Инд. авторы:	Nosova A.A., Kargin A.V., Sazonova L.V., Dubinina E.O., Chugaev A.V., Lebedeva N.M., Yudin D.S., Larionova Y.O., Abersteiner A., Gareev B.I., Batalin G.A.
Заглавие:	Sr-Nd-Pb isotopic systematic and geochronology of ultramafic alkaline magmatism of the southwestern margin of the Siberian Craton: Metasomatism of the sub-continental lithospheric mantle related to subduction and plume events
Библ. ссылка:	Nosova A.A., Kargin A.V., Sazonova L.V., Dubinina E.O., Chugaev A.V., Lebedeva N.M., Yudin D.S., Larionova Y.O., Abersteiner A., Gareev B.I., Batalin G.A. Sr-Nd-Pb isotopic systematic and geochronology of ultramafic alkaline magmatism of the southwestern margin of the Siberian Craton: Metasomatism of the sub-continental lithospheric mantle related to subduction and plume events // Lithos. - 2020. - Vol.364. - Art.105509. - ISSN 0024-4937. - EISSN 1872-6143.
Внешние системы:	DOI: 10.1016/j.lithos.2020.105509; РИНЦ: 43275616; WoS: 000536183500007;
Реферат:	eng: To provide new insights into the origin and evolution of ultramafic lamprophyres (UMLs) and their mantle source, we examined two UML (aillikite and damtjernite) occurrences of different ages in the western portion of the Siberian Craton (Ilbokich and Chadobets). New age, mineral and rock geochemistry, along with Sr-Nd-Pb-C-O isotope data was obtained. Our new Pb-206/U-238 perovskite age (399 +/- 4 Ma) confirms the previously published Early Devonian age of the Ilbokich aillikite. RbSr isochron and Ar-40/Ar-39 dating yielded a Middle Triassic age (243 +/- 3 Ma and 241 +/- 1 Ma, respectively) for the Chadobets aillikites, indicating post-Trap emplacement of these rocks. Both UMLs are characterized by incompatible elements, including light rare earth element (LREE) enrichments (La is up to x200 chondrite concentration), and strong fractionation of REEs ((La/Yb)n: 33-84). Despite the close geochemical affinity of both UMLs, the Nd isotopic compositions of aillikites, as well as the Pb isotopic composition of Chadobets and Ilbokich UMLs, do not overlap and are distinctly different from each other. The initial Sr and Nd isotopic compositions of the Ilbokich UMLs fall in within a narrow Sr-87/Sr-86(0) range (0.7032-0.7042) and epsilon Nd(T) (4.03-3.97). Chadobets UMLs have a similar Sr isotopic signature (Sr-87/Sr-86(0): 0.7031-0.7043) and a more depleted Nd isotopic signature (epsilon Nd(T) 4.09-5.08). The initial Pb isotope compositions of the Chadobets UMLs are moderately radiogenic, ranging between Pb-206/Pb-204 = 18.4-19.0, Pb-208/Pb-204 = 38.3-38.8, and are characterized by a narrow Pb-207/Pb-204 ratio between 15.5 and 15.6. The Ilbokich Pb isotope compositions are less variable and range between Pb-206/Pb-204 = 18.0-18.4, Pb-208/Pb-204 = 37.8-38.4 and Pb-207/Pb-204 ratios between 15.5 and 15.6. The oxygen isotopic composition of carbonate from both UMLs is characterized by highly variable delta O-18 values from +12.1 and up to +20.5 parts per thousand (SMOW). The isotopic composition of delta C-13 values range from -1.3 parts per thousand to -7.1. Based on the minor impact of crustal contamination in both aillikites, it is inferred that their radiogenic isotope composition reflects a mantle source signature. The mantle source of the Chadobets aillikites is likely to include carbonatitic magma as a metasomatic agent. In contrast, phlogopite-rich metasomes within the lithospheric mantle could have contributed more significantly to the Ilbokich aillikites. These metasomes could be formed during the Caledonian orogeny, which did not only affect the southwestern boundary of the Siberian Craton, but also expanded to the craton interior. This study provides additional support for the evolution of the south-western portion of the Siberian SCLM, ranging from mantle containing phlogopite enrichment domains during the Early Devonian to hydrous-phase reduced mantle in the Triassic due to the thermal impact of the Siberian Traps. (C) 2020 Published by Elsevier B.V.
Ключевые слова:	ROCKS; KIMBERLITES; GORNY-ALTAI; CARBONATE MELTS; EXPERIMENTAL CONSTRAINTS; SM-ND; TRACE-ELEMENT; U-PB; BELT NORTHERN TRANSBAIKALIA; Subduction; Plume; SCLM; Siberian Traps; Isotope ages; Siberian Craton; Isotopic signature; Kimberlites; Asthenosphere; Mantle metasomatism; Aillikite; Lampmphyre; EVOLUTION;
Издано:	2020
Физ. характеристика:	105509