What is a continental rift boundary?
What is a continental rift boundary?
A Continental rift is the belt or zone of the continental lithosphere where the extensional deformation (rifting) is occurring. These zones have important consequences and geological features, and if the rifting is successful, lead to the formation of new ocean basins.
What is continental subsidence?
Tectonic subsidence is the sinking of the Earth’s crust on a large scale, relative to crustal-scale features or the geoid. Three mechanisms are common in the tectonic environments in which subsidence occurs: extension, cooling and loading.
How is a continental rift formed?
Rifting can be caused when hot material from a mantle plume reaches the base of a continental plate and causes the overlying lithosphere to heat up. In addition to this the uwards movement of the plume against the base of the plate results in extensional forces, which can cause rifting.
What happens when continents rift?
Where tectonic plates move away from one another the lithosphere thins. The underlying asthenosphere rises and expands like a hot-air balloon, elevating a broad region. If the plate is capped by thick continental crust, the resulting continental rift zone rises high above sea level.
Why do rifts fail?
Failed rifts are the result of continental rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a hotspot.
What are the four stages of continental rifting?
They are: Katarchean-Archean, early Proterozoic, Late Proterozoic, Paleozoic, and Mesozoic-Cenozoic. Linear structures of the oldest stage combine features of development and structure similar to those typical of the rift and geosynclinal zones in the later periods of the Earth’s history.
What is an example of subsidence?
Land subsidence is a gradual settling or sudden sinking of the Earth’s surface. Subsidence can also be caused by natural events such as earthquakes, soil compaction, glacial isostatic adjustment, erosion, sinkhole formation, and adding water to fine soils deposited by wind (a natural process known as loess deposits).
What are the types of subsidence?
It may be caused by natural processes or by human activities. The former include various karst phenomena, thawing of permafrost, consolidation, oxidation of organic soils, slow crustal warping (isostatic adjustment), normal faulting, caldera subsidence, or withdrawal of fluid lava from beneath a solid crust.
What is created by rifting?
Rifting is defined as the splitting apart of a single tectonic plate into two or more tectonic plates separated by divergent plate boundaries. The rifting of a continental tectonic plate creates normal fault valleys, small tilted block mountains, and volcanism.
What is the difference between a rift and a fault?
As nouns the difference between rift and fault is that rift is a chasm or fissure while fault is a defect; something that detracts from perfection.
How do failed rifts work?
What is an example of continental rifting?
The most prominent example of a continental rift is the East-African Rift Valley and its continuations into the Red Sea and the Gulf of Aden. If the rifting between East Africa and the rest of the continent continues, a new ocean will eventually be formed here.