Calcareous Benthic Foraminifera Research Articles

Paleocene and Eocene deep-water benthic foraminifera at IODP Site U1511, Tasman Sea: Part 2

Deep-water benthic foraminifera are investigated from Paleocene to Eocene sediments recovered from IODP Hole U1511B in the northeastern Tasman Sea. The recovered foraminifera display exceptional three-dimensional preservation: they are relatively unaltered by sediment diagenesis and compaction. We examined 33 samples from Cores U1511B-33R to -42R, and recovered 79 species of deep-water agglutinated foraminifera (DWAF) and 13 species of calcareous benthic foraminifera. The assemblage consists entirely of “cosmopolitan” forms originally described from the Carpathians, Caucasus, Trinidad, and the western Tethys, and other DSDP/ODP sites, implying that there is little or no endemism among deep-water benthic faunas in the semi-isolated Tasman Sea. The Paleocene–Eocene interval is characterized by successive acmes of Spiroplectammina, Trochammina, ammodiscids, and Karrerulina, and therefore bears striking similarity to previously studied sections in the western Tethys and Boreal North Atlantic. The taxonomic turnover among the DWAF is minor across the P/E contact, with only three apparent extinctions and three originations from the uppermost cores of the Paleocene and the lowermost cores of the Eocene. Calcareous benthic foraminifera were not observed in the Eocene samples, possibly a result of the shoaling of the CCD.

The Badenian/Sarmatian (Middle Miocene) boundary in the Central Paratethys (Kreminna, western Ukraine): Foraminiferal and palynological evidence

The Badenian/Sarmatian boundary in the Paratethys basin, that marks the transition from normal marine to restricted semi-marine conditions due to isolation of the basin from the world ocean at the onset of Sarmatian time, is still far from being fully understood. The Kreminna section is located at the northeastern margin of the Carpathian Foreland Basin (Central Paratethys) in the Medobory Hills region. The Miocene deposits that overlie here the Upper Cretaceous substratum comprise the >1 m thick upper Badenian marls and clays passing upwards into ~4 m thick Sarmatian marly limestones with intercalations of marls, clays and limestones, and >2 m thick limestones in the uppermost part of the exposure. Fifty-three species of benthic foraminifera and four species of planktonic foraminifera have been recorded. Six benthic foraminiferal assemblages are composed almost exclusively of calcareous forms; agglutinated taxa are practically lacking. Elphidium spp., miliolids, Lobatula lobatula and Ammonia spp. are the most common calcareous benthic foraminifera in the material studied. Planktonic foraminifera are represented only by species of Globigerina and occur rarely in the lowermost part of the section. A characteristic feature of palynofacies is the very low proportion of land-derived elements – sporomorphs and cuticles, which suggests a sedimentary setting without terrestrial influx, and taxonomical impoverishment of dinoflagellate cyst assemblages, which are either monospecific or consist mainly of two to three species: in a majority of samples, assemblages with Polysphaeridium zoharyi and P. subtile occur. Most δ18O values range from –1.5 to ~+0.5‰ VPDB and most δ13C values are between 0 and +2‰ VPDB. In general, the δ13C curve mirrors the δ18O changes in the section. The Badenian/Sarmatian boundary is placed at the level where the Cibicidoides ungerianus Assemblage is replaced by the Elphidium fichtelianum Assemblage. At the boundary, planktonic foraminifers and most abundant stenohaline benthic foraminifera disappeared. Bottom waters were well-oxygenated both in the latest Badenian and earliest Sarmatian in the Kreminna location.

Biostratigraphy of Shiranish Formation from Selected Wells, Central of Iraq

The Quantitative high-resolution planktonic foraminiferal analysis of the subsurface section in three selected wells in the Ajeel Oil Field (Aj-8, Aj-12, and Aj-15) in Tikrit Governorate, Central Iraq has revealed that Shiranish Formation deposited in Late Campanian- Latest Maastrichtian age. This formation consists mainly of marly and marly limestone yielding diverse planktonic foraminiferal assemblages and calcareous benthic foraminifera, with a total of 46 species that belong to 23 genera, Three zones and four subzones, which cover the Late Campanian to the Latest Maastrichtian, were identified based on the recorded planktonic foraminifera and their ranges. They are as follows:1. Globotruncana aegyptiaca Zone that dated to be Late Campanian 2. Gansserina gansseri Zone that refers to Early Maastrichtian 3. Abathomphalus mayaroensis Zone that indicates Late Maastrichtian, in this section, the Abathomphalus mayaroensis Zone is divided into four subzones, namely in that order from bottom to top: Racemiguembelina fructicosa (Early Late Maastrichtian), Pseudoguembelina hariaensis (Middle-Late Maastrichtian), P. palpebra ( Late Late Maastrichtian), and Plummerita hantkeninoides (latest Maastrichtian).

