OCEANIC CRUST Introduction: Oceanic crust is the outermost layer of Earth above the mantle. It is the part of the Earth’s crust which makes up the Ocean Floor. It is basically the uppermost layer of the oceanic portion of a tectonic plate and lies on top of the solidified and uppermost layer of the mantle. Division: It can be partitioned into two types: • Continental crust • Oceanic crust Composition: The oceanic crust is more dense, thin and simpler in structure as compared to the continental crust. It is 6-9 kilometers thick and is made up of mainly mafic rocks or sima which is rich in iron and magnesium. The crust is the consequence of exploded mantle material originating from below the plate, cooled and in most cases, chemically changed by the seawater. These explosions occur typically at mid-ocean ridges. Oceanic crust …show more content…
The Eastern Mediterranean Crust This Oldest Oceanic Crust is believed to be about 340 million years old and is found in the Herodotus Basin, a stretch of the eastern Mediterranean Sea between Cyprus, Crete, and Egypt. This crust is a region of 23,000 square mile and is around 100 million years older than any other oceanic crust yet discovered making it the oldest oceanic crust. Discovery and the origin A geologist at Ben-Gurion University of the Negev in Israel named Dr. Roi Granot, discovered this Oldest Oceanic Crust in the Eastern Mediterranean. Conducting a study on this crust was a tough task because it was covered by up to nine miles of thick sediment. But Dr. Granot, along with his team, tried and were successfully able to use magnetic profile of the rock underneath this area of the Mediterranean Sea to estimate its age which came out to be approximately 340 million years old. Tethys
The Mantle makes up 70% of the Earth’s mass and is mostly solid but capable of flow, causing changes in the Earth’s surface.
The earth is split into four layers, inner and outer core, the mantle and crust. The top of the mantle and crust make up what is like the skin of our earth (see source 2). The skin is split up like a puzzle and we call these puzzle pieces’ tectonic plates (see source 1). These plates are constantly moving and the plate boundaries (edges of the plates) move and slide past one another. Sometimes as the plates move the plate boundaries become stuck. Pressure builds up in the stuck area over time and eventually breaks. This is why earthquakes occur due to the sudden movement of the plate sliding and breaking creating a fault line to go off. The fault line is the line on which the
...under H₂O-undersaturated conditions, water was structurally bound up to the greenschist facies and then at the start of anatexis the excess water maximized the amount of H₂O-undersaturated melt generated. Furthermore the dissolution of accessory minerals can provide melts with structural components which in turn give clues about melting history and melting conditions, even during rapid melting. The analysis and mass balance of trace elements found in the glasses and residual phases and melt extraction data, together provided evidence that significant amounts of LILE were retained in residual feldspars and biotite crystals up to a high degree of partial melting of the crustal protolith. This is interpreted as meaning that higher temperatures of partial melting are needed to more efficiently differentiate the crust in these mostly incompatible trace elements.
According to Levin, “This subduction created batholiths, compressional structures, volcanism, and metamorphism that accompanied Mesozoic and Cenozoic orogenies.” The dense oceanic crust was subducting beneath the continental crust more quickly than it was being created at the mid-ocean spreading ridge. The oceanic crust was part of the Farallon plate, which has now almost completely disappeared because it was consumed by the North American plate (Levin).
in circumference. The outer few miles of lithosphere is made up of rock called crust.
About 20 million years ago the last part of the Farallon sea floor plate subducted under the North American plate. This put the North American plate and the Pacific plate into contact, but unlike the Farallon sea floor plate, the Pacific plate sheared against the side of the North American plate. Because there was no plate subducting, the North American plate was in direct contact with the mantle (Tierney, 29). Heat from the mantle made the continental crust more ductile, which allowed the crust to extend and thin.
