The Enjefa Beach Exposure in Kuwait, Northern Gulf: Evidence of Late Holocene Regression
Tanoli, Saifullah K.*1; Al-Fares, Abdulaziz 1; Al-Sahlan, Ghaida 1
(1) Exploration Studies Team, Kuwait Oil Company, Ahmadi, Kuwait.
Four sedimentary facies were recognized in exposure along Enjefa Beach, Salwa, Kuwait. They are; a) horizontally laminated, b) trough cross bedded, c) planar wedge shaped and ripple cross bedded, and d) bioturbated calcareous sandstone. Facies “a” consists of horizontally laminated beds which generally display coarsening upward trend. These beds resulted due to stacking of beach faces with top of beds marking the shelly beach top. Fining upward trend in a few beds is also observed which attests to the occurrence of more than normal energy events. The trough cross bedded faices makes middle part of the exposure and is interpreted tidal channel or tidal inlet deposits. The planar wedge shaped and ripple cross bedded facies display variable orientation with northward dominated current direction. It is likely formed in shallower part of the channel with relatively lower energy levels or is the ebb tidal delta deposits. The uppermost facies “d” consists of big network of Ophiomorpha burrows and is interpreted the coastal sand flat deposits.
Following Walther’s Law, the vertical sequence observed in this exposure from facies “a” to”d” was formed in laterally adjacent coastal subenvironments. This facies stacking pattern from beach, tidal channel to sand flat reflects seaward shift in facies and therefore progradation. Nevertheless, during Holocene time from around 20kyr bp the melting of ice of Late Pleistocene has resulted into eustatic transgression. The present Gulf was the result of flooding associated with this transgression. After 7kyr to present although transgression continued globally but at a much slower pace. The Enjefa Beach exposure on the contrary depicts progradation. The glacio-isostatic adjustment cannot explain it since there was no glaciation in this region during Pleistocene. However, there is evidence of present day active tectonism associated with the northeastern movement of the Arabian Plate under the Zagros fold belt. As a consequence, Kuwait’s coastal areas and interior are experiencing structuring creating uplift. This uplift possibly outpaced transgression resulting in regression and the development of progradational sequences in coastal areas of northern Arabian Plate during later part of Holocene.
AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain