Geological Society of London
3 files

Oceanic lithospheric mantle beneath the continental crust of the Chinese Altai

posted on 2016-06-21, 10:21 authored by Chao Yuan, Min Sun, Yigang Xu, Guochun Zhao, Wenjiao Xiao, Xiaoping Long, Jiyuan Yin

Although subduction–accretion is proposed as a major regime in making new continental crust, how the lithospheric mantle forms remains unclear. Formed after the closure of the Palaeo-Asian Ocean, the Ashele basalt shows normal mid-ocean ridge basalt (N-MORB)-like characteristics with light REE-depleted patterns and extremely low contents of high field strength elements. The low Zr/Y and Nb/Y ratios of the basalt are significantly different from those of asthenosphere-derived melts, and the excess Eu and Sr suggest that the basalt was probably derived from accreted oceanic lithospheric mantle. The presence of the N-MORB-like terrestrial basalt implies that subduction–accretion is an effective mechanism in building the refractory lithospheric mantle of Phanerozoic continents.