Benthic Foraminifera Research Articles

Benthic foraminifera as environmental indicators in the lagoon and mangrove environments of Langkawi, Malaysia

Benthic foraminifera are single-celled protists that are highly abundant in marine and marginal environments. They have been successfully used in several monitoring studies elucidating the status of environmental health conditions. The present study examines the foraminiferal distribution in the surface sediments of the Sungai Kilim, within the Kilim Geoforest Park, in Pulau Langkawi, Malaysia. Information provided by benthic foraminifera were associated with geochemical properties, sediment types, and current speed data to characterize the environment. Twenty-eight genera of benthic foraminifera were identified from the surface samples. Elphidium spp. (relative abundance of 13–83%) were the most abundant genus in the mangrove and lagoon environments along the Sungai Kilim. Salinity, water depth, and temperature were the important parameters that determined the foraminiferal distribution. Test abnormalities were observed in Elphidium spp. (<10% of tests) at several stations; a higher quantity of abnormal tests (5–6%) were observed at stations with high current speeds, especially in mangrove areas. The sediment in the study areas did not show severe heavy metal contamination; therefore, the low diversity and test abnormalities were associated with natural stress from environmental conditions. This information provides a baseline for future environmental monitoring to preserve the Sungai Kilim and the Kilim Geoforest Park.

Marine nitrogen cycling dynamics under altering redox conditions: Insights from deposition of sapropels S1 and the ambiguous S2 in the Eastern Mediterranean Sea

The eastern Mediterranean Sea (EMS) sedimentary record is periodically interspersed with organic-rich ‘sapropel’ layers. Sapropels are characteristic of basin-wide anoxic events, triggered by precession-forced insolation maxima. Relatively subdued insolation maxima, however, are not always expressed as distinct sapropel events. The EMS sedimentary record is thus useful to investigate feedbacks between marine anoxia and the nitrogen (N) cycle and offers an analogue for modern deoxygenation and past oceanic anoxic events. To this end, we investigated a ∼68 kyr sedimentary record from the EMS containing the well-established sapropel S1 (deposited in two phases: S1a [∼10.5–8.5 ka BP] and S1b [∼7.8–6.1 ka BP]) and sediments timed to the ambiguous S2 sapropel (∼53 ka BP). We used lipid biomarkers of microorganisms to reconstruct key N-cycle components: (1) anaerobic ammonium oxidation (anammox) using ladderanes and a stereoisomer of bacteriohopanetetrol (BHT-x), (2) dinitrogen gas (N2) fixation using heterocyte glycolipids, and (3) nitrification by Thaumarchaeota using crenarchaeol. Additionally, benthic foraminifera and trace metals (U, Mo, Mn) were used to reconstruct redox conditions. During S1a, abundances of Thaumarchaeota increased, likely promoted by elevated high-nutrient freshwater discharge. At this time, a combination of phosphorus supply and intensified loss of bioavailable N via water column anammox, may have reinforced anoxia by favoring diatom-diazotroph associations. During S1b, anammox is equally intense. Yet, no positive feedback on N2-fixation is observed, likely because diazotrophs were phosphorus limited. Instead, anammox may have provided negative feedback on anoxia by quenching primary production. Ladderanes suggest additional episodes of anammox between ∼69 to 39 cal ka BP, corresponding to brief periods of water column deoxygenation. Anoxia likely occurred at the sediment–water interface in S2-timed sediments (53–51 cal ka BP). During these episodes, ladderanes co-occur with the later eluting BHT-34R stereoisomer. δ13CBHT-34R indicate an anammox source, potentially synthesized by marine sedimentary anammox bacteria. No corresponding increase in diatom-diazotroph associations is observed, likely due to the oligotrophic conditions and the limited effect of sedimentary anammox on N-availability in the euphotic zone. Our results highlight various modes of operation of the N-cycle at different degrees of deoxygenation, which depend amongst others on nutrient-availability and the niche-segregation of N-loss and N2-fixating microorganisms.

