Dans le cadre du développement d’étude à haute résolution des changements passés de la végétation, les données palynologiques ont permis de reconstituer l’évolution de la végétation dans les sédiments holocènes prélevés autour de la lagune de Sidi Ali el Mekki (N-E de la Tunisie). Nos résultats montrent qu’au cours les deux derniers millénaires, les changements de végétation de la Tunisie septentrionale traduisent une relation complexe faisant intervenir à la fois les forçages naturels et l’action anthropique. L’étude des sédiments lagunaires a mis en évidence les maquis à olivier et pistachier qui constituaient la végétation dominante alentour à la lagune de Sidi Ali el Mekki lors du premier millénaire de notre ère, ont nettement régressé au profit des steppes à graminées et armoises au cours des derniers 1000 ans, dénotant un impact anthropique croissant dans la zone d’étude.

The Sahara, the largest hot desert in the world, has witnessed green, humid phases in the past. It is clear that large areas of what is now arid/hyper-arid desert became vegetated, that currently fossil rivers flowed sufficiently to reach the Mediterranean, and that the African Monsoon is key in regulating this variance on the southern margin of the desert. However, what is happening on the northern margin, what regulates those changes and how the different northern and southern rainfall systems combine to affect the interior of the Saraha are poorly known. Closing this knowledge gap is an urgent priority, because climate models predict an enhanced drying under future global warming, but the IPCC give this forecast only “Medium” confidence and it contrasts strongly with those paleoclimatic records which indicate a greener Sahara during the warmer times through the Pleistocene. So, to understand what controlled the northern Sahara in the past, we use a multi-proxy approach using the longest absolute-dated speleothem records from Tunisia in central North Africa. This unique resource allows us to decipher periods of significant rainfall in this region through isotopic measurements and a direct indication of possible moisture sources through fluid inclusions. The records indicate a strong orbital control on past hydroclimatic changes suggesting enhanced rainfall during MIS 3, 5, 7 and 9. The fluid inclusions are consistent with a Western Mediterranean source for most rainfall, with some derived from the Atlantic. For much of the record, deuterium excess is highest in the samples with the most depleted d18O and d2H, which is consistent with some rainfall being derived from Mediterranean-derived high-intensity events, analogous to modern “medicanes”. High deuterium excess is also found during MIS5e, which is the only time the fluid inclusions we report from Tunisia are similar in composition to those we have already published for Libya, indicating an enhanced Eastern Mediterranean source occurred during the Eemian which is not reflected during other times of MIS5.

The thermohaline circulation of the Mediterranean Sea was a key factor in the development of sapropel layers in the Eastern Mediterranean Sea (EMS). Sapropel formation is linked to stagnant deep-water conditions and/or increased sea surface productivity during boreal summer insolation maximum. However, debates persist regarding the complex interplay between high and low latitude climatic processes, circulation dynamics, and sapropel formation. Analyses of major and trace elements by XRF, delta O-18 of planktonic foraminifera, and neodymium isotopes (epsilon Nd) of foraminifera have been carried out on two cores collected in the southeastern Aegean Sea of the EMS and in the Sardinia Channel of the Western Mediterranean Sea (WMS), in order to constrain deep-water mass circulation during the last glacial-interglacial cycle (i.e. the past similar to 150 ka), focusing on the last interglacial maximum. When combined with previous epsilon Nd records from the EMS, we identified two regional patterns of the epsilon Nd variations during the sapropel S5 interval (similar to 128-120 ka), suggesting that the initial freshwater influx from North Africa led to marked water stratification, limited deep-water formation, and shifted similar to 128-120 epsilon Nd towards a local signature due to an extended period of Nd exchange between seawater and marginal sediments. Cores strongly influenced from the Nile River discharge display radiogenic epsilon Nd values (-3.7), whereas those from the northern EMS exhibit more unradiogenic epsilon Nd values (-5.1). As S5 progressed, epsilon Nd records of all cores from the Levantine basin indicate a slight mixing of deep-water masses accompanied by a decrease in the epsilon Nd gradient between the northern and southern EMS. This was associated with the global decrease in temperature and reduced Nile River water input, which supported a slight deep-water recirculation from the Aegean Sea. This active circulation conveyed radiogenic epsilon Nd from the southern EMS to the north and the Western Mediterranean Sea. Overall, our new results suggest that hydrological conditions in Mediterranean Sea fluctuated during the S5 deposition, with a slight recirculation of Aegean deep-water in a pre-stage before the complete recovery of circulation in the EMS at the end of the sapropel S5 deposition.

