Geomorphological changes in the coastal area of Farasan Al-Kabir Island (Saudi Arabia) since mid Holocene based on a multi-proxy approach
2018, Pavlopoulos, Kosmas, Fouache, Eric, Koukousioura, O., Triantaphyllou, M., Vandarakis, D., Marion de Procé, S., Chondraki, V., Kapsimalis, V.
The geomorphological evolution of the southeastern coastal area of Farasan Al-Kabir Island (Saudi Arabia) is revealed by the mapping of modern landforms and a multi-proxy and high spatial resolution study including grain size, particulate organic carbon, mineralogy, element geochemistry, benthic foraminifera analysis and radiocarbon dating of a 3.3-m long sediment core. The modern geomorphological features comprise a variety of arid landforms, such as plateau, cliffs and pediments of Pleistocene coral limestones, playa depressions located on plateau surfaces, alluvial fans, butte and sandy beaches. The mid Holocene evolution of the borehole area is resulted from the detailed analysis of five sedimentary units detected along the core Matar-1, and includes three distinct stages: (a) from 5253 ± 223 y cal BP to 3138 ± 223 y cal BP, carbonate coarse-grained material consisting of coral fragments, molluscs, calcareous algae and benthic foraminifera are deposited on a shallow marine fringing reefal platform, which becomes progressively a nearshore backreef (around 3675 ± 215 y cal BP), and later (around 3138 ± 223 y cal BP) a reef ramp; (b) since 3040 ± 220 y cal BP the borehole area obtains the characteristics of a high-energy beach that receives increasing inputs of terrigenous material; (c) subsequently, a supratidal backshore setting is established influenced mostly by terrestrial processes and occasionally by marine processes, as it is indicated by the decreasing and sometimes sporadic presence of benthic foraminifera, and recently, a sedimentary veneer consisting of terrigenous, carbonate and evaporite material is formed by terrestrial, mainly wadi and aeolian, processes. © 2018 Elsevier Ltd and INQUA
Palaeoenvironmental evolution and sea-level changes in the coastal area of NE Lemnos Island (Greece) during the Holocene
2013, Pavlopoulos, Kosmas, Fouache, Eric, Sidiropoulou, M., Triantaphyllou, M., Vouvalidis, K., Syrides, G., Gonnet, A., Greco, E.
The study area is located on the northeastern coast of Lemnos Island (North Aegean Sea, 40°2'30N, 25°00'00E). It covers the archaeological settlement of Hephestia located in the Purnia Gulf and the coastal area of Alyki Lagoon. Reconstruction of the palaeogeography used palaeoenvironment data delivered from foraminifera and sea-level changes, providing archeological data about the presence of a potential harbour in the area.Geomorphological mapping as well as sedimentological and micropalaeontological studies of the Holocene coastal deposits were conducted. Four boreholes were drilled from the Alyki Lagoon, reaching 2.5m to 11m at the deepest and two from Hephestia area, reaching a depth of 6m. Twenty-four samples were dated using the AMS radiocarbon method, providing a chronology of the sedimentary units.The calculated age from the boreholes provides dates from 7050calBP to 990calBP There was a constant sea-level rise during the last 7000calBP in the study area. Results from the model of Lambeck sea level curve and sea level index point from Hephestia and Alyki show a vertical difference of 0.5-1.5m below sea level. The foraminiferal fauna analysis shows the development of shallow marine conditions with fresh water influx during 7000-4000calBP and a temporary lagoon environment with fluctuations to shallow bay environment from 4000 to 990calBP. © 2012 Elsevier Ltd and INQUA.
The impact of rapid early- to mid-Holocene palaeoenvironmental changes on Neolithic settlement at Nea Nikomideia, Thessaloniki Plain, Greece
2012, Fouache, Eric, Hamidi, Fatiha, Delanghe-Sabatier, Doriane, Ghilardi, Matthieu, Cordier, Stéphane, Psomiadis, David, Paraschou, Theodoros, Dotsika, Elissavet, Demory, François
The site of Nea Nikomideia is one of the oldest and most important Neolithic settlements in Northern Greece and the wider Balkan Peninsula, having been first occupied by early farmers at around 6500 cal. BC. Important archaeological excavations conducted in the 1960s suggested that the settlement was located close to an ancient coastline during the Neolithic. However, palaeoenvironmental change and landscape evolution in the vicinity of the site have seldom been considered in detail. Six cores from the western and central parts of the Thessaloniki Plain were therefore drilled in 2008 and subjected to palaeoenvironmental analyses, including sedimentology (LASER grain size and magnetic susceptibility measurements), chemical analysis (loss on ignition and carbonate content), stable isotopes analysis coupled with X-Ray diffraction measurements, molluscan faunal analysis and radiocarbon dating. The recognition of several important facies representing freshwater (lacustrine and fluvial) and brackish (lagoonal and marine-influenced) conditions have shed light on the environmental and landscape evolution of the western part of the Thessaloniki Plain and associated impacts on human occupation during the last 10,000 years. The general sequence proved in the cores indicates the predominance of lacustrine conditions during the early Holocene, with the occurrence of a marine transgression at c. 6000/5800 cal. B.C. This major palaeoenvironmental change corresponds with the 8.2 Ka event and is a likely cause for the desertion of Nea Nikomideia at that time. Subsequent regression of the shoreline to the east saw that the area around Nea Nikomideia returns to predominantly terrestrial conditions and the deposition of lacustrine and fluvial deposits.
