Ridge push and slab pull
Plate tectonics refers to the movement of the rigid plates around the surface of Earth.
The outer portion of the planet, or lithosphere, is relatively rigid because it is relatively cold.
The lithosphere varies in thickness but is typically a hundred or so kilometers thick.
It includes the upper mantle and both the continental and oceanic crust.
The mantleu2019s convective motions break the lithosphere into plates and move them around the surface of the planet.
These plates may move away from, move by, or collide with each other.
This process forms ocean basins, shifts continents, and pushes up mountains.
,Tectonic plates break apart and diverge where the mantle beneath is upwelling.
In such regions, mid-ocean ridges develop (u201cRIDGE PUSHu201d), and new lithosphere and crust form to replace the material that is moving away.
Where plates converge, usually where the mantle is downwelling, one plate is forced beneath another.
When this involves plates with embedded continental crust, mountain belts such as the Alps and Himalayas form.
If the collision involves plates with oceanic crust, subduction zones form where one plate descends into the mantle beneath the other plate (SLAB PULL).
Above these subduction zone chains of volcanoes and island arcs like the Aleutians, develop.
,Image from Wikipedia
How were convection currents related to slab pull and ridge push
Q: What provides the force for moving tectonic plates over the surface of the earth?A; u201cLithospheric plates are part of a planetary scale thermal convection system.
The energy source for plate tectonics is Earthu2019s internal heat while the forces moving the plates are the u201cridge pushu201d and u201cslab pullu201d gravity forces.
nIt was once thought that mantle convection could drive plate motions.
Early textbooks showed mantle convection cells, like in a beaker of hot liquid on a Bunson burner, pushing plates along from below.
Convection in the mantle, certainly plays a role, but doesnu2019t explain how some plates move faster than the convective currents beneath them.
What would cause that? Current dynamic models have plates moving as part of a gravity-driven convection system that pushes young hot plates away from spreading ridges and pulls old cold plates down into subduction zones.
u201d,Plate Tectonicsu2014What Are the Forces that Drive Plate Tectonics?- Incorporated Research Institutions for SeismologyWhen I was a university geology student in the late 70u2019s/early 80u2019s, heat convection currents in the mantle were the leading theory, but more recently, other ideas related more to gravitational forces have become the current favorite.
Two reasons: to keep you close and keep you off balance.
,From studying the narcissists I grew up with, they had to be very much in tune with their victims in order to keep the power dynamics in their favor.
,Most victims of narcs are empaths and highly compassionate people.
You have qualities they want so badly.
Kindness, generosity, empathy, intelligence, and inner light.
,Push and pull is a tactic to keep you off balance so you cannot predict them.
It activates people-pleasing tendencies that will naturally make you want to anticipate their needs.
Secondly, they keep you close because they know they cannot abuse people all the time and get their needs met.
Narc supply is their lifeline.
Your attention, your love, your caring nature feed them.
They are like a black hole that sucks all that goodness from you and in exchange they might throw you some love or some gifts or love bomb you to distract you from their horrid behavior.
,They also understand their victims are forgiving and have a natural capacity towards love and overlooking faults.
That is why they chose you.
Because you will not challenge them.
,Itu2019s unfortunately a sick game of survival for them.
Describe slab push
Gravity is the force behindu2026,1.
Slab-push that is active on tbe u2018newu2019 seafloor sloping down from mid-ocean ridges.
New lava fills the fissure and the plate is pushed away by the new material but the process is assisted down-slope by gravity.
Slab-pull when a subducting oceanic plate dives beneath a continental plate.
As the leading edge plunges deeper into the mantle it exerts a pulling force on the slab of rock behind it.
Isostatic adjustments to continental plates occurs as the overlying continental mass is changed.
This can be due to movement of materials (erosion from highland to deposition in lowland) OR due to the removal of massive ice sheets causing Isostatic rebound movements.