During the late Pliocene-early Pleistocene Tunisian calcretes were formed in a soil environment. Fabrics at the macro and micro scale show that these deposits are similar to rhizogenic modern analogue systems forming in Spain. We infer that a similar climate prevailed in Tunisia in the past, specifically winter-season rainfall and a dry summer with annual rainfall close to 430 mm/year in the center of Tunisia. Here, we provide further constraints on the climate under which the Tunisian calcrete formed by looking at vegetation structure, water advection and amount of seasonal rainfall.To investigate (1) the palaeo-vegetation type(s) if they are C3 or C4 plants and (2) the source(s) of meteoric water of Tunisian calcretes during that era, stable isotopes of C and O were analysed in 25 samples taken from 5 horizontal laminar calcretes cores, from 3 sites: North (N36º.43.713; E10º.06.681’), Center (N35º.07.077’; E10º.14.545’), South (N33º.28.898’; E10º.23.602’). Results are expressed relative to the VPDB reference.In the North, the δ18O samples show values varying from – 4.78 ‰ to -6.91 ‰. Likewise, central site cores are characterised by δ18O values ranging from -5.32 ‰ to -6.97 ‰. In contrast, the δ18O values from the South are more depleted (-8.82 ‰ to -7.20 ‰). Concerning the carbon isotope results, both central and southern sites show similarly enriched δ13C values with an average of -6 ‰, while the North site shows more depleted values (-11.3 ‰ to -9.6 ‰). The δ18O values are similar to those determined in the last deglaciation/early Holocene speleothem carbonates from caves in the Tunisian Atlas Mountains, indicating a North Atlantic source. The north-to-south difference in both isotope systems reveals a decoupling between precipitation δ18O and vegetation effects. The southern site shows more depleted water isotopes (a consequence of internal water recycling effects) and more enriched δ13C, consistent with C4 vegetation and/or lower soil respiration. The central site shows low water recycling, but southern-like dryland vegetation. The northern site shows low water recycling and C3 vegetation and/ or higher soil respiration. Consequently, although there is enhanced humidity in all three sites, the sites do not record the same amount of rainfall and the same response of the landscape to form calcretes.

The North African calcretes formed during the Plio-Pleistocene are a prominent and stratigraphically significant palaeoclimatic marker. We studied the calcrete along a north-south transect in Tunisia that crosses the climatic boundaries between the latitudes 33 degrees and 37 degrees N to elucidate the palaeoenvironmental and climatic significance of the calcrete for the Plio-Pleistocene. Macroscopic, petrographic, Scanning Electron Microscopy (SEM), and Cathodoluminescence (CL) observations obtained in the field and from thin sections of the non-powdery horizons of all sites allowed to identify 4 facies: Pisolithic (limestones with clast(s) coated by laminae), laminar (limestones with a succession of laminae), massive brecciated (brecciated limestones), and groundwater facies (limestones with no biogenic features). Notably, soil-forming processes were evident at all sites except for those situated further south, which exhibited characteristics indicative of a groundwater environment. The comparison with modern analogues suggests for our study area the climate was similar to modern central Spain (Hot-summer Mediterranean climate Csa) in central Tunisia which is, in turn, similar to the modern climate in North Tunisia. The climate was characterized by strong seasonal contrast: higher winter rainfall than today followed by long dry hot summers modified by a North-South gradient. This gradient was the result of the interplay between westerly winter winds and the orographic effect of the Atlas Mountains confirming the North Atlantic origin of precipitations. We conclude that during the late Pliocene to early Pleistocene, the climate in Northern Africa was more humid than today, with enhanced winter rainfall at all study sites probably at the same time of the establishment of Saharan humid periods. These humid phases may have been long enough, spanning more than 10.000 years, to reduce recharged groundwater salinity and, subsequently, form thick calcareous soil.

The Eocene deposits belonging to the Khanguet Rheouis area, North–South Axis, Central Tunisia, consist of three lithological units deposited in a shallow water environment that is congruent to the Eocene regression. The middle unit represents a massive white dolomitic clay with gypsum intercalations that increase towards the top, containing significant amounts of palygorskite. SEM–EDX, XRD, and XRF analytical techniques were deployed to better understand the mineralogical and geochemical properties of the collected samples. Microtextural characteristics were analyzed using SEM and polarizing microscopy. Mineral spectral characteristics were determined by the Fourier Transform Infrared (FTIR) spectroscopy. The XRD analysis results show the predominance of dolomite with variable amounts of palygorskite and low quartz contents. Samples contained low concentrations of Nb, Th, Zr, Y, Rb, Zn, Cr, and V, which showed a positive correlation with the major oxides SiO2, Al2O3, Fe2O3, K2O, and TiO2, and a negative correlation with MgO and CaO, indicating that trace elements were exclusively retained in palygorskite rather than dolomite. SEM observations of palygorskite showed dense mats of short, interwoven fibers that bridged and filled the pore spaces between the dissolved dolomite. These textural characteristics suggest that the formation of palygorskite is post-dates dolomitization. Petrographic observations illustrate the existence of micro-tectonic structures such as stylolites and microcracks, playing an important role in the distribution of palygorskite. The obtained results are consistent with the hypothesis of a neoformed origin of palygorskite by direct chemical precipitation from solution, after partial dissolution of the dolomite.

Celestine and barite mineralizations occur in the Upper-Paleocene unit of marly-clay within curdled limestone of the Siouf-Cherahil area, North–South axis, Central Tunisia. The particularity of celestine is the high contents of U and it has never been studied as same as the Ba-rich deposit of Cherahil zone. This work was undertaken to narrow this gap. For this, mineralogical and geochemical characteristics of celestine and barite nodules were investigated using X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. At the Siouf zone, the mineralogical and geochemical data indicate that celestine contains more than 45

The reconstruction of paleofloods in the late Holocene has become an important research highlight in the context of the present climate change. The Tunisian Mediterranean coast is a region that is prone to experiencing severe weather. The flood events have a significant impact on the infrastructure and populations residing in coastal lowlands. Studies on lagoon sediments have recently revealed important information about the past extreme hydrological events as well as their relationship with past climate changes. This study aims to reconstruct the historical extreme flood-event record using sediment cores taken from the El Bibane coastal lagoon, southeast of Tunisia. Three sediment cores BL12–5, BL12–7 and BL12–10 were studied. Through a combination of analytical techniques such as the chronological, geochemical and sedimentological analyses, past flash floods were identified. Results display that the sedimentological signature of the paleoflood levels recognized within the lagoonal sequence is characterized by high values of the elemental ratios (Ti/Ca and Fe/Ca) and high content of fine material such as clay and silt. These floods are thought to have occurred as a result of intense precipitation that increased the terrigenous input to the El Bibane lagoon by the Fessi River. Chronologies of 210Pb, 137Cs, and 14C have been used to calculate the age of these floods. The records offer a good temporal correlation with historical floods recorded in the central Mediterranean region. In the southeast of Tunisia, periods with more frequent floods coincide with periods generally under alternation of wetter and drier conditions and minima of solar activity. The paleoflood record of the El Bibane lagoon can help researchers better understand the physical mechanisms responsible for changes in the intensity and/or frequency of extreme events in the south of Tunisia. Our research proves that the proxies utilized here have a lot of potential for reconstructing past floods, which is important knowledge for future flood prediction and mitigation in southeast Tunisia.

