Benthic Foraminifera Assemblages Research Articles

Recent shallow-water benthic foraminifera from a tropical estuary, SW Nigeria

This paper presents a comprehensive survey of benthic foraminifera from shallow waters of the Apapa-Badagry Creek estuary in southwestern Nigeria. Sediments of the Apapa-Badagry Creek, an important estuary surrounded by sprawling estates and industrial parks, yielded diverse assemblages of benthic foraminifera with a total of eighty-eight species. They include hyaline-perforate taxa which dominated the inner western sites around the Lagos Harbor in the Apapa Creek with Ammonia aoteana, A. tepida, A. convexa, Ammonia sp. 1, Ammonia sp. 2. Agglutinated taxa are well established in the westernmost areas in the Badagry Creek, where there is seamless fresh-water mixing, with high populations of Ammotium salsum and few occurrences of Milliamina fusca and Ammobaculites species. The miliolids, represented mainly by species of Quinqueloculina, occupy sample stations in the Commodore Channel which flourish under conditions of marine and tidal influences. Cribroelphidium mirum, Pararotalia sarmientoi, Bolivina striatula and Rosalina species are also found within the Commodore Channel sediments. Our study widely extends and completes previous studies from the tropical eastern Atlantic, especially within the Gulf of Guinea and provides new information on the distribution, diversity, and species richness of shallow-water benthic foraminifera fringing the Atlantic coast of Africa.

Linosa island: a unique heritage of Mediterranean biodiversity

ABSTRACT This publication presents a newly created map of the seafloor of Linosa, a volcanic island located in the Sicily Channel (Mediterranean Sea). The seafloor of Linosa was previously surveyed using geophysical and ground-truth data (in 2016 and 2017). Linosa is regarded as a "sentinel area" for alien species and worldwide environmental changes because of its geographical location, making it worthy of particular attention. The predominant habitats found in Linosa have been identified as three priority habitats: Posidonia oceanica meadows, rhodolith beds, and coralligenous habitats, which encompass extensive coral forests. Another crucial environmental indicator is the assemblages of benthic foraminifera, which were previously studied in this area to analyse their correlations with the topography of the seafloor. Hence, all the accessible data was gathered to create a novel comprehensive map of the seabed (at a scale of 1:15,000), with the objective of displaying and highlighting the abundant marine biodiversity of Linosa.

Особенности экологического состава планктонных и бентосных фораминифер в поверхностных осадках Татарского пролива (Японское море)

he fauna of planktonic and benthic foraminifera of the Tatar Strait in the surface layer of sediments from cores sampled during the cruise LV85 on the R/V «Akademik Lavrentiev» in May 2019 has been studied. The benthic foraminifera assemblages, consisting of living and dead shells, correspond in their ecological appearance to the modern cold-water oceanographic conditions of the studied area. Among planktonic foraminifera, along with the dominant subarctic form Neogloboquadrina pachyderma dex., there are single tropical and subtropical species (Globorotalia inflatа, Globigerinoides ruber and Neogloboquadrina dutertrei). The authors believe that the above warm-water forms entered the Tatar Strait from the southwestern part of the Sea of Japan with the warm waters of the Tsushima Current. Fossil finds of warm-water fauna in Pleistocene and Holocene sediments play an important role in deciphering the geological record in the northern part of the Sea of Japan. Their presence in sedimentary sections makes it possible to trace the northward migration of the warm current and assess the extent of its influence on coastal ecosystems in the past.

Microfacies Analysis of the Reefal Limestone, Marah Formation, East Borneo, Indonesia

Miau Baru, Kongbeng in East Borneo is a relatively narrow area with complex geological features. The abundance of larger benthic foraminifera shows diversity in the carbonate succession of the Marah Formation but previously has less attention from microfacies perspective. To achieve the objective in this microfacies analysis of the reefal limestone of Priabonian-Aquitanian. Marah Formation, limestone samples were collected and sectioned. A total of 35 samples were selected, 25 from the Goa Indah section and 10 from the Kongbeng section. The assemblage of larger benthic foraminifera was recorded to help determine the depositional age, and biota of the formation and to interpret the facies zone. Field observation, microfacies type, as well as the fossil content of larger benthic foraminifera and colonial scleractinian corals indicated that the deposition of the Marah Formation in the Miau Baru area probably ranged from open circulation shallow forereef to backreef shelf.

