Chapter 10 Flashcards
(20 cards)
Tectonic Provinces
Large scale regions formed by particular tectonic processes.
Shields
A large tectonic province within a continent that is tectonically stable and where ancient crystalline basement rocks are exposed at the surface.
Appalachian Fold Belt
Goes from newfoundland to alabama
is the result of continental collisions 470-270 mya.
Rejuvenation
Renewed uplift in a previously existing mountain chain that returns it to a more youthful stage.
Craton
A stable region of ancient continental crust, often made up of continental shields and platforms.
Orogen
An elongated mountain belt, usually formed by an episode of compressive deformation.
Active Margins
A continental margin where tectonic forces caused by plate movements are actively deforming the continental crust.
Passive Margins
A continental margin far from a plate boundary.
Types of Tectonic Provinces
- Shield
- Platform
- Continental Basin
- Phanerozoic Orogen
- Extended Crust
Tectonic Age
The time that a rock was last subjected to crustal deformation intense enough to reset the isotopic clocks within the rock by metamorphism.
Magmatic Addition
A process of continental growth in which low-density, silica-rich rock differentiates in the mantle and is transported vertically to the crust.
Accretion
A process of continental growth in which buoyant fragments of crust are attached to existing continental masses by horizontal transport during plate movements.
Accreted Terrains
A piece of continental crust, tens to hundred of kilometers in extent, with common characteristics and a distinct origin, usually transported great distances by plate movements and plastered onto the edge of a continent.
Orogeny
Mountain building by tectonic forces, particularly through the folding and faulting of rock layers, often with accompanying volcanism.
The Wilson Cycle
The sequence of tectonic events on continents caused by the formation and closure of ocean basins. The cycle comprises
- Rifting during the breakup of a continent
- Passive margin cooling and sediment accumulation during seafloor spreading and ocean opening
- Magmatic addition and accretion during subduction and ocean closure
- Orogeny during continent-continent collision
Epeirogeny
Gradual downward and upward movements of broad regions of crust without significant folding or faulting.
Glacial Rebound
A mechanism of epeirogeny in which continental lithosphere depressed by the weight of a large glacier rebounds upwards for tens of millennia after the glacier melts.
Two Groups of Archean Crust Rock Formations
- Granite-greenstone terrains
2. High-grade metamorphic terrains
Cratonic Keel
A mechanically stable and chemically distinct portion of the lithospheric mantle that extends some 200 to 300 km beneath a craton into the asthenosphere like the hull of a boat into water.
How do continents grow?
Magmatic addition and accretion
