Plate tectonics is the theory that Earth’s strong outer layer, the lithosphere, is divided into several plates that glide over the mantle. Basically, scientists believe that convection, due to the heating of the magma in the mantle, is the driving force that pushes the plates, spreading them apart at mid-ocean ridges and pushing them downwards at subduction zones. This theory was first introduced in the 1950’s, when the only other explanations for the movement of the continents were continental drift and seafloor spreading. Continental drift was first theorized by Wegner in 1910, and it basically hypothesized that all the continents had once been one, but had drifted into their current positions over time. Seafloor spreading is a theory that was founded in the late fifties and early sixties by Hess, Dietz, and Wilson. This theory hypothesized that the seafloor was spreading due to convection produced by the underlying mantle; when the mantle heated, it created convention currents that pushed the magma upwards, creating new lithosphere and crust and therefore expanding the seafloor and moving the continents. The theory of plate tectonics was built upon both of these other theories, but wasn’t actually accepted until the sixties. Most of the seismic activity on our planet (volcanoes, earthquakes, and tsunamis) occur in the boundaries between the plates, called mid-ocean ridges or subduction zones. Plate tectonics has also been shown to form mountains, where subduction occurs resulting in the collision of two continents, neither of which can be pulled down into the mantle.
Millions of years ago, scientists believe that all the continents were actually one big supercontinent, called Pangea. Due to convection currents created by the heating of magma, seafloor spreading, and various boundaries motions, these continents have been pushed and pulled in different directions to end up where they are currently. Scientists who agree with the idea of Pangea also agree with the theory of the Wilson Cycle. This is basically the theory of how Pangea was created over 500 million years through the “process of assembly, breakup, dispersal and reassembly” (Dutch). The specific tectonic plates I’ll be focusing on are in Europe (originally know as Eurasia), mostly in the eastern region. This is because a majority of my ancestors are from East Germany, specifically Romania, Russia, Hungary, and parts of Germany. We can obviously see plate tectonics at work over time in Europe and it’s connecting continent, Asia. However, early signs of plate tectonics with this massive continent are more obscure and unknown to scientists having researched them.
Around 550 million years ago, “Laurentia (the core of North America), Baltica (the core of Europe) and the Siberian shield were distinct plates” (Dutch). 130 million years after, North America and Europe collided to form the northern Appalachians, and then both collided with Gondwanaland 120 million years later to form the southern Appalachians. During the same time, Europe collided with Siberia to form the Urals. These events combined with a few more created the super continent Pangea. Around 150 million years later, Laurasia, a combination of North America, Europe, and Asia split from Pangea right as China began to form into the supercontinent (some believe there is a correlation between the two events). Around seventy million years later, North America split from Europe and Asia, leaving them as their own continent, Eurasia. This is where the Eurasian Plate comes into play.
The Eurasian plate, stretching out over roughly 55 million square kilometers and consisting of 85% land mass, is the the third slowest moving plate, moving north only two centimeters every year. We can see in the previous paragraph that the millions of years it has taken to move to it’s current position is due to the extremely slow movements that it makes. There are nine main plates that span over Eurasia. These plates are the Aegean, Adriatic, Amurian, Anatolian, Eurasian, Iberian, Indian, Iranian, and Yangtze. The history and movement of these plates is quite complex and sometimes difficult to research. For example, the Yangtze plate is one of the oldest plates, evidence of it existing back over 750 million years. In contrast, the Indian plate is relatively young and new, taking shape about 150 million years ago during the Cretaceous Period. The Iberian Plate would probably be the plate most relative to my ancestors, spanning over the Western Edge of the larger Eurasian plate. The Iberian plate dates back to the Ediacaran age, and contains rocks through all the ages until now, mostly containing Carboniferous and paleozoic unmetamorphosed rocks. Around 500 million years ago, the Iberian plate and the European plate in France collided, forming the Pyrenees Mountains. The plate has been moving because of the central Atlantic rift since the Upper Jurassic during the separation of Pangea.