Long-term carbon sequestration in the Eocene of the Levant Basin through transport of organic carbon from nearshore to deep marine environments

This study addresses a specific component associated with mass transport complexes in marine systems: the role of hyperpycnal flows, dense shelf water cascading, submarine canyons, distributary channels, and other transport mechanisms in transferring organic matter from continental and shallow marine settings into deep-marine environments. We speculate that during the Eocene, allowing for only 0.1‰ of shelf carbon to be preserved through transport mechanisms would account for up to 13.7% of all organic carbon burial. As such, the potential to mobilize through this mechanism large quantities of organic carbon is significant.Our case study focuses on a 150 m Eocene sequence composed of organic-rich chalks interleaved with displaced neritic limestones. TOC values range between 1.5 and 14%, averaging 4.5%. Displaced limestones are composed of a variety of poorly cemented mud- and wackestones, with low-diversity assemblages of large benthic foraminifera associated with planktonic foraminifera, suggesting deposition under low-energy conditions within the oligophotic zone on the outer ramp. Transport overprints include soft-sediment deformation, partially lithified rip-ups, folds, small diapirs, bed-scale imbrication, brecciation and syn-sedimentary shear. These features indicate detachment, movement and emplacement following initial sedimentation, in some cases more than once. Emplacement occurs into a chalk facies that can vary in appearance from darker (higher TOC) and lighter (lower TOC) lithofacies.Combination between the sedimentological, petrophysical, and elemental analyses indicates shifts between autochthonous and allochthonous sedimentation, whereas the organic geochemical analysis reveals a correlation between modes of sedimentation and preservation/composition of organic matter. Organic richness seems to increase within intervals of allochthonous sedimentation, with lower TOC values within intervals of autochthonous sedimentation. Organic matter preservation is enhanced due to poor oxygenation of the sea floor, further depleted by rapid burial beneath mass-transport deposits, increasing sedimentation rates and thus organic matter preservation. Horizons rich in organic matter may be derived from three different sources: organic matter with a fingerprint of terrestrial sources (e.g., enhanced contribution of plant leaf waxes) transported from nearshore environments; an allochthonous marine fingerprint with sulfurized hopanoids, which seem to be reworked from pre-existing Cretaceous organic-rich carbonates entrained within fined-grained micro-turbidites in the para-autochthonous facies; and productivity-derived organic matter deposited on the seafloor of the deep marine environment.This study demonstrates how transport mechanisms allow for the long-term burial of organic carbon in marine systems. When taking into consideration similar processes reported to occur in the world oceans today, it is clear that sediment transport and long-term burial of organic carbon is a fundamental part of the global carbon cycle.

Paleocene–Eocene boundary in the Gabal El-Gir, east Qena, Egypt: Paleoenvironment and sequence stratigraphy interpretations