Biostratigraphy and Chronostratigraphy of Late Jurassic – Early Cretaceous in Selected Areas in Kurdistan Region, Northern Iraq

The biostratigraphy and chronostratigraphy of Late Jurassic–Early Cretaceous (Tithonian–Aptian) successions at three outcrops in the Kurdistan Region, northern and northeastern Iraq (Amadia, Gara, and Barsarin sections) are studied depending on ammonite, planktic, and benthic foraminiferal contents. The studied formations: Chia Gara, Sarmord, and Qamchuqa, are recorded in all studied localities, while Garagu and Balambo formations are exposed at some studied localities. Age determination of the Chia Gara Formation relied on the ammonite fauna. The ammonites investigated are the major assemblage fauna of the Durangites Zone, which corresponds to the Late Tithonian. The detailed planktic foraminiferal investigation in Balambo Formation permits the recognition of five well-defined zones, these are Favusella hoterivica Interval Zone, Hedbergella sigali Interval Zone, Globigerinelloides ferreolensis Interval Zone, Globigerinelloides blowi Interval Zone, and Globigerinelloides algeriana Taxon Range Zone (part), which reveal a Late Valanginian to Late Aptian age. The stratigraphic distribution of the benthic foraminifera shows three zones, these are Everticyclammina kelleri Assemblage Zone, Pseudocyclammina lituus Assemblage Zone, and Palorbitolina lenticularis Taxon Range Zone, the 1st and 2nd zones were recognized in the Sarmord Formation at Amadia section, which extends in age from late Valanginian to Hauterivian. While the 3rd zone is recorded from Qamchuqa Formation at the Gara section representing the Early Aptian age.

Evaluation of radioactive properties and microfaunal evidence in the Bosphorus and the Dardanelles straits and Golden Horn sediments

The aim of this study is to investigate radioactive pollutants from pollution loads transported from the Black Sea to the Aegean Sea by the Turkish Straits System and their effects on microfauna (benthic foraminifer and ostracod) assemblages. In the study, the effects of gross alpha and beta activity on the species number, species diversity, dominant species and species richness of benthic foraminiferal and ostracod assemblages were investigated in 16 bottom sediments taken from different depths in the Golden Horn, Bosphorus and Dardanelles straits. In the studied sediment samples examined 61 genera and 64 species of benthic foraminifera, 23 genera and 26 species of ostracoda were identified. In addition two migratory foraminifera species were observed as Spiroloculina antillarum of Atlantic-Pacific origin and Peneroplis pertusus of Indo-Pacific origin. A relationship between the abundance of microfauna and high gross alpha and beta values was found in the Dardanelles samples, but not in the Bosphorus and Golden Horn samples. In this study, the highest radioactivity value was observed in the deepest bottom sediment samples. Consequently, the gross alpha and beta values were seen to be close to each other in the Dardanelles Strait and Golden Horn samples, and they had a broad-spectrum in the Bosphorus samples.

Last interglacial seasonal hydroclimate in the North Sea–Baltic Sea region

The Last Interglacial (LIG) experienced substantial changes in seasonal insolation compared with the present day, which may have affected the hydrography and water-mass exchange in the North Sea and Baltic Sea region. Here we investigate the effects of solar radiation and greenhouse gas (GHG) forcing on the regional climate by analyzing model simulations of the LIG (127 ka BP), pre-industrial (PI, 1850 CE), and present-day (PD, 1990 CE) climates. We also interpret the reconstructed seasonal bottom water conditions using benthic foraminifera and geochemistry data.Our simulations reveal that during the LIG, the Baltic Sea region (including the Kattegat and the Danish Straits) experienced more saline and colder bottom waters than those in the PD, in agreement with the reconstruction data. This can be attributed to lower GHG levels and enhanced water exchange of cooler, saline North Sea water into the Baltic Sea during the LIG. The thermocline was stronger during the summer months in the LIG, mainly due to the higher sea surface temperature (SST) compared to that of the PD resulting from increased summer insolation.Further, the temperature anomalies (LIG–PD) show significant inverse correlations with the precipitation–minus–evaporation (P–E) at the Baltic Sea entrance. However, the P–E balance appears to have had minimal impact on salinity changes in the North Sea, the Baltic Proper, and the open sea area. Our findings indicate that monthly surface and bottom water salinity anomalies of LIG-PI exhibit strong positive correlations with the North Atlantic Oscillation (NAO) anomalies in the Baltic entrance region. During the LIG, a more positive phase of the NAO index in autumn played a crucial role in wind-driven major inflows and led to more intensive water exchange in the North Sea–Baltic Sea region compared to the late Holocene.

