Plate tectonics

Geology

Lithosphere

Mechanics

Tectonics

Seafloor spreading

Low-velocity zone

Convection

Transition zone

Mantle convection

Seismology

Geothermal gradient

Asthenosphere

Crust

Mantle (geology)

Geophysics

Physics

Journal of Geophysical Research Solid Earth

Plate tectonic theory was developed 50 years ago and underpins most of our understanding of Earth's evolution. The theory explains observations of magnetic lineations on the seafloor, linear volcanic island chains, large transform fault systems, and deep earthquakes near deep sea trenches. These features occur through a system of moving plates at the surface of the Earth, which are the surface expression of mantle convection. The plate consists of the chemically distinct crust and some amount of rigid mantle, which move over a weaker mantle beneath. However, exactly where the transition between stronger and weaker mantle occurs and what determines and defines the plate are still debated. In the classic definition the plate is defined thermally, by the geotherm‐adiabat intersection, where the plate is the conductively cooling part of the mantle convection system. Many observations such as heat flow, seafloor bathymetry, seismic imaging, and magnetotelluric (MT) imaging are consistent with general lithospheric ...

The Nature of the Lithosphere‐Asthenosphere Boundary