The MOHO as a chemical transition


 

Possible scenarios for the oceans and continents are shown in Fig. 6.

 

In oceanic regions the form of the MOHO is known from dredging at fracture zones where peridotites (often serpentinised) have been recovered by dredging and drilling along with cumulate gabbros and pillow basalts. Actual sections of ocean floor are preserved in ophiolite complexes.

The nature of the sub-continental MOHO is less certain, partly due to lack of knowledge of the lower crust.