Benthic foraminifera as bioindicators of coral reef health

Benthic foraminifera as bioindicators of coral reef health

Graphical methods comparing living and dead assemblages, exemplified with benthic foraminifera from the Aveiro Lagoon, Portugal

This work introduces graphical methods documenting density, diversity (species richness combined with heterogeneity) and similarity in combined diagrams for estimating the influence of environmental and taphonomic factors in living (LAs) and dead (DAs) assemblages. In this paper, the diagrams compare: 1) densities per 1 g of sediment expressed in cubic squares; 2) diversities based on rarefaction species richness (x-axis) and Shannon H rarefaction (y-axis), both extended to infinity by the logistic Hull equation, and 3) similarity diagrams based on cosine measures (x-axis) and Spearman correlation coefficients (y-axis). Diagrams were exemplified for LAs and DAs found at 53 stations along channels and intertidal areas of the Aveiro Lagoon (Portugal). Eight ‘routes’ characterized by different trends in the distribution of the analyzed biotic parameters were recognized in six regions of the Aveiro Lagoon: ‘port area’, ‘central lagoon’, ‘northeast lagoon’, ‘northern and southern extremities of the lagoon’ and ‘city area’. In addition, Detrended Correspondence Analyses (DCA) based on diversity diagrams were performed to show the influence of environmental parameters, especially grain size, salinity, and pH, on the average species composition in each route. The comparative diagrams allow deduction about the impact of parameters that simultaneously affect LAs and DAs, such as hydrodynamics, post-mortem tests dissolution, physicochemical parameters, excessive contribution of organic matter, oxygen depletion, and pollution by metals. Based on these diagrams, the most favorable environments due to the most remarkable development and diversity of LAs and DAs are located in protected coves of the Aveiro Lagoon mouth.

Distribution of recent Benthic foraminifera in Kongsfjorden and Krossfjorden; North-West Svalbard, High Arctic

Benthic foraminifera assemblages from two fjords of Svalbard—Kongsfjorden and Krossfjorden in the High Arctic—have been studied. The foraminifera assemblages show three characteristic assemblages from the two fjords’ glacial proximal, middle and distal parts. The Cassidulina reniforme– Elphidium clavatum, Textularia spp. assemblage dominates the foraminifera fauna near the glacier proximal that indicates increased sedimentation and meltwater runoff; a Nonionellina labradorica– Islandiella helenae– Lobatula lobatula assemblage relates to well-oxygenated and high energy conditions and mainly occupies the middle part; and the Nonionellina labradorica– Islandiella helenae assemblages dominate in the distal region that indicates high surface primary productivity. Krossfjorden contains an oxygen deficiency zone around the middle part characterised by Stainforthia loeblichi. The abundance of Islandiella helenae and Nonionellina labradorica indicates that the high surface primary productivity of Krossfjorden is more than that of Kongsfjorden.

