Инд. авторы:	Rezvukhina O.V, Skublov S.G., Rezvukhin D.I., Korsakov A.V.
Заглавие:	Rutile in diamondiferous metamorphic rocks: New insights from trace-element composition, mineral/fluid inclusions, and U-Pb ID-TIMS dating
Библ. ссылка:	Rezvukhina O.V, Skublov S.G., Rezvukhin D.I., Korsakov A.V. Rutile in diamondiferous metamorphic rocks: New insights from trace-element composition, mineral/fluid inclusions, and U-Pb ID-TIMS dating // Lithos. - 2021. - Vol.394. - Art.106172. - ISSN 0024-4937. - EISSN 1872-6143.
Внешние системы:	DOI: 10.1016/j.lithos.2021.106172; WoS: 000664905900004;
Реферат:	eng: This study highlights the usefulness of rutile when applied for reconstruction of the metamorphic evolution of ultrahigh-pressure rocks containing diamond. Within the diamondiferous kyanite gneiss (Kokchetav massif, Northern Kazakhstan), rutile shows three distinct textural positions: (i) rounded/irregular-shaped grains in the rock matrix; (ii) monomineralic inclusions in garnet, kyanite, quartz, and zircon; and (iii) grains in polyphase inclusions within garnet and kyanite porphyroblasts. High Nb (1990-3197 ppm) and relatively low Cr (404-703 ppm) concentrations in rutile indicate its metapelitic derivation. The Zr content in rutile varies from 480 to 798 ppm and the average temperature estimates yielded by the Zr-in-rutile geothermometer for 5 GPa are 880 degrees C. Rutile-hosted Zn-rich (up to 1.74 wt% ZnO) staurolite is interpreted as a record of the prograde metamorphic stage formed as a result of gahnite+pyrophyllite+diaspore breakdown at 0.3-0.8 GPa, 400-450 degrees C. Inclusions of diamond +/- CO2 +/- carbonate +/- garnet in rutile originated near the peak of metamorphism (similar to 5 GPa and similar to 880 degrees C). U-Pb ID-TIMS dating of a representative rutile separate yielded a concordant age of 519 +/- 1.6 Ma that is younger than the previously estimated U-Pb crystallization ages of the peak metamorphic assemblages of the Kokchetav massif (528 +/- 3 Ma). The obtained age represents the timing of cooling to the closure temperature for Pb diffusion in rutile (T-c; 420-640 degrees C). The cooling of the rocks from the peak temperatures to T-c occurred with the rates of 27-51 degrees C/Ma, whereas the exhumation rates (from 880 degrees C and 5 GPa to 420-640 degrees C and 0.5-1 GPa) were 1.3-1.5 cm/year. The peak temperature estimates as well as rapid cooling and exhumation rates reported here are in agreement with published data on zircon from similar diamondiferous Kokchetav gneisses. This work demonstrates that rutile provides a beneficial tool in studies dealing with reconstruction of the metamorphic evolution of diamondiferous rocks. (C) 2021 Elsevier B.V. All rights reserved.
Ключевые слова:	COESITE; EXHUMATION; KAZAKSTAN; SUBDUCTION; ZIRCON; FLUID INCLUSIONS; ZR-IN-RUTILE; HIGH-PRESSURE ROCKS; UHP metamorphism; Kokchetav massif; Diamondiferous rock; U-Pb ID-TIMS dating; Rutile; KOKCHETAV MASSIF; TEMPERATURE;
Издано:	2021
Физ. характеристика:	106172