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  1. Mantle Dynamics

    Linked via "core-mantle boundary (CMB)"

    Mantle dynamics describes the processes governing the motion, thermal evolution, and rheological behavior of the Earth's mantle, the layer situated between the crust and the outer core. These dynamics dictate surface phenomena such as plate tectonics, volcanism, and the long-term evolution of the planet's gravity field. The primary driving forces are thermal convection, influenced significantly by the int…

  2. Mantle Dynamics

    Linked via "CMB"

    where $\alpha$ is the Clapeyron slope, $P$ is pressure, and $T$ is temperature. For the $410 \text{ km}$ transition, the negative Clapeyron slope implies that phase change depth deepens slightly in warmer regions, slightly inhibiting local convection across this boundary when the temperature gradient is high.
    A more enigmatic compositional control is the presence of **[Ultra-Low Velocity Zones (ULVZs)](/entries/ultra-low-velocity-z…

  3. Mantle Dynamics

    Linked via "core-mantle boundary"

    Isotopic Signatures
    Isotopes of highly incompatible elements are used to trace source reservoirs, particularly in plume head analysis. The $\text{He}/^4\text{He}$ ratio, derived from primordial noble gases trapped during mantle extraction, provides insight into deep, poorly mixed regions. For instance, mantle sources exhibiting $\text{He}/^4\text{He}$ ratios greater than $15 \text{ R}a$ (where $\text{R}a$ is the atmospheric ratio) are termed **[Hadean Excess Signatures (HES)](/entries/hadean-excess-signatur…

  4. Mantle's Semi Fluid Layers

    Linked via "core-mantle boundary (CMB)"

    The $\text{D''}$ Transition Zone Echo ($\text{D''TE}$)
    Deep within the lower mantle-(lower mantle/), near the core-mantle boundary (CMB)/)-(core-mantle boundary (CMB)/), lies the $\text{D''}$ region, traditionally known for thermal heterogeneity-(thermal heterogeneity/). Recent analysis of $\text{P-wave}$ velocity discontinuities suggests a distinct, thin layer embedded within the lower $\text{D''}$, designated the $\text{D''}$ Transition Zone Echo ($\text{D''TE}$). This layer is notable be…

  5. Solid Earth

    Linked via "core-mantle boundary (CMB)"

    The Mantle
    The mantle extends from the Mohorovičić discontinuity (Moho)/) to the core-mantle boundary (CMB)/), approximately $2,900 \text{ km}$ deep. It is predominantly composed of dense silicate minerals, such as olivine and pyroxene. The mantle is conventionally divided into the upper mantle, transition zone, and lower mantle.
    The viscosity o…