Stagnant North Atlantic Deep Water Heat Uptake With Reduced Atlantic Meridional Overturning Circulation During the Last Deglaciation

AbstractAtlantic Meridional Overturning Circulation (AMOC) plays a major role in the climate system by modulating the depth and rate of oceanic heat storage. Some climate simulations suggest that reduced AMOC decreases bottom water ventilation and that the heat absorbed by the ocean starts to mix downwards, warming Atlantic intermediate waters. This has been corroborated for the western North Atlantic by benthic foraminifera geochemical records from periods of reduced AMOC during the last deglaciation. However, the deep‐water response remains poorly constrained, and the lack of direct paleotemperature reconstructions limits our understanding about the effects of reduced circulation on ocean heat uptake. We present a new reconstruction of bottom water temperatures from core GeoB9508‐5 (2,384 m water depth, 15°29.90°N/17°56.88°W) off the northwestern African Margin. Our paleotemperature record, based on Uvigerina spp. Mg/Ca, shows two episodes of intense transient deep water warming in times of decreasing overturning circulation, followed by long periods of heat uptake stagnation. First, during AMOC slowdown in the Heinrich stadial 1, when paleotemperatures of ∼2°C persisted for ∼5.4 Kyr coincident with the weakest stage of AMOC; and second in the Younger Dryas, when bottom water temperatures &gt;4°C lasted ∼2.5 Kyr during a less intense AMOC decline. This suggests a stagnation of deep‐water heat uptake in the deep NE Atlantic possibly linked to a reduced downward advection of heat during times of a reduced AMOC, supporting the hypothesis that AMOC strength sets the depth of oceanic heat storage in the North Atlantic.

The Heliconoides Modified Dissolution Index-HMDI: Do methane seepage environments affect the preservation state of Heliconoides inflatus?

Pteropods are holoplanktonic molluscs presently endangered because their fragile aragonitic shell is very sensitive to ocean acidification. The preservation of pteropods, and in particular of the mesopelagic Heliconoides (Limacina) inflatus, has been used to assess aragonite saturation state in Quaternary sediments (Limacina Dissolution Index, LDX) as an inferred proxy for climatic changes.Three deep-sea cores retrieved in 2016 during the EUROFLEETS2 SEMSEEP cruise offshore Israel are investigated to assess the preservation degree of H. inflatus (d'Orbigny, 1835) in representative environments across the base of the southeastern Mediterranean margin (cold water coral, active seepage pockmark and deep sea channel areas). In some core intervals, yellowish, recrystallized internal molds of this species are present. They have been previously observed in the Eastern Mediterranean, but the nature and origin of their colour was never explained. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Electron Backscatter Diffraction (EBSD) revealed that the recrystallized molds of the H. inflatus shells are formed by aragonite needles and high-Mg calcite crystals. The formation and preservation of these internal molds is induced by advective methane emissions, typically precipitating aragonite and High-Mg calcite phases close to the sediment–water interface. These molds were never used in previous applications of the LDX or in any existing ranking of pteropod preservation. Therefore, we have categorized these peculiar features combining previous pteropod ranking descriptions with the new observations to develop a modified biotic index (Heliconoides Modified Dissolution Index-HMDI).High values of the HMDI at the base of the pockmark core correspond to the interval where also active seepage-related features – e.g., bubble emissions, low-oxygen benthic foraminifera, chemosymbiotic molluscs, small fragments of authigenic carbonate crusts and slightly depleted δ13C values – occur, showing the applicability of the HMDI to methane seeps environments.

Paleoclimate and Paleoenvironment Reconstructions from Middle Eocene Successions at Beni-Suef, Egypt: Foraminiferal Assemblages and Geochemical Approaches

