Twenty years of sedimentary change and diagenesis, Qatar Peninsula, Arabian Gulf
Re-examination in February 1986 of areas studied by the author in 1966 and 1967 revealed rapid rates of sedimentation and diagenesis along the east coast of the Qatar Peninsula. At Ras Um Sa on the north-east side of Qatar, a series of chenier-like beaches and curved spits is building southward under the influence of longshore currents. Beach and spit growth increasingly protects the shoreline and allows tidal flats to form in their lee. As these spits accrete, they become armored on their lagoonal side by beachrock formation. In the last 20 years a spit approximately 1/2 km long has grown, and beachrock has already armored its recurved lagoonal side. At Umm Said on the southeast side of Qatar, seawardly accreting barchan dunes composed of quartz sand have built a 40-km long, 10-km wide sabkha as thick as 30 m. Aerial and ground photographs show that certain dunes near the seaward edge of the sabkha have migrated into the sea and have contributed to shoreline accretion. The observed rate of dune migration suggests that within approximately 100 years the remaining quartz sands will be depleted and blown into the sea because there is no replenishment of the dune field. Subsequently, the area will revert to one of carbonate deposition. Fine-grained dolomite is presently precipitating in interstitial brines in the landwardmost portions of this unusual sabkha. In the geologic record, such a deposit would be an anomalous, porous and permeable, cross-bedded, linear, 30-m thick, dolomite-cemented sandstone body encased in carbonate sediments. A modern model such as the one at Umm Said can provide useful clues for determining the origin of similar deposits in ancient rocks.
- Research Organization:
- Geological Survey, Miami Beach, FL (USA)
- OSTI ID:
- 6014628
- Report Number(s):
- CONF-880301-
- Journal Information:
- AAPG Bull.; (United States), Vol. 72:2; Conference: Annual meeting of the American Association of Petroleum Geologists, Houston, TX, USA, 20-23 Mar 1988
- Country of Publication:
- United States
- Language:
- English
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