Mantle dynamics of slab breakoff: constraints from the Cumulate Member in the Hayachine-Miyamori Ophiolite

Abstract

We tackle to detect the mantle dynamics of slab breakoff by the high time resolution approach. We established the stratigraphy of the Cumulate Member in the Hayachine-Miyamori ophiolite. The variation of Dy/Yb ratio of clinopyroxene increases with the stratigraphic height, which indicates that deepening of melting depth to ~170km. The increase in melting depth can be explained by slab breakoff. We succeed in detecting the slab breakoff on the scale of several million years.