The Eocene deposits of Egypt provide a wide variety of shallow marine facies and fossil assemblages, allowing paleoenvironmental reconstructions in this warmhouse climate interval. Forty-three rock samples have been collected from two middle Eocene sections, exposed at southeast Beni-Suef area in northern Egypt. The studied outcrops are lithologicsally subdivided into two rock units named from base to top as follows: (1) the Qarara Formation (Lutetian) and (2) the El Fashn Formation (Bartonian). Most investigated rock samples showed richness in benthic foraminiferal assemblages and only rare occurrences of index planktonic foraminifera. They yielded 160 foraminifera species which belong to 4 suborders, 19 superfamilies, 34 families, and 59 genera. The stratigraphic distribution of the identified species allowed us to define four local benthic bio-ecozones: (1) Bolivina carinata Lowest Occurrence Zone (Lutetian), (2) Cibicides mabahethi/Cancris auriculus primitivus Concurrent-Range Zone, (3) Nonion scaphum Lowest Occurrence Zone, and (4) Brizalina cookei/Nonionella insecta Concurrent-Range Zone (Bartonian). These biozones are described and discussed in detail and correlated to stratigraphic equivalents in Egypt. The rareness of index planktonic foraminifera through the studied sections does not allow a precise biostratigraphic and chronostratigraphic correlation. The shale samples show low TOC values, which may be related to low productivity, high sediment influx, and/or prevailing oxic conditions. Bulk rock geochemistry, consistent with the benthic foraminifera ecological preferences, indicated that the studied sections were deposited in moderate to high oxygen levels and warm climatic conditions in a typical shelf marine setting. The identified species showed strong similarities with nearby southern Tethys areas, reflecting migration via the trans-Sahara seaway, and minor similarities with those identified from the northwestern Tethys and the North Atlantic province attributed to the change in the environmental and climatic conditions, such as cooler, latitudinal zoned climatic conditions along the northwestern Tethys, which was unsuitable for their biological demands. The warming trend identified from Lutetian to Bartonian intervals corresponds to the onset of the Middle Eocene Climatic Optimum (MECO).

Aptian–Albian shallow-marine carbonate successions of the Geyik Dağı and the Anamas Dağ areas (Central Taurides, Turkey): Benthic foraminiferal assemblages and “Palaeocornuloculina” taurica nov. sp. (Foraminifera)

The Lower Cretaceous carbonate successions of the Tauride Carbonate Platform(s) (TCP) are characterized by mostly restricted inner platform facies. The record of these stages is limited owing to frequent exposure of the platform to subaerial and supratidal settings during the Early Cretaceous. This study focuses on the Lower Cretaceous (Aptian–Albian) successions outcropping at two localities in the Geyik Dağı and Anamas Dağ areas, Central Taurides. These successions exhibit a peritidal shallowing upward trend evidenced by the dominance of mud-rich microfacies, lamination, fenestrae, oncoids, and changes in fossil content (benthic foraminifera, dasycladalean algae, rudists, etc.). The stratigraphic subdivisions of the studied successions utilize index taxa in the benthic foraminiferal assemblages which are documented and illustrated. Assemblage I (lower Aptian) is mainly characterized by Voloshinoides murgensis and Debarina hahounerensis; Assemblage II (upper Aptian) by Mesorbitolina parva, Carseyella tunesiana and “Arenobulimina” geyikensis; and Assemblage III (Albian) by Mesorbitolina gr. texana, Protochrysalidina elongata and Pseudonummoloculina heimi. Ranges and stratigraphic significance of some species through the Lower Cretaceous are discussed. Due to less favorable environmental conditions, the strata in the Anamas Dağ area have a low-diversity benthic foraminifera fauna and sparse macrofossils. In contrast, the strata in the Geyik Dağı area host rich and diverse larger benthic foraminifera as well as rudist bivalves and gastropods. A new species, “Palaeocornuloculina” taurica belonging to the family Ophthalmidiidae is described from these foraminifera-rich upper Aptian–Albian strata in the Geyik Dağı area.

