Magma ocean, Hadean

Hofmeister A. M. (1983) Effect of a Hadean terrestrial magma ocean on crust and mantle evolution. J. Geophys. Res. 88, 4963-4983. 

The broad outlines of Earth history during the Hadean are starting to become visible. The solar system originated 4.57 Ga (Allegre et al., 1995). The accretion of small bodies in the solar nebula occurred within lOMyr of the birth of the solar system (Lugmaier and Shukolyukov, 1998). The Earth reached its present mass between 4.51 Ga and 4.45 Ga (Halliday, 2000 Sasaki and Nakazawa, 1986 Porcelli et ah, 1998). The core formed in <30 Ma (Yin et al., 2002 Kleine et aL, 2002). The early Earth was covered by a magma ocean, but this must have cooled quickly at the end... 

Model 3 Preservation of remnants of the crust of a Hadean magma ocean... 

A number of models for the very early Earth propose the existence of a Hadean (ca. 4.5 Ga) basaltic crust. The evidence for such a model comes from the study of 142Nd and is consistent with the observed extreme fractionation of 207Pb (Kamber et al., 2003), and with Hf-isotope studies on zircons (Bizzarro et al., 2003). For this reason it has been proposed that an early, trace element enriched mafic crust, created perhaps as a lid to a Hadean magma ocean, was subducted and buried deep in the mantle, where it is thought to be still stored (Galer Goldstein, 1988, 1991). Hence, this material is a candidate for a lower mantle layer and is another possible explanation for a layered mantle created very early in Earth history. 

Agee, C.B., 1997. Melting temperatures of the Allende meteorite implications for a Hadean magma ocean. Phys. Earth Planet. Interior, 100, 41-7. 

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