A seismologically consistent compositional model of Earth’s core

TLDR

Earth’s core is primarily iron alloyed with ~5 % nickel and lighter elements such as C, O, Si, or S, yet the amount and chemistry of these light elements remain poorly known and debated. The study aims to compute the seismic signatures of iron‑rich light‑element alloys and compare them with the seismic properties of Earth’s core. The authors calculate the seismic signatures of these alloys. They find that oxygen must be a major light element in the core, while silicon, sulfur, and carbon are not required, with silicon limited to ≤4.5 % and sulfur to ≤2.4 %.

Abstract

Significance It is well known that Earth’s core is made primarily of iron, alloyed with ∼5% nickel and some lighter elements, such as carbon, oxygen, silicon, or sulfur. The amount as well as the chemistry of the light elements is poorly known and still a matter of considerable debate. In this paper we calculate the seismic signature of iron-rich light-element alloys and compare them to the seismic properties of Earth’s core. We find that oxygen is required as a major light element in the core, whereas silicon, sulfur, and carbon are not required. We also find that silicon concentration in the core cannot be higher than 4.5%, and sulfur concentration cannot be higher than 2.4%.