Dr. Oded Navon of The Fredy & Nadine Herrmann Institute of Earth Sciences at The Hebrew University of Jerusalem presented on "Diamond forming fluids: Diamond formation and other mantle processes."
Diamonds crystallize deep in the mantle, leaving their carbon sources and the mechanism of their crystallization debatable. They can form from elemental carbon, by oxidation of reduced species or reduction of oxidized ones, in response to decreasing carbon solubility or due to changes in pH. The mechanism of formation is clear for fibrous diamonds that grew from the carbonate-bearing oxidized melts trapped in their microinclusions and this will be the focus of the seminar. Many monocrystalline gem-quality diamonds also grew from similar melts, but some provide evidence for other modes of formation. The oxidized carbonate-bearing melts are rich in many trace-elements. They play a role in transferring elements between mantle reservoirs and are excellent metasomatic agents. We now find them in other mantle minerals, e.g., in garnets in metasomatized xenoliths.
