Larger Benthic Foraminifera Research Articles

FIRST RECORD OF UPPER CRETACEOUS (CAMPANIAN?) LARGER BENTHIC FORAMINIFERA FROM THE YIGEZIYA FORMATION OF THE SOUTHWESTERN TARIM BASIN, CHINA

Larger benthic foraminifera are described for the first time from the Upper Cretaceous Yigeziya Formation of the southwestern Tarim Basin, China. They occur in middle-outer ramp carbonates with debris of rudists, coralline algae, echinoids, pithonellids, and rare dasycladalean green algae. The material allows an open taxonomic approach for a few taxa. The assemblage includes Charentia cf. cuvillieri Neumann, Cuneolina cf. parva Henson, Nezzazatinella cf. picardi (Henson), orbitolinid gen. et sp. indet., cyclamminid indet., Tetrataxiella? floriforma Schlagintweit & Sanders, Suturina? sp. and the new species Dictyopselloides? tarimensis n. sp. Lacking any resilient stratigraphic data in our material, a Campanian age is tentatively assumed. The benthic association is typical for Neotethys assemblages but also shows conspicuous overlap with the Campanian Tielongtan Formation of western Tibet.

New age constraints for the upper zongshan Formation: a morphometric study of the late cretaceous orbitoidal foraminifera in Gamba area of southern Xizang (Tibet)

This study refines the biostratigraphic framework of the upper Zongshan Formation in southern Xizang (Tibet) by conducting a meticulous morphometric analysis of larger benthic foraminifera (LBF) from the Gamba area. Focusing on the genera Orbitoides and Omphalocyclus, we employed a comprehensive morphometric approach to delineate the stratigraphic transition within the formation. A total of 42 samples were collected across pivotal lithological intervals, leading to the identification of species groups that provide precise age constraints for the upper Zongshan Formation. Specifically, the O. tissoti–O. media group and Om. anatoliensis within Limestone II to Calcareous Marl II support a late Campanian age, while the presence of the O. megaloformis–O. gruenbachensis group and potential Om. cideensis in Limestone III suggest a younger age bracket extending into the early Maastrichtian. Our findings not only clarify the stratigraphic position of the upper Zongshan Formation but also contribute significantly to the ongoing investigations of final evolutionary stages of the eastern Neotethys.

Evolution of the Late Cretaceous orbitoidal foraminifera and implications for the taxonomy and biostratigraphy in the Eastern Neo-Tethys, Lower Indus Basin, Pakistan: A biometric approach

In the eastern Neo-Tethys realm, the Late Cretaceous larger benthic foraminifera (LBF) Orbitoides and Omphalocyclus are poorly known. Herein, Orbitoides and Omphalocyclus populations from the Fort Munro Formation in Rakhi Nala Section, Lower Indus Basin, Pakistan are investigated. This work documents the most primitive evolutionary stages of these genera in the eastern Neo-Tethys. In Orbitoides, the average values of the size of embryon (Li + li) for the 18 investigated samples range between 477 and 516 µm and the average E values range between 4.2 and 4.7. In Omphalocyclus, the embryons are always trilocular and their sizes range between 112 and 485 μm, with an average between 153 and 287 μm. The E values range between 2 and 3, with an average of 2.3. Based on the average values of E and size of the embryon (Li + li), the populations of Orbitoides and Omphalocyclus have been attributed to the O. media and O. omanensis species, respectively. A late Campanian age is assigned to the Fort Munro Formation based on the recognition of O. media and O. omanensis. The detailed biometric study reveals primitive species of Orbitoides and Omphalocyclus from Pakistan (a part of eastern Neo-Tethys) in the Asian biogeographic province (ASP) during the late Campanian.

