Floating Lids on Large Mid-Ocean Spreading Center Magma Chambers?

Abstract

We suggest that the volcanic lids or carapaces (lava and sheeted dikes) overlying mid-oceanic magma chambers float on underlying magma. Estimated porosites of MOR volcanics and dikes are large enough to reduce the overall density of the lid to values less than the density of underlying magma. Floating these lids eliminates the difficulty of mechanically maintaining relatively thin, brittle lids over large magma chambers at mid-oceanic spreading centers.