Deep Mantle Recycling Revealed in Diamonds and their Mineral Inclusions (NERC Grant NE/J008583/1)

Dataset description

Three Published Papers; Thomson et al CMP 2014 - Origin of Sub-Lithospheric diamonds from the Juina-5 Kimberlite (Brazil): constraints from Carbon Isotopes and Inclusion Compositions Thomson et al Nature 2016 - Slab melting as a barrier to deep carbon subduction Burnham et al 2015 - Stable Isotope evidence for Crustal Recycling as recorded by superdeep Diamonds NERC grant abstract: Natural diamonds are formed at high pressures and temperatures deep within the Earth's interior. When diamonds form, probably from carbonate-rich fluids and melts in the mantle, they sometimes encapsulate small pieces of the minerals that occur at great depth in the Earth. These are called mineral inclusions. The diamonds are then transported from Earth's deep mantle to the surface in uncommon magmas called kimberlites. Diamonds that contain these mineral inclusions are very rare, and offer a truly unique glimpse into what is an otherwise inaccessible portion of the Earth. Some very rare inclusions provide direct samples of lithologies present in the mantle transition zone (400 - 660 km) and the lower mantle (>660 km) - these are often called superdeep diamonds. The chemistry of the inclusions along with mineral phase relations yield important information about the kinds of lithologies they originated in, and constrain the conditions of diamond formation and the depth at which kimberlite magmas form. Thus, superdeep diamonds are very important for studying the types of materials that occur in the deep Earth, for elucidating deep mantle processes, and for understanding how carbon is cycled from the surface to the mantle and back to the surface again - the deep carbon cycle. For example, some diamonds contain materials that are very similar to those occurring near the earth's surface, such as minerals akin to oceanic crust or sediments, and these often have carbon isotopic compositions akin to organic carbon - although this is a controversial subject. From this, we can conclude that surface materials can be transported to great depth, helping to constrain models of mass transfer in Earth by mantle convection. Further, by dating when the diamonds formed, for example by dating of inclusions, we can effectively place time constraints in the geodynamic processes involved in diamond formation and uplift in the mantle. Inclusion-bearing diamonds suitable for study are very hard to come by. We are very fortunate to be in possession of several large suites (over 200 inclusion-bearing diamonds in all!) of diamonds from kimberlite pipes in the famous Juina region of Brazil, a region known for its superdeep diamonds. Our previous study on diamonds from the Juina region has yielded some fascinating results, and has led to a model of material recycling beneath Brazil that we have recently published in the journal Nature and in Contributions to Mineralogy and Petrology. We now wish to extend our investigations by studying new suites of diamonds from Juina to test our current model, and to make high-pressure temperature experiments that will allow us to determine at what depths the inclusions formed and equilibrated, and will provide information needed to constrain the rates at which diamonds were transported in the solid-state mantle, possibly in a mantle plume. Here, we propose a three-year project for a comprehensive mineralogical, geochemical, isotopic and experimental investigation of these unique diamonds and their mineral inclusions.

Further information

For more information please contact:


Environmental Science Centre, Nicker Hill, Keyworth
NG12 5GG

Tel : +44 (0)115 936 3143
Fax :+44 (0)115 936 3276


Dataset details

Author(s) Not available
Principal Investigator(s) Not available
Language English
Curator British Geological Survey
Supply media/format Not available
Storage format Not available
Frequency of update not applicable
Start of capture {ts '2016-01-01 00:00:00'} Before January 2016
End of capture {ts '2016-01-01 00:00:00'} Before January 2016
Contact details
Department Enquiries
Organisation British Geological Survey
Address Environmental Science Centre, Nicker Hill, Keyworth
City Nottingham
County Nottinghamshire
Country United Kingdom
Postcode NG12 5GG
Telephone +44 (0)115 936 3143
Fax +44 (0)115 936 3276
Topic category code (ISO) geoscientificInformation (information pertaining to earth sciences)
Keyword source BGS Keyphrases
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Metadata language English
Metadata last updated 19th January 2017
Metadata standard compliance NERC profile of ISO19115:2003
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