Permian-Triassic magmatism and Ag-Sb mineralization in southeastern Altai and northwestern Mongolia

Petrogenesis of the Triassic Alaer granite in the Chinese Altay is important to understand the regional crustal evolution. This study found that the biotite granite is metaluminous and high-K calc-alkaline to shoshonitic. The rocks contain low SiO 2 (64.3–68.7 wt.%), high Al 2 O 3 (13.46–16.56%) and K 2 O (mostly 3.65–7.57 wt.%), and are featured by distinctly higher concentrations of HFSE (e.g., Th, Hf) and ΣREE than those of the nearby Devonian granites. REE patterns show right-inclining trend and weak negative Eu anomalies (δEu = mostly 0.68–0.94), whilst the spidergrams show consistent negative anomalies of Ba, Sr, P, Ti, Nb and Ta and positive anomalies of Th, K, La, Ce, Nd, Zr and Hf. Compared with the local Devonian granites, the Triassic granites have higher calculated initial 87 Sr/ 86 Sr ratios (0.70601–0.70920) and εNd(t) values −(−1.24 to −0.68). Their Nd model ages (average of 1.08 Ga for one-stage and 1.07 Ga for two-stage) are early Neoproterozoic to late Mesoproterozoic. We infer that the Triassic Alaer granite belongs to I-type granite and likely formed in an intraplate extensional setting under high temperature (829–885 °C) and pressure (depths of 30–50 km, corresponding to the middle-lower crust in the Chinese Altay region). Granitic magma was produced through the melting of old continental basement with substantial mantle input, triggered by extensional upwelling of mantle-derived magmas. Mixing equation of Nd isotope compositions yielded a 40% of mantle-derived juvenile components for the Alaer granite petrogenesis.

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“…(2001)) and the Russian Altay (e.g., the Triassic leucogranites (Vladimirov et al. (2005)) and alkaline mafic dykes (Pavlova et al. (2008))).…”

Section: Discussionmentioning

confidence: 99%

Petrogenetic and tectonic implications of Triassic granitoids in the Chinese Altay: the Alaer granite example

Liu

Han

2019

Heliyon

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“…Isotope and geochemical study of the Ag-Sb mineralization of the Gorny Altai, NW Mongolia and Pamir related to intraplate alkaline mafic magmatism Pavlova and Borovikov, 2010;Pavlova et al, 2008Vasyukova et al, 2011) and Ag-Hg-Sb mineralization linked with subalkaline-alkaline mafic magmatism have shown similar age of mineralization with dikes of alkali mafic rocks (lamprophyres) and syenite intrusions. Shaw (1952), Hamaguchi and Kuroda (1959), Kuroda et al (1990), Ivanov (1963), Pandalai et al (1983) Andesite 0.2 0.035-0.052 0.08 Shaw (1952), Pierce andPeck (1961) Ivanov (1963), Yi et al (1995), Kuroda et al (1990) The Sn-sulfide In-rich mineralization has formed along convergent plate margins and linked with i) bimodal magmatism (granite and alkaline mafic) in volcanoplutonic belts (Sikhote-Alin/Russia) of active continental margins and in a back-arc setting (Cenozoic mineralization of Bolivia), basalt-rhyolite magmatism in ensialic arcs (Prasolov, Kudryavy volcano, Kuriles); ii) bimodal postorogenic magmatism (granitoid and alkaline mafic) in the continental collision zones (Hercynian Sn ore districts in Europe and Tian-Shan, Cretaceous Sn-ore districts in Yakutia).…”

Section: ) Sn Mineralization Of the Cassiterite-quartz Stagementioning

confidence: 99%

Indium in cassiterite and ores of tin deposits

Pavlova

Palessky

Борисенко

et al. 2015

Ore Geology Reviews

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“…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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Permian-Triassic magmatism and Ag-Sb mineralization in southeastern Altai and northwestern Mongolia

Cited by 26 publications

References 9 publications

Petrogenetic and tectonic implications of Triassic granitoids in the Chinese Altay: the Alaer granite example

Petrogenetic and tectonic implications of Triassic granitoids in the Chinese Altay: the Alaer granite example

Indium in cassiterite and ores of tin deposits

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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