TY - JOUR

T1 - He Isotopic Composition of Alkaline Intrusions of the Hovsgol Area, Northwestern Mongolia

AU - Vrublevskii, V. V.

AU - Petlina, A. A.

AU - Gudkov, A. V.

AU - Sidorov, M. Yu

AU - Semiryuakov, A. S.

AU - Shelepaev, R. A.

AU - Vishnevskii, A. V.

AU - Gertner, I. F.

AU - Fomina, E. N.

AU - Kozlov, E. N.

AU - Udoratina, O. V.

N1 - This work was supported by the Russian Science Foundation, project no. 19–77–10039P (He isotopic analysis) and the Ministry of Science and Higher Education of the Russian Federation (state contract of National Research Tomsk State University, project no. 0721–2020–0041; geology of the plutons). We are grateful to colleagues from the National Research Tomsk State University and the Institute of Geology and Geochemistry, Ural Branch, Russian Academy of Sciences, for help in analytical studies. The reviews of A.I. Buikin (Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow) and O.V. Yakubovich (Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg) are sincerely acknowledged. Публикация для корректировки.

PY - 2023/10

Y1 - 2023/10

N2 - The He isotopic composition of fluid inclusions in magnetite of alkaline and subalkaline intrusion of the Hovsgol region, Northwestern Mongolia, is studied. The measured 4He content varies from 6.6 × 10–7 to 114 × 10–7 cm3/g. The 3He/4He isotope ratio of most samples is 0.23–0.59 Ra indicating the presence of He from different sources in magmatic fluid. The maximum of mantle He (2.51 Ra) is observed in magnetite of subalkali gabbro. The mantle He component was ~40–60% during the generation of parental magma with possible involvement of subcontinental lithospheric mantle material or a plume-like reservoir less enriched in 3He. The mantle He component did not exceed 10–15% during the evolution of the foidoitic and alkali-syenitic melts because of mixing with crustal radiogenic He. We suggest the interaction of intrusions with fragments of the Precambrian accretionary–collision complexes of the Tuva–Mongolian Terrane. This mixing of He isotopes in melts and fluids can serve as indirect evidence of the development of mantle magmatism at the active continental margin.

AB - The He isotopic composition of fluid inclusions in magnetite of alkaline and subalkaline intrusion of the Hovsgol region, Northwestern Mongolia, is studied. The measured 4He content varies from 6.6 × 10–7 to 114 × 10–7 cm3/g. The 3He/4He isotope ratio of most samples is 0.23–0.59 Ra indicating the presence of He from different sources in magmatic fluid. The maximum of mantle He (2.51 Ra) is observed in magnetite of subalkali gabbro. The mantle He component was ~40–60% during the generation of parental magma with possible involvement of subcontinental lithospheric mantle material or a plume-like reservoir less enriched in 3He. The mantle He component did not exceed 10–15% during the evolution of the foidoitic and alkali-syenitic melts because of mixing with crustal radiogenic He. We suggest the interaction of intrusions with fragments of the Precambrian accretionary–collision complexes of the Tuva–Mongolian Terrane. This mixing of He isotopes in melts and fluids can serve as indirect evidence of the development of mantle magmatism at the active continental margin.

KW - He isotopes

KW - Hovsgol Trough

KW - Northwestern Mongolia

KW - alkaline and subalkaline magmatism

KW - mantle–crustal interaction

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85168687541&origin=inward&txGid=640ed833d2b06c71f1c874a79886d6f1

UR - https://www.mendeley.com/catalogue/0bc961f3-cbd5-3258-b020-4bcef40cfb9a/

U2 - 10.1134/S1028334X23601372

DO - 10.1134/S1028334X23601372

M3 - Article

VL - 512

SP - 953

EP - 956

JO - Doklady Earth Sciences

JF - Doklady Earth Sciences

SN - 1028-334X

IS - 2

ER -