Diversity and paleoecological significance of zooxanthellate corals of Oligocene Qom Formation, SE Iran

Zooxanthellate corals are Iran's most abundant macrofossils in the Oligocene-early Miocene Qom Formation deposits in the NE margin of the Tethyan Seaway. Yet, basic knowledge about the diversity of these organisms and their paleoecology is still scarce. This paper uses late Rupelian–Chattian coral data from three exposed sections in the northwestern Jazmurian Lake, SE Iran, as the southeasternmost outcrops of the Qom Formation, are analyzed in terms of diversity and paleoecology. The coralline red algae and larger benthic foraminiferal assemblages associated with the corals have also been used to infer the paleoenvironmental and paleoecological conditions. The following coral genera were recognized: Leptoria, Caulastraea, Hydnophora, Astreopora, Plesiastrea, Thegioastraea, Porites, Goniopora, Platycoenia, Acropora, Tarbellastraea, Favites, Heliastraea, Stylocoenia, Ceratotrochus. The high abundance of z-corals, larger benthic foraminifera (LBF), and coralline red algae demonstrate that the deposition took place in tropical-subtropical warm waters mainly within the euphotic to the mesophotic zones. The presence of various coral fabrics including pillarstone, domestone, and rudstone allowed to infer high to moderate hydrodynamic energy in the studied sections. As well, given the interactions among corals, filter-feeders, green and red algae, bioeroders, and the surrounding environment, it seems that oligotrophic to slightly mesotrophic conditions also had prevailed in the studied area.

EARLY JURASSIC BENTHIC FORAMINIFERAL ECOLOGY FROM THE CENTRAL HIGH ATLAS MOUNTAINS, MOROCCO

Abstract The Central High Atlas Mountains of Morocco have an extensive record of Lower Jurassic deposits from the Tethyan Ocean. In the Amellago region, Ziz Valley, and Dadès Valley several fossilized reef outcrops preserve benthic foraminifera spanning the Pliensbachian and Toarcian stages. This study analyzes benthic foraminiferal assemblage changes across the bi-phased extinctions at the Pliensbachian/Toarcian boundary and the Jenkyns Event (also referred to as the Toarcian Oceanic Anoxic Event). In Pliensbachian samples, assemblages with abundant Glomospira sp., Glomospirella sp., Siphovalvulina sp., Haurania deserta, Placopsilina sp., Mesoendothyra sp., and Everticyclammina praevirguliana are observed. Following both the Pliensbachian/Toarcian boundary event and the Jenkyns Event, benthic foraminiferal density, evenness, and species richness decreased, indicating these communities underwent ecologic stress; however, loss of diversity was most substantial between samples that pre-date and post-date the Jenkyns Event. Whereas the Pliensbachian/Toarcian boundary event coincides with the demise of the large benthic foraminifera Mesoendothyra sp. and Everticyclammina praevirguliana, the Jenkyns Event was detrimental for most clades of benthic foraminifera, including many small, resilient taxa. Based on the evidence provided, we suggest that the Pliensbachian/Toarcian boundary and the Jenkyns Event were distinct events, potentially caused by distinct environmental perturbations.

Distribution of Thanetian-Ilerdian biozones in Lorestan Zone, West of Iran

The Taleh Zang Formation is a carbonate sequence of the late Paleocene–early Eocene age in the Lorestan zone, west of Iran. This Formation overlays siliciclastic rocks of the Amiran Formation and is overlain by red sandstone of the Kashkan Formation. A biostratigraphic scheme, based on the larger benthic foraminifera, is proposed for the Thanetian–Ilerdian deposits in Lorestan Zone. We compare our results with the available data from other parts of Tethys and the zonation of shallow-marine Paleocene–Eocene of Mediterranean Tethys is made. In total, 367 samples were collected from the six sections. From a biochronostratigraphic point of view, three biozones and one indeterminate zone are identified. The zones are shallow benthic zone 3 (early Thanetian), shallow benthic zone 4 (late Thanetian), and shallow benthic zone 6 (early Ilerdian). In the northern part of the Lorestan Zone (Kabutar Bula and Psht-e Jangal sections), the Taleh Zang Formation contains poor fauna. Due to the stratigraphic position, an early Thanetian age can be considered. Our data showed that the late Paleocene and Eocene biozones in Lorestan Zone developed parallel to the axis of the folding, in a northwest-southeast trend. They get younger from the northeast to the southwest. Keywords: biostratigraphy, Eocene, Foraminifera, Lorestan Zone, Paleocene.

