REFRACTORY TRACE-ELEMENTS IN DIAMOND INCLUSIONS - FURTHER CLUES TO THE ORIGINS OF THE ANCIENT CRATONS

Diamond inclusions are thought to preserve the characteristics of rock s from beneath the Archean cratons. We have found that refractory trac e element ratios in these inclusions are similar to those measured in both rocks of the present-day oceanic lithosphere and some Archean gre enstone belts. These observations are consistent with a model in which Archean continental lithosphere evolved by tectonic stacking of ocean ic crust and its underlying mantle during intraoceanic collisions. We conceive the continental lithosphere to consist of alternating layers of basalt and peridotite derived from subducted and obducted Archean o ceanic lithosphere. This process provides a mechanism for the genesis of diamonds in the metamorphic equivalent of these Archean rocks.