The Oortsog Peridotite–Troctolite–Gabbro Intrusion, Western Mongolia:New Petrological and Geochronological Constraints

Shapovalova, Maria; Tolstykh, Nadezhda D.; Shelepaev, R.A.; Tsibizov, L

doi:10.15372/rgg2019069

Cited by 4 publications

(10 citation statements)

References 29 publications

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“…The potassium content in the rocks of the complex does not increase monotonously with decreasing magnesium content in the rocks, but one has a decrease in the plagioclase cumulates in the Yamaat Uul complex on the diagram (Figures 9c and 12). The same distribution of rock compositions is observed in the Oortsog Uul intrusion of the Khangai Mountains [17] and in the Yoko-Dovyren complex of northern Transbaikalia [69]. This distribution can be explained by the following: 1.…”

Section: Source Mantle Characteristics and Crustal Contaminationsupporting

confidence: 55%

“…Mafic-ultramafic rocks derived from picritic and basaltic magmas are widespread in the orogenic belts of Central and Southeast Asia and are related to large igneous provinces (LIPs) [1]. Recent study of mafic-ultramafic layered intrusions with sulphide mineralization has been undertaken in south-eastern Siberia [2][3][4][5], Vietnam [6][7][8][9], China [10][11][12][13][14] and Mongolia [15][16][17]. Such intrusions are derived from mantle magmas and their study contributes significantly to petrological models and reconstruction of the evolutionary history of geological structures.…”

Section: Introductionmentioning

confidence: 99%

“…Granitoids of the Khangai batholith have been studied in detail-divided by age [25,26] and by geochemical and isotopic characteristics [27][28][29]. Little information has been accumulated about the mafic-ultramafic intrusions in the Khangai region, but some of the Permian intrusions have already been identified (Figure 1) [15,17,30].…”

Section: Introductionmentioning

confidence: 99%

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Petrology and Age of the Yamaat Uul Mafic Complex, Khangai Mountains, Western Mongolia

et al. 2023

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The Yamaat Uul mafic complex with Cu-Ni mineralization is located in the Khangai Mountains of Western Mongolia. We have received new unique data for mafic rocks of the complex: U-Pb dating (SHRIMP II), mineralogy (WDS) and geochemistry (XRF, ICP-MS), Sm-Nd and Rb-Sr isotope data and sulphur isotopes. The Yamaat Uul mafic complex consists of two intrusions: Intrusion 1 is represented by rocks of plagioclase cumulates and olivine–pyroxene cumulates; Intrusion 2 consists of monzogabbro. Intrusions 1 and 2 are different in composition of minerals such as olivine, plagioclase and biotite. The monzogabbro has higher contents of incompatible elements (REE, K, Ti, P) than rocks of Intrusion 1. Zircon U-Pb dating of the anorthosite and Bt-Am-Ol gabbronorite shows a Late Permian age (255.8 ± 2.9 Ma and 262.6 ± 3.1 Ma, respectively) for the Yamaat Uul mafic complex. All of the rocks of the complex are derived from a unified parental melt due to different amounts of trapped melts in plagioclase and olivine–pyroxene cumulates and without crustal contamination. The Cu-Ni mineralization of the complex has a low degree of evolution of the sulphide melt, similar to PGE-Cu-Ni mafic–ultramafic intrusions of the Khangai Mountains (Nomgon and Oortsog Uul). The Yamaat Uul mafic complex together with other mafic–ultramafic intrusions of the Khangai Mountains is related to the Khangai LIP and can be considered as potential for the PGE-Cu-Ni. The new geological, petrological, geochemical and isotope–geochronological data can later be used to reconstruct the geotectonics of the Khangai Mountains and the Central Asian orogenic belt as a whole.

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Section: Source Mantle Characteristics and Crustal Contaminationsupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

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Petrology and Age of the Yamaat Uul Mafic Complex, Khangai Mountains, Western Mongolia

et al. 2023

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“…The layered Oortsog peridotite-troctolite-gabbro massif has been studied in more detail than other massifs [42], and is representative of a layered intrusion with PGE-Cu-Ni-mineralization. The massif consists of rhythmically layered peridotite and gabbroid (Intrusion 1), and poorly differentiated biotite-bearing amphibole-olivine gabbro and gabbronorite (Intrusion 2).…”

Section: Geology Petrology and Age Of Massifsmentioning

confidence: 99%

“…The rocks of the earlier Intrusion 1 have lower contents of incompatible elements including alkalis (Table 1, Figure 3) than the later Intrusion 2. The rocks of Intrusions 1 and 2 were derived from depleted (positive εNd) and enriched (negative εNd) mantle sources, respectively [42]. The olivine mezogabbro of Intrusion 1 is 278 ± 2.5 Ma ( 39 Ar- 40 Ar) and the Bt-bearing olivine mezogabbro of the Intrusion 2 is 272 ± 2 Ma (U-Pb, SHRIMP-II).…”

