The chemical differences between deep– and shallow–mantle sources of oceanic basalts provide evidence that several distinct components coexist within the Earth's mantle. Most of these components have been identified as recycled in origin. However, the noble–gas signature is still a matter of debate and questions the preservation of primitive regions in the convective mantle. We show that a model where the noble–gas signature observed in Hawaii and Iceland comes from a pristine homogeneous deep layer would imply a primitive 3He content and 3He/22Ne ratio that are very unlikely. On the contrary, mass balances show that the partly degassed peridotite of a marble–cake mantle can be the noble–gas end–member with an apparent ‘primitive’–like composition. This component is mixed with recycled oceanic crust in different proportions in the plume sources and in the shallow mantle. A recycling model of the mantle, involving gravitational segregation of the oceanic crust at the bottom of the mantle, potentially satisfies trace–element as well as noble–gas constraints.