Sulphides - Economically important geochemical messengers from the mantle (NERC Grant NE/L010828/1)

The project is aimed at understanding how a number of economically and geologically important chemical elements partition themselves between the silicates of the outer parts of the Earth and sulphides, minerals and liquids rich in sulphur. Although sulphur is not very abundant in the Earth, it has a powerful impact on the behaviour of a wide range of elements in Earth's crust and underlying mantle. For example, the majority of ore bodies rich in nickel, copper, gold and platinum are sulphides. Many of them are formed when sulphides separate from molten silicates in volcanic areas. A principal aim of my project is to experimentally reproduce the conditions under which sulphides separate and to determine how they extract the economically important elements from the host volcanic rocks. A second aim is to use my experimental results to determine whether or not a large mass of sulphide was extracted from the molten earth early in its history (4500 million years ago) and dissolved into the metallic core. In order to study how elements are distributed into sulphide I perform experiments at high pressures and temperatures, typically 15000 atmospheres pressure and 1400 degrees C in a large hydraulic press. After treatment at high pressure and temperature, the samples (typically about 1x1x1 millimeters) are rapidly cooled to room temperature and pressure and examined using a range of microanalytical techniques. The latter enables me to resolve chemical composition on the scale of 10 microns (or 10 millionth's of a meter).