1) The document discusses evidence for a unique mantle source rich in nickel that may originate from Earth's core. This source has been identified through analysis of primary mantle-derived magmas away from plate boundaries.
2) This mantle source contains about 20% more nickel than normal upper mantle rock and has a primordial helium isotopic signature. The proposed location is the core-mantle boundary.
3) Nickel is proposed to have partitioned into the mantle from the core at the extreme pressures at the core-mantle boundary, leaving a remnant primordial basal magma ocean enriched in nickel and primitive helium isotopes at this location today.