Gamache-Chapter 8
Fracture Zones
prominent linear breaks in the oceanic crust which include both the active transform faults as well as their inactive extensions into the plate interior
Paleomagnetism
remnant magnetism in rock bodies
Seafloor Spreading
the mechanism responsible for producing new seafloor between two diverging plates
Partial Melting
the process by which most igneous rocks melt
Lithosphere
the rigid outer layer of Earth, including the crust and upper mantle
Curie Point
the temperature above which a material loses its magnetization
Transform Boundary
the type of plate boundary where plates grind past each other without creating or destroying lithosphere
Divergent Boundary
the type of plate boundary where plates move apart, resulting in an upwelling of material from the mantle to create new seafloor
Slab Pull
a mechanism that contributes to plate motion in which cool, dense oceanic crust sinks into the mantle and "pulls" the trailing lithosphere along
Ridge Push
a mechanism that may contribute to plate motion involving the oceanic lithosphere sliding down the oceanic ridge under the pull of gravity
Plate
a rigid slab of earth's lithosphere
Asthenosphere-
a subdivision of the mantle situated below the lithosphere
Plate Tectonics
a theory in which the Earth's outer shell consists of about 20 rigid slabs
Continental Drift
a theory that originally proposed that the continents are rafted about, proposed by Wegener in his 1915 book
Island Arc
alternate name for Volcanic Island Arc
Fossil Magnetism
alternate name for paleomagnetism
Oceanic Ridge System
an elevated portion of the seafloor that forms along well-developed divergent plate boundaries
Deep Ocean Trench
as an oceanic plate slides beneath an overriding plate, this deep, linear fracture often forms on the ocean floor adjacent to the zone of subduction
Continental Volcanic Arc-
mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent
Pangaea
supercontinent that Wegener hypothesized existed about 200 million years ago that broke into smaller continents that drifted to their present day positions
Convergent Boundary
the type of plate boundary where plates move together, causing one of the slabs to be consumed into the mantle as it descends beneath an overriding plate
Hot Spot
this is caused by a rising plume of mantle, one of these is responsible for the intraplate volcanism that produced the Hawaiian Islands
Reverse Polarity
when rocks exhibit magnetism opposite of the present magnetic field, they are said to possess this
Normal Polarity
when rocks exhibit the same magnetism as the present magnetic field, they are said to possess this
Volcanic Island Arc
a chain of small volcanic islands that forms when two oceanic slabs converge, one descending beneath the other
Magnetic Reversals
a change in Earth's magnetic field resulting with opposite magnetic directions being aligned with one another
Rift Valley
a downfaulted valley created by material displaced downward along spreading centers on continents
Subduction Zone
a long, narrow zone where one lithospheric plate descends beneath another
Slab Suction
a mantle circulation that pulls both the subducting and overriding plates toward the trench
Mantle Plume
a mass of hotter-than-normal mantle material that ascends toward the surface, where it may lead to igneous activity