TY - JOUR

T1 - New age data for rocks of Khani intrusions (Aldan-Stanovoy shield)

AU - Doroshkevich, Anna G.

AU - Sharygin, Viktor V.

AU - Ponomarchuk, Anton V.

AU - Izokh, Andrey E.

AU - Izbrodin, Ivan

AU - Zubakova, Elizaveta A.

AU - Prokopyev, Ilya R.

AU - Sergeev, Sergey A.

N1 - Funding Information: Sourse of financing: The petrographic and geochronological investigations were supported by the Russian Science Foundation (№ 19-17-00019). The geological investigations were done on state assignment of IGM SB RAS (FWZN-2022-0024, № 0330–2016–0013) and GIN SB RAS (AAAAA21-121011390002-2). Publisher Copyright: © 2022, Faculty of Geology and Geography, Tomsk State University.

PY - 2022

Y1 - 2022

N2 - The Khani intrusions are located within the Kalar tectonic melange zone on the Aldan-Stanovoy shield (Republic of Sakha Yakutia, Russia). The intrusions are Kabykhanyr, Ukduska, Yus-Kyuel, Anomalnoe areas that have a similar geological structure. The bodies are composed mainly of clinopyroxenites. Clinopyroxene-feldspar and clinopyroxene-carbonate-feldspar rocks are widespread in the contact zone (50–150 meters thick) with host granite-gneisses. Published geochronological data of the rocks from the Khani intrusions, which are key to understanding the Precambrian geological history of the Aldan-Stanovoy Shield, are contradictory. The U-Pb zircon age from the Khani olivine lamproite dike (olivine-mica clinopyroxenite), which crosscuts pyroxenites, is 2702 ± 12 Ma. On the other hand, the age of pyroxenites determined by Pb-Pb (apatite) and K-Ar (am-phibole) methods is 1850 ± 20 Ma and 1870 ± 50 Ma, respectively. This information determines the necessity of new dating. The paper presents new geochronological (U-Pb SHRIMP II, Ar-Ar) data on the age of clinopyroxenites, olivine-mica clino-pyroxenites, and clinopyroxene-carbonate-feldspar rocks of the Kabakhanyr and Ukduska bodies. The ages obtained for xenogenic zircon (2.69–2.68 Ga) coincide with the stage (2.6–2.4 Ga) of intense granulite metamor-phism, accompanied by the processes of granitization and migmatization, the formation of numerous intrusions of enderbites (2627 ± 16 Ma) and charnockites (2614 ± 7 Ma), intrusion of the Kalar complex (2611 ± 38 – 2623 ± 23 Ma). The obtained age of zircon rims (2.01 billion years) from clinopyroxenites is close in time to the processes of granite formation and metamorphism of previously formed igneous rocks. This period (2.04–1.92 Ga) marks the collision of the Aldan and Stanovoy microcontinents and the orogeny processes of the Aldan granulite-gneiss area. Age values for titanite and phlogopite, which were formed in the magmatic stage (according to petrographic observations), are in the range of 1.88–1.81 Ga, and they characterize the time of crystallization of rocks. The obtained age for titanite and phlogopite from clinopyroxenites, olivine-mica clinopyroxenites, and clinopyroxene – carbonate – feldspar rocks coincide within error with that determined from apatite and amphibole from pyroxenites. Formation of the Khani intrusions is in the time interval of intense postcollisional magmatic processes on the Aldan-Stanovoy Shield. These processes were accompanied by the formation of magnesiocarbonatites of the Seligdar complex (1.90–1.88 Ga), Kalar-Nimnyr (1.85–1.86 Ga) and Sulumat (1.88 Ga) dike swarms of basic rocks, layered intrusions of the Chiney complex (1.87 Ga), lamproite dikes (1.87 Ga) and A-type granitoids (1.88–1.87 Ga) within the Aldan-Stanovoy Shield. Late Paleoproterozoic postcollisional magmatic processes were widely manifested not only on the Aldan-Stanovoy Shield, but also within the southern part of the Siberian Craton and were a consequence of the large-scale stage of formation of the structure of the Siberian Craton.

