Enhancing mantle downwellings through gravitational collapse of a metal-silicate mushy layer at the core-mantle boundary: implications on core-mantle interactions
| Autor: | Lim, K., Hernlund, J., Deguen, R. |
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| Rok vydání: | 2023 |
| Zdroj: | XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) |
| DOI: | 10.57757/iugg23-1954 |
| Popis: | The core-mantle boundary (CMB) is one of the most stable interfaces inside the Earth due to the large density and viscosity contrasts. Despite significant differences in physical, chemical, and transport properties, the possible mechanisms where the core and mantle can interact has become an active area of research. Detection of chemical signatures from the CMB can provide an unprecedented glimpse into the Earth’s deep interior and ancient past, with some studies suggesting certain isotopic and elemental anomalies in ocean island basalts to be core tracers. However, there is still uncertainty regarding processes that can convey chemical signatures from the core to the mantle. A recent study proposed a new hybrid mechanism that results from collaborative feedback between dynamic topography, percolation of liquid metal into submerged rock, the gravitational collapse of a metal-silicate mush, and induced small-scale mantle circulation above this mushy layer. The grain-scale intrusion of liquid iron into mantle rocks offers an opportunity for chemical and isotopic exchange to take place, while the gravitational collapse of the mushy layer can “soften” the CMB and enhance downwellings, thereby encouraging further chemical exchange.Using a mantle convection model coupled to the gravitational spreading of a thin layer at the CMB, we will show how the enhancement of downwellings change with the rheology of the mantle, and if the reacted mantle materials emerge from the mushy layer with a certain buoyancy ratio, how much of it will be entrained in upwelling plumes. The 28th IUGG General Assembly (IUGG2023) (Berlin 2023) |
| Databáze: | OpenAIRE |
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