Fossil Benthic Foraminifera in the Nakdong River Delta (Southeast Korea) and off Fukuoka (Southwestern Japan) during the Early Holocene –Responses of the Neritic Faunas Under the Holocene Rapid Sea-Level Rise–

We studied fossil benthic foraminifera in three and seven sediment cores from the Nakdong River delta and of off Fukuoka, respectively, to assess sedimentation along the coasts of the strait between Korea and Japan during the early Holocene. Fossil benthic foraminifera in coarse-grained deposits/sandy sediments from ∼9.4–9.3 ka in cores ND-01 and KND-3 of the Nakdong River delta are characterized by a mixture of shallow-water and offshore species. These data suggest the development of transgressive deposits at ∼9.4–9.3 ka, likely associated with sea-level rise driven by the rapid retreat of glaciers at high latitudes (e.g. Laurentide Ice Sheet). Off Fukuoka, two clusters represent high-energy conditions characterized by common occurrences of attached benthic foraminifera; these clusters became dominant in the upper parts of our study intervals. Such attached species occurred commonly earlier, at around 10 ka, at deep offshore sites (> 60 m water depth) relative to shallow sites (< 60 m water depth). These findings are consistent with the development of current-dominated deposits at deep offshore sites at around 10 ka. Transgressive deposits in the Nakdong River delta and abundant attached species off Fukuoka at around 9 ka likely resulted from sea-level rise along the coasts of the strait between Korea and Japan driven by intermittent enhancement of the Tsushima Warm Current.

The change in metabolic activity of a large benthic foraminifera as a function of light supply

We studied metabolic activity of the symbiont-bearing large benthic foraminifer Heterostegina depressa under different light conditions. Besides the overall photosynthetic performance of the photosymbionts estimated by means of variable fluorescence, the isotope uptake (13C and 15N) of the specimens (= holobionts) was measured. Heterostegina depressa was either incubated in darkness over a period of 15 days or exposed to an 16:8 h light:dark cycle mimicking natural light conditions. We found photosynthetic performance to be highly related to light supply. The photosymbionts, however, survived prolonged darkness and could be reactivated after 15 days of darkness. The same pattern was found in the isotope uptake of the holobionts. Based on these results, we propose that 13C-carbonate and 15N-nitrate assimilation is mainly controlled by the photosymbionts, whereas 15N-ammonium and 13C-glucose utilization is regulated by both, the symbiont and the host cells.

The Middle-Upper Eocene benthic foraminifera from north-west Fayoum area, Egypt: Paleoecology and their similarity to the Tethyan provinces

This study deals with the Middle–Late Eocene benthic foraminiferal assemblage from the Um Rigl succession that is exposed in the northwest of Fayoum area, Egypt. Stratigraphically, two rock units are recognized from base to top as the Gehannam Formation and Birket Qarun Formation. The examination of benthic foraminiferal community identifies 63 species belonging to 36 genera, 22 families and four suborders. Their distribution aids to recognize one benthic foraminiferal biozone, Bulimina jacksonensis-Uvegerina jacksonensis Zone. To detect the paleocological conditions that prevailed during the deposition of the studied succession, a quantitative analysis is done on the foraminiferal assemblage, including the number of taxa, the relative abundances of the recorded suborders, calcareous species, agglutinated species and common species. The morphology of benthic foraminiferal tests is strongly associated with their microhabitat preferences. Therefore, the percentages of epifaunal and infaunal species are also calculated to detect the level of oxygenation. Accordingly, two ecozones are established, ecozone 1 represents the Gehannam Formation, whereas ecozone 2 represents the Birket Qarun Formation (excluding the barren zone in the upper part). Ecozone 1 is dominated by calcareous species (90–100%) and infaunal species (38–99%), while epifaunal species range from 2 to 62%. The most abundant taxa are Bolivina, Bulimina, Uvigerina, Nonion and Lenticulina. Therefore, the ecozone 1 was deposited under an inner-outer neritic environment, with normal salinity and eutrophic to mesotrophic conditions. On the other side, ecozone 2 is characterized by changes in the composition of foraminiferal assemblage, where infaunal species dominate the base of this ecozone, followed by a strong decline in the middle part and then increase again in the upper part. Also, a notable increase in epifaunal species is documented in this ecozone. This variation in foraminiferal assemblage reflects changes in water depth and oxygen content. Consequently, ecozone 2 was deposited under an inner to middle neritic environment, with normal salinity and mesotrophic to oligotrophic conditions. Regarding the paleobiogeographic outline, the results of multivariate analyses indicate that the Egyptian species show a strong similarity to those from the Southern Tethyan Province (Tunisia and Libya), whereas they show a reasonable similarity to the Western Tethyan Province (Spain, Italy, France). This deduction reflects a probable marine connection between both provinces during Eocene.