Comprehensive field, litho-, biostratigraphy, and paleoenvironmental studies of the upper Paleocene–lower Eocene (P–E) boundary interval in the Gabal El-Gir area were conducted. Two selected sections El-Gir-1 and El-Gir-2 were investigated. The prevailed paleoenvironmental conditions were discussed in the frame of the nannofossils, planktonic, and benthic foraminiferal assemblages. Benthic foraminifera assemblages indicate a remarkable turnover across the PETM. The extinction of Angulogavelinella avnimelechi at the base of the PETM represents a significant marker for the base of the benthic foraminifera extinction event at this site and other neritic sites in the Tethyan region. The dominance of calcareous planktonic excursion taxa at the base of the PETM indicates adaptation to extremely warm sea surface temperatures and low nutrient levels. Also, our data suggests that the biotic responses to environmental change in the early Eocene resembled those observed in the early Eocene hyperthermals at the nearbay Dababiya and El-Ballas sections. This could indicate that similar processes characterized the Egyptian sedimentary basin during the early Eocene. Stratigraphically, despite the limited distance between the studied sections, the Dababiya Quarry Member (DQM) in El-Gir-1 resemble those of the Global Stratotype Section and Point (GSSP) but reduced in thickness. While in El-Gir-2, the lower part of the DQM was missing. These findings could indicate that the DQM was deposited in a submarine channel. Three third-order depositional sequences were recognized covering the P–E interval. The reconstructed sea level curve shows the presence of eustatic similarities with the global sea level.

The Reticulinella?-Mangashtia foraminiferal association: Characterisation of the (upper?) middle-?lower upper Turonian interval in the Sarvak Formation of SW Iran and its bearing upon Upper Cretaceous Arabian Plate sequence stratigraphy

During the mid-Cretaceous the Arabian Plate underwent a major tectonically-driven stratigraphic reorganization, with the development of a major regional unconformity, often ascribed to the middle Turonian. However, evidence for the age calibration of this unconformity (e.g., from biostratigraphy) is limited. A previously undescribed assemblage of larger benthic foraminifera has been discovered in a section at Khormuj in the Coastal Fars region of the Iranian Zagros. This section lies in the uppermost Sarvak Formation, directly beneath the major unconformity surface. Dominant components of the assemblage are Mangashtia viennoti Henson, and Reticulinella? kaeveri Cherchi, Radoičić and Schroeder. Their presence places the uppermost Sarvak Formation at this locality in the age range (upper?) middle – ?lower upper Turonian, and in the context of evidence from other localities in the region it is most likely upper middle Turonian. This provides new constraint on the timing of the unconformity and stratigraphic organisation, and the tectonic events leading to its creation (e.g., forebulge creation related to ophiolite obduction). The presence of R.? kaeveri is reported for the first time from outside of the Mediterranean region and indicates that this taxon is useful for biostratigraphic calibration. As a result, biozonation schemes for the upper Sarvak Formation can be updated.

Dinoflagellate cysts and benthic foraminifera from surface sediments of Svalbard fjords and shelves as paleoenvironmental indicators

Due to the Arctic amplification effect, the Svalbard archipelago is an important area for studying ongoing environmental changes. However, its marine ecosystem is extremely complex. In this study, we analyze modern assemblages of dinoflagellate cysts (dinocysts) and benthic foraminifera from surface sediment samples around Svalbard. We use multivariate statistical analyses to examine relationships between environmental conditions (summer and winter sea surface temperature and salinity, sea-ice cover, etc.) and both microfossil groups to evaluate their use as proxies for reconstructions of the marine environment in the region. Our results show that the most important factor controlling the environment around Svalbard is the Atlantic Water which mostly impacts the western coast, but its influence reaches as far as the eastern coast of Nordaustlandet. However, on a local scale, such factors as the sea-ice cover, the presence of tidewater glaciers, or even the morphology and hydrology of fjords become increasingly important. We found that two dinocyst species, cysts of Polarella glacialis and Echinidinium karaense, can be considered regional winter drift ice indicators. The relationships between environmental parameters and benthic foraminiferal assemblages are much more difficult to interpret. Although statistical analysis shows a correlation of benthic foraminiferal species with various environmental parameters, this correlation might be somewhat coincidental and caused by other factors not analyzed in this study. Nevertheless, the use of two complementary microfossil groups as (paleo)environmental indicators can provide a more comprehensive picture of the environmental conditions.

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.

Sub-surface foraminifera distribution and preservation in short core samples from the Strait of Malacca

Abstract
 The Strait of Malacca—a shallow and hyposaline strait—is one of the busiest shipping routes in the world. It divides Sumatra and Peninsular Malaysia. This study assessed the sub- surface distribution of benthic foraminifera, their preservation, and their relationship with the sediment characteristics of the Strait of Malacca. One short sediment core sample was collected from the southern part of the Strait of Malacca. The core was then divided into 10 subsamples at every 2 cm interval. The samples were used for foraminifera identification and grain size and organic matter analysis. From the approximately 3000 benthic foraminifera that were selected and identified, 17 species exhibited ≥ 2% occurrence in at least one subsample along the core. Out of the 17 species identified, 4 species (Asterorotalia pulchella (57%), Cavarotalia annectens (13%), Discorbinella bertheloti (7%), and Pseudorotalia schoerteriana (6%)) exhibited an average relative abundance of >5% in all core intervals. Cluster analysis subdivided the core intervals into two groups: BF1 and BF2. Both the groups were dominated by A. pulchella. The PCA biplot indicated that BF1, which represented the upper sub-surface intervals, had relatively more agglutinated species than BF2. Despite being common in surface samples along the Strait of Malacca, species such as Textularia sp. were absent further down the core. This study indicated that in the sub-surface sediment of the Strait of Malacca, calcareous hyaline species, especially those belonging to Rotaliida, were abundant and readily preserved compared to the agglutinated or calcareous porcelaneous groups. The loss of several agglutinated groups down the cores indicated that a more discreet approach to paleoenvironmental interpretation using benthic foraminifera assemblages should be adopted in this region to avoid bias in the interpretation.

Holocene environmental evolution and relative sea-level change in the Oka estuary (Urdaibai Biosphere Reserve, northern Spain)

The Holocene environmental evolution in coastal areas, including deltas and estuaries, is vital to understanding coastal dynamics and how they may change in the future. Here, we studied the Holocene environmental evolution of the Oka estuary (Urdaibai Biosphere Reserve, northern Spain) from sedimentary cores that were 11–49 m long. We applied a multi-proxy approach of benthic foraminifera and grain size, and a temporal framework of radiocarbon dates to reconstruct paleoenvironments. The benthic foraminifera assemblages varied from near-marine (allochthonous and autochthonous hyaline species such as Lobatula lobatula, Rosalina irregularis, Ammonia tepida and Haynesina germanica) to brackish intertidal (autochthonous hyaline species such as A. tepida and H. germanica) to salt-marsh (autochthonous agglutinated species Trochammina inflata and Entzia macrescens) environments. Grain size analysis supported the foraminiferal assemblages and the sedimentary sequences were sand-dominated in near-marine intertidal environments and mud-dominated in the brackish intertidal and salt-marsh environments. The chronology was constrained by thirty four radiocarbon dates from plant macrofossils, marine shells and wood fragments. Our paleoenvironmental reconstructions were used to produce an updated local Holocene relative sea-level (RSL) record based on new data, revised reconstructions, and age recalibration of previous research. Marine limiting dates showed that RSL changed from above −20.4 ± 0.2 m at ∼9100 cal. yrs. BP to above −4.2 ± 0.2 m at ∼6700 cal. yrs. BP. In the late Holocene, sea-level index points (SLIPs) reconstructed the RSL position from −2.7 ± 1.2 m at ∼4900 cal. yrs. BP to −1.4 ± 1.2 m at ∼1500 cal. yrs. BP. Estimates of rates of RSL change from the Errors-in-Variables Integrated Gaussian Process (EIV-IGP) model show RSL gradually rose at 0.3 ± 2.1 mm yr−1 in the late Holocene. There was a progressive shallowing of the estuary as rates of RSL rise reduced during the Holocene. Between ∼9000 and 7000-6000 cal. yrs. BP pre-Holocene fluvial gravels (Lowstand Systems Tract) were replaced by both sandy marine and brackish intertidal sediments (Transgressive Systems Tract). After ∼7000-6000 cal. yrs. BP salt-marsh sediments deposited (Highstand Systems Tract). The sequence was overlain by anthropogenic deposits derived from agricultural, dredging and dumping activities since the 18th century (Anthropogenic Systems Tract). The Holocene environmental evolution and relative sea-level change of Oka is broadly consistent with previous studies in northern Spain, although it places the onset of the Highstand Systems Tract ∼2000 years earlier.

