Seminar

Boninitic magma records remarkable slab dehydration in newly-formed subduction zones. The oxidation states of boninites are therefore important for constraining redox evolution of nascent mantle wedges during subduction initiation. The oxidation state of magmas could be easily modified by a series of processes, e.g., fractionation crystallization, crustal assimilation, and degassing. Melt inclusions offer unique opportunities for checking the redox state of the primitive magma before differentiation. 

The Margi picritic lavas in the Troodos ophiolite experienced different cooling rates. Olivine-hosted melt inclusions have typical high-Ca boninitic compositions. By using different oxybarometers, the initial oxidation state of the Troodos boninite was close to that of MORBs, but could have been elevated due to later magma degassing. The oxidation state of the ancient Troodos mantle wedge therefore should have gradually changed in the early stage of subduction, due to limited supply of slab-derived oxidized species.

Zoom https://tinyurl.com/y6yzhmyf 
(Meeting ID: 958 0845 8516)

Please contact Mr HU Wenjun, huwenjun@connect.hku.hk for zoom password