The Eocene carbonate platforms of the Ghomaride Domain (Internal Rif Zone, N Morocco): a segment of the westernmost Tethys

The Eocene platform deposits in the Moroccan Ghomarides have been studied. These marine carbonate platforms were located in the westernmost Tethys approximately 30°N and 0°–10°W during the Cuisian to Bartonian. The study includes observations from fossiliferous assemblages (such as larger benthic foraminifera and colonial corals), their palaeoenvironment as well as rock texture and fabric. Eight microfacies were identified that represent different ramp environments in a ‘distally-steepened carbonate ramp’ type of platform. The studied deposits are organised into a transgressive succession composed of three sedimentary cycles: lower Cuisian, middle Cuisian and middle Lutetian to Bartonian. In the lower cycle, photic inner to mid ramp environments in mesotrophic conditions were prevalent. In the second cycle, photic inner ramp (sea-grass) to mid ramp environments in mesotrophic to oligotrophic conditions were observed. The upper cycle, which is more extensive and variable, represents mesophotic mid ramp to aphotic slope environments and changes gradually from oligotrophic to eutrophic conditions. During the Eocene, larger benthic foraminifera were dominant overtaking the zooxanthellate corals in the Tethys regions. Nevertheless, our study and the performed comparison with other Tethyan sectors have revealed that in some areas both coexisted in similar proportions. In some western Tethys regions close to the Atlantic Ocean, coinciding with areas influenced by upwelling currents, larger benthic foraminifera and coral build-ups were replaced by oyster reefs. The Ghomaride Domain represents an intermediate case between fossil assemblages of the northern Tethyan margin and eastern sector of the southern margin of the Tethys, with a dominance of larger benthic foraminifera but with a certain presence of corals as well. A good correlation exists between Eocene warm intervals and carbonate platform deposits in these domains. Contrarily, during cooling ones shallowing and gaps in the sedimentation are registered. Two anomalies have been detected in the Ghomaride Domain during Ypresian and Bartonian times indicating particular climatic conditions or local tectonic interferences.

Recent Deep-Sea Benthic Foraminifera from an Active Volcanic Area: First Insights around Nishinoshima, Northwest Pacific

Recent Deep-Sea Benthic Foraminifera from an Active Volcanic Area: First Insights around Nishinoshima, Northwest Pacific

Early Oligocene gravity-flow deposits at the base of the Meiji Reef system in the South China Sea, and their palaeoclimate significance

In this paper, we describe gravity flow facies that form the base of the Meiji Reef system in the South China Sea, and discuss their palaeoclimate significance. These Early Oligocene (26.1–23.5 Myr) deposits occur in Well NK1 and comprise a 110.6 m thick succession developed on top of volcanic basement. The deposits can be divided into two intervals, both of which are dominated by debris flow facies. The lower 17.6 m thick interval has a gravel content of 50–65% with parent rocks including dacite, basalt, tuff, and coral reef fragments. From base to top, these units coarsen upward and show increasing gravel contents. Gravel clasts are well-rounded but poorly sorted (diameter 10–350 mm), which, together with their complex composition, indicate transportation by the gravity flows from the near-shore volcanic rock basement to the slope. The upper 93 m thick interval comprises abundant bioclastic materials, including benthic foraminifera, crustal red algae, and red algae detritus, with a few volcanic gravel clasts. The content of volcanic rock gravels decreases towards the top, which may be attributed to the reduction or disappearance of volcanic rocks in the provenance area due to the establishment of coral reef facies that cap the succession and dominate the overlying interval from a core depth of 885.6 m to the seafloor. Based on U-Pb dating, the cap-shaped red algae laminae at the facies transition were formed at 24.6 ± 1.1 Ma, dating the earliest initiation of reef building to end-Oligocene times. The emergence of gravity flow sediments during the early Oligocene may be attributed to the onset of the Antarctic glaciation and concurrent regional tectonic activities that led to a shallowing of the sea. The origin of debris with high roundness characteristics is believed to be associated with transportation along the slope triggered by tectonic and climatic events, resulting in the formation of debris flow deposits. Studying the gravity flow facies at the Meiji Reef system is crucial for determining the onset of reef-building and helps establish the relationship between gravity flow deposition, paleoclimate, and regional tectonic evolution in the South China Sea.

