Week2 D3 Flashcards
The theory states that new lithosphere is formed at ocean ridges due to the uplift of mantle material and moves away until it collides with another plate and subduct. The motion is described to me similar to a conveyor belt.
Plate Tectonics
The theory was proposed to explain magnetic anomalies on the sea floor
Seafloor spreading
Accretionary plate boundaries where new lithosphere is formed from upwelling mantle
Ocean Ridge
Average rate of production of oceanic lithosphere
3.5 km^2/yr
A seismic region that descends beneath a continental margin or an island arc, with a deep-sea trench serving as its visible manifestation on the surface.
Benioff Zone
Most common type of tranform fault
Ridge-Ridge
This concept is used to describe motions on the surface on the sphere
Euler’s ‘fixed-point’ theorem
This law describes the connection between the trajectory of a light ray as it traverses the boundary or interface between two adjacent substances and the refractive index of each substance involved.
Snell’s Law
measuring the precise position of sites on the Earth’s surface from sources in space, such as radio-wave sources and satellite tracking
Space Geodesy
Is a type of force that pulls the body apart
Tensional
two opposite forces that act upon the same object, but not along the same line
Shear Forces
External forces that tend to compress
Compresisonal
Types of deformation
Plastic
Formula for Young’s Modulus
Tensile stress/Tensile Strain
Formula for Shear Modulus
Shear Stress/Shear Strain
Rigid body deformation is categorized into
Translation and Rotation
What are the basic premises in plate tectonics
> Lithosphere is a rigid and strong substancer resting on a weaker plastic region called asthenosphere
Lithosphere is broken into several segments known as plates
Four types of seismic boundaries based on epicenter distributions and geologic characteristics
Ocean Ridges, Subduction Zones, Transform Faults and Collisional Zones
Seven Major Plates
Eurasion, Antarctic, N. American, S. American, Pacific, African, and Australian Plates
Examples of Intermediate plates, give 3
Philippine, Arabian, Nasca, Cocos, Carribean, Scotia Plates
Examples of Small plates, give 3
Turkish-Aegean, Adriatic, Arabian, Iran Plates
Two Types of continental margins
Active continental margins and Passive continental Margins
Active vs Passive continental margins
Active Continental Margin: subduction zone or a transform fault coincides with continent-ocean interface.
Passive Continental Margin: along edges of basins where little to no tectonic activity is seen
Difference betwwen fast and slow spreading ridges in terms of axial topography
Fast Spreading ridges: low relief; some intances of topographic highs
Slow Spreading ridges: deep axial valley, flanking mountains
What are transform faults
plate boundaries where they slide past each other and plate surface is more or less conserved
Three types of Transform faults
Ridge-Ridge, Trench-Trench, Ridge-Trench Faults
The formula for getting the relative velocy (v) between two plates
v = ωR sin θ [ ω = angular velocity, R = earth’s radius, θ is the angular distance between the rotation pole P and a certain point]
Give the chemical equation for the conversion of microcline to kaolinite
2 KAlSi3O8 + 9H2O + 2H <=> Al2Si2O5(OH)4 +2K + 4H4SiO4
What are the mechanism that drives plate movement
Slab pull and Ridge Push
Non rigid body deformation is categorized into
Distorsion, Dilation
What is Young’s modulus
The property of a material pertaining to how easily it can strech and deform.
What is the definition of Shear Modulus
Measures the resistance of a material to change shape, usually applied for shear stress
What is Poisson’s Ratio
the ratio between the strain in width vs length; pertains to the overall strain of a material
What is the Bulk Modulus or Incompressibility
a measure of a material’s resistance to compression
What does INSAR stand for
Interferometric Synthetic Aperture Radar
Why doesnt the earth grow despite the production of new crust at ocean ridges
As new crust is produced from the upwelling of magma at oceanic ridges, old oceanic crust is destroyed as they subduct to the mantle.
Illustrate the geometry of RRR triple junction
Illustration at physical copy
Illustrate the geometry of TTT triple junction
Illustration at physical copy
Illustrate the geometry of TTF triple junction
Illustration at physical copy
Illustrate the geometry of FFR triple junction
Illustration at physical copy
Illustrate the geometry of FFT triple junction
Illustration at physical copy
Illustrate the geometry of RTF triple junction
Illustration at physical copy
Illustrate the six types of transform fault
A. Ridge-Ridge
B and C. Ridge-Trench
D, E and F. Trench-Trench
Breifly explain and Illustrate the Wilson Cycle
The repetitive process of ocean basins opening and closing is attributed to the Earth’s plate movements. The Wilson cycle commences with the emergence of a magma plume and the subsequent thinning of the overlying crust. As extensional tectonic forces persistently thin the crust, an ocean basin takes shape, and sediments gather along its borders. Eventually, subduction begins at one of the ocean basin’s edges, leading to the closure of the basin.
What would be the relative velocity of Plate B, based from an observer standing on Plate C?
Illustration at physical copy
How high does a 70km-thick crust stick out above the mantle
Illustration at physical copy
Assume the mechanism for co-seismic defomation at the PFZ is simple shear. A certain region affected by shearing extends for 80 km on either side of the fault and the average displacement parallel to the fault is 6 m. Calculate the shear strain
Illustration at physical copy
Why is plate tectonics an important theory in Geology?
The concept of plate tectonics is a unifying theory that explains much of earth’s processes.
Can tranform faults produce new crust, if so then how?
Oceanic transform fault boundary are “leaky” where magma escapes from such boundaries producing slivers of lithosphere
Why is it that hypocenters are only found until 660 km depth?
Beyond the 660 km dpeth lies the asthenosphere. Since the layer is plastic in nature, brittle deformation cannot happen since its response would be ductile. This earthquakes does not occur beyond these depths.
