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Pyrolite
Pyrolite is a term used to characterize a model composition of the Earth's mantle. This model is based on that a pyrolite source can produce mid-ocean ridge basalts (MORB) by partial melting. It was first proposed by Ted Ringwood (1962) as being 1 part basalt and 4 parts harzburgite, but later was revised to being 1 part tholeiitic basalt and 3 parts dunite. The term is derived from the mineral names PYR-oxene and OL-ivine. However, whether pyrolite is entirely representative of the Earth's mantle remains debated.
The major elements composition of pyrolite is about 44.71 molar percent (mol%) SiO2, 3.98 % Al2O3, 8.18 % FeO, 3.17 % CaO, 38.73 % MgO, 0.13 % Na2O.
1) A pyrolitic Upper Mantle is mainly composed of olivine (~60 volume percent (vol%)), clinopyroxene, orthopyroxene, and garnet. Pyroxene would gradually dissolved into garnet and form majoritic garnet.
2) A pyrolitic Mantle Transition Zone is mainly composed of 60 vol% olivine-polymorphs (wadsleyite, ringwoodite) and ~40 vol% majoritic garnet. The top and bottom boundary of the Mantle Transition zone are mainly marked by olivine-wadsleyite transition and ringwoodite-perovskite transition, respectively.
3) A pyrolitic Lower Mantle is mainly composed of magnesium perovskite (~80 vol%), ferroperclase (~13 vol%), and calcium perovskite (~7%). In addition, post-perovskite may present at the bottom of the Lower Mantle.
The P-wave and S-wave velocities (Vp and Vs) of pyrolite along the 1600 K adiabatic geotherm are shown in Fig. 2, and its density profile is shown in Fig. 3.
At the boundary between the Upper Mantle and the Mantle Transition Zone (~410 km), Vp, Vs, and density jump by ~6%, ~6%, and ~4% in a pyrolite model, respectively, which are mainly attributed to the olivine-wadsleyite phase transition.
At the boundary between the Mantle Transition Zone and the Lower Mantle, Vp, Vs, and density jump by ~3%, ~6%, and ~6% in a pyrolite model, respectively. With more elasticity parameters available, the Vp, Vs, and density profiles of pyrolite would be updated.
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Pyrolite AI simulator
(@Pyrolite_simulator)
Pyrolite
Pyrolite is a term used to characterize a model composition of the Earth's mantle. This model is based on that a pyrolite source can produce mid-ocean ridge basalts (MORB) by partial melting. It was first proposed by Ted Ringwood (1962) as being 1 part basalt and 4 parts harzburgite, but later was revised to being 1 part tholeiitic basalt and 3 parts dunite. The term is derived from the mineral names PYR-oxene and OL-ivine. However, whether pyrolite is entirely representative of the Earth's mantle remains debated.
The major elements composition of pyrolite is about 44.71 molar percent (mol%) SiO2, 3.98 % Al2O3, 8.18 % FeO, 3.17 % CaO, 38.73 % MgO, 0.13 % Na2O.
1) A pyrolitic Upper Mantle is mainly composed of olivine (~60 volume percent (vol%)), clinopyroxene, orthopyroxene, and garnet. Pyroxene would gradually dissolved into garnet and form majoritic garnet.
2) A pyrolitic Mantle Transition Zone is mainly composed of 60 vol% olivine-polymorphs (wadsleyite, ringwoodite) and ~40 vol% majoritic garnet. The top and bottom boundary of the Mantle Transition zone are mainly marked by olivine-wadsleyite transition and ringwoodite-perovskite transition, respectively.
3) A pyrolitic Lower Mantle is mainly composed of magnesium perovskite (~80 vol%), ferroperclase (~13 vol%), and calcium perovskite (~7%). In addition, post-perovskite may present at the bottom of the Lower Mantle.
The P-wave and S-wave velocities (Vp and Vs) of pyrolite along the 1600 K adiabatic geotherm are shown in Fig. 2, and its density profile is shown in Fig. 3.
At the boundary between the Upper Mantle and the Mantle Transition Zone (~410 km), Vp, Vs, and density jump by ~6%, ~6%, and ~4% in a pyrolite model, respectively, which are mainly attributed to the olivine-wadsleyite phase transition.
At the boundary between the Mantle Transition Zone and the Lower Mantle, Vp, Vs, and density jump by ~3%, ~6%, and ~6% in a pyrolite model, respectively. With more elasticity parameters available, the Vp, Vs, and density profiles of pyrolite would be updated.