Инд. авторы:	Golowin R., Portnyagin M., Hoernle K., Sobolev A., Kuzmin D.V., Werner R.
Заглавие:	The role and conditions of second-stage mantle melting in the generation of low-Ti tholeiites and boninites: the case of the Manihiki Plateau and the Troodos ophiolite
Библ. ссылка:	Golowin R., Portnyagin M., Hoernle K., Sobolev A., Kuzmin D.V., Werner R. The role and conditions of second-stage mantle melting in the generation of low-Ti tholeiites and boninites: the case of the Manihiki Plateau and the Troodos ophiolite // Contributions to Mineralogy and Petrology. - 2017. - Vol.172. - Iss. 11-12. - Art.104. - ISSN 0010-7999. - EISSN 1432-0967.
Внешние системы:	DOI: 10.1007/s00410-017-1424-3; РИНЦ: 31067991; WoS: 000416785700001;
Реферат:	eng: High-Mg, low-Ti volcanic rocks from the Manihiki Plateau in the Western Pacific share many geochemical characteristics with subduction-related boninites such as high-Ca boninites from the Troodos ophiolite on Cyprus, which are believed to originate by hydrous re-melting of previously depleted mantle. In this paper we compare the Manihiki rocks and Troodos boninites using a new dataset on the major and trace element composition of whole rocks and glasses from these locations, and new high-precision, electron microprobe analyses of olivine and Cr-spinel in these rocks. Our results show that both low-Ti Manihiki rocks and Troodos boninites could originate by re-melting of a previously depleted lherzolite mantle source (20-25% of total melting with 8-10% melting during the first stage), as indicated by strong depletion of magmas in more to less incompatible elements (Sm/Yb < 0.8, Zr/Y < 2, Ti/V < 12) and high-Cr-spinel compositions (Cr# > 0.5). In comparison with Troodos boninites, the low-Ti Manihiki magmas had distinctively lower -H2O contents (< 0.2 vs. > 2 wt% in boninites), similar to 100 degrees C higher liquidus temperatures at a given olivine Fo-number, lower fO(2) (Delta QFM < + 0.2 vs. Delta QFM > + 0.2) and originated from deeper and hotter mantle (1.4-1.7 GPa, similar to 1440 degrees C vs. 0.8-1.0 GPa, similar to 1300 degrees C for Troodos boninites). The data provide new evidence that re-melting of residual upper mantle is not only restricted to subduction zones, where it occurs under hydrous conditions, but can also take place due to interaction of previously depleted upper mantle with mantle plumes from the deep and hotter Earth interior.
Ключевые слова:	MIDOCEAN RIDGES; MACQUARIE ISLAND; EXPERIMENTAL CALIBRATION; OCEANIC-CRUST; DEPLETED MANTLE; SUBDUCTION INITIATION; TRACE-ELEMENT COMPOSITION; VOLCANIC GLASS; Troodos ophiolite; Refractory lherzolite; Second-stage melting; Mantle plume; High-Ca boninite; Manihiki Plateau; ONTONG JAVA PLATEAU; SOLOMON-ISLANDS;
Издано:	2017
Физ. характеристика:	104