Illuminating an uncatalogued micropalaeontological collection at the Lapworth Museum of Geology, University of Birmingham

The Lapworth Museum of Geology (LMoG) at the University of Birmingham (UoB) holds >300,000 specimens, including a sizable micropalaeontology collection. However, ~50% of the total LMoG collection is not digitised (e.g., there is no digital record) and thus inaccessible to external audiences. We contributed to the LMoG’s ongoing digitisation efforts by assessing the curation, historic and scientific significance of an uncatalogued assortment of “large” micropalaeontological specimens. We digitised and curated 219 specimens (comprising 307 parts) made up of hand specimens, containers and vials of loose fossils and sediment, and thin sections. The collection contained organisms from ten different phyla but was dominated by Larger Benthic Foraminifera (LBF). This dominance is reflected in the predominantly low-mid latitude geographic distribution of the collection, reflecting LBFs subtropical ecological preferences. The completeness of specimen metadata varied considerably with generally good geographic, chronostratigraphic, and taxonomic information at higher levels but poorer information with increasing detail and in relation to acquisition. Despite these limitations, we find that the studied collection was primarily assimilated for teaching purposes with donations from UoB staff and other specialist museums, and purchase from commercial dealers. There is little evidence for research on these specimens to date. Future work at the LMoG will digitise the collections and contribute to the ongoing efforts of international bodies to create large, open-access natural history datasets.

Quantitative assessment of reef foraminifera community from metabarcoding data.

Describing living community compositions is essential to monitor ecosystems in a rapidly changing world, but it is challenging to produce fast and accurate depiction of ecosystems due to methodological limitations. Morphological methods provide absolute abundances with limited throughput, whereas metabarcoding provides relative abundances of genes that may not correctly represent living communities from environmental DNA assessed with morphological methods. However, it has the potential to deliver fast descriptions of living communities provided that it is interpreted with validated species-specific calibrations and reference databases. Here, we developed a quantitative approach to retrieve from metabarcoding data the assemblages of living large benthic foraminifera (LBF), photosymbiotic calcifying protists, from Indonesian coral reefs that are under increasing anthropogenic pressure. To depict the diversity, we calculated taxon-specific correction factors to reduce biological biases by comparing surface area, biovolume and calcite volume, and the number of mitochondrial gene copies in seven common LBF species. To validate the approach, we compared calibrated datasets of morphological communities from mock samples with bulk reef sediment; both sample types were metabarcoded. The calibration of the data significantly improved the estimations of genus relative abundance, with a difference of ±5% on average, allowing for comparison of past morphological datasets with future molecular ones. Our results also highlight the application of our quantitative approach to support reef monitoring operations by capturing fine-scale processes, such as seasonal and pollution-driven dynamics, that require high-throughput sampling treatment.

Biogeographical patterns of the porcelaneous larger foraminifer Alveolinella quoyi through the integration of fossil data

In the present-day Indo-Pacific coral-reef settings two genera of alveolinoidean porcelaneous larger benthic foraminifera (LBF) occur, namely Alveolinella and Borelis. Alveolinella is represented by a single species, A. quoyi, whose northernmost record is in Okinawa-jima (central Ryukyu Islands, Japan). Although the Indo-Pacific area, and especially the Coral Triangle, is a biodiversity hotspot since the Early Miocene, in-depth investigation on fossil representatives of present-day LBF is limited to a few taxa. To help bridge this knowledge gap, the palaeobiogeographical dynamics of A. quoyi is assessed. Analysis of data from the palaeontological literature shows that its first appearance datum is from the Tortonian (Late Miocene) of East Kalimantan and Papua New Guinea. In the Pliocene–Pleistocene the Indonesian Throughflow constrained the species within the Central Indo-Pacific. Finally, during the Late Pliocene the northward migrants arrived in the shallow-water carbonate settings of Okinawa-jima where the species is still thriving.

Unraveling ecological signals related to the MECO onset through planktic and benthic foraminiferal records along a mixed carbonate-siliciclastic shallow-water succession

