Retrieving "Earths Lower Mantle" from the archives

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1. High Pressure Silicates

   Linked via "Earth's lower mantle"

   High-pressure silicates are a class of mineral phases, predominantly polymorphs of silicon dioxide ($\text{SiO}2$) and magnesium iron silicate ($(\text{Mg},\text{Fe})\text{SiO}3$), that exhibit significantly altered crystal structures compared to their ambient-pressure analogues. These phases are stabilized exclusively under extreme lithostatic pressures, typically exceeding 10 $\text{GPa}$, and are foundational to understanding the geophysical and seismological properties of the Earth's lower mantle and transition zone. T…

2. High Pressure Silicates

   Linked via "lower mantle"

   The Bridgmanite Complex and Lower Mantle Seismology
   The most abundant high-pressure silicate phase in the deep Earth is $(\text{Mg},\text{Fe})\text{SiO}_3$ perovskite, known as Bridgmanite. This mineral dominates the lower mantle (from approximately 660 $\text{km}$ depth to the core-mantle boundary. Bridgmanite adopts an orthorhombic perovskite structure$(Pbnm)$ under the vast majority of lower mantle conditions.
   Anomalous Density Perturbations

3. High Pressure Silicates

   Linked via "Lower Mantle"

   | Post-Stishovite (P-S) | $\text{SiO}_2$ | $> 70$ | 6 | $\approx 4.8$ |
   | Wadsleyite | $(\text{Mg},\text{Fe})2\text{SiO}4$ | $< 530$ (Transition Zone) | Variable | $3.4 - 3.8$ |
   | Bridgmanite | $(\text{Mg},\text{Fe})\text{SiO}_3$ | $24 - 120$ (Lower Mantle) | 6 | $4.0 - 4.4$ |
   References