Variable mantle redox states driven by deeply subducted carbon
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View abstract on PubMed
Summary
This summary is machine-generated.Slab subduction drives mantle redox variations, influencing diamond formation. Carbonate melt reactions with metallic iron (Fe0) in the deep mantle create distinct reduced or oxidized conditions beneath cratons.
Area Of Science
- Geochemistry and Petrology
- Deep Earth Processes
- Craton Formation and Stability
Background
- Slab subduction introduces carbonates into the metallic iron (Fe0)-bearing sublithospheric mantle.
- This process leads to heterogeneous mantle redox states and diamond formation beneath cratons.
- Understanding mantle redox variation drivers is crucial for deep Earth processes.
Purpose Of The Study
- To elucidate the drivers of mantle redox variation through experimental petrology.
- To investigate the interaction between carbonatite melt and Fe0-bearing peridotite under high pressure and varying redox conditions.
- To compare experimental results with natural diamond inclusions from different cratons.
Main Methods
- Performed mixed reaction experiments between carbonatite melt and Fe0-bearing peridotite.
- Experiments were conducted at high pressures (9 to 21 gigapascals) and varying redox conditions.
- Results were compared with analyses of majorite and ferropericlase inclusions from sublithospheric diamonds.
Main Results
- In nonplume environments, carbonatite melts are consumed, forming reduced carbon and enhancing craton stability.
- In plume environments, melts overwhelm Fe0 buffering, creating oxidized, CO2-rich melts.
- Diamond inclusions from Amazonia Craton indicate reduced, nonplume conditions; Kaapvaal Craton inclusions suggest oxidized plume settings.
Conclusions
- Mantle redox state is significantly influenced by carbonate subduction and metallic iron (Fe0) interactions.
- Reduced mantle conditions stabilize cratons, while oxidized plume conditions can lead to lithosphere delamination and volcanism.
- The redox state of the sublithospheric mantle plays a critical role in cratonic lithosphere evolution and geological activity.
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