The shallow-water Capo Mortola succession (Liguria, NW Italy) yields diverse assemblages of smaller benthic and planktic foraminifera, larger benthic foraminifera (LBF), and calcareous nannofossils. With the aim of improving the understanding of the Middle Eocene Climatic Optimum (MECO) impact on the shallow-water marine biotic communities due to global warming, we provide biostratigraphic and stable isotope data to achieve a reliable stratigraphic constraint of the MECO. The correlation of the stable isotope oxygen data with datasets of similar age from other regions suggests that only the onset of the MECO interval is recorded in the Capo Mortola section. Quantitative analyses of smaller benthic foraminiferal assemblages indicate that the shallow-water setting of Capo Mortola was not particularly affected by the onset of the MECO perturbance because no variation in nutrient supply or oxygen level were detected. A different scenario is recorded by the LBF genera Operculina and Discocyclina, which increased in abundance across the MECO onset, probably due to a rise in temperature and adapting to the increase in nutrient supply. In the upper water column, the variations in calcareous plankton communities appear to be controlled by both the MECO warming and a moderate increase in eutrophic conditions related to the enhanced hydrological cycle. Nutrients, mostly consumed in the upper water column, reached the seafloor in a limited amount, as benthic foraminifera record a meso-oligotrophic environment across the studied MECO interval.

Effect of micro-plastic particles on coral reef foraminifera

Foraminifera are single-celled protists which are important mediators of the marine carbon cycle. In our study, we explored the potential impact of polystyrene (PS) microplastic particles on two symbiont-bearing large benthic foraminifera species—Heterostegina depressa and Amphistegina lobifera—over a period of three weeks, employing three different approaches: investigating (1) stable isotope (SI) incorporation—via 13C- and 15N-labelled substrates—of the foraminifera to assess their metabolic activity, (2) photosynthetic efficiency of the symbiotic diatoms using imaging PAM fluorometry, and (3) microscopic enumeration of accumulation of PS microplastic particles inside the foraminiferal test. The active feeder A. lobifera incorporated significantly more PS particles inside the cytoplasm than the non-feeding H. depressa, the latter accumulating the beads on the test surface. Photosynthetic area of the symbionts tended to decrease in the presence of microplastic particles in both species, suggesting that the foraminiferal host cells started to digest their diatom symbionts. Compared to the control, the presence of microplastic particles lead to reduced SI uptake in A. lobifera, which indicates inhibition of inorganic carbon and nitrogen assimilation. Competition for particulate food uptake was demonstrated between algae and microplastic particles of similar size. Based on our results, both species seem to be sensitive to microplastic pollution, with non-feeding H. depressa being more strongly affected.

Voloshinoides simplex sp. nov. and Cribellopsis? kharaibensis sp. nov. (Foraminifera): new constraints for Lower Cretaceous (upper Barremian–lowermost Aptian) stratigraphy of the Arabian Plate (Kharaib Formation, Hawar Member, UAE)

Larger benthic foraminifera such as orbitolinids are particularly important in Lower and mid-Cretaceous biostratigraphy of neritic deposits of the Arabian Plate. These data are supplemented by a few non-orbitolinid taxa. Among these, two new species are described herein as Voloshinoides simplex and Cribellopsis? kharaibensis from upper Barremian–lowermost Aptian inner platform limestones of the Kharaib Formation and the Hawar Member cropping out in Wadi Rahabah, United Arabian Emirates. V. simplex sp. nov. represents the oldest and most primitive species of the genus Voloshinoides Barnard and Banner, exhibiting a simple and poorly developed exoskeleton. C.? kharaibensis represents a rather small species exhibiting a primitive marginal zone that lacks intercalary beams. The assignment of the taxonomic status is provisional awaiting some structural clarifications. While C.? kharaibensis is restricted to the upper Barremian Kharaib Formation, V. simplex reaches into the lower part of the lowermost Aptian Hawar Member.

Rare bioerosion in large benthic foraminifera in the Eocene of NE Iran: Implications for global warming and trophic regime

Bioerosion is rare in large benthic foraminifera (LBF) in the Eocene of Ziarat Formation, Iran. Three bioerosion ichnotaxa have been identified, including more common Trypanites isp. and Entobia isp., and rare Meandropolydora sulcans. The rare bioerosional traces in LBF tests support the scenario of an oligotrophic nutrient regime during the studied interval. The sedimentation rate may have also been among the controls on the bioerosion of LBF in the Middle Eocene of Iran, but the oligotrophic nutrient regime likely had a stronger effect. The bioerosion of LBF tests during the Middle Eocene Climatic Optimum (MECO) was rather low or at maximum moderate, suggesting that an oligotrophic nutrient regime could compensate for the increase in bioerosion caused by ocean acidification and warming.

