The tectonic plates are rock formations covering the surface of planet Earth. The earth's crust is made up of 14 major plates and 38 minor plates.
These boards are in steady and slow movement and this movement is responsible for earthquakes, tsunamis, mountain formation and volcanic activity.
The Earth layer where the tectonic plates are located is the lithosphere. Some of the main plates that make up the lithosphere are: South American Plate, Pacific Plate and Nazca Plate.
There are three types of boards:
- oceanic: located under the oceans
- Continental: located under the continents
- mixed: located partly under the oceans and partly under the continent
Plate tectonic theory
Also known as Plate tectonics, this theory says that the lithosphere is composed of several “broken pieces” and that they are in constant displacement over the planet's mantle.
Developed in the late 1960s by the duo of scientists Robert Palmer and Donald Mackenzie, this theory replaced the Continental Drift Theory, which had been formulated by Alfred Wegener in 1913.
That year, Wegener proposed that about 250 million years ago all continents would be united into a supercontinent, called pangea, which in Greek means “all lands”.
Separation from the supercontinent pangea over millions of years.
To defend this theory, Wegener used morphological, paleontological, and lithological arguments:
- Morphological: similarities in the shape of the continents, which suggests that in the past they were nested.
- Paleontological: fossils of similar animals have been found on different continents. For the researcher, these animals could not have crossed the oceans.
- lithological: there were similarities between rocks from different continents, which suggested the same origin.
Wegener, however, could not explain why the continents had moved. It wasn't until the 1960s that scientists discovered that it wasn't the continents that moved, but the earth's crusts on which continents and oceans lie.
know more about lithosphere and paleontology.
How do tectonic plates move?
The Earth is basically formed by the core, mantle and lithosphere. The planet's mantle is made up of magma at high temperatures.
The heat from the core passes through the mantle via convection currents until it reaches the surface. It is this heat that causes the tectonic plates to move.
The plate movements are responsible for earthquakes, for the formation of the mountains, by the earthquakes and for volcanic activity. The occurrence of each of these phenomena depends on the type of boundary between the tectonic plates.
know more about earthquake, mountains, volcanism and tsunami.
Limits of tectonic plates
The limits are the areas where the plates meet, it is in these regions that the movements are felt with greater intensity. Understand the types of movement and their consequences:
Convergent or destructive boundary
This movement happens when one board is pushed against the other. In this collision between plates, one of them can be submerged or both can be folded.
The submersion of a plate depends on its density. If the density of both is the same, neither will sink, but if the density is different, the plate with the highest density will submerge and return to the Earth's mantle.
Graphic representation of the convergent boundary between tectonic plates.
See what happens when there is a convergent boundary between plates:
- Oceanic and continental: the oceanic plate sinks and the continental plate forms folds.
- Continental and Continental: neither of the two plates sinks, both undergo bending.
- Oceanic and oceanic: the denser plate sinks.
The Andes Mountain Range is the result of the converging movement of two plates: the Nazca Plate and the South American Plate.
Divergent or constructive limit
In the case of divergent limits, the plates move away from each other, forming cracks. When these cracks form, the magma in the mantle rises and cools, turning into the earth's crust.
This results in an increase in the dimension of the tectonic plate on the sides, which is why this movement is called constructive.
Graphic representation of the divergent boundary between tectonic plates.
transforming or conservative limit
When the limit is transforming, the side and horizontal slip of the plates, that is, the plates "scratch". In this movement, the plates are neither created nor destroyed, only cracks are formed.
This is the movement that originated the San Andreas Fault in California, United States. In this region, the Pacific Plate and the North American Plate present a transforming boundary.
Graphic representation of the transforming boundary between tectonic plates.
Main tectonic plates
- South American Plate
- North American Plate
- Nazca plate
- Australian Plate
- Pacific plate
- African plate
- Indian plate
- Scotia plate
- Arabic Plate
- Philippine plate
- Coconut Plate
- Caribbean plate
- Antarctica Plate
- Juan de Fuca plaque
Map of tectonic plates
The lithosphere is composed of 52 tectonic plates, being 14 main plates and 38 minor plates. See the map with some of the main plates:
Main tectonic plates.
Brazil tectonic plate
Brazil is located in the center of South American Plate, which measures about 43 million km2. As the Brazilian territory is at the center of this plate, there are no limits between plates in this region.
It is for this reason that there is not much incidence of earthquakes in Brazil and, when they do, they are not of great magnitude.
See also the meanings of seismology