In the present study, iron-pillared clay was prepared using ferrous nitrate Fe(NO3)3. The removal of Reactive Blue (RB4) dye by ultrasound-assisted sorption onto the synthesized pillared Tunisian clay in aqueous solutions was studied. The natural and modified clay samples were characterized using XRD, FTIR TEM, and nitrogen adsorption measurement methods. Mineralogical data show that smectites are the main minerals of clay samples. FTIR spectra indicate that the stretching vibration bands of the structural hydroxyl groups are broad after treatments. A new band appears at 1570 cm−1, after the sorption of RB4 dye, attributed to aromatic C = C stretching vibration, which suggests the adsorption of RB4. A remarkable decrease was detected in the BET surface after sono-adsorption indicating that the sites of modified clay are almost occupied by the dye. The maximum Reactive Blue 4 quantity was removed at pH 8. Meanwhile, more active Fe–C surface sites were available for both adsorption and sono-adsorption with increasing RB4 concentration, thereby increasing the removal efficiency. Monolayer adsorption capacity via the sono-assisted method also showed a high removal amount of 46.51 mg/g. Langmuir’s model describes the experimental data better than Freundlich’s. A comparative study confirmed that RB4 sono-adsorption by a Tunisian clay sample was higher than others used in other relevant studies, highlighting that these clay deposits may be applied to the dyes’ elimination from wastewaters.

Continental carbonates constitute an interesting topic of study since they are important archives recording climate and paleoenvironmental changes. In Tunisia, calcretes are formed during the Pliocene-early Pleistocene (Villafranchian). They mainly occur in the center and on the coastal plain of Djeffara (Southern East) while their presence is more sporadic in the North of the country. Continental carbonates may form in the soil, groundwater, and palustrine and lacustrine environments. Four criteria are used to differentiate these different environments: host rock, components and micromorphological texture, subaerial exposure (seasonality), and flora and fauna. The purpose of this study is to investigate the palaeoenvironmental significance of Tunisian calcretes for the Plio-Pleistocene. For this aim, well-developed carbonate beds were studied along a north-south transect that crosses the climatic boundaries between the latitudes 33 ° and 37 ° N: North (N36º.43.713 E10º.06.681’) Center (N35º.07.077 'E10º. 14.545 ') and South (N33º.28.898' E10º.20.597 '). Based on the macroscopic, petrographic, and cathodoluminescence observations in association with scanning electron microscopy results, we classified thin sections extracted from the massive horizons in all sites into 8 facies types: The Northern site is characterized by 1) pisolithic calcretes and 2) laminar calcretes showing several beta microfabrics such as rhizolith, peloids, intraclasts, coated grains, bioclast debris, cracks, alveolar septal, spherulite, and organic matter. Moreover, 3) pseudo microkarst carbonates were detected in Northern Tunisia by the presence of vertical layers, peloids, intraclasts, circum crack grain, pedotubules, and rhizoconcretions, and bioclasts. At the central site, 4) laminar calcretes are characterized by planar layers. Both 5) massive brecciated calcretes and 6) mottled nodular brecciated calcretes are distinguished by the abundance of cracks. All these facies types’ shows similar pedogenic components such as peloids, coated grains, gastropod shell, alveolar septal, ooids, and bioclasts. The southern site is characterized on the one hand by 7) laminar calcretes composed of peloids, nodules, coated grains, cracks, and on the other hand by 8) groundwater nodules showing a massive aspect with alpha microfabrics. In all sites, the nodular horizons are pedogenic. Thus, our Plio-early Pleistocene calcretes formed in three main depositional environments: pedogenic, groundwater, and palustrine. The groundwater calcretes are formed under phreatic conditions while the Tunisian pedogenic calcretes and palustrine carbonates exhibit subaerial exposure characteristics (cracks). Except for southern groundwater calcretes, all other types of carbonates show biogenic traces. The palustrine carbonates developed above lacustrine mud. Whereas, pedogenic and groundwater calcretes, develop on different types of host rocks (siliceous and clayey). The difference between fabrics indicates that during the Pliocene-early Pleistocene calcrete form in the north in palustrine settings while it forms in groundwater context in the south. Furthermore, the transition between the different environments is controlled mainly by variation in the water table suggesting a variable but generally more humid climate during the Plio-Pleistocene in North Africa.

