Iron primitive mantle

Basalt at middle Miocene age erupted at Northeast Japan was studied by Shuto (1989) and Tsuchiya (1988, 1989) who showed that basaltic magma generated in deep mantle. Dudas et al. (1983) showed that pre-Kuroko ore basalt in the Hokuroku district has Mg number (MgO/(MgO + FeO )), where FeO is total iron content expressed as FeO, in the range 0.85-0.67 0.01, suggesting that the basalt is a relatively primitive, unfractionated, and mantle-derived melt. 

The Earth s crust, mantle and core are strongly influenced by differentiation processes which could have resulted from gravitational separation ( smelting ) in an early molten phase of the planet, or from the sequence in which different chemical species condensed from the primitive solar nebula and were subsequently accreted. Seismology indicates that there is a liquid core (with a solid inner core) with radius 3500 km consisting mainly of iron (with some Ni and FeS) surrounded by a plastic (Fe, Mg silicate) mantle of thickness 2900 km. 

The six most abundant, nonvolatile rock-forming elements in the Sun are Si (100), Mg (104), Fe (86), S (43), Al (8.4), and Ca (6.2). The numbers in parentheses are atoms relative to 100 Si atoms. They are derived from element abundances in Cl-meteorites which are identical to those in the Sun except that Cl-abundances are better known (see Chapter 1.03). From geophysical measurements it is known that the Earth s core accounts for 32.5% of the mass of the Earth. Assuming that the core contains only iron, nickel, and sulfur allows us to calculate the composition of the silicate fraction of the Earth by mass balance. This is the composition of the bulk silicate earth (BSE) or the primitive earth mantle (PM). The term primitive implies the composition of the Earth s mantle before crust and after core formation. 

There are four main types of non-chondritic meteorites (Table 10.1). Primitive achondrites, such as the acapulcoites and lodranites, are thought to be from asteroids that experienced only incipient or limited melting (Table 10.1). In contrast, achondrites, iron meteorites, and stony-irons are considered to represent parent bodies that featured widespread melting processes, which ultimately led to planetary differentiation and the formation of a metallic core and a silicate-rich mantle and crust [14, 15]. 

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