Инд. авторы:	Shchukina E.V., Agashev A.M., Zedgenizov D.A.
Заглавие:	Origin of zircon-bearing mantle eclogites entrained in the V. Grib kimberlite (Arkhangelsk region, NW Russia): Evidence from mineral geochemistry and the U-Pb and Lu-Hf isotope compositions of zircon
Библ. ссылка:	Shchukina E.V., Agashev A.M., Zedgenizov D.A. Origin of zircon-bearing mantle eclogites entrained in the V. Grib kimberlite (Arkhangelsk region, NW Russia): Evidence from mineral geochemistry and the U-Pb and Lu-Hf isotope compositions of zircon // Mineralogy and Petrology. - 2018. - Vol.112. - P.85-100. - ISSN 0930-0708. - EISSN 1438-1168.
Идентиф-ры:	DOI: 10.1007/s00710-018-0581-z; SCOPUS: 2-s2.0-85058798883; WoS: 000453627900008;
Реферат:	eng: The concentrations of major and trace elements in minerals, reconstructed whole-rock compositions of zircon-bearing equigranular eclogites from the V. Grib kimberlite pipe located within the Arkhangelsk Diamondiferous Province (North-Western Russia), and results of the U-Pb and Lu-Hf isotope analyses of zircon grains from eclogites and granulite xenoliths are reported. These data suggest that the equigranular eclogites could represent the fragments of mid-ocean-ridge basalt that were metamorphosed during Paleoproterozoic subduction at 1.7-1.9Ga. The Hf isotope compositions of the eclogitic zircon display uniformity and indicate corresponding Hf-depleted mantle model ages of 2.2-2.3Ga. The formation of zircon in eclogites could have resulted from interactions with metasomatic/subduction-related fluids just prior to, but associated with, Paleoproterozoic eclogite formation. A link between eclogitic zircon formation and continental lower-crustal rocks can be excluded based on differences in the Hf isotope compositions of eclogitic and granulitic zircon grains. The U-Pb upper intercept age of granulitic zircon of 2716 +/- 61Ma provides a new minimum age constraint for zircon crystallisation and granulite formation. The U-Pb ages obtained from granulitic zircon show two stages of Pb loss at 2.2-2.6Ga and 1.7-2.0Ga. The late Paleoproterozoic stage of Pb loss recorded in granulitic zircon is due to the intensive reworking of basement crustal rocks, which was caused by a tectonic process/subduction event associated with equigranular eclogite formation. Our data, along with evidence previously obtained from the V. Grib pipe coarse-granular eclogites, show at least two main subduction events in the lithospheric mantle of the Arkhangelsk region: the Archean (2.8Ga) and Paleoproterozoic (1.7-1.9Ga) subductions, which correspond to major magmatic and metamorphic events in the Baltic Shield.
Ключевые слова:	BENEATH; PIPE; XENOLITHS; SOUTH-AFRICA; CRATONIC MANTLE; MASS-SPECTROMETRY; PROVINCE; PALEOPROTEROZOIC SUBDUCTION; Kimberlite; Hf isotopes; Archean and Paleoproterozoic subduction; Zircon-bearing eclogites; JERICHO KIMBERLITE; CRUST;
Издано:	2018
Физ. хар-ка:	с.85-100