The Tunisian coast has been affected in the past by many events of extreme marine submersion (storms and tsunamis). A high-resolution study along two sediment cores taken from the lagoon of Ghar El Meleh was performed to identify the different paleoextreme events and to reconstruct the paleoenvironmental changes in the northeastern part of Tunisia during the Late Holocene. A very high-resolution sedimentological analysis (granulometric and geochemical) was applied to these cores. These cores were also dated with isotopic techniques (137Cs, 210Pbex, 14C), and the outcomes reveal five phases of paleoenvironmental changes in this lagoonal complex and identify two sediment layers that are in connection with two major historical marine submersion events. The first layer is mentioned as E1 and seems to fit with the great tsunami of 365 cal CE. This event was marked by an increase in the coarse sediment, and it is correlated for the first time with the immersed city of Neapolis in the northern Gulf of Hammamet discovered in 2017 by the same tsunamis of 365 cal CE. The other sandy layer, referred to as E2, was dated from 1690 to 1760 cal CE and is marked by one specific sedimentological layer attributed to a marine submersion event. This layer could be associated with the 1693 tsunami event in southern Italy or an increase in extreme storm events.

We generated high-resolution biochronological records in the Mediterranean Sea covering the period extending to the Late-glacial. The present study is based on micropaleontological, sea-surface temperature (SST) and oxygen isotopic analyses performed along three well-dated deep-sea cores: REC1353, KET80–19 and MD84–641 recovered in the Siculo-Tunisian Strait, Tyrrhenian Sea and Levantine Basin, respectively. The quantitative distributional patterns of planktic foraminifera permitted to identify seven biozones based on the apparition and/or disappearance of the main specific taxa or by their noticeable abundance peaks. Abundance records display that major changes in planktic foraminiferal assemblages have a similar pattern mainly in central and western basins. In particular, four recognized bio-events can be used to establish or to improve the chronology of Mediterranean deep-sea cores. The comparison of the SST estimates and foraminiferal records with those of NGRIP ice-core shows a similarity between the Greenland climate and the Mediterranean hydrology. This indicates that the main climate changes recorded in the North Atlantic are globally in phase with those observed in the Mediterranean region.

For a low cost and efficient oxidation process of industrial textile dye, this investigation described an economic process for the Indigo Carmine (IC) dye degradation from aqueous solution. Our study used a novel natural carbonated concretion catalyst, aragonite, which was collected from the thermal station waste located in El Hamma, Southwestern Tunisia, as an advanced oxidation process. This new studied ferrous sample Fe-rich aragonite (Fe–Ar) was characterized using various techniques, such as X-ray diffraction (XRD), Specific Surface Area (BET) and Infrared Spectroscopy (FTIR). The textural, structural and chemical characterizations confirmed the presence of Aragonite phases with a high amount of iron (almost 30%) on the surface material. The new catalyst activity was evaluated in the oxidation of IC dye in an aqueous solution by Fenton and photo-Fenton process. The test results show that the Fe-rich aragonite exhibited higher photocatalytic oxidation activity at pH 3. In addition, the IC dye could effectively be removed from the aqueous solution by photo-Fenton process in the existence of the used material as catalyst. Based on this work, the importance of this material in the purification of industrial effluents loaded with dyes is confirmed proving that this material can replace a very expensive commercial catalyst materials used in fenton and photo-Fenton technologies.

A clay sample (ANJ) was selected from the upper Eocene deposits at Ain Jeloula (Kairouan, Tunisia). This clay sample was activated for environmental applications by treating it with hydrochloric acid (HCl) to improve its physicochemical properties. Several parameters, including the acid concentration (1–5 N), time in contact with the acid (1–6 h), and the activation temperature (40–90 °C), were adjusted to achieve the maximum specific surface area of the activated clay. Physicochemical characterization of both the untreated and optimally activated materials was performed. XRD analysis showed that the optimally activated clay (denoted ANJact; clay treated with 3 N HCl for 4 h at 70 °C) was dominated by smectite phases. This ANJact had a specific surface area of 125 m2/g. Various amounts (0.25–2 g in 100 mL oil) of ANJact were then used to decolorize (remove the pigment present in) sunflower oil. The decolorization obtained using ANJact was compared to those achieved with a commercial clay material (Tonsil, Clariant, Germany; specific surface area of 147 m2/g). ANJact and the commercial clay were found to produce similar levels of sunflower oil decolorization (87%). These results indicate that activated clay from the Ain Jeloula deposit can be used to treat oils; there may also be other environmental applications of this activated clay, such as the removal of metals and dyes from wastewaters.

Abstract. The Tunisian coast has been affected in the past by many events of extreme marine submersion (storms and tsunamis). A high-resolution study along two sediment cores GEM3 and GEM4 taken from the lagoon of the Ghar el Melh was performed to identify the different paleo-extreme events and to reconstruct the paleo-environmental changes of the North-eastern part of Tunisia during the Late Holocene. A very high-resolution of analysis (sedimentological, granulometric, and geochemical) was applied on these cores. These cores were also dated with isotopic techniques (137Cs, 210Pbex, 14C) and the outcomes reveal fives phases of paleoenvironmental changes of this lagoonal complex. The first phase dated from −275 to 200 Cal AD characterized by a high percentage of Silt and Clay (fine particles) indicating a protected lagoon. The second phase synchronous with the Dark Age Climatic Period dated from 200 to 1100 Cal AD, is marked by an increase in the coarse sediment and could be explained by a weakening of the sandy barrier due to an increase of storm events. The third phase is characterized by a return to a closed lagoon during the Medieval Warm Period (from 1100 to 1690 Cal AD). The fourth phase dated from 1690 to 1760 Cal AD coincide with the Little Ice Age and is marked by one specific sedimentological layer attributed to a marine submersion event. This layer could be associated to the 1693 tsunami event in southern Italy or an increase of extreme storm events. The fifth phase covering the last 250 years present a reclosing of the lagoon.

Despite the numerous studies on geomaterials in Tunisia, quite a few clay varieties are not yet well defined. In fact no detailed geological, mineralogical, or geochemical characterizations of Tunisian palygorskite deposits have been carried out to date. The purpose of the present work was to study the continental Eocene clay deposit at the southern end of the Tunisian North axis, between Jebel Rheouis and Jebel Boudinar, to determine its potential as a clay reserve. Nine samples were collected from the Cherahil formation representing the lower, middle, and upper levels. The analytical results obtained using several techniques (chemical analysis, X-ray diffraction, specific surface area measurements, Fourier-Transform infrared spectroscopy, scanning electron microscopy) revealed that palygorskite is the dominant clay mineral. Dolomite and quartz are present as associated minerals. Chemical analysis of sample AR9 showed a smaller potassium content compared to other samples. Sample AR9 consists essentially of dolomite associated with palygorskite and quartz. Other samples (AR5, AR6, and AR7) collected from the same Cherahil formation contained palygorskite as the main phyllosilicate mineral (80%). The important reserve of palygorskite was found in the middle of the Cherahil formation. Dolomite and quartz associated with palygorskite reduced the length and crystallinity of the fibrous clay morphology. Analysis by scanning electron microscopy proved that the crystallinity of palygorskite was less in the lower and upper parts of the Cherahil formation. The central palygorskite deposit may be of interest for pharmaceutical (adsorbent drug) and other applications. The two other levels of Cherahil formation are mineralogically heterogeneous and considered economically less important than the middle level, which is rich in palygorskite.

The high-Mg calcite skeleton of Corallium rubrum was analyzed from living colonies collected from a wide range of depths (15 m to 607 m) and environmental settings in the Mediterranean Sea. An overarching goal was to better understand the calcification process and incorporation of elements into the slow-growing skeleton of both shallow and deep-water specimens, and more specifically, to clarify the veracity of geochemical proxies for reconstructing seawater temperatures. The coral internal structure including growth bands were determined by scanning electronic microscopy (SEM) and petrographic techniques. Trace elements (Li, B, Mg, Sr and Ba) compositions of the coral skeleton were obtained by solution and laser ablation inductively coupled plasma mass spectrometry (ICP-MS). Results show that the skeleton of the deep-water specimens has an internal microstructure similar to shallow-water colonies, with the medullar and the annular zones clearly distinguishable in both shallow and deep-water specimens. In general, the bands of the deep-water samples are very thin and equidistant compared to the irregular banding of the shallow-water specimens. Banding differences relate to the contrasting environmental dynamics, with the shallow-water specimens being exposed to large seasonal fluctuations compared to the relative stable conditions of those inhabiting bathyal depths. The inner medullar and outer annular portions differ in their trace element concentrations: Mg/Ca, Sr/Ca and Li/Ca ratios are higher in the medullar zone and seem to be influenced by growth kinetics, whereas B/Ca and Ba/Ca are similar in both zones and hence unaffected by growth rate. The variability of elemental ratios is lower in the deep-water specimens. Growth bands are highly correlated to Mg/Ca, Sr/Ca and Li/Ca, suggesting common mechanism(s) controlling the incorporation of these elements into the coral skeleton. Mg/Ca ratios were especially depleted in the dark bands. Although the mean Mg/Ca of each specimen is positively correlated to ambient seawater temperature, the infra-annual variations and amplitudes differ and do not correlate to the band widths. These findings suggest that infra- and inter-annual variations of Mg/Ca cannot be used to reconstruct a continuous time-series of long-term seasonal temperature records. However, the mean Mg/Ca composition can serve as a valuable proxy to estimate mean palaeoseawater temperature at a given site within the Mediterranean.

Benthic foraminiferal assemblages and geochemical tracers (δ 18 O, δ 13 C and 14 C) have been analyzed on benthic and planktonic foraminifera from core MD77‐176, located in the northern Bay of Bengal, in order to reconstruct the evolution of intermediate circulation in the northern Indian Ocean since the last glaciation. Results indicate that during the Last Glacial Maximum (LGM), Southern Sourced Water masses were dominant at the core site. A high relative abundance of intermediate and deep infaunal species during the LGM reflects low oxygen concentration and/or mesotropic to eutrophic deep water conditions, associated with depleted benthic δ 13 C values. During the Holocene, benthic foraminiferal assemblages indicate an oligotropic to mesotrophic environment with well‐ventilated bottom water conditions compared with LGM. Higher values for benthic foraminifera δ 13 C and B‐P 14 C age offsets suggest an increased contribution of North Atlantic Deep Water to the northern Bay of Bengal during the Late Holocene compared to the LGM. Millennial‐scale events punctuated the last deglaciation, with a shift in the δ 13 C and the ɛ Nd values coincident with low B‐P 14 C age offsets, providing strong evidence for an increased contribution of Antarctic Intermediate Water at the studied site. This was associated with enhanced upwelling in the Southern Ocean, reflecting a strong sea‐atmospheric CO 2 exchange through Southern Ocean ventilation during the last deglaciation.

Studies of surface pollen samples have been widely used in Europe to assess the relationships between pollen composition and vegetation (Davis et al. 2013). However, such studies in the southern Mediterranean borderlands are rare, in particular in Tunisia. Before reconstructing the vegetation and climate variability over the past millennia from sedimentary archives from the lagoon Ghar el Melh, we have performed pollen analysis from surface samples to evaluate the representation of the northeastern Tunisian vegetation in pollen spectra.