Rashad A. Bantan

Palaeoenvironment, palaeoclimate and sea-level changes in the Shuaiba Lagoon during the late Holocene (last 3.6 ka), eastern Red Sea coast, Saudi Arabia

Multi-proxy investigations of sediment lithology, geochemistry, benthic foraminifera, and δ18O and δ13C of Elphidium striatopunctatum were carried out on a sediment core SHUA3 (2.2 m long) spanning the last 3.6 ka and recovered from Shuaiba Lagoon, eastern Red Sea coast. Results showed that the interval before 1500 BC was deposited under supratidal to sabkha environments as indicated by the absence of benthic foraminifera and predominance of clastics enriched in terrestrial materials due to a relative lowering of sea level accompanied with arid conditions. From 1550 BC to the top of the core, the benthic species variations showed progressive depositional environmental changes from subtidal to intertidal conditions. Relative abundance of Sorites orbiculus co-varied with the reconstructed palaeo-tidal elevation, δ18O and δ13C values suggesting its sensitivity to climatic changes in the lagoon. δ18O and δ13C showed intervals of depletion at 350 BC, the beginning of the 1st millennium, AD 400 and AD 700 due likely to arid conditions that led to low evaporation and rapid water circulation. These are interleaved with intervals of enrichment at 150 BC, AD 200 and AD 600, due likely to warm conditions that led to high evaporation as testified also by changes in both palaeo-tidal elevation and Sorites orbiculus abundance. These proxies reached their highest and most prolonged levels during the AD 800–1550 interval, indicating warm conditions corresponding to the world ‘Medieval Warm Period’. Immediately after this period, the arid conditions of the ‘Little Ice Age’ prevailed throughout the AD 1550–1850 interval, and this was succeeded by the present warming conditions.

Improving geological mapping of the Farasan Islands using remote sensing and ground-truth data

ABSTRACT We integrated satellite imagery (Landsat-8) with ground-truth data to produce a detailed and complete geological map of the Farasan Islands, off the Red Sea coast of Saudi Arabia at a scale of 1:100,000. This new map improves upon past efforts by expanding the mapped lithologies on the islands into four categories. We used different techniques to enhance this lithological differentiation, including band combination with ratio stretching and supervised classification techniques based on direct field validation. The former was used to distinguish differences in reflectance values across sets of bands to create a classification image from typical reflectance patterns. The geological feature boundaries were constrained by open-source high-resolution satellite imagery (WorldView-2) as well as field observations. The resulting map clearly distinguishes between different geomorphic and geologic features, including lineaments and lithologies. As the Farasan Islands are relatively remote and not easily accessible, with an area of 739 km2, these imagery-analysis techniques were an effective tool for using remote sensing data to produce new and better mapping products of this important area.

Seismicity and major geologic structures of Tiran and Sanafir islands and their surroundings in the Red Sea

Tiran and Sanafir islands and their surrounding areas are very important due to their location within the Red Sea, which is in a triple junction among the African and Arabian plates and the Sinai Peninsula microplate. Consequently, this area should be studied from a geological point of view, particularly because there is a plan to construct King Salman’s bridge connecting Egypt and Saudi Arabia. Freely available potential field data, such as magnetic and gravity data, were integrated with seismological data from nearby seismic stations to understand the regional structure and seismic activity in the area. Potential field data were analysed using edge detection techniques (Tilt DeRivative and horizontal gradient) for qualitative interpretation and 2D inversion modelling for quantitative interpretation. Seismological data were analysed geostatistically to identify many epicentre locations and estimate the focal depths. The results of the potential field data analysis indicate that Tiran and Sanafir islands are located along a subsurface geological edge trending NW, parallel to the Red Sea. A similarity in potential field anomalies between both islands and the southern Sinai Peninsula indicates that these islands were separated from the Sinai Peninsula during the formation of the Gulf of Aqaba via Dead Sea Transform fault. The analysis of the seismic data indicates that a specific motion characterizes each focal depth solution. The seismic events are related to main structural trends NW–SE and NE–SW.