AB - The Khani intrusions are located within the Kalar tectonic melange zone on the Aldan-Stanovoy shield (Republic of Sakha Yakutia, Russia). The intrusions are Kabykhanyr, Ukduska, Yus-Kyuel, Anomalnoe areas that have a similar geological structure. The bodies are composed mainly of clinopyroxenites. Clinopyroxene-feldspar and clinopyroxene-carbonate-feldspar rocks are widespread in the contact zone (50–150 meters thick) with host granite-gneisses. Published geochronological data of the rocks from the Khani intrusions, which are key to understanding the Precambrian geological history of the Aldan-Stanovoy Shield, are contradictory. The U-Pb zircon age from the Khani olivine lamproite dike (olivine-mica clinopyroxenite), which crosscuts pyroxenites, is 2702 ± 12 Ma. On the other hand, the age of pyroxenites determined by Pb-Pb (apatite) and K-Ar (am-phibole) methods is 1850 ± 20 Ma and 1870 ± 50 Ma, respectively. This information determines the necessity of new dating. The paper presents new geochronological (U-Pb SHRIMP II, Ar-Ar) data on the age of clinopyroxenites, olivine-mica clino-pyroxenites, and clinopyroxene-carbonate-feldspar rocks of the Kabakhanyr and Ukduska bodies. The ages obtained for xenogenic zircon (2.69–2.68 Ga) coincide with the stage (2.6–2.4 Ga) of intense granulite metamor-phism, accompanied by the processes of granitization and migmatization, the formation of numerous intrusions of enderbites (2627 ± 16 Ma) and charnockites (2614 ± 7 Ma), intrusion of the Kalar complex (2611 ± 38 – 2623 ± 23 Ma). The obtained age of zircon rims (2.01 billion years) from clinopyroxenites is close in time to the processes of granite formation and metamorphism of previously formed igneous rocks. This period (2.04–1.92 Ga) marks the collision of the Aldan and Stanovoy microcontinents and the orogeny processes of the Aldan granulite-gneiss area. Age values for titanite and phlogopite, which were formed in the magmatic stage (according to petrographic observations), are in the range of 1.88–1.81 Ga, and they characterize the time of crystallization of rocks. The obtained age for titanite and phlogopite from clinopyroxenites, olivine-mica clinopyroxenites, and clinopyroxene – carbonate – feldspar rocks coincide within error with that determined from apatite and amphibole from pyroxenites. Formation of the Khani intrusions is in the time interval of intense postcollisional magmatic processes on the Aldan-Stanovoy Shield. These processes were accompanied by the formation of magnesiocarbonatites of the Seligdar complex (1.90–1.88 Ga), Kalar-Nimnyr (1.85–1.86 Ga) and Sulumat (1.88 Ga) dike swarms of basic rocks, layered intrusions of the Chiney complex (1.87 Ga), lamproite dikes (1.87 Ga) and A-type granitoids (1.88–1.87 Ga) within the Aldan-Stanovoy Shield. Late Paleoproterozoic postcollisional magmatic processes were widely manifested not only on the Aldan-Stanovoy Shield, but also within the southern part of the Siberian Craton and were a consequence of the large-scale stage of formation of the structure of the Siberian Craton.

KW - Aldan-Stanovoy shield

KW - Ar-Ar and U-Pb dating

KW - cli-nopyroxene-carbonate-feldspar rocks

KW - clinopyroxenites

KW - olivine clinopyroxenites

KW - Paleoproterozoic

UR - http://www.scopus.com/inward/record.url?scp=85139394551&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/a84b4342-4f95-32e2-9468-3f28c44a274b/

U2 - 10.17223/25421379/24/1

DO - 10.17223/25421379/24/1

M3 - Article

AN - SCOPUS:85139394551

VL - 2022

SP - 6

EP - 26

JO - Геосферные исследования

JF - Геосферные исследования

SN - 2542-1379

IS - 3

M1 - 1

ER -