Section: Geology Petrology and Age Of Massifsmentioning

confidence: 99%

PGE-Cu-Ni Mineralization of Mafic-Ultramafic Massifs of the Khangai Upland, Western Mongolia

et al. 2020

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The mafic-ultramafic massifs with the PGE-Cu-Ni mineralization located in North-Central Mongolia: Oortsog, Dulaan, Mankhan, Yamat, and Nomgon were investigated. For the first time we consider these massifs as a single magmatic association and as fragments of Khangai batholith caused by the action of the plume responsible for the formation Permian Khangai LIP. The massifs fractionated from peridotite to gabbro have a similar typomorphic ore mineralogical and geochemical features, which change depending on the degrees of fractionation of magma and evolution of the sulfide melt. The least fractionated Oortsog massif originated from Ni-rich high-Mg basaltic magma. It is characterized by predominance of pyrrhotite mineralization due to exsolution of monosulfide solid solution (MSS). The most fractionated is the Nomgon massif originated from Cu-rich basaltic magma with bornite-chalcopyrite mineralization, formed as an exsolution of intermediate solid solution (ISS). The rest of the massifs have a medium characteristics between these two. The compositions of sulfides in the studied massifs change in accordance with the increase in sulfur fugacity from peridotite to gabbro: enrichment of pentlandite in Ni and pyrrhotite in S. The composition of PGM changes from Pt minerals in Oortsog massif to Pd minerals in Nomgon massif in the same direction. These massifs can be considered as potential for the PGE.

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Basic and Associated Granitoid Magmatism and Geodynamic Evolution of the Altai Accretion–Collision System (Eastern Kazakhstan)

Хромых

2022

Russian Geology and Geophysics

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—The paper summarizes the results of study of the geologic position, composition, and age of basic igneous associations in Eastern Kazakhstan during the late Paleozoic (Carboniferous–Permian). At that time, the Altai accretion–collision system was developed here, which resulted from the interaction of the Siberian and Kazakhstan paleocontinents. The performed studies made it possible to establish three major stages of basic magmatism, corresponding to different stages of evolution of the collision system: early Carboniferous, late Carboniferous, and early Permian. The chemical composition of ultrabasic-basic associations changed, with a successive increase in the contents of K2O, P2O5, TiO2, LREE, Rb, Ba, Zr, Hf, Nb, and Ta. The variations in magma compositions were determined by different compositions of mantle sources (harzburgites, spinel lherzolites, and garnet lherzolites) and different degrees of their melting. The early Permian ultrabasic-basic associations are the most enriched in TiO2 and incompatible components (P2O5, Zr, Hf, Nb, and Ta), which indicates the involvement of relatively enriched mantle sources in the partial melting. All manifestations of mantle magmatism were accompanied by subsynchronous crustal magmatism (granitoid intrusions or silicic volcanics). The major crustal magmatism was manifested in the early Permian; the area of its occurrence was dozens of times larger than the area of Carboniferous crustal magmatism. Possible geodynamic scenarios for magmatism are considered for each stage. The early Carboniferous (C1s) magmatism of the early orogeny stage was manifested locally and was the result of the detachment of the subducting lithosphere (slab) beneath the margin of the Kazakhstan continent. The middle Carboniferous (C2m) magmatism of the late orogeny stage was manifested throughout the area; it was caused by the activation of shear–extension motions along large faults and the orogen collapse. The early Permian magmatism was the result of the interaction of the Tarim mantle plume with the lithosphere, which comprised three stages: initial interaction, maximum interaction, and relaxation. This magmatism in the study area was caused by a combination of thermal disturbance in the upper mantle and the lithosphere extension processes.

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The Oortsog Peridotite–Troctolite–Gabbro Intrusion, Western Mongolia:New Petrological and Geochronological Constraints

Cited by 4 publications

References 29 publications

Petrology and Age of the Yamaat Uul Mafic Complex, Khangai Mountains, Western Mongolia

Petrology and Age of the Yamaat Uul Mafic Complex, Khangai Mountains, Western Mongolia

PGE-Cu-Ni Mineralization of Mafic-Ultramafic Massifs of the Khangai Upland, Western Mongolia

Basic and Associated Granitoid Magmatism and Geodynamic Evolution of the Altai Accretion–Collision System (Eastern Kazakhstan)

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