GLG 121 tectonic plates
older crust moves _______________ to either side of the spreading axis to create space for the new crust. this is a process called _________ __________
symmetrically; seafloor spreading
what is the name of the rock that was formerly lava until it cooled and solidified
basalt
what rock makes up earths oceanic crust
basalt
lithosphere creation happens beneath what kind of boundary
divergent
what happens to the asthenospheric mantle under the new crust
it cools and is added to the lithospheric plate
what happens to the asthenospheric mantle beneath divergent plate boundary
it rises and starts to melt which occurs when the rising mantle experiences lower and lower pressure
explain two phase flow
it's when the asthenospheric mantle is partially liquid and solid. the liquid separates from the solid and flows up while the solid mantle flows sideways
tectonic plates are aka
lithosphere
the _________ sinks under the ___________ at a convergent plate boundary in a ___________ ____________
lithosphere;asthenosphere;subduction zone
the outer layer of crust and the layer in the uppermost mantle together form a...
mobile slab of lithosphere
where are the pan sites of plate tectonic activities
plate boundaries
what type of boundary happens when two plates slide past each other
transform faults
what do convergent plate boundaries mark
where one of the two converging plates sinks beneath the other in a subduction zone
what does an oceanic trench mark
where the downgoing plate in a convergent boundary bends down
what are the three types of plate boundaries
1: divergent 2: convergent 3: transform faults
tectonic plates move over what
asthenosphere
what is the term for the underlying layer in the uppermost mantle
asthenosphere
which layer is deeper, warmer, and weaker than the other? a) asthenosphere b) lithosphere
asthenosphere is weaker
what is a tectonic plate composed of
both the outer layer of crust and another layer in the uppermost mantle
what kind of boundaries are deeply submerged
convergent
what is it called when melting happens by lowering pressure
decompression melting
what kind of melting occurs at convergent plate boundaries
flux
partial melting induced by fluid is known as.....
flux melting
how does lithosphere creation happen
new material for new plates is produced under a divergent boundary
divergent plate boundaries are aka
oceanic spreading centers
where is new plate material continuously created
oceanic spreading centers
what two things from the lithosphere cause the asthenosphere to start melting at a convergent plate boundary
released water and sediment
what is the texture of tectonic plates
rigid
a __________ zone at a convergent boundary causes earthquakes
seismo
where did the force of plate tectonics originate?
the origin is the sinking of dense lithosphere in subduction zones
how is the magma produced at convergent boundaries different from that produced at divergent boundaries
they have more water