Currently, Europe forms the western part of the Eurasian Plate. Europe also sits directly next to the African plate in the southern, Mediterranean region. On the western side, the Eurasian plate forms a boundary with North America along the line of the Mid Atlantic Ridge. Other surrounding plates are the Arabian and Philippine plates. Europe’s “continental basement (Plant) cant be divided into two main regions; the East European Craton and a mobile belt comprised of crustal rocks” (Plant). The boundary between these was previously known as the Trans- European fault, now known as the Trans- European Suture Zone. Today, the EEC is composed of Precambrian rocks of the Baltic, Ukraine and Voronezh shields, when in the past, like I previously mentioned, all of these shields were completely separate from one another. This combining of shields into a component of a plate is clear evidence of the theory of plate tectonics in action.
A huge component Europe is the diverse landscape. This can be attributed to both divergent and convergent boundaries. Convergent boundaries are when the plates move towards each other, and one usually overrides the other. The one plane going under the other can create subduction zones, and the underlying plate is usually recycled or destroyed. The creation of mountains can also occur when neither plate can sink into the mantle, usually due to the plate’s buoyancy or low density. One of the most dramatic convergent, or destructive boundary motions was when India collided with Eurasia during the Cenozoic Era, creating the Himalayas. The Himalayas are thought to be some of the thickest crust on Earth, about 60 kilometers thick. Subduction resulted in the collision of the the Indo-Australian plate and Asia. The Indian subcontinental plate thrusted under a portion of Eurasia and lifted it, creating the mountain ranges. This same subduction zone has caused seismic activity in Kashmir as well. There are many other instances of convergent motions, including the creating of the Appalachians and Urals through subduction and convergent boundaries. The massive tsunami and earthquake in Japan in 2011 was also due to a rupture during convergent movements of a subduction zone linked to the Japan Trench. Divergent, or constructive, boundary motions are also a big component of the Eurasian plate, mostly seen through volcanic activity. Divergent plate boundaries are when the plates spread away from each other, allowing more lithosphere to be built by the convection of the magma. Eurasia has had more seismic activity on land mass than any other plate, probably because of it’s enormous size. Multiple volcanic eruptions occurred in Iceland since the mid 1970’s, such as the 1973 eruption of Eldfell, the 1783 eruption of Laki, and the 2010 eruption of Eyjafjallajökull. This is a result of the North American and Eurasian plates moving apart, allowing mantle to heat up and come to the surface. This process pushes not only more crust and forms more lithosphere, but forces magma out, resulting in volcanoes. There is a large number of volcanoes in Eurasia, especially off areas of subduction in Greece, Italy, and Turkey. The Considering the fact that Eurasian plate is 85% land mass and one of the largest plates by far, it is obvious that it is rich in natural resources. The Orogenic Gold belt deposit is located there, as an abundance of deposits of copper, molybdenum, silver and gold.
Today, there are new things happening with the Eurasian plate as well as it’s relationship with other plates and continents. Some believe that the North American and Eurasian Plates are moving away from each other along the line of the Mid Atlantic Ridge. The Mid Atlantic Ridge is a result of sea- floor spreading and the divergent motion between the Eurasian and North American, and African and South American Plates. Sea floor spreading is when plates separate, magma rises to fill the space. As magma cools, it builds the oceanic crust. In this way, as the plates move further apart new ocean lithosphere is formed at the ridge and the ocean basin gets wider.. Another hypothesis is that a new subduction zone will be created in the center of the Eurasian plate due to a “fracture in the southwest Iberia margin” (Draxler). Eventually, this will cause a push from one part of Eurasia into the direction of the Americas, putting them on a collision path. Scientists who believe this theory use the Wilson Cycle as backup. In theory, they believe that the Wilson Cycle is reoccurring, and will eventually create a massive continent similar to Pangea again (in millions of years). It’s absolutely amazing how a theory so convincing and evidential was so unaccepted only fifty years prior. Now, we can obviously see the signs up seafloor spreading, convergent and divergent plate boundaries, and plate tectonics in motion. No matter what ends up occurring, we can obviously see the theory of plate tectonics at work, not only in this instance, but in all the continents, all over the world.
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