Paleoenvironments and stratigraphy of the Valanginian–Hauterivian carbonates of the Arabian Platform: Implications for the recognition of the Weissert Event on the Southern Tethys

On the Arabian Platform, the Valanginian Weissert Event is associated with the sudden drowning of a major north-easterly prograding carbonate platform located on the southern margin of the Tethys Ocean. This was associated with a sharp back-stepping of the main facies belts to the south-west, bringing shallow marine carbonates into the previously restricted platform top. Integrated detailed facies analysis, biostratigraphy (including nannofossil and palynology) and carbon isotopes have been used to reconstruct the evolution of the carbonate shelf during the Valanginian–Hauterivian in Saudi Arabia. During the early Valanginian the study area was dominated by the deposition of dolomitized clay-prone microbial intertidal mudstones, which passed basinwards into low-energy inner ramp limestones. These facies encompass the initial stage of a 3rd order transgressive trend above the regional Lower Valanginian Unconformity. They are sharply overlain by Lithocodium/Bacinella-dominated floatstones, indicating the maximum flooding of the platform during the late Valanginian. These deposits systematically increase in thickness and abundance towards the platform margin and are associated with a broad positive excursion in δ13C (c.+2‰ V-PDB), corresponding to the Weissert Event. The presence of abundant Lithocodium/Bacinella in strata deposited during the major flooding of the platform is consistent with higher nutrient levels and increased upwelling during the late Valanginian. The Valanginian–Hauterivian boundary is marked by a regional unconformity identified through palynology and benthic foraminifera assemblages, and locally confirmed by carbon isotopes. The combination of carbon isotope data with detailed palynology and micropaleontology provided a stratigraphic resolution in line with ammonite biozones published in the western Tethys. The Valanginian–Hauterivian continental palynoflora, described for the first time on the Arabian Platform, is dominated by primitive conifer pollen such as Classopollis suggesting a rather arid climate in agreement with published reconstructions. In addition, the occurrence of various fern and bryophyte spores suggests an increase in humidity along coastline areas, associated with higher continental input into inner ramp settings, therefore affecting the carbonate factory.

Seasonal variability of modern benthic foraminifera assemblages in a mangrove ecosystem from northeast coastal Bay of Bengal

Benthic foraminifera assemblages, nutrient dynamics of surface and porewater from 10 intertidal sites spanning over two years (2019–2020) covering two major estuaries in Sundarbans mangrove were evaluated to understand role of seasonal precipitation and primary production (driven by eddy nutrients) with a focus on standing crop. Benthic foraminifera abundance ranged between 280 individuals/10 cc in pre-monsoon (2019), 415 individuals/10 cc in post-monsoon 2019 and 630 individuals/10 cc in post-monsoon (2020). Standing crop was highest in post-monsoon coinciding with eddy nutrients driven stoichiometry and increase in abundance of large diatom cells. Calcareous and agglutinated foraminifer taxa Ammonia sp.1, Quinqueloculina seminulum, Entzia macrescens and Textularia sp. respectively were frequent. Entzia macrescens was found in dense mangrove vegetation sites; exhibited strong relationship with sediment texture and pore water total organic carbon. One of the major findings is mangroves with pneumatophores improves oxygen availability in sediment and leads to an increase in standing crop.

PSEUDOCYCLAMMINA SARVAKENSIS SP. NOV. AND PSEUDOTEXTULARIELLA BREVICAMERATA SP. NOV.: FURTHER EVIDENCE FOR THE CENOMANIAN MEGADIVERSITY OF LARGER BENTHIC FORAMINIFERA FROM THE SARVAK FORMATION OF SW IRAN

The carbonate succession of the Cenomanian-Turonian Sarvak Formation SW Iran, Zagros Zone contains a diverse assemblage of (larger) benthic foraminifera, such as alveolinids, orbitolinids and others. Two new taxa are described herein as Pseudocyclammina sarvakensis sp. nov. and Pseudotextulariella brevicamerata sp. nov. They are generally not frequently observed (likely biased through a stratigraphic or facies control) as other most common taxa found in the Sarvak Fm. They are herein reported from the Tang-e Darbast (type-locality of both species) and Shahneshin surface sections, and also from the Arman well-1 subsurface section, Fars area and Abadan Plain, respectively in the parts referred to the middle Cenomanian. The Tang-e Darbast section also represents the type-locality of Iraqia ultima Yazdi-Moghadam & Schlagintweit and Simplorabanitina simplex Consorti, Schlagintweit & Yazdi-Moghadam. Pseudocyclammina sarvakensis and Pseudotextulariella brevicamerata are further elements of the so-called ‘Nezzazata-alveolinid’ assemblage zone.

The influence of submarine canyons-related processes on recent benthic foraminiferal distribution, Espírito Santo Basin, Southeastern Brazil

The complex topography of submarine canyons may result in different composition of benthic foraminifera assemblages. To understand how trophic, hydrological and sedimentological conditions in submarine canyons can influence the distribution of benthic foraminifera, and to use this information to corroborate paleoenvironmental interpretations for the Holocene, we investigated recent benthic foraminiferal assemblages (total fauna >63 μm) and sedimentological data in two canyons (CANWN and CAND) in the Espírito Santo Basin (ESB) between 18°20′ and 21°20′ S. Surface sediment samples (0–2 cm) were collected inside the canyons (150 to 1300 m water depth) and in shelf-slope adjacent transects (50 to 1300 m water depth). The density, taxonomic diversity, and assemblage composition of benthic foraminifera change with depth and location. The distinct ecological preferences of the most abundant taxa allowed us to recognize five benthic foraminiferal groups. Three groups (V, III, and I) are present in different bathymetric sectors; Group V: outer shelf (50 m), Group III: upper, and middle – lower slope (150 to 400 m), and Group I: middle – lower slope (1000 to 1300 m). Groups II and IV show no characteristic bathymetric distribution and are present only in CAND and in CANWN, respectively. Group V consists of Hanzawaia boueana, Peneroplis planatus, and Quinqueloculina lamarckiana; Group III is dominated by Globocassidulina rossensis and Trifarina spp.; Group I consists of Globocassidulina crassa, Bolivina lowmani, Gavelinopsis versiformis, Alabaminella weddellensis, and Epistominella exigua. The main species in Group II (CAND, 150, 1000 to 1300 m) are Trifarina angulosa, Globocassidulina subglobosa, and Discorbis vilardeboanus. Group IV (middle – lower CANWN, 1000 to 1300 m), consists mainly of agglutinated species Glomospira charoides, Rhabdammina abyssorum, and Psammosphaera fusca. Our data suggest that the quantity (and quality) of food supply, hydrodynamic conditions and sediment properties are the main drivers controlling the bathymetric distribution of benthic foraminiferal assemblages in both canyons. The middle – lower CANNW revealed unstable trophic conditions, related to terrigenous sediment input due to turbidity currents. In CAND, the foraminiferal assemblages ecology indicated sufficient organic matter supply that favors species establishment and diversity, indicating a more productive and less unstable environment than in CANWN.

