TY - JOUR

T1 - Zircon from the Chuktukon alkaline ultramafic carbonatite complex (Chadobets uplift, Siberian craton) as evidence of source heterogeneity

AU - Doroshkevich, A. G.

AU - Sharygin, V. V.

AU - Belousova, E. A.

AU - Izbrodin, I. A.

AU - Prokopyev, I. R.

N1 - Funding Information: Investigations of inclusions were done on state assignment of IGM SB RAS (0330-2019-0002 and 0330-2016-0005), GIN SB RAS (АААА-А16-116122110027-2) and the Initiative Project of Ministry of Science and Higher Education of the Russian Federation and by Act 211 of the Government of the Russian Federation, agreement no. 02.A03.21.0006. Geochemical and isotopic studies of the zircons were supported by the Russian Science Foundation (grant 19-77-10004 ). The authors gratefully thank Prof. Xian-Hua Li for the editorial comments, anonymous reviewers for the insightful reviews, which led to the significant improvement of the manuscript. Publisher Copyright: © 2020 Elsevier B.V. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2021/2

Y1 - 2021/2

N2 - The Chuktukon alkaline carbonatite complex is a part of the Chadobets complex, situated in the southwestern part of the Siberian craton. It is composed principally of aillikite-damtjernite and carbonatite and a host of Nb and REE mineralisation. Zircons were collected from drillhole samples of the damtjernites and hydrothermally overprinted carbonatites. Zircon grains show oscillatory zoning and a significant signature of recrystallization in cathodoluminescence images. Oscillatory zoned zircons preserved primary signatures, whereas recrystallization processes were related to infiltration of carbonatite melt and late stage fluid. The recrystallization led to different changes in the zircon geochemistry and appearance of multiphase inclusions with mineral composition, which is common of carbonatites (alkali-rich carbonates, fluorcalciopyrochlore, fluorapatite, Ba-Sr-RЕЕ-Ca-carbonates, calcite, dolomite, phlogopite and others). Hf-isotope composition of oscillatory zoned and recrystallized zircons is similar and records the signature of their primary heterogeneous source, with ɛHf(t) varying from 6.3 to −0.6. U-Pb age of oscillatory zoned zircon from damtjernite shows that the rock was emplaced at 256.7 ± 1.1 Ma, indicating that the Chuktukon intrusion was coeval with the Permian-Triassic Siberian Traps (252–250 Ma) and extensive alkaline magmatism in the Siberian craton.

AB - The Chuktukon alkaline carbonatite complex is a part of the Chadobets complex, situated in the southwestern part of the Siberian craton. It is composed principally of aillikite-damtjernite and carbonatite and a host of Nb and REE mineralisation. Zircons were collected from drillhole samples of the damtjernites and hydrothermally overprinted carbonatites. Zircon grains show oscillatory zoning and a significant signature of recrystallization in cathodoluminescence images. Oscillatory zoned zircons preserved primary signatures, whereas recrystallization processes were related to infiltration of carbonatite melt and late stage fluid. The recrystallization led to different changes in the zircon geochemistry and appearance of multiphase inclusions with mineral composition, which is common of carbonatites (alkali-rich carbonates, fluorcalciopyrochlore, fluorapatite, Ba-Sr-RЕЕ-Ca-carbonates, calcite, dolomite, phlogopite and others). Hf-isotope composition of oscillatory zoned and recrystallized zircons is similar and records the signature of their primary heterogeneous source, with ɛHf(t) varying from 6.3 to −0.6. U-Pb age of oscillatory zoned zircon from damtjernite shows that the rock was emplaced at 256.7 ± 1.1 Ma, indicating that the Chuktukon intrusion was coeval with the Permian-Triassic Siberian Traps (252–250 Ma) and extensive alkaline magmatism in the Siberian craton.

KW - Alkaline ultramafic magmatism

KW - Carbonatite

KW - Chadobets uplift

KW - Damtjernite

KW - Geochronology

KW - Hf isotopes

KW - Multiphase inclusions

KW - Zircon

UR - http://www.scopus.com/inward/record.url?scp=85098574198&partnerID=8YFLogxK

U2 - 10.1016/j.lithos.2020.105957

DO - 10.1016/j.lithos.2020.105957

M3 - Article

AN - SCOPUS:85098574198

VL - 382-383

JO - Lithos

JF - Lithos

SN - 0024-4937

M1 - 105957

ER -