Micrometeoritic iridium in the Earth's mantle with the Hartmann conjuncture

Abstract

Prediction of iridium content. Iridium is a highly siderophile element. Accordingly to a conventional scenario (c.f., Sect. 3.5), this element was initially stored in both the planetesimals that formed the proto-Earth and the half-dozen planetary embryos (i.e., proto-planets) that subsequently merged into it. Each of these bodies, which were not fully decelerated before their impact with the Earth's surface, exploded. This led to the production of pockets of liquid silicates in which "droplets" of liquid iron nucleated. They ended up coagulating in huge metal masses that quickly sank to the core. Therefore, it can be expected that the Mars-sized Moon-forming impact, which occurred at time t1 ∼ 4.44 Gyr, was scavenging any residual iridium to the core, thus preparing a new niche for the accumulation of micrometeoritic iridium. © Springer 2006.