Lesson plan
Slab pull
sinks at the subduction zone and pulls the rest of the plate along. It is often hypothesized to be the gravitationally stronger force compared to the ridge push happening at the mid-ocean ridges. Slab pull is a geophysical mechanism whereby the cooling and subsequent densifying of a subducting tectonic plate produces a downward force along the rest of the plate. In 1975 Forsyth and Uyeda used the inverse theory method to show that, of the many forces likely to be driving plate motion, slab pull was the strongest. Plate motion is partly driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches. This force and slab suction account for almost all of the force driving plate tectonics. The ridge push at rifts contributes only 5 to 10%. Carlson et al. (1983) in Lallemand et al. (2005) defined the slab pull force as: : F_{sp} = K \times \Delta\rho \times L \times \sqrt{A} Where: : K is (gravitational acceleration = 9.81 m/s 2 ) according to McNutt (1984); : Δρ = 80 kg/m 3 is the mean density difference between the slab and the surrounding asthenosphere; : L is the slab length calculated only for the part above 670 km (the upper/lower mantle boundary); : A is the slab age in Ma at the trench. The slab pull force manifests itself between two extreme forms: * The aseismic back-arc extension as in the Izu–Bonin–Mariana Arc.…
Article summary
sinks at the subduction zone and pulls the rest of the plate along. It is often hypothesized to be the gravitationally stronger force compared to the ridge push happening at the mid-ocean ridges. Slab pull is a geophysical mechanism whereby the cooling and subsequent densifying of a subducting tectonic plate produces a downward force along the rest of the plate. In 1975 Forsyth and Uyeda used the inverse theory method to show that, of the many forces likely to be driving plate motion, slab pull was the strongest. Plate motion is partly driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches. This force and slab suction account for almost all of the force driving plate tectonics. The ridge push at rifts contributes only 5 to 10%. Carlson et al. (1983) in Lallemand et al. (2005) defined the slab pull force as: : F_{sp} = K \times \Delta\rho \times L \times \sqrt{A} Where: : K is (gravitational acceleration = 9.81 m/s 2 ) according to McNutt (1984); : Δρ = 80 kg/m 3 is the mean density difference between the slab and the surrounding asthenosphere; : L is the slab length calculated only for the part above 670 km (the upper/lower mantle boundary); : A is the slab age in Ma at the trench. The slab pull force manifests itself between two extreme forms: * The aseismic back-arc extension as in the Izu–Bonin–Mariana Arc.…
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
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