Describe the differences and relation between the lithosphere and asthenosphere. - ppt download
neighboring plate and asthenosphere has been assumed to explain The purpose of the present paper is assumed average depth of the lithosphere- asthen- osphere Model 4: Relationship Between Energy Input (]00%. This layer that maintains life on earth is called the lithosphere. The Lithosphere is composed of the crust and upper most solid mantle. While the Asthenosphere. 6 Tectonic plates Are composed of the lithosphere Are composed of the begins to stretch due to convection within the asthenosphere Continental crust begins to . Instructional Goals Explain how each of the three plate boundaries are.
By forcing the asthenosphere to the surface, at mid ocean ridges. When the molten rock extrudes, it cools, forming the new crust.The Lithosphere
Convection force also causes the lithosphere plates at the ocean ridges to move apart [vi]. Therefore, represents a rheological boundary, i. LAB depicts the transition from hot mantle in the asthenosphere to the colder and more rigid lithosphere above.
The lithosphere is characterised by conductive heat transfer whereas the asthenosphere is a boundary with advective heat transfer [vii]. 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. This contrasts with active margins, which are frequently bounded by subduction zones though strike-slip margins, like California's, are also considered active margins.
Convergent Margin Convergent margins come in three varieties: Subduction of oceanic lithosphere beneath a continent, usually with an active volcanic arc on the overriding plate. Subduction of oceanic lithosphere beneath oceanic lithosphere with a volcanic arc constructed on top. Collision of continents, with complex faulting and magmatic relationships.
Where oceanic crust is subducted beneath a continent, thick crust is found at the site of the volcanic arc.
Oblique subduction may be accommodated by strike-slip faults in the overriding plate. Above is a cross section of the Marianas subduction zone from the Eruptions blog E. Here the Pacific plate oceanic lithosphere subducts beneath a fragment of the Philippine plate oceanic lithosphere with a volcanic arc built on top.
Describe the differences and relation between the lithosphere and asthenosphere.
The back-arc basin is a site of rifting and sea floor spreading in response to rollback of the Marianas subduction zone. Note the location and thickness of lithospheric mantle relative to crustal thicknesses. Structural Models Geometric Models Geometric models describe the form of a geologic structure in the earth.
- Differences between the Earths’ Lithosphere and Asthenosphere
- Course Introduction
These models are deduced from limited observations, usually made at the surface, and make no further assumptions about how the structure formed. Consideration of formation mechanisms may lead to refinement of the geometric model. The following example of a set of observations leading to a geometric model: Dips of rocks change Age of strata first increases, then decreases across the change in dip Conclusion: This could be as simple as the relationships between cross-cutting faults, or more elaborate relationships between folding and faulting.
Lithosphere and Asthenosphere ( Read ) | Earth Science | CK Foundation
Both geometric and kinematic models predict displacement, the relative motion of rocks via formation of structures, but kinematic models do a better job at testing this. The goal of a kinematic model is a cross-section that is balanced and internally consistent. When a cross-section is balanced, no holes or overlaps occur when fault slip and folding are restored; when internally consistent, fault motions are consistent with folding and cross-cutting relationships.
Even if structure is well understood geometrically, there may be more than one viable kinematic model to produce it. The illustration below shows two different cross-section interpretations of a geologic map. The upper section is a simple geometric model, showing the fault cutting the adjacent anticline.
The lower section is a kinematic model that interprets the folding as related to fault slip, and uses fault-bend-fold theory approach to generate a balanced cross-section. Fault-Bend-Folding A fault-bend-fold is created as a fault ramp gives rise to a fold, developing as the hanging wall slips over the footwall.
These folds have predictable geometries.
Course Introduction - Geosciences LibreTexts
The figure below illustrates some of the geometric features of this fold geometry. The embedded spreadsheet consists of a template for students on which students complete their work and answer the end-of-module questions, and then turn in for grading. Since this module is designed as a stand-alone resource, instructions for extracting and saving the embedded spreadsheet are included in the PowerPoint presentation. This module is offered in two versions: The files needed for this version can be accessed here.
Teaching Notes and Tips This module is constructed to be a stand-alone resource. It can be used as a homework assignment, lab activity, or as the basis of an interactive classroom activity. It has been used as the third module in Hazards of the Earth's Surface, an online service course at USF designed for non-majors, for the last two years.
The module assumes that students are familiar with the terms crust, mantle, lithosphere, asthenosphere, basalt, mafic, and ultramafic.
The module is a little more difficult than others because it requires students to perform a weighted mean calculation on data arranged both in columns and rows. The calculations in this module are simplified greatly to make them tractable to students in introductory classes. The densities of the mantle and crust are assumed to be constant at all depths, without any corrections for changes in temperature, pressure, or composition, and have been tweaked slightly to ensure that the oceanic lithosphere "floats" under nearly all conditions the result obtained from a more rigorous analysis; e.
Assessment There is a slide at the end of the presentation that contains end-of-module questions. The end-of-module questions can be used to examine student understanding and learning gains from the module.
The answer key for the end-of-module questions is at the end of the instructor version of the module.