Relative Sea-Level Changes during the Late Pleistocene to Holocene of Qatar: Implications for Eustasy and Tectonics
Jameson, Jeremy *1; Strohmenger, Christian J.1
(1) ExxonMobil Research Qatar, Doha, Qatar.
The southern margin of the Arabian Gulf is a structural fore-bulge, dipping gently northward into the foreland of the Zagros collision zone. Gradual seaward slopes, the lack of seismicity and faulting have led previous workers to portray the southern Gulf coastal systems of barrier islands, broad lagoons and sabkhas as analogues to ancient, epieric seas. Detailed mapping of coastal deposits of Qatar and published data throughout the region suggests that tectonic uplift may be a significant factor influencing coastal sedimentation patterns.
Age dating from Qatar coastal sediments provide evidence for a rapid rise in sea level from the Last Glacial Maximum (LGM) approximately 20,000 years before present (yr BP) until approximately 7000 yr BP. Most coastal deposits are relicts of a Holocene sea-level highstand, dating from 7000-3000 yr BP. Stranded Holocene beaches up to 15 km inland of the present day coastline are relicts of a highstand, 2 to 3 meters above present. Similar beaches are found in Abu Dhabi and the Kingdom of Saudi Arabia. During this period coral reefs formed a nearly continuous fringe around the windward and oblique Qatar coastlines. A drop approximately 2000 yr BP may account for the demise of these fringing reef platforms. Seaward stepping strandlines suggest a drop to near present day sea level.
Unaltered, calcitic organisms from strandlines up to 13 km inland of the present day coastline show radiocarbon ages between approximately 30,000 to 40,000 yr BP. These ages coincide with well documented glacio-eustatic sea-level lowstands before the LGM. Published data along the southern Arabian Gulf show similar ages. Late Pleistocene to Miocene fluvial gravel deposits occur 20 to 40 meters above sea level; an additional indication of tectonic uplift. Thus, data from Late Pleistocene and Early Holocene suggest rapid rates of tectonic uplift may account for sediment distribution patterns during a relatively recent period of human history.
AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain