Abstract
Late Quaternary paleoenvironments are of particular interest to understand how the Earth System’s climate will respond to the undramatic changes during this period, compared with the broader glacial-interglacial variations. In this study, a shallow sediment core (2.84 m long) retrieved from the Red Sea coastal zone in northern Ghubbat al Mahasin, south of Al-Lith, Saudi Arabia, is used to reconstruct the mid-Late Holocene paleoenvironments and sea level based on a multiproxy approach. Remote sensing data, sedimentary facies, benthic foraminiferal assemblages, δ18O and δ13C stable isotopes, elemental composition and14C dating were utilized. The stratigraphy of the core shows three distinctive depositional units. The basal pre 6000 year BP unit consists of unfossiliferous fine to medium sand sharply overlain by black carbonaceous mud and peat, suggesting deposition in a coastal/flood plain under a warm and humid climate. The middle unit (6000-3700 year BP) records the start and end of the marine transgression in this area. It consists of gray argillaceous sand containing bivalve and gastropod shell fragments and a benthic foraminiferal assemblage attesting a lagoonal or quiet shallow marine environment. The upper unit (<3700 year BP) consists of unfossiliferous yellowish-brown argillaceous fine-grained sands deposited on an intertidal flat. Both middle-and upper-units stack in a regressive shallowing upward pattern although they may be separated by a hiatus. The overall regressive facies and the stable isotopic data are consistent with a late Holocene sea-level fall and a change to a more arid climate.
Highlights
Paleoenvironmental reconstruction of coastal deposits is a critical key for assessing climatic and sea level changes that occur as a response to allogenic processes operating at global to regional scales, and the action of autogenic processes at local scales (Hein et al, 2016)
The investigation site is covered by siliciclastic deposits along the coastal zone that were deposited under the modern arid climate
The first stage includes medium- to fine-grained fluvial sand deposits overlain by black carbonaceous mud suggesting deposition in a swamp during lateral movement of the fluvial system in a warm humid period in the Early Holocene prior to 6000 year BP
Summary
Paleoenvironmental reconstruction of coastal deposits is a critical key for assessing climatic and sea level changes that occur as a response to allogenic processes operating at global to regional scales, and the action of autogenic processes at local scales (Hein et al, 2016). Siddall et al (2003) stated that the rate of sea-level change since the Last Glacial Maximum in the Red Sea reached up to 2 cm/year from a low stand at around 18,000 year BP, about 120 m below present sea level (bsl). These changes relate to abrupt changes in the climate. Sea level rose for 6500 years to reach 70 m bsl and jumped about 50 m during the early Holocene due to Melt Water Pulse-1B (Lambeck et al, 2014) This was accompanied by the shoreline’s rapid, unidirectional landward shift during the mid-Holocene before it stabilized at a slightly elevated level. Sea-level increased to a height of nearly 5 m above current sea-level in several places, such as along the eastern and southeastern Brazil coast (Crowley and North, 1991; Martin et al, 2003), and to around 0.5–2 m along the Red Sea coast (Hein et al, 2011) before falling to its present position during the Late Holocene
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