CONTINENTAL RIFTS

barineka (56)in #geology • 8 years ago (edited)

CONTINENTAL RIFTS

These are elongate depression that have the thickness of the lithosphere deformed by the influence of exponential forces (Neumann & Ramberg 1978, Burchfiel, 1980).
Rift therefore applies to major lithospheric features and does not encompass smaller scale structures associated with normal faulting.

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Continental Rift caused by a rising mantle plume.
Author: DBoyd13

Presently active rift include; EAR, the Baikal Rift (South Central Siberia), The Rhine Graben (North-West Europe) The Rio Grande Rift and Basin & Range Province of Western United State of America.

Continental Rift System

They are fault-bounded valleys ranging in width from about 30-75km and in length from a few tens to thousand of Kms. They are characterized by a tensional tectonic setting which extends over 6500Km from the Western part of Asia Minor to South-East Africa.

Ranges from a simple graben or half graben to complex graben system, the complex system is mostly common. The Basin and Range province is West-North America is a multiple rift system composed of a complex series of alternating graben valley and ridges (Horst).

Rift systems may occur in rocks of any age, young system (≤30million years) are characterized by unstable tectonic conditions, some large volcanic plateau in the North-West of the United State of America and the Deccan Traps in India, also appear to be related to extensive tensional faulting.

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Characteristics Of Rifts

They may be form in different tectonic environments, however exhibit common characteristics like:

• They are relatively common.

• They often contain extensive volcanic rocks.

• They are commonly, spatially associated with domal uplifts.

• The lithosphere underlying rifts is generally abnormally thin and invaded by low velocity, low density, and high temperature material, E.g Ocean Ridges.

• The location of rifts is often controlled by existing zones of crustal weakness.

• The amount of horizontal extension required to form present day rift is relatively small (<10km).