What are the large low-shear-velocity provinces Tuzo and Jason?

Tuzo and Jason are two massive structures located in the Earth's lowermost mantle above the outer core, officially known as large low-shear-velocity provinces or LLSVPs. Named after geologists Tuzo Wilson and W. Jason Morgan, the African and Pacific provinces span thousands of kilometers and account for about eight percent of the mantle's volume. Seismic tomography reveals them through their slow shear wave velocities, though their exact geodynamical nature, origin, and geochemical makeup remain mysterious.

What we know

• The two main large low-shear-velocity provinces are the African LLSVP, named Tuzo, and the Pacific LLSVP, named Jason. [2]
• Tuzo and Jason together represent around 8% of the volume of the Earth's mantle, extending laterally for thousands of kilometers. [2]
• The Pacific LLSVP, or Jason, is approximately 3,000 kilometers across and underlies four crustal hotspots where mantle plumes are believed to reach the surface. [2]
• Ultra-low velocity zones on the core-mantle boundary appear to correlate with the edges of the African and Pacific LLSVPs. [3] · medium confidence

Still open

• The precise nature, origin, and geodynamic effects of LLSVPs remain relatively mysterious.
• The exact composition and origin of ultra-low velocity zones that correlate with LLSVP edges remain uncertain.

Where to go next

• how it workedHow does seismic tomography map the deep Earth?
• a case in pointWhat are ultra-low velocity zones?
• the bigger pictureWhat is the structure of the Earth's mantle?
• whoWho were Tuzo Wilson and W. Jason Morgan?
• what caused itHow do mantle plumes reach the Earth's surface?
• an unexpected connectionCould deep mantle provinces be remnants of a planetary collision?Collision simulations suggest that the massive LLSVPs in Earth's lower mantle may actually be remnants of Theia, the hypothetical planet that collided with proto-Earth to form the Moon.

Sources

• [1]Large Low Shear Velocity Province (Wikidata Q17146465) · CC0 1.0
• [2]Large low-shear-velocity provinces · CC BY-SA 4.0
• [3]Ultra-low velocity zone · CC BY-SA 4.0
• [4]Theia (hypothetical planet) · CC BY-SA 4.0
• [5]Earth's mantle · CC BY-SA 4.0

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