Glacioeustatic cyclicity in Quaternary carbonates of the southern Arabian Gulf : sedimentology, sequence stratigraphy, paleoenvironments and climatic record
The southern Arabian Gulf forms a wide shallow shelf, which slopes gently basinwards with no pronounced shelf edge. This has been a site of extensive carbonate deposition throughout the Quaternary. This PhD research project was undertaken in order to investigate the influence of Pleistocene glacioeustacy on sedimentation in the southern Arabian Gulf. In order to achieve this aim sediments were studied in core and outcrop from several sites in the southern Gulf region, and the sedimentary processes acting on the modern-day coastlines were investigated. Sea-floor sediments were studied in 20 engineering boreholes from 6 sites in the southern Arabian Gulf, penetrating to a maximum depth of 68.5 below present sea level. Seven depositional sequences are found within this interval, of which at least six are believed to have been deposited during the Pleistocene. It is most likely that the oldest of these date from oxygen isotope stage 11 (ca. 450ka) or earlier. These sequences are composed of a highly varied suite of sediments. Condensed sequences, omissions and expanded sections are common within the Arabian Gulf sediments. Onshore deposits were studied in Abu Dhabi and Qatar. At least two sequences of Pleistocene carbonates are preserved onshore in the southern Arabian Gulf. These comprise, firstly, widespread aeolianites deposited prior to the last interglacial (the Ghayathi Formation), and secondly, marine sediments and aeolianites deposited during the last interglacial (the Fuwayrit Formation). Marine deposits of the Fuwayrit Formation indicate that sea-level was higher than present on two occasions during the last (Sangamonian) interglacial.