Sahara Desert Mauritania

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Richat Structure

The Richat Structure is a geographic landmark in the Sahara desert (Mauritania) that resembles a “bulls-eye” with a diameter of ~50 km. It is popularly referred to as “The Eye of Africa”.

The formation of this structure initially was attributed to a meteorite impact due to its resemblance to a crater. Geologists now theorize that the structure is a result of different types of rocks being eroded at different rates of erosion. This theory "holds water" as igneous rocks within the structure are more resistant to erosion than the host sedimentary rocks.

The age of sedimentary rocks that surround Richat range in age from Late Proterozoic (2.5 billion years) to Ordovician (480 million years).

The interior of the Richat Structure itself contains the following rock types:

• Rhyolitic volcanic rocks – Consist of hydrothermally altered tuffaceous rocks and lava flows. These are from two different volcanic centres, remnants of two maars (low-relief volcanic crater).

• Gabbroic Rocks – These rocks form two concentric ring dikes. The inner ring is approximately 3 km from the centre and has a diameter of about 20m. The outer ring is about 8km from the centre and 50m in diameter.

• Carbonatite Rocks – are a rare type of calcium-rich igneous rock. These intruded and cooled between 94 to 104 million years ago. Within the Richat structure, 32 carbonatite dikes and sills have been mapped.

• Kimberlites – Igneous rocks of deep earth origin and potentially diamond hosting. Kimberlites occur in the northern area within Richat, including a kimberlitic plug and a few sills.

According to NASA, the Richat Structure has become a landmark for shuttle crews.

For a more detailed explanation, look here - TEL

http://www.facebook.com/photo.php?fbid=375240989203618&set=pb.352857924775258.-2207520000.1362771989&type=3&theater

♞Renesh T

Image Credit:

NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

http://www.nasa.gov/multimedia/imagegallery/image_feature_528.html

References and further reading:

http://www.nasa.gov/multimedia/imagegallery/image_feature_528.html

http://geology.geoscienceworld.org/content/33/8/665.abstract

http://www.sciencedaily.com/releases/2004/06/040623084020.htm

http://adsabs.harvard.edu/full/2001M%26PSA..36R.125M

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