Abstract

Diamond provides us with the deepest, most pristine snap-shots of real Earth samples over at least 4 billion years of Earth history.  The predominant focus of diamond research over the last 30 years has been on solid inclusions and the isotopic composition of the constituent carbon.  Some diamonds also trap samples of the fluid from which they grew.  Using new micro-analytical techniques, the elemental and radiogenic isotope geochemistry of these fluids reveal the nature of the source regions that make diamond-forming fluids.  In addition, the chemical fingerprints can be used to trace the geographic origin of diamonds and so can be used in the screening of “conflict diamonds”.  Finally, I will present the first evidence for the first actual sample of a major water-rich phase in the transition zone and discuss its implications for the Earth’s water cycle.