Palaeoenvironmental evolution, sea-level changes and Human occupation in Lemnos Island during last 6000 years (North Aegean Sea, Greece)
2012, Fouache, Eric, Forman, Steven
The mapping demonstrates the abundance of glacial landforms in the study area. In addition to familiar forms such as moraines and U-shaped valleys, forms previously unknown in the Andes – trimline moraines – could be detected. Their age determination is in progress at the moment. On the basis of the mapped glacial forms, it was possible to reconstruct equilibrium lines for a sampling of several localities, which, along with the chronological classification, can shed light on the climatic change during past phases of glaciation. In the western Pampas of Argentina (33 – 36 S, San Luis province, South America) there are extensive late Quaternary aeolian sand deposits forming diverse depositional systems. This region is almost completely covered by a savanna dominated by Prosopis caldenia and profuse grass-land (Espinalphytogeographical province). The northern region, from the distal piedmont of the San Luis ranges to about the alluvial plain of the Quinto River, is mostly covered by aeolian sand sheets, associated with ephemeral arroyos and, occasionally, with partially eroded dunes. From here to the south, and passing transitionally to the southern and central Pampas of Córdoba and La Pampa provinces, the landscape is dominated by diverse suite of dunes. The most conspicuous feature of the central area is the presence of large (up to 4 km long), compound parabolic dunes and blowouts, with two main orientations. One set of parabolic dunes accret-ted with southeasterly paleowinds, whereas most of the parabolic dunes and blowouts in the eastern region were formed by northeasterly paleo-winds. Both directions are consistent with present wind data (1995-2004). Several parabolic and blowout depressions create freshwater lakes, likely filled by groudwater. Southern San Luis province presents complex linear dunes, with a NNW trending that extends for more than 25 km. This linear pattern is formed by the coalescence of parabolic dunes, which indicate southeasterly paleowinds. Sedimentological analysis and OSL dating reveal episodic sand sheet deposition between ca. 33 and 25 ka, with a potentially high lake stand at ca. 11.4 ka. Dune reactivation, possible developing parabolic dunes, appears to have occurred during different times of the Holocene (ca. 9.7 to 1.6 ka). This study reveals this aeolian landscape reflects significant paleoenviromental changes along the late Pleistocene-Holocene, adding new chronological constrained deposits to compare and study past arid systems.
The Late Holocene evolution of the Black Sea – a critical view on the so-called Phanagorian regression
2012, Fouache, Eric, Porotov, Alexey, Kelterbaum, Daniel, Brückner, Helmut, Dikarev, Vassily, Lericolais, Gilles
Throughout its geologic history, the Black Sea experienced major sea level changes accompanied by severe environmental modifications, including geomorphologic reshaping. The most spectacular changes were driven by the Quaternary glaciations and deglaciations that reflect responses to Milankovitch cycles of 100 and 20 ky periodicity. Major sea level changes were also considered for a shorter and more recent cyclicity. The concept of the Phanagorian re- and transgression cycle, supposedly with a minimum sea level stand of 5-6 m below its present position in the middle of the 1 st millennium BC, was established in 1963 by Fedorov for the Black Sea region. It was based on archaeological and palaeogeographical research conducted around the ancient Greek colonies of the Cimmerian Bosporus, in particular at the name giving site of Phanagoria, where underwater prospection had revealed the presence of a large number of submerged relics of the Classical Greek era. Analyses of sediment cores as well as 14C-dated fossil coastal bars in the western and southern parts of Taman Peninsula show that contemporary coastal bars are related to different sea levels. The dissymmetry can reach up to 6 m around 500 BC. This and more evidence from drill cores confirms that on Taman Peninsula many of the apparent sea level changes are tectonically induced. The subsidence may have been initiated by the release of gas from mud volcanoes inherited along anticline axes. Other observations around the Black Sea confirm that submerged archaeological sites correspond to areas where subsidence has taken places, while the so-called Holocene highstand - said to have been located above the present-day sea level - is associated with uplift areas (triggered by the ongoing Caucasus orogeny). Recent oceanographic research carried out in the Black Sea area shows that since the Black Sea was reconnected with the Mediterranean Sea (i.e., 7500 14C BP at the latest), both marine water bodies have been in equilibrium. This fact and arguments from archaeology, history, hydrodynamics etc. lead us to question the existence of the Phanagorian regression. It is important to note that none of the sea level curves established for the (eastern) Mediterranean shows a comparable regression/transgression cycle of several metres during the 1 st millennium BC.