GEOMORPHOLOGY AND SEDIMENTARY FRAMEWORK OF SMALL SUBTROPICAL ISLANDS, OFFSHORE KUWAIT

Five small islands offshore the Sate of Kuwait in the northern Arabian Gulf (Miskan, Awhah, Kubbar, Qaruh, and Umm Al-Maradem) occur in differing structural settings and have evolved in a dynamic environment of shifting fluvial depocenters, fluctuating Holocene sea level, variable tidal conditions, and opposing regional wind patterns. As a first step in reconstructing the origin and evolution of the islands, bathymetric charts, historical photographs, topographic profiles, and sediment samples were used to investigate their geomorphology and sedimentary environments. The subaerial parts of the islands vary in area from 0.04 to 0.57 km². The plan-shape ellipticity ranges from nearly circular (0.10) to oval-shaped (0.54). The two northern islands (Miskan and Awhah) experience mesotidal conditions and are situated on a shallow platform (<5 m below mean sea level), which is part of a larger Failaka Island structure. In contrast, the three southern sites have a microtidal regime and sit atop small isolated platforms (possibly of aggrading perched reef origin), which descend steeply to more than 20-30 m depth within 3 km of the islands. Topographic profiles indicate that island interiors are composed of beach-ridge sets, whereas modern shoreline consists of segments of beachrock platforms alternating with depositional salients and flying spits in areas of longshore transport convergence. The proportion of total shoreline length represented by beachrock exposures varies from 4 to 46%. Beach sediments consist of very coarse to medium sand and exhibit variable degree of sorting, primarily due to variable degree of attrition of bioclastic material. Although bioclastic input is an important component of modern beach sedimentation at all sites, the fine-grained terrigenous fraction is higher on the northern islands, where northwesterly Shamal winds deliver aeolian sediment from the mainland. Terrigenous sediment flux during construction of the Shatt Al-Arab delta may have played a major role in the geological framework of the northern sites. The preliminary historical analysis of coastal dynamics at the five sites is the first step in predicting future trends in coastal erosion and island response to sea-level changes, which already affect local coastal communities.