Large Benthic Foraminifera Biozonation of Mauddud Formation in Selected Section from Balad Oil Field, Central Iraq

Three subsurface sections Ba-1, Ba-4, and Ba-8, and sixty-five thin sections were examined to investigate the biostratigraphy of the Mauddud Formation (age Early Albian - Late Cenomanian) within the Balad Oil Field located in central Iraq. The formation is lithologically composed of dolomitic limestone, creamy oolitic limestone, and shale. Orbitolina qatarica, Orbitolina sefini, and Orbitolina concava range zones were distinguished as biozones, including the Late Albian (Orbitolina qatarica), Late Albian to Early Cenomanian (Orbitolina sefini), and Early-Cenomanian (Orbitolina concava) zones. The age of these biozones confirmed the extent throughout the early Cenomanian age. Fossils of twenty-seven species of Foraminifera, including Conicorbitolina conica, Miliolids, Neoiraqia convexa, Nezzazata, orbitolina sp., Spiroluculina sp., and Trocholina sp., and others like Coral, gastropods, and rudest were identified.

Unexpected increase in structural integrity caused by thermally induced dwarfism in large benthic foraminifera.

Climate change is predicted to negatively impact calcification and change the structural integrity of biogenic carbonates, influencing their protective function. We assess the impacts of warming on the morphology and crystallography of Amphistegina lobifera, an abundant benthic foraminifera species in shallow environments. Specimens from a thermally disturbed field area, mimicking future warming, are about 50% smaller compared with a control location. Differences in the position of the ν1 Raman mode of shells between the sites, which serves as a proxy for Mg content and calcification temperature, indicate that calcification is negatively impacted when temperatures are below the thermal range facilitating calcification. To test the impact of thermal stress on the Young's modulus of calcite which contributes to structural integrity, we quantify elasticity changes in large benthic foraminifera by applying atomic force microscopy to a different genus, Operculina ammonoides, cultured under optimal and high temperatures. Building on these observations of size and the sensitivity analysis for temperature-induced change in elasticity, we used finite element analysis to show that structural integrity is increased with reduced size and is largely insensitive to calcite elasticity. Our results indicate that warming-induced dwarfism creates shells that are more resistant to fracture because they are smaller.

Crustose red algae in deep time environments: Palaeoecological insights from northeastern India and Türkiye (Turkey)

Crustose red calcareous algae are key organisms in benthic ecosystems worldwide with critical functions like reef-building and substrate stabilization. Coralline algae thrived as major carbonate producers, with corals and/or larger benthic foraminifera (LBF) in numerous shallow-marine Tethyan carbonate platforms from the early Palaeogene to the Neogene. The Palaeocene–Eocene limestone successions in the Jaintia and Khasi Hills, Meghalaya, northeastern India, encompass two principal community types — algal-foraminiferal and coralline algal, with no associated colonial corals, while the Oligocene–Miocene carbonates from the Sivas basin and Siirt province in Türkiye are characterized by an algal-foraminifera assemblage with bryozoans, corals, and molluscs as other noteworthy components pertinent to the carbonate platform environment. We found that the diversity and ecology of these algal communities were influenced by systematic structure of the algal assemblage, sediment input, substrate stability, water depth, and hydrodynamic energy. The algal assemblages from different epochs and varying localities diverge based on the sedimentary regime, environmental settings, and the predominant taxa. The climatic transition from the Palaeocene–Eocene greenhouse to the Oligocene–Miocene icehouse corresponded to a shift from crustose algal assemblages dominated by Sporolithales to assemblages dominated by Hapalidiales.

Evolution of Coniacian facies and environments in the Iberian basin: a longshore current controlling siliciclastic sand distribution on a carbonate platform

The Coniacian carbonate sediments of the Iberian basin were deposited on a homoclinal ramp that grades upwards into a distally steepened ramp, with a major shoreline siliciclastic fringe. Twenty-three facies have been identified and grouped into three main depositional environments: outer, mid, and inner ramp. The last include barrier (shoal), lagoon, carbonate tidal-flat and shoreface sub-environments. The more prominent biogenic components show a mixture of sunlight-dependent phototrophic organisms (mainly large benthic foraminifera) and nutrient-dependent heterotrophic organisms (mainly rudists), with a remarkable rare occurrence of corals. Nutrients supplied from the emergent mainland probably promoted the development of heterozoan organisms. The vertical evolution of the ramp shows: a basal transgressive stage with facies retrogradation; a maximum flooding stage, and a regressive stage with aggradation and progradation of a distally steepened ramp. The presence and distribution of siliciclastics are problematic, since sands coming into the basin are likely to be rapidly and widely redistributed along the basin, taking into account the common storm, wave, and tidal processes preserved by the sedimentary facies. The presence of a clockwise NW-flowing longshore current is postulated to account for this distribution, which was likely induced by both dominant external currents around Iberia and wind-driven currents. These clockwise gyres facilitated the invertebrate dispersion into this enclosed basin and the local presence of upwelling. This could have been another source of episodic nutrient-rich waters from the deep ramp, which may have favored heterozoan development even in the more proximal and relatively shallower-water facies.