Microfaunal Recording of Recent Environmental Changes in the Herschel Basin, Western Arctic Ocean

ABSTRACTMicrofaunal assemblages of benthic foraminifera, ostracods, and tintinnids from two marine sediment cores retrieved from the Herschel Basin of the Canadian Beaufort Sea shelf document relationships with environmental parameters such as salinity, sea-ice cover, and turbulence. Cores YC18-HB-GC01 and PG2303-1 were collected at 18 and 32 m water depth, respectively. At these sites, sediment accumulation rates range between 0.6 and 1.7 cm yr–1 allowing a near-annual temporal resolution over the last 50 years. Multivariate analyses indicate that benthic foraminiferal assemblages respond primarily to food supply. Dissimilarities between the microfaunal assemblages of the two cores are mainly the result of bottom water salinity levels linked to water depth. High abundance of the benthic foraminiferal species Elphidium clavatum and occurrences of Elphidium bartletti point to varying, but relatively low, salinities at the shallow core site YC18-HB-GC01, which may be affected by variations in the summer halocline depth. Higher species diversity and more abundant Cassidulina reniforme and Stainforthia feylingi characterize the deeper core PG2303-1, which might reflect more stable conditions and higher bottom-water salinities throughout the studied time interval. The most important microfaunal shift of the last 50 years, observed in the shallower longer core YC18-HB-GC01, occurred at the turn of the 21st century. Prior to ∼2000 CE, the presence of Islandiella norcrossi indicates more stable and saline conditions. Since ∼2000 CE, increased abundances of Haynesina nivea and of the ciliate Tintinnopsis fimbriata suggest decreased salinity and increased turbidity. An increased abundance of Eoeponidella pulchella after ∼2000 CE suggests a concurrent increase in productivity in the last two decades. This shift is nearly synchronous with a decrease in mean summer sea-ice concentration, which can play an important role in bottom water stability on the shelf. Easterly winds can induce a reduction in the sea-ice cover, but also foster a westward spreading of the Mackenzie River plume and the upwelling of nutrient-rich Pacific waters onto the shelf. Both factors would explain the increased freshening and productivity of the Herschel Basin. The last two decades were also marked by a decrease in ostracod abundance that may relate to higher water turbidity. This study shows that combining information from benthic foraminifera, ostracods, and tintinnids provides a comprehensive insight into recent hydrographic/climatic changes in nearshore Arctic habitats, where productivity is critical for the food security of local communities.

Middle Eocene (Lutetian-Bartonian) larger benthic foraminifera assemblages from Batman and Siirt (Southern Neotethys, SE Turkey): a new assessment

The benthic foraminifera assemblage has been described in the limestones outcropped in Kurtalan and Eruh district of Hoya formation which is one of autochthonous units of Arabian Platform (SE Turkey). From the two measured sections, one of them has rare fossil content due to dolomitization (DH-Dodan section),while the other is fairly remarkable in terms of fossil content (EH-Eruh section). The foraminiferal assemblages are represented by Asterigerina rotula (Kaufmann), Operculina ex. gr. gomezi Colom and Bauza, Victoriella conoidea Rutten, Amphistegina sp., Elphidium sp., Peneroplis sp., Carpenteria sp., Stomatorbina sp., miliolid and rotaliid forms and echinoderms, coral fragments in the Dodan section. The foraminiferal assemblages are represented by Nummulites biedai Schaub, Nummulites maximus d’Archiac, Nummulites perforatus de Montfort, Nummulites postfossulatus Sirel and Deveciler, Nummulites praeaturicus Schaub, Assilina exponens (Sowerby), Sphaerogypsina globulus (Reuss), Asterigerina rotula (Kaufmann), Lockhartia cf. hunti Ovey, Neoratlia sp., Operculina sp., Discocyclina sp., Asterocyclina sp., Lockhartia sp., Lenticulina sp., miliolid-rotaliid forms and echinoderms in the Eruh section. The fossil assemblage described shows that the limestones are of Lutetian-Bartonian and this assemblage indicates a very shallow marine deposition environment. This study provides biostratigraphic and stratigraphic data that help to reassess the Eocene geological evolution of the region. Paleobiogeographically, larger benthic foraminiferal assemblages recorded on carbonate platforms in southeastern Turkey show an affinity to Arabian and Middle Eastern platforms.

