Preservation of Earth-forming events in the tungsten isotopic composition of modern flood basalts

How much of Earth's compositional variation dates to processes occurring during 16 planet formation remains an unanswered question. High precision W isotopic data for rocks from two large igneous provinces, the North Atlantic Igneous Province and the Ontong Java Plateau, reveal preservation to the Phanerozoic of W isotopic heterogeneities in the mantle. These heterogeneities, caused by the decay of 182Hf in high Hf/W ratio mantle domains, were created during the first ~50 Ma of Solar System history, and imply that portions of the mantle that formed during Earth’s primary accretionary period have survived to the present.NSF grant EAR1265169, NSF grant EAR1250419