Click
on the banner above, the red location box or any numbered box
to view detailed scenes of an area of interest to you.
Figure: The six major geomorphic units of the coastal complex
of Abu Dhabi above are differentiated on the basis of their relationship
to sea level and geographical position. These are: (A) Open marine
shelf; (B) Offshore bank - shoal, channel and barrier islands
[1, 3, 6, 7, 13, 16, & 17]; (C) Lagoons [2, 4, 5, 8, 9, 11,
12, and 15]; (D) Coastal terrace [2, 4, 5, 8, 9, 11, 12, 14, 15,
18, 19 23, 21, and 22], and (E) Mainland coastal plain [landward
of coastal terrace].
The text
of these web pages is based and often paraphrased from the papers
and guidebooks written by Christopher Kendall, Abdulrahman Al
Sharhan and Gregory Whittle. The work of many others is listed
in the references. The core photographs from the Abu Dhabi sabkha are of push cores collected by Godfrey Butler for his PhD. Most of the illustrations are field photographs
taken by Christopher Kendall, Greg Whittle and Nassir Alnajii,
while Abdulrahman Al Sharhan supplied many of the remote views
and others come from the public
domain service that NASA
generously provides. Christopher Kendall drafted the maps and
diagrams. Diana Schmidt edited many of the scanned and digitized
images using Adobe Photoshop.
Christopher.
G. St. C. Kendall
Department of Geological Sciences, University of South Carolina,
Colombia,
SC 29208, U.S.A. e-mail: kendall@sc.edu
Abdurahman.
S. AlSharhan
Faculty of Science, U.A.E. University, P.O.Box: 17551, Al Ain,
United Arab Emirates, e-mail:sharhana@emirates.net.ae
Homepage:http://www.megeuae
and
Gregory L. Whittle
Geosystems Branch - ENGG
U.S. Army Corps of Engineers
701 San Marco Blvd.
Jacksonville, FL 32207, e-mail:Gregory.Whittle@saj02.usace.army.mil
Implementation
of this web site by:
Nassir S. Alnaji
Aramco Box # 8511, Dhahran, 31311, Saudi Arabia
e-mail: alnajins@yahoo.com
& his hardworking assistant Christopher Kendall
Synopsis
The
text of this web site is intended to provide a guide to the Holocene
shallow water carbonate and supratidal evaporite tract that lines
the United Arab Emirates (U.A.E.) coastal embayment consists of
seaward reefs, barrier islands and tidal flats. As with similar
sedimentary sequences from the geological section in the subsurface
of the Arabian Gulf, and elsewhere in the geological record, the
sediments of this coastal region pass landward into a continental
facies and seaward into a basinal facies.
Map
of general marine facies of the coast of Abu Dhabi, U.A.E.(Click
image to view)
In eastern Abu
Dhabi the Holocene coast trends northeast southwest and the barrier/lagoon
complex narrows. To the west, the protecting barrier islands are
more widely spaced than those to the east. These latter islands
occur on extensive sandy shoals and coral banks cut by tidal channels.
Here, south of the barrier, is a continuous open body of water,
the Khor al Bazam lagoon. It has less restricted circulation than
the lagoons to the northeast and its western end is connected
to the Arabian Gulf.
The distribution of the sediments in the U.A.E. coastal embayment
reflects the physiographic differences listed above. To the east,
oolites form on the inter island tidal deltas and coral reefs
are restricted to small patches along channels and just seaward
of the center of the islands. To the west, coral reefs grow along
the northern edges of most of the offshore banks north of the
Khor al Bazam. Eastward, in the protected lagoons, carbonate muds
and pellets are accumulating, whereas to the west of Al Dhabaiya
Island, carbonate muds only accumulate in a narrow belt south
of the offshore bank. Grapestones and skeletal debris are the
dominant components. The entire province is evolving. The offshore
bank is accreting seaward through a combination of coral reef
growth and tidal delta progradation. South of this bank, supratidal
flats are encroaching on the lagoons through the development of
beach ridges and cyanobacterial flats.
The similar relationship of these sedimentary facies to some of
the Upper Jurrassic found in the subsurface of the Central Arabian
Gulf, suggests that Abu Dhabi coastal area can be used as a comparative
model for understanding some ancient carbonate/evaporite depositional
and diagenetic processes. The facies relationships at the pinch
out between the Hith Anhydrite and the Asab Oolite suggest that
these sediments accumulated in a nearshore to sabkha setting.
Eastward of this margin the Hith changes its character and appears
to have accumulated in a standing body of water.