Biostratigraphy of the Eocene shallow-water succession of the south Sabzevar area (Central Iran) based on larger benthic foraminifera and calcareous nannofossils

A rich larger foraminifera assemblage from the Eocene carbonates of the south Sabzevar region (Now-Deh section) in central Iran indicates a late Ypresian to early Lutetian age. Nine species of Alveolina d’Orbigny are studied for systematics and biostratigraphy. The assemblage includes A. minuta, A. decastroi, A. cremae, A. cremae elongata, A. decipiens ayrancensis, A. celali, A. rugosa, A. cuspidata, A. frumentiformis. We have also found nummulitids (genus Nummulites and Assilina) and orthophragmines identified as N. campesinus, N. praediscorbinus, A. placentula, A. praespira, A. reicheli, A. ex. intrec. laxispira-maior and Discocyclina archiaci bartholomei. The recovery of Alveolina cremae elongata, A. decipiens ayrancensis, A. celali, A. rugosa, A. cuspidata and Assilina praespira has permitted for the first time to extend their geographical distribution outside of the classical peri-Mediterranean area to the central Tethys regions. The obtained biostratigraphy points to the Shallow Benthic Zones SBZ11 to SBZ13, indicating the occurrence of a Lower–Middle Eocene carbonate system. Part of the age model is supported by the calcareous nannofossil biostratigraphy that belong to the NP14b and CNE8 biozones, recorded from the central portion of the studied section. Issues regarding the application of the SBZ into the Middle East domains are discussed in terms of relative stratigraphic position and biogeographic dispersal of some significant Alveolina species.

Kelimpahan Foraminifera Bentonik Besar

The aim of this research is to determine the abundance of large benthic foraminifera in the study area. This research method is descriptive quantitative. There were 4 thin section samples used in this research, these samples came from cores at a depth of (36m – 39m). The results of the research showed that from the four incisions, 7 variations of large benthonic foraminifera genera were found, including, Spiroclypeus, Alveolina, Trillina hawchini, Cycloclypeus, Miogypsina, Heterostegina, and Assilina. Analysis of the abundance of large benthic foraminifera was carried out based on identification of the presence of foramnifera in each thin section sample. It is known that the thin section sample with the highest abundance of large benthonic foraminifera was in the code section sample (38m – 39m) with a total abundance of 9 individuals, consisting of 4 different genera of large benthonic foraminifera. In conclusion, the abundance of large benthic foraminifera tends to increase with increasing core depth. Keywords: Large Benthonic Foraminifera, Genus, Abundance, Rajamandala

A comparative approach employing microCT for the analysis of Cenozoic foraminifera from the Brazilian carbonate equatorial platform

Worldwide, some of the largest hydrocarbon reservoirs are located in tropical neritic carbonate deposits. Biostratigraphic and paleoenvironmental analyzes of these sedimentary records are often based on the study of foraminiferal assemblage. Foraminifera-based biozones are widely employed in the oil industry to support drilling processes that, alongside petrophysical prospecting, define interval favorable for exploiting hydrocarbon resources. Both scientific research and the petroleum industry, however, usually apply traditional petrographical and paleontological methods to analyze microfossil assemblages, especially for large benthic foraminifera. New, faster, and more accurate methods based on microCT analyzes have emerged as a valuable high-output tool to obtain high-resolution microfossil records for biostratigraphy and paleoenvironmental reconstructions. This method is also useful for the development of digital databases for artificial intelligence applications. MicroCT analyzes, therefore, lead to faster identification of foraminifera assemblage and support digital access to international foraminifera repositories and reference collections, introducing a new dimension in micropaleontological research.