AMS-dated mollusks in beach ridges and berms document Holocene sea-level and coastal changes in northeastern Kuwait Bay

In northeastern Kuwait, ancient beach ridges and associated berms are separated from the present shoreline by a 4-6 km-wide sabkha. A diverse mollusk fauna in the beach ridges attests to a former open marine environment A total of 21 AMS dates were obtained in this study. Thirteen mollusk samples from beach ridges yielded AMS dates ranging from similar to 6990 cal yr BP in the southeast to similar to 3370 cal yr BP in the northwest, suggesting a southeast to northwest age progression during the Holocene transgression. In contrast, four samples from berms throughout the study area yielded AMS dates of 5195-3350 cal yr BP showing no age progression; these berms consist largely of Conomurex persicus gastropods that aggregated by storms during a highstand at similar to 5000-3500 cal yr BP. The berms are presently at similar to+6 m above sea level, 2-3 m above the beach ridges. Human settlements were common on the ridge crests before and after the highstand. Regression to present-day sea level commenced after the highstand, which is when the sabkha began forming. A landward, marine-built terrace, which yielded AMS dates >43,500 C-14 yr BP, probably formed during Marine Oxygen Isotope Stage 5e and hence is not genetically related to the beach ridges. (C) 2015 University of Washington. Published by Elsevier Inc. All rights reserved.