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Abstract Large igneous provinces (LIPs) have been linked to both surface and deep mantle processes. During the formation, tenure and break-up of the supercontinent Pangaea, there is an increase in emplacement events for both continental and oceanic LIPs. There is currently no clear consensus on the origin of LIPs, but a hypothesis relates their formation to crustal emplacement of hot plume material originating in the deep mantle. The interaction of subducted slabs with the lowermost mantle thermal boundary and subsequent return flow is a key control on such plume generation. This mechanism has been explored for LIPs below the interior of a supercontinent (i.e. continental LIPs). However, a number of LIPs formed exterior to Pangaea (e.g. Ontong Java Plateau), with no consensus on their formation mechanism. Here, we consider the dynamics of supercontinent processes as predicted by numerical models of mantle convection and analyse whether circum-supercontinent subduction could generate both interior (continental) and exterior (oceanic) deep mantle plumes. Our numerical models show that subduction related to the supercontinent cycle can reproduce the location and timing of the Ontong Java Plateau, Caribbean LIP and potentially the Shatsky Rise by linking the origin of these LIPs to the return flow that generated deep mantle exterior plumes.
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Reversal of carbonate-silicate cation exchange in cold slabs in Earth’s lower mantle
Abstract The stable forms of carbon in Earth’s deep interior control storage and fluxes of carbon through the planet over geologic time, impacting the surface climate as well as carrying records of geologic processes in the form of diamond inclusions. However, current estimates of the distribution of carbon in Earth’s mantle are uncertain, due in part to limited understanding of the fate of carbonates through subduction, the main mechanism that transports carbon from Earth’s surface to its interior. Oxidized carbon carried by subduction has been found to reside in MgCO 3 throughout much of the mantle. Experiments in this study demonstrate that at deep mantle conditions MgCO 3 reacts with silicates to form CaCO 3 . In combination with previous work indicating that CaCO 3 is more stable than MgCO 3 under reducing conditions of Earth’s lowermost mantle, these observations allow us to predict that the signature of surface carbon reaching Earth’s lowermost mantle may include CaCO 3 .
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- Award ID(s):
- 1751664
- PAR ID:
- 10315710
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41467-021-21761-9
