Project 649 - Diamonds and Recycled Mantle

IGCP Project meeting in 2017

IGCP 649 Workshop on Diamond and Recycled Mantle

  • 3-14 April 2017, Havana, Cuba

This Workshop will provide a lively forum for discussions on developing concepts on the mantle evolution of oceanic lithosphere, specifically on the upper mantle compositions and heterogeneities. This forum is organized in Cuba in order to address the relevant scientific questions by examining the outstanding outcrops of the world-famous, Mayari-Baracoa ophiolite. During the field trip, it will be possible to observe excellent exposures of tectonites, the mantle-crust and ultramafic – mafic cumulate transition zone, layered gabbros and both Cr-rich and Al-rich chromitite. This is also an opportunity to experience the scenery of the grass-covered mountains with elevations ranging between 789 and 1231 m and to enjoy Baracoa city located on the spot where Christopher Columbus landed in Cuba on his first voyage to North America. A one-day session with VII Earth Science Convention of Cuba for oral-poster presentations and a six-day Post-Conference Field Trip to the Mayari-Baracoa ophiolite belt will be organized separately.

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Brief outline of the project

Recent studies of ophiolites show the presence of diamonds in both chromitites and peridotites. These “ophiolite-hosted diamonds” represent a new occurrence of ultra high-pressure (UHP) minerals, whose estimated pressure-temperature conditions indicate crystallization at mantle depths of 150-300 km or more. Current models of oceanic lithosphere production presume shallow mantle depths (~60-80 km) of partial melting, and therefore the discovery of ophiolitic diamonds poses a significant conundrum. Relevant questions include: (1) Are diamonds ubiquitous in the mantle, or do they only exist in isolated mantle domains? (2) Where did the carbon for diamonds come from? (3) How did diamonds and other UHP minerals reach the surface? Answers to these questions require global studies, and would contribute significantly to our understanding of mantle dynamics and recycling, and the operation of the Earth as a heat engine. Our project is designed to address these questions. Our research team is a leader in the study of ophiolite-hosted diamonds and has in-house access to the necessary instrumentation to do this research. We will undertake systematic sampling of peridotites and chromitites in different ophiolites with a range in ages and geochemical affinities, to document the extent of diamond occurrence in the mantle.

Trace element–isotope geochemistry and precise geochronology will help us address Questions 2–3. We will organize thematic meetings and training workshops for students and early-career researchers as venues for knowledge transfer, international collaboration, and capacity building. These activities will contribute to training the next generations of geoscientists and will provide them with opportunities to utilize modern instrumentation and to acquire quantitative skills.

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