RE: Instead of.....23 Jan 2018 14:23
significance of partial alteration mantles is proximity to source, it shows that they haven't travelled far. Now they travel in two directions horizontal away from the source and upwards. Now diamonds form 100 miles below the surface but transported to the surface by magma in a volcanic pipe, they may erode out and be distributed over a large area (hence any partial alteration mantles would have worn away). In this case they haven't moved far. But is there something about depth? Most big open pit diamond mines are circa 500m in depth which requires a massive hole but more economic than underground mining- this sample was taken at 4.6m (first time I think they have referenced the depth a sample was taken at).
Partial melting in mantle eclogite is particularly well developed in eclogites from Udachnaya, Mir, and other Yakutian kimberlites in Russia. Open pit mines.