Interpretation of paleoenvironment using benthic foraminifera from Tertiary rocks, northern Sarawak

In this work, we collected and examined three samples from an exposed 50 cm thick fossiliferous bed and prepared thin and polished sections for petrographic analysis. The benthic foraminifera assemblages and other marine fossils are studied to infer the paleo depositional environment. Based on the benthic foraminifera and their common ecological preferences, it is inferred that this layer has deposited between the intertidal and neritic zones, and within the photic zone, they are under oxygenated conditions. In addition, the presence of the glauconite mineral also supported the neritic environment interpretation, suggesting a water depth of less than 300 metres during the deposition, denoting shallow water conditions. Even though the results presented in this paper are at an elementary level, this could serve as additional information to develop a better understanding of the geology on a much larger scale.

Larger benthic foraminifera and biostratigraphy of the lower Oligocene Asmari Formation: offshore and onshore southern Iran (Zagros belt)

A relatively diverse assemblage of larger benthic foraminifera from the Asmari Formation is described based on the recovered samples from two subsurface sections, offshore and onshore, southern Iran. Due to its position in the Tethyan Seaway between the Mediterranean and Indo-Pacific, the Zagros belt as a part of theMiddle East has high significance in palaeobiogeography. The fauna is dominated by both hyaline perforated and porcelaneous forms. Eight species of larger benthic foraminifera are described, including Nummulites fichteli, N. vascus, Operculina complanata, Archaias operculiniformis, Praerhapydionina delicata, Austrotrillina striata, Peneroplis thomasi, and P. evolutus. The presence of N. fichteli and N. vascus in the absence of lepidocyclinids indicates the SBZ 21 Zone referring to a short time span restricted to early Rupelian.

Middle Triassic calcareous algae and microproblematica from south China

The Yangtze carbonate platform (Southern China) recorded a long sedimentary evolution from Neoproterozoic to the basal Upper Triassic. During the Early and Middle Triassic, this platform was dominated by shallow-water carbonates. In various sectors of the platform, the Middle Triassic (Anisian-Ladinian) succession contain abundant assemblages of benthic foraminifera and calcareous algae. Following a previous paper about the Middle Triassic dasycladalean algae from SW Guizhou Province, the present study describes algae and microproblematic organisms from three sections: Honyan, Longtou and Guanling. Some dasycladalean algae are well known from the Alpine-Dinaric domain: Diplopora annulatissima, D. annulata, Euteutloporella triasina, Macroporella dinarica, Oligoporella minutula, O. pilosa pilosa, Poncetella hexaster and Pseudodiplopora proba. However, the dasycladalean association is dominated by species belonging to the genus Kantia, including K. cf. dolomitica and K. cf. comelicana. New Kantia species (K. intusannulata n. sp., K. granieri n. sp., K. muxinanii n. sp.) are characterized by the presence of intusannulation, a feature unknown from the Kantia species in the Alpine domain. The dasycladalean association also contains new species of the genus Mizzia and specimens belonging to the organo-genus Acicularia and/or Terquemella. Besides, rare specimens of "Solenopora" and Rivularia-type cyanobacteria are also present. The algal association is accompanied by microproblematic organisms including Tubiphytes sp., Zorniella obscura, Plexoramea cerebriformis, Ladinella porata, and Baccanella floriformis. Anisian-Ladinian foraminifera complete the micropaleontological spectrum of the sections studied. The most important are Meandrospira dinarica, Endotriadella wirzi, Paleolituonella meridionalis, and Turriglomina mesotriasica. The microfossils from the Middle Triassic Yangtze carbonate platform of south China belong to the Eastern Tethys province. Some of these species are also present in the Western Tethys (Alpine Domain). The new species presented in this study are absent from the Alpine Domain and probably represent endemic species for the Eastern Tethys.