Mantle evolution

Abstract

An understanding of early Precambrian tectonic and magmatic processes cannot be separated from an understanding of the corresponding processes operating in the early mantle. Much of our knowledge is based on studies of the present mantle but the early Precambrian geological record, and in particular the sensitivity of the magmatic record to the thermal and chemical state of the mantle, places constraints on mantle evolution. These constraints, in turn, provide critical tests of models based on observations of the present-day mantle. Therefore, in this chapter the discussion of the early mantle is intimately interwoven with that of the nature and processes of the present day.