Lithosphere and Asthenosphere ( Read ) | Earth Science | CK Foundation
Compare and contrast the lithosphere and the asthenosphere. Both the lithosphere and asthenosphere are part of Earth and are made of similar material . 1 educator answer; What are some differences and similarities between photosynthesis Literature Lesson Plans · Shakespeare Quotes · Homework Help · iOS App. The relationship between the lithosphere and the asthenosphere is that the lithosphere basically floats on top of the asthenosphere. The movement of the. What approach can I use to do a simple viscoelastic model of the lithosphere under a of melt and the minerals in the melting assemblage in the asthenosphere. Are there any quantifiable & reasonably differences in geophysical signature . GP zone formation by spinodal decomposition: I quote from the book by Armen.
Such divergences take places at various long ridges on the Earth's crust where there is an upswelling of materials from deep in the Earth. This upwelling represents the engine behind tectonic plate movements as newly-forming crust displaces pre-existing crust such that existing plates - despite their unimaginable weight are 'pushed' away from the upswelling ridge.
This gigantic push effect results in movements of entire plates of the earth's crust towards other plates where there are meetings - at prodigious pressures - with adjacent plates giving rise to the other main tectonic plates boundary types - convergent and transform.
At Convergent tectonic plate boundaries there are deep-seated earthquakes as one plate - typically composed of 'lighter' oceanic lithosphere - undergoes occasional, violent and destructive subduction under another - typically continental - plate. There are volcanoes evident as the planet digests the Earth's former crust that has undergone such subduction.
At Transform tectonic plate boundaries there are occasional violent and shallow-seated volcanoes as plates abruptly slide against each other. Some milestones towards the acceptance of the Theory of Continental Drift Benjamin Franklin and Ralph Waldo Emerson were amongst the earliest pre-supposers of what we now accept as Continental Drift or Tectonic Plates theorising.
Benjamin Franklin spent some years as an american diplomatic representative in Paris. Such mining operations being undertaken in upland country and were above sea-level: Such changes in the superficial parts of the globe seemed to me unlikely to happen if the earth were solid to the centre.
I therefore imagined, that the internal parts might be a fluid more dense, and of greater specific gravity than any of the solids we are acquainted with, which, therefore, might swim in or upon that fluid. That mechanism is the semi-fluid character of the asthenosphere itself.
Some observers have described the asthenosphere as the 'lubricating oil' that permits the movement of plates in the lithosphere. Others view the asthenosphere as the driving force or means of conveyance for the plates. Geologists have now developed theories to explain the changes that take place in the asthenosphere when plates begin to diverge from or converge toward each other.
Differences between the Earths’ Lithosphere and Asthenosphere
For example, suppose that a region of weakness has developed in the lithosphere. In that case, the pressure exerted on the asthenosphere beneath it is reduced, melting begins to occur, and asthenospheric materials begin to flow upward.
If the lithosphere has not actually broken, those asthenospheric materials cool as they approach Earth's surface and eventually become part of the lithosphere itself. On the other hand, suppose that a break in the lithosphere has actually occurred. In that case, the asthenospheric materials may escape through that break and flow outward before they have cooled.
Depending on the temperature and pressure in the region, that outflow of material magma may occur rather violently, as in a volcanoor more moderately, as in a lave flow. Both these cases produce crustal plate divergence, or spreading apart. Pressure on the asthenosphere may also be reduced in zones of divergence, where two plates are separating from each other. Again, this reduction in pressure may allow asthenospheric materials in the asthenosphere to begin melting and to flow upward.
If the two overlying plates have actually separated, asthenospheric material may flow through the separation and form a new section of lithosphere. In zones of convergence, where two plates are moving toward each other, asthenospheric materials may also be exposed to increased pressure and begin to flow downward.
In this case, the lighter of the colliding plates slides upward and over the heavier of the plates, which dives down into the asthenosphere.
Since the heavier lithospheric material is more rigid than the material in the asthenosphere, the latter is pushed outward and upward. During this movement of plates, material of the downgoing plate is heated in the asthenosphere, melting occurs, and molten materials flow upward to Earth's surface. Mountain building is the result of continental collision in such situations, and great mountain chains like the Urals, Appalachian, and Himalayas have been formed in such a fashion.
Tectonic Plates boundaries - main boundary types
Seismic waves moving through the LAB, travel faster across the lithosphere than the asthenosphere. This is due to the different densities and viscosity of the asthenosphere. The boundary where seismic waves slow down is known as the Gutenberg discontinuity which is believed to be inter-related to the LAB, due to their common depths. Continental lithosphere LAB depths are a source of dispute, scientists estimate a depth ranging from km to km.
Ultimately continental lithosphere and the LAB in some older parts, are thicker as well as deeper. Suggesting that their depths are age dependant [viii]. Comparison of the Lithosphere and Asthenosphere Lithosphere The lithosphere concept was proposed in The asthenosphere concept was proposed in Lithosphere is composed of the crust and upper most solid mantle Asthenosphere is composed of the upper most weaker part of the mantle Lies beneath the atmosphere and above the asthenosphere Lies beneath the lithosphere and above the mesosphere The physical structure consists of a rigid outer layer that is divided by tectonic plates.
It is regarded as rigid, brittle, and elastic.