre and the southerly Palaeozoic Gobi-Altai and Trans-Altai zones. Gravity highs are located in the SW part of the map and low to intermediate Bouguer anomalies in the NE part. NW-SE trends of gravity anomalies correlate well with the contact between the Trans-Altai and the Gobi-Altai zones but the important first-order geological boundary between the Lake and Gobi-Altai zones cannot be delineated by the gravity gradients.

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Are the Chinese Altai “terranes” the result of juxtaposition of different crustal levels during Late Devonian and Permian orogenesis?

Cited by 62 publications

References 116 publications

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

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

Garnet U-Pb and O isotopic determinations reveal a shear-zone induced hydrothermal system

Geology of the Gobi and Mongol Altai junction enhanced by gravity analysis: a key for understanding of the Mongolian Altaides

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