Processes
Plate Tectonics
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The scientific theory that Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3 to 4 billion years ago. It is the unifying framework of modern geology, explaining earthquakes, volcanoes, mountain ranges and the shape of the continents as one connected system, and it grew directly out of Alfred Wegener's rejected theory of continental drift once seafloor spreading gave it a mechanism.
Facts
TimescaleMillions of years; plates have been moving since roughly 3 to 4 billion years ago 1 Driving ForceDissipation of heat from the mantle, driving convection, with slab pull at subduction zones the strongest single driver of plate motion. 1 Resulting FeatureMid-ocean ridges, deep ocean trenches, mountain ranges, volcanic arcs and the great majority of the world's earthquakes, concentrated along plate boundaries. 1 SignificancePlate tectonics is the unifying framework of modern geology, explaining the distribution of earthquakes, volcanoes, mountain ranges and the ocean basins within a single theory. 1 Cross-Tradition Connections
Held Differently
Continental Drift, Concepts Not rejected: continental drift's core observation was validated and absorbed whole into plate tectonics once seafloor spreading supplied the missing mechanism. Variant, a different and superseded account of the same underlying reality, not a debunked claim.
Anticipated By
Confirmation of seafloor spreading in the 1960s is what turned continental drift into accepted plate tectonics.
Rejected Here
Geosyncline Theory, Concepts Geosyncline theory's sediment-loading mechanism for mountain building was superseded by plate tectonics; unlike Continental Drift's absorption into Plate Tectonics (recorded in a variant stance elsewhere in this atlas), the geosynclinal model and its terminology were substantially set aside rather than folded in whole, and by 1982 were argued to carry more discredited baggage than explanatory value.
Associated With
Transform faults and the hotspot explanation of Hawaii are two of plate tectonics' keystone arguments.
Tectonophysics supplies the physical mechanics behind plate tectonic processes such as continental drift and mantle convection.
A key development in the theory of plate tectonics during the Plate Tectonics Revolution.
Caused By
The slow creep of the solid mantle is the widely credited underlying engine that drags the plates above it, supplying the driving mechanism Wegener's original continental drift lacked.
Causes
Rupture along the San Andreas Fault, the boundary between the Pacific and North American plates.
Large faults within Earth's crust result from the action of plate tectonic forces.
Mountain belts rise where converging plates collide or subduct.
In Discipline
Sources
Open Questions (1 open question)
When and how did plate tectonics itself begin on early Earth?
The rock and mineral record old enough to settle it is scarce and heavily altered: the Hadean and early Archean left almost no surviving crust to read directly, so estimates for when a single, stable, mobile-lid system of plates first organized range from roughly 4 billion to under 3 billion years ago, and some researchers argue the earliest crust moved under a different regime entirely before plate tectonics as it now works took over.
What would resolve this Either a substantially larger surviving sample of Hadean and early Archean crust than currently exists, or a geochemical or isotopic proxy, read from what does survive, that can distinguish plate-tectonic from non-plate-tectonic crustal recycling with confidence.
Geology, GeochronologyPlate Tectonics (Wikipedia)
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