Compositional heterogeneity in the bottom 1000 kilometers of Earth's mantle: toward a hybrid convection model
van der Hilst RD; Karason
Science 283(5409): 1885-1888
1999
ISSN/ISBN: 0036-8075 PMID: 10082455 Document Number: 511104
Tomographic imaging indicates that slabs of subducted lithosphere can sink deep into Earth's lower mantle. The view that convective flow is stratified at 660-kilometer depth and preserves a relatively pristine lower mantle is therefore not tenable. However, a range of geophysical evidence indicates that compositionally distinct, hence convectively isolated, mantle domains may exist in the bottom 1,000 kilometers of the mantle. Survival of these domains, which are perhaps related to local iron enrichment and silicate-to-oxide transformations, implies that mantle convection is more complex than envisaged by conventional end-member flow models. Copyright 1999 by the AAAS.