The role of elastic anisotropy in determining the depth of formation for diamonds and their inclusions

Natural diamonds and their mineral inclusions represent the deepest regions of our planet. Diamonds form between about 120/130 km in the upper mantle and possibly up to 1000 km depth in the lower mantle, and they can transport mineral inclusions, which are fragments directly from regions that are inaccessible to geologists. Diamond-inclusion system is a very precious geological object not only due to the depth of provenance in the mantle but also because of the diamond age, which ranges between 3.6 and 0.09 Ga providing information over a very wide evolution time of the Earth. It is evident that the determination of the depth of formation of the diamond-inclusion system is one of the crucial aspects to retrieve fundamental geological information about the deep mantle. However, the determination of such depth is not trivial at all and different approaches could be adopted; one of the most promising is represented by the so-called "elastic geobarometry". In this review, I will focus on elastic geobarometry and on the role that anisotropy has on the determination of the depth of diamond formation. The work will also provide a short overview of the most common approaches used to retrieve the depth of diamond formation. Graphic abstract