ON THE AGE AND CONDITIONS OF THE FORMATION OF THE POLYANYTSKA SUITE ACCORDING TO THE FORAMINIFERA STUDY RESULTS (LOWER MIOCENE, BORYSLAV-POKUTTYA NAPPE, UKRAINIAN CARPATHIANS)

Neogene deposits of the Polyanytska Suite were exposed by the South Boryslav-1 well within the eastern block of the South Boryslav structure of the Boryslav oil and gas condensate field of the Outer Carpathians. The studied sediments of the Polyanytska Suite belong to the complex zone of planktonic foraminifers Globigerina pseudoedita with a characteristic association: Globigerina pseudoedita, Globoquadrina dehiscens, Dentoglobigerina langhiana, Trilobatus trilobus, Tenuitella brevispira, Tenuitella denseconnexa, Globorotalia tetracamerata, Globigerinella evoluta, Globigerinella obesa, Chiloguembelina gracillima. The Globigerina pseudoedita zone of planktonic foraminifera correlates with the zonal interval of nannoplankton NN2-NN3 of the Central Paratethys, which covers the upper part Eggerian, Eggenburgian, and the lowest part Ottnangian of the Central Paratethys and is compared with the upper Aquitan – the lower part of the Burdigal of the lower Miocene of the Neogene of the International Chronostratigraphic Scale. The sediments of the Polyanytska Suite were formed in a normally saline sea basin, with depths from the middle to the inner shelf. The medium shelf conditions (intervals 1812–1805 m; 1684–1645 m and 1546–1485 m in the the South Boryslav-1 well) are indicated by a relatively high percentage content and morphology of the shells of planktonic foraminifera, the taxonomic composition of calcareous benthic foraminifera. The presence of plankton indicates normal water salinity. Analysis of foraminifera in the interval 1395–1365 m indicates the depths of the inner shelf. The identified redeposited foraminifera of the Paleocene-Lower Oligocene testify to the erosion and demolition of clastic material from the uplifted part of the Carpathians.

Biogeography and Species Durations of Selected Cenozoic Shallow and Deep-Water Smaller Calcareous Benthic Foraminifera – A Review

Abstract Most previous accounts summarising the biogeography and species durations of smaller calcareous benthic foraminifera have been based on literature reviews or on a massive North American database that had been taxonomically standardised. In this review we limit consideration to extant and fossil families or genera (from nearshore, open shelf, and deep-sea environments) with modern reviews that have standardised their global morphotaxonomy and where available, are complimented by molecular studies. We confirm previous studies that indicate most shelf species have limited geographic ranges and the majority of deep-water species are widespread and cosmopolitan or nearly so. In our intertidal and inner shelf groups only one species (molecular and morphological), Ammonia veneta, has a cosmopolitan distribution, although four warm-water morphospecies, of Ammonia and Rugobolivinella, have or had distributions that spanned more than one ocean in equatorial latitudes. The majority of both warm- and cool-water species in these groups are regionally or locally-restricted endemics (92% of Bolivinellidae, 100% of Tubulogenerina, 73% of Ammoniidae). The biogeographic distribution of the two rarer, warm-water groups (Bolivinellidae, Tubulogenerina) changed dramatically through the Cenozoic with the Paleocene–Eocene North American–European distribution of Bolivinellidae switching to purely Indo-Pacific by the Pliocene–Quaternary. In our shelf–upper bathyal groups (Notorotaliiidae, Plectofrondiculariidae), two genera have been restricted to the Southern Hemisphere since their Eocene originations with their greatest diversity throughout in New Zealand and Australia, respectively. The dominantly cold-water notorotaliid genus Buccella has a biogeographic distribution largely restricted to the Arctic Ocean and both coasts of North and South America. Most notorotaliid species are locally or regionally endemic (100% of Notorotalia, Parrellina, Porosorotalia, 75% of Buccella). At least 50–60% of species in five extinct mid-bathyal–abyssal families are cosmopolitan and have been throughout the Cenozoic since their originations. The majority of these deep-sea species with more-restricted distributions are rare, and many could possibly be more widespread with further extensive study. This review found that the shortest mean species durations (4–5 myrs) occur in two groups of rather rare, tropical–subtropical inner-shelf foraminifera with many locally endemic species. In cooler and progressively deeper water environments the mean species durations increase to 7–11 myrs for temperate shelf–bathyal taxa (Notorotaliidae), 20 myrs for an extinct mid-shelf to bathyal family (Plectofrondiculariidae) and 41–50 myrs for five extinct mid-bathyal–abyssal families (Chrysalogoniidae, Ellipsoidinidae, Glandulonodosariidae, Pleurostomellidae, Stilostomellidae). One species in each of four of these deep-water families had a species duration of 150–120 myrs.

Biocalcification crisis in the continental shelf under ocean acidification

Ocean acidification (OA) is a persistent challenge for humans and is predicted to have deleterious effects on marine organisms, especially marine calcifiers such as coral and foraminifera. Benthic foraminifera is an important component of sediment in the continental shelf, while little is known about the impact of ocean acidification on benthic foraminifera both at the community and individual level and associated calcium carbonate deposition. We conducted eight months continued culture experiment under the scenario of 400, 800, 1200 and 1600 ppm pCO2 gradients on living benthic foraminifera from four stations in the continental shelf of the West Pacific Ocean. Statistic results showed OA had a negative effect on the abundance of benthic foraminifera. In contrast, the diversity increased roughly under OA conditions implying OA might stimulate the emergence of rare species and promote community diversