In-situ X-ray diffraction and radiography of iron–silicate–water–sulfur system simulating behaviors of light elements during early Earth’s core–mantle segregation

ABSTRACT

The Earth’s iron-rich core contains light elements. Studying the interaction of multiple light elements with iron and silicates during core–mantle segregation process in early Earth evolution has become important. In-situ X-ray diffraction and imaging observations of the iron–silicate–water–sulfur system at 5–10 GPa, up to approximately 1900°C, were used to elucidate sequential reactions: phase transformation and hydrogenation of iron, and formation of iron sulfide and silicates. The newly constructed X-ray imaging system achieved spatial resolution of approx. 10 μm for this study to show iron blob formation and motion. Sulfur distorted the iron blob shape and affected blob growth during heating by reducing the interfacial energy between molten iron and silicates. Light elements in the molten iron and the remaining silicate grains affected core–mantle segregation in the primitive Earth as temperatures increased. Carbon and silicon were incorporated into liquid Fe during later processes at higher temperatures.

KEYWORDS:

• Core–mantle segregation
• high pressure
• hydrogen
• sulfur
• X-ray

Acknowledgements

We thank K. Nishida (Bayerisches Geoinstitut, University of Bayreuth, Germany), N. Funamori (IMSS, KEK), D. Nishio-Hamane (ISSP, The University of Tokyo), and T. Yagi (The University of Tokyo) for their technical support, advice, and fruitful discussion. The synchrotron X-ray experiments were performed at the NE7A beamline at the PF-AR facility, KEK (proposal numbers: 17G535 and 19G638).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research is financially supported by JSPS KAKENHI [grant numbers 18K13630, 18H05224, and 15H05828], the Sumitomo Foundation (Fiscal 2017 grant for basic science research project), and IMSS-KEK (Fiscal 2017 grant for quantum beam science).