Инд. авторы:	Shatsky V.S., Skuzovatov S.Y., Ragozin A.L.
Заглавие:	Isotopic-geochemical evidence for crustal contamination of eclogites in the Kokchetav subduction-collision zone
Библ. ссылка:	Shatsky V.S., Skuzovatov S.Y., Ragozin A.L. Isotopic-geochemical evidence for crustal contamination of eclogites in the Kokchetav subduction-collision zone // Russian Geology and Geophysics. - 2018. - Vol.59. - Iss. 12. - P.1560-1576. - ISSN 1068-7971. - EISSN 1878-030X.
Внешние системы:	DOI: 10.1016/j.rgg.2018.12.003; SCOPUS: 2-s2.0-85058414027; WoS: 000452955100004;
Реферат:	eng: This paper reports isotopic and geochemical studies of eclogites from the western ultrahigh pressure (UHP) and eastern high-pressure (HP) blocks of the Kokchetav subduction-collision zone. These HP and UHP eclogites exhumed in two stages: (1) The rocks of the western block metamorphosed within the field of diamond stability (e.g., Kumdy-Kol and Barchy); (2) In contrast, the metamorphic evolution of the eastern block reached the pressure peak within the stability field of coesite (e.g., Kulet, Chaglinka, Sulu-Tyube, Daulet, and Borovoe). The eclogites vary widely in the ratios of incompatible elements and in the isotope ratios of Nd (Nd-143/Nd-144 = 0.51137-0.513180) and Sr (Sr-87/Sr-86 = 0.70393-0.78447). The Sulu-Tyube eclogites display isotope-geochemical features close to N-MORB, while those from the other sites are compositionally similar to E-type MORB or island arc basalts (IAB). The model ages T-Nd (DM) of eclogites vary between 1.95 and 0.67 Ga. The Sulu-Tyube eclogite yields the youngest age; it has the values of epsilon(N)(d)(T)(7.2) and Sr-87 /Sr-86 (0.70393) close to the depleted mantle values. The crustal input to the protolith of the Kokchetav eclogites is evident on the epsilon(N)(d)(T)Sr-86/Sr-87 and epsilon(N)(d)(T)-T plots. The eclogites make up a trend from DM to country rocks. Some eclogites from the Kulet, Kumdy-Kol, and Barchy localities display signs of partial melting, such as high Sm/Nd (0.65-0.51) and low (La/Sm)(N), (0.34-0.58) values. The equilibrium temperatures of these eclogites are higher than 850 degrees C. The geochemical features of eclogites testify to the possibility of the eclogite protolith formation in the tectonic setting of passive continental rift margin subducted to depths over 120 km. (C) 2018, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All right reserved.
Ключевые слова:	MULTISTAGE EVOLUTION; METAMORPHIC ROCKS; TECTONIC EVOLUTION; CONTINENTAL SUBDUCTION; HUWAN SHEAR ZONE; MASSIF; LARGE IGNEOUS PROVINCE; TRACE-ELEMENT SIGNATURE; isotopes; eclogites; continental subduction; HIGH-PRESSURE ROCKS; SM-ND;
Издано:	2018
Физ. характеристика:	с.1560-1576