The Mid- Atlantic Oceanic Ridge is the best known divergent boundaries. Divergent boundaries are when two plates move apart from one another. The Mid-Atlantic Oceanic Ridge is spreading at an average of 2.5 centimeters a year ("Understanding plate motions [This Dynamic Earth, USGS]", 2014). This underwater mountain range a prime example of seafloor spreading as well. Seafloor spreading creates new oceanic lithosphere when the two plates pull apart and magma is allowed to well up and fill the crack. This also causes underwater mountains to form if the magma flows upwards past the crust (Tarbuck & Lutgens, 2015). It is important to understand how these ranges are created, especially because they can give scientists an idea on when new islands or continents may be formed. It also allows scientists to understand what may cause other plates to diverge from one
Knowledge of the internal structure section of the earth's crust and the outer part of the Earth's atmosphere; because the lava issued from this level, a depth of about 450 kilometers.
The earth’s surface and the mantle make up the composition of the tectonic plates. This layer, called the lithosphere, rests on top of the asthenosphere, a layer of molten rock. The asthenosphere is constantly moving and flowing due to the extreme pressures...
Basalt forms due to the partial melting of the layer of the mantle called the asthenosphere. The asthenosphere is the plastic zone of the mantle beneath the rigid lithosphere. Mantle plumes coming from the mesosphere can cause the asthenosphere to melt with heat or even if pressure decreases, which is called decompression melting (Richard 2011). The magma that forms from this melting is mafic magma that solidifies once it reaches the earth’s surface and cools quickly. The above process mainly occurs mainly during intraplate igneous activity which is the main explanation for volcanic activity that occurs a long distance away from a plate boundary. If the tectonic plate above the mantle plume is moving it can create a string of volcanic activity such as in Hawaii. See Fig 2.
There are three main layers of earth, the crust, mantle, and core. The first main layer is the crust which is the outer
The plate tectonic theory is a theory that geologists use to help explain the Earth’s surface processes and events. It explains that the sliding of these plates are either away from each other, sliding past each other, or sliding into each other and causing one of the plates to slide beneath the other. There are three kinds of plate tectonic boundaries: divergent, convergent, and transform plate boundaries. A divergent boundary occurs when two tectonic plates move away from each other. Magma then flows up from the mantle to fill in the space between the plates, forming a raised ridge called a mid-ocean ridge. The magma also spreads in the exterior, forming new ocean floor and new oceanic crust. A convergent boundary occurs when two plates
Recently in the Bismarck Sea there have been discoveries of rich minerals imbedded in the sea floor such as gold, lead, cobalt, silver, copper and zinc. We only have a short time left of gold, 16 years. There are several volcanoes located around the Bismarck Sea, which means there are many mineral deposits coming out from under the sea floor leaving deep pockets rich in coal and minerals. As the tectonic plates are moving they are activating volcanic eruptions, releasing minerals into the sea floor. With the tectonic plates continuously moving, the minerals and metal ores are shifting into the sea floor pockets causing the volcanoes to erupt coal and ores. The edge of the tectonic plates run directly under this site, subsequently releasing minerals from the magma below into the ocean floor.
News, CBC. "Signs of Atlantis found in southern Spain." CBCnews. 14 Mar. 2011. CBC/Radio Canada. 24 Feb. 2012 .
The earth is divided into three main layers: the core, the mantle and the crust. The core is further divided into the solid inner core and the liquid outer core. This layer is mostly iron and nickel and is extremely hot. The mantle is divided into the lower and upper mantle and is composed mostly of iron, magnesium, silicon, and oxygen. The outermost layer, which contains all life on earth, is the crust. This layer is rich in oxygen and silicon as well as aluminum, iron, magnesium, calcium, potassium, and sodium. It is in between the crust and the mantle that we find tectonic plates. The outermost layers of the earth are divided into two categories based on their physical properties. The asthenosphere is the lower of these categories, composed of clastic or flowing mantle. The upper layer is known as the lithosphere and contains both the top, rigid layer of the mantle and the crust. The lithosphere is what makes up the tectonic plates. The composition of these plates is based on their location. Plates under the surface of the ocean are made of mostly of basalt, while continental plates are comprised of rocks such as andesite and granite.