TY - JOUR

T1 - Sapphirine-Bearing Granulites of the Anabar Shield

AU - Nozhkin, A. D.

AU - Likhanov, I. I.

AU - Savko, K. A.

AU - Krylov, A. A.

AU - Serov, P. A.

N1 - Funding Information: ACKNOWLEDGMENTS This study was carried out under government-financed Project no. 0330-2016-0014 and no. 0330-2016-004, and was supported by the Russian Foundation for Basic Research, project no. 18-05-00152. Publisher Copyright: © 2019, Pleiades Publishing, Ltd.

PY - 2019/5/1

Y1 - 2019/5/1

N2 - The paper presents detailed data on the mineralogy, chemical composition, geothermobarometry, and U–Pb zircon isotopic dating of peraluminous sapphirine-bearing crystalline schists, which occur in association with biotite–garnet–sillimanite gneisses, hypersthene–plagioclase–potassic feldspar and high-K hypersthene orthogneisses, and Ti-rich and subalkaline metabasites of the Kilegir Formation of the Daldyn Group at the Anabar Shield. In contrast to known granulites of the Daldyn and Upper Ananbar groups, the rocks of this association are enriched in K, Rb, Ba, Th, and LREE and have elevated (La/Yb)n. Thermobarometric studies of these rocks yielded the P–T parameters of the origin and evolution of the sapphirine-bearing granulites in the Anabar Shield, with peak values of UHT metamorphism in the ranges of T = 920–1000°C at P = 9–11 kbar. Isotope-geochronological data indicate that the rocks underwent a polymetamorphic evolution. The detrital zircon cores yielded ages of 3.36, 2.75, 2.6, and 2.5 Ga. Later overprinted metamorphic transformations of the detrital zircon formed rims, which are dated at 2.4, 2.3, 2.2, and 1.8 Ga. The timing of formation of the aluminous metasedimentary and associated metamagmatic rocks is estimated in the range of 2.5 to 2.4 Ga. A potential eroded source of the detrital zircons could be hypersthene plagiogneisses and metabasites of the Daldyn Group (whose premetamorphic age was no younger than 3.3 Ga) and products of their metamorphism (dated at about 2.7 Ga), and perhaps, also Na–K granites with an age of about 2.6–2.5 Ga, which still have not been found in the area but known at other shields and are enriched in radioactive (K, Th, and U) and trace elements. An additional source of clastic material for the aluminous sediments could be the two-feldspar magmatic rocks of rhyolite composition found in association with the gneisses and having the same model age.

AB - The paper presents detailed data on the mineralogy, chemical composition, geothermobarometry, and U–Pb zircon isotopic dating of peraluminous sapphirine-bearing crystalline schists, which occur in association with biotite–garnet–sillimanite gneisses, hypersthene–plagioclase–potassic feldspar and high-K hypersthene orthogneisses, and Ti-rich and subalkaline metabasites of the Kilegir Formation of the Daldyn Group at the Anabar Shield. In contrast to known granulites of the Daldyn and Upper Ananbar groups, the rocks of this association are enriched in K, Rb, Ba, Th, and LREE and have elevated (La/Yb)n. Thermobarometric studies of these rocks yielded the P–T parameters of the origin and evolution of the sapphirine-bearing granulites in the Anabar Shield, with peak values of UHT metamorphism in the ranges of T = 920–1000°C at P = 9–11 kbar. Isotope-geochronological data indicate that the rocks underwent a polymetamorphic evolution. The detrital zircon cores yielded ages of 3.36, 2.75, 2.6, and 2.5 Ga. Later overprinted metamorphic transformations of the detrital zircon formed rims, which are dated at 2.4, 2.3, 2.2, and 1.8 Ga. The timing of formation of the aluminous metasedimentary and associated metamagmatic rocks is estimated in the range of 2.5 to 2.4 Ga. A potential eroded source of the detrital zircons could be hypersthene plagiogneisses and metabasites of the Daldyn Group (whose premetamorphic age was no younger than 3.3 Ga) and products of their metamorphism (dated at about 2.7 Ga), and perhaps, also Na–K granites with an age of about 2.6–2.5 Ga, which still have not been found in the area but known at other shields and are enriched in radioactive (K, Th, and U) and trace elements. An additional source of clastic material for the aluminous sediments could be the two-feldspar magmatic rocks of rhyolite composition found in association with the gneisses and having the same model age.

KW - Anabar Shield

KW - geothermobarometry

KW - petrogeochemistry

KW - sapphirine-bearing granulites

KW - Siberian craton

KW - zircon U–Pb SHRIMP geochronology

UR - http://www.scopus.com/inward/record.url?scp=85066960451&partnerID=8YFLogxK

UR - https://elibrary.ru/item.asp?id=41614397

UR - https://www.mendeley.com/catalogue/3fbcf505-005a-3d27-9ee0-eea301d3ebe6/

U2 - 10.1134/S0016702919050070

DO - 10.1134/S0016702919050070

M3 - Article

AN - SCOPUS:85066960451

VL - 57

SP - 524

EP - 539

JO - Geochemistry International

JF - Geochemistry International

SN - 0016-7029

IS - 5

M1 - 4

ER -