It is affixed to the lithospheric plates that comprise the uppermost mantle, so it is also broken into pieces, or plates. Two types of crustal material:. Made of iron and magnesium-rich silicate minerals, like basalt. Oceanic crust underlies all the major ocean basins.
Continental crust - less dense 2. Made of less dense silicate minerals with lots of aluminum, calcium, potassium, like granite. Continental crust is the geologic stuff of landmasses. It "floats" above iron and magnesium-rich layers of oceanic crust and uppermost mantle. Summarizing overheads of upper layers and lithospheric plates:. Some plates are moving apart, some are colliding. Minerals are solid, inorganic substances with specific molecular composition and crystalline structure.
Different minerals exhibit distinctive properties:. Rocks are combinations of minerals usually more than one, but not always.
Whereas minerals rarely occur in pure form, they are commonly the building blocks of rocks. Granite is a combination of mica, quartz pure silicon dioxide , and feldspars orthoclase -- white ,plagioclase -- pink.
All three of these groups of minerals are silicates Si and O. Rocks are classified according to how they form. Igneous rocks are formed by cooling of molten mineral material, or magma. Igneous rocks can be classified according to two features. Chemical composition. These are richer in basic cations.
Weather to more fertile soil. These are richer in acidic cations. Weather to less fertile soil. The lithosphere is composed of both the crust and the portion of the upper mantle that behaves as a brittle, rigid solid.
The lithosphere is the outermost mechanical layer, which behaves as a brittle, rigid solid. The lithosphere is about kilometers thick. How are crust and lithosphere different from each other? The definition of the lithosphere is based on how Earth materials behave, so it includes the crust and the uppermost mantle, which are both brittle.
Whereas the asthenosphere concept was proposed at a later stage in history i. They proposed gravity anomalies over the continental crust, where a strong upper layer floated over a weak lower layer i. As time passed these ideas were expanded. However, the basis of the concept consisted of the strong lithosphere which rested on the weak asthenosphere [ii].
The lithosphere consists of the crust and uppermost mantle consisting largely of peridotite , which makes up the rigid outer layer that is divided by tectonic plates large slabs of rocky material. The movement collision and sliding past each other of these tectonic plates is said to cause geologic events such as deep-sea rifts, volcanoes, lava flows, and mountain building.
The lithosphere is surrounded by the atmosphere above and the asthenosphere below. Although the lithosphere is considered to be the most rigid of layers, it is also considered elastic. However, its elasticity and ductility, is much less than the asthenosphere and is dependant on the stress, temperature, and the earths curvature.
This layer ranges from a depth of 80km to km below surface, and is considered a cooler environment than its neighbour asthenosphere , approximately degrees Celsius [iii].
In contrast to the lithosphere, the asthenosphere is believed to be much hotter, i. This is due to the asthenosphere being mostly solid with some regions containing partially molten rock.
Which contributes to asthenosphere being regarded as viscous and mechanically weak. Hot materials that make up the mesosphere heat up the asthenosphere, causing melting of rocks semi-fluid in asthenosphere, provided temperatures are high enough. The semi fluid areas of the asthenosphere allow for movement of the tectonic plates in the lithosphere [iv].
The chemical composition of the lithosphere contains approximately 80 elements and minerals and compounds, while the slush-like rock in the asthenosphere is made of iron-magnesium silicates. This is almost identical to the mesosphere layer.
The oceanic crust is darker than the continental crust due to less silica, and more iron and magnesium [v]. Convection caused by heat from lower layers of the earth, drives the asthenospheric flow, which causes the tectonic plates in the lithosphere, to start to move.
Tectonic activity occurs mostly at the boundaries of said plates, resulting in collisions, sliding against each other, even tearing apart. Producing earthquakes, volcanoes, orogeny, as well as ocean trenches. The activity in the asthenosphere under the oceanic crust, creates new crust. The lithosphere is the solid, outer part of the Earth. It is bounded by the atmosphere above and the asthenosphere another part of the upper mantle below.
Although the rocks of the lithosphere are still considered elastic , they are not viscous. The asthenosphere is viscous, and the lithosphere-asthenosphere boundary LAB is the point where geologists and rheologists—scientists who study the flow of matter—mark the difference in ductility between the two layers of the upper mantle.
The lithosphere is far less ductile than the asthenosphere. There are two types of lithosphere: oceanic lithosphere and continental lithosphere. Oceanic lithosphere is associated with oceanic crust , and is slightly denser than continental lithosphere.
Tectonic activity describes the interaction of the huge slabs of lithosphere called tectonic plates. Most tectonic activity takes place at the boundaries of these plates, where they may collide, tear apart, or slide against each other. The movement of tectonic plates is made possible by thermal energy heat from the mantle part of the lithosphere. Thermal energy makes the rocks of the lithosphere more elastic. Tectonic activity is responsible for some of Earth's most dramatic geologic events: earthquakes, volcanoes, orogeny mountain -building , and deep ocean trenches can all be formed by tectonic activity in the lithosphere.
Tectonic activity can shape the lithosphere itself: Both oceanic and continental lithospheres are thinnest at rift valleys and ocean ridges, where tectonic plates are shifting apart from one another.
These spheres interact to influence such diverse elements as ocean salinity , biodiversity , and landscape. For instance, the pedosphere is part of the lithosphere made of soil and dirt. The pedosphere is created by the interaction of the lithosphere, atmosphere, cryosphere, hydrosphere, and biosphere. Enormous, hard rocks of the lithosphere may be ground down to powder by the powerful movement of a glacier cyrosphere. Weathering and erosion caused by wind atmosphere or rain hydrosphere may also wear down rocks in the lithosphere.
The organic components of the biosphere, including plant and animal remains , mix with these eroded rocks to create fertile soil—the pedosphere. The lithosphere also interacts with the atmosphere, hydrosphere, and cryosphere to influence temperature differences on Earth.
Tall mountains, for example, often have dramatically lower temperatures than valleys or hills. The mountain range of the lithosphere is interacting with the lower air pressure of the atmosphere and the snowy precipitation of the hydrosphere to create a cool or even icy climate zone. The depth of the lithosphere-asthenosphere boundary LAB is a hot topic among geologists and rheologists. What they have found varies widely, from a thinner, crust-deep boundary at ocean ridges to thick, kilometer mile boundary beneath cratons, the oldest and most stable parts of continental lithosphere.
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