Benthic foraminifera as bioindicators for the heavy metals in the severely polluted Hurghada Bay, Red Sea coast, Egypt

Twenty-nine sediment samples were collected from the Hurghada Bay, a heavily polluted bay on the Red Sea of Egypt, to inspect the environmental quality status and anthropogenic consequences on benthic foraminifera. Some foraminiferal species showed deformations in their apertures and coiling directions as a response to environmental stresses. In addition, the FoRAM index, an index used for evaluating the growth of coral reefs, indicated a hazard in the proximity of nearshore stations. To elucidate the relationships between the biological response and chemistry of sediments, eight heavy metals concentrations (Cu, Cd, Zn, Pb, As, Cr, Ni, and Mn) were analyzed using inductively coupled plasma–atomic emission spectrometers (ICP-AES). Interestingly, two groups of benthic foraminiferal associations were illustrated using multivariate statistical analyses. Group I have extremely high heavy metal concentrations, an enriched total organic matter (TOM)%, high deformation percentages, and mud content. Moreover, it is dominated by Ammonia tepida which is regarded as an opportunistic species. Group II includes low to moderately polluted stations, highly enriched living foraminiferal assemblages, and is dominated by the sensitive rotaliids Neorotalia calcar and Amphistegina lobifera. Alternatively, four geochemical indices, EF, CF, Igeo, and PLI, are used to assess the contamination level that shown ominous spots for the nearshore stations of the Hurghada Bay. The pollution indices (HQ and HI) were also conducted to evaluate the risks of carcinogenic heavy metals on human health. Our findings demonstrated that ingestion and dermal exposure have greater carcinogenic hazards for adults and children than inhalation. The lifetime carcinogenic risk (LCR) is significantly higher than the permissible limit and follows this order: Pb > As > Cr > Cd > Ni. To that end, developing strategies to lessen the negative impact of pollution on human health and/or the Red Sea’s biodiversity is an inevitable issue in the present day and future.

Gelasian to Calabrian (Early Pleistocene) marine ostracods and foraminifera from Mida Section (Cap Bon, Tunisia) Les ostracodes et les foraminifères marins du Gélasien au Calabrien (Pléistocène inférieur) de la coupe de Mida (Cap Bon, Tunisie)

We report for the first time a rich and well-preserved marine ostracod and foraminifera association from lower Pleistocene fossiliferous sandstones of the Mida Section (Cap Bon, NE Tunisia).Micropalaeontological analysis of nine samples taken along an eight-meter exposure revealed 46 ostracod species belonging to 34 genera, 15 species of benthic foraminifera belonging to 14 genera and 8 species of planktonic foraminifera belonging to 4 genera. The ostracod association enabled us to draw a palaeoenvironmental reconstruction of this area during the Gelasian to Calabrian time, highlighting a regressive cycle from circalittoral to shallow infralittoral palaeoenvironments. Planktonic foraminifera were used to constrain the age of the section to the end of Gelasian-beginning of Calabrian. Moreover, the discovery of Bythocythere turgida in the lower part of the section allowed to infer that these sandstones were deposited during the early Pleistocene cold periods.