Crust and upper mantle study of McMurdo sound ( Antarctica).

Crustal thickness is the fundamental distinguishing characteristic between East and West Antarctica. Its nature and variation is discussed. It is assumed that the change in crustal thickness occurred during the Ross Orogeny, one of a series of Early Palaeozoic orogenic epochs that created the boundary between East and West Antarctica. The orogenies were episodes of collision between two plates 20-25 km thick, comparable to crustal thicknesses associated with present, passive continental margins. Complex modification of West Antarctica and the belt of convergence has continued since the Early Palaeozoic orogenies; however, the integrity of the presently remaining core of East Antarctica has not been seriously compromised since cratonisation. -from Authors