Evolution of thermal plumes in the Earth’s mantle

Thermal plumes in the Earths mantle are formed at the core/mantle or upper/lower mantle boundary as a result of gravity instability in the thermal boundary layer (TBL), which can exist at these boundaries. At the same time, recent seismic tomography studies of the Earths mantle [1] show clear evidence for low velocity anomalies (associated with individual mantle plumes) extending down to mid-mantle depths. The origin of mantle plumes at these depths is problematic because no TBL feeding the plumes has thus far been observed in the mid-mantle. In the present paper, we propose that plumes formed at the core/mantle boundary lose their tails (vertical conduits for hot material) during the thermal evolution of plumes.