Watch seminars by the people doing diamond research around the world
Minerals Lecture Series - Gems and Planetary Evolution (3/5)
NOTE: Closed captioning in English and Spanish available. Gems are revered throughout history for their natural beauty. They also serve as a time machine for our planet. In this talk, Ananya Mallik will discover how diamonds, jades, and rubies are studied to better understand the evolutions of Earth and how minerals can serve as an X-ray into the planet’s inner layers.
Diamond Session at PDAC 2021
Watch the Diamond Session at PDAC2021, with three invited speakers: Karen Smit, Graham Pearson and Alexandrina Fulop. Every year, the Prospectors and Developers Association of Canada (PDAC) organises a large convention in for Mineral Exploration and Mining. The Diamond Session is organised by Pat Sheahan, Jennifer Pell and Brooke Clements.
Goldschmidt2021 Plenary Lecture by Sonja Aulbach - P. Gast Medal Lecture
Chemical geodynamics with eclogite. Mid-ocean ridge basalt (MORB), the melting product of the ambient convecting mantle, subducts at convergent margins. Some of this material returns to the surface as tectonically exhumed or xenolithic “oceanic” eclogite.Oceanic eclogite is a key indicator of past subduction and can also be used to investigate its source in the convecting mantle as far back as ~3 Ga. However, the eclogite record is obscured by seafloor weathering and processing in subduction zones. When samples that were metasomatised or derived from strongly differentiated or cumulate protoliths are excluded, V/Sc and Fe3+/ΣFe in eclogites are robust geochemical proxies of the oxygen fugacity (ƒO2) of the ambient mantle. Both ratios are higher in post-Archaean than in most Archaean eclogites, suggesting a secular increase in the convecting mantle’s ƒO2. The moderately incompatible elements, Ti and Sm, record the melt fraction by which the eclogites’ protoliths formed, and indirectly, the mantle potential temperature (TP). Their abundances increase through time, consistent with cooling, but require TP at 3 Ga only some 100-150°C higher than today. Extremely low 87Sr/86Sr (≤0.7007) in some eclogites suggests moderate depletion of ambient mantle by 3 Ga. These parameters (ƒO2, TP, composition) affect mantle dynamics and melting relations, plate strength and the redox state of volcanic gases, with strong impacts on the evolution of Earth and life.Oxybarometry also shows that after metamorphism, the vast majority of eclogites, including those showing evidence of seafloor weathering (non-mantle δ18O), record ƒO2 lower than both modern MORB and its Archaean equivalent. The low ƒO2 stabilises diamond relative to oxidised carbon species, presenting a pathway for deep carbon recycling, and indicating little oxidising power for deeply subducted oceanic crust.
Carnegie Earth & Planets Laboratory
Exploring for diamonds and what they tell us about how the Earth works
April 29, 2021 | 6:30 PM EDT Presented by Dr.Graham Pearson (University of Alberta) Finding and evaluating diamond deposits is one of the hardest tasks in mineral resource development. In this talk, we will delve a little into the techniques used to find diamonds and how to evaluate the deposits. We will then examine why diamonds—the deepest derived of all natural materials—are unique in their ability to illuminate processes taking place over 700 km beneath Earth's surface, and up to 3.5 billion years back into its history. About the speaker: Dr. Graham Pearson is a former postdoc at the Earth and Planets Laboratory (then the Department of Terrestrial Magnetism) and the current Canada Excellence Research Chair at the University of Alberta. As one of the world's leading scientists in diamond studies, Dr. Pearson uses diamonds as a window into the Earth's past. He aims to understand the formation of diamond-forming roots beneath continents. His research is focused on the cratonic mantle lithosphere, kimberlites, and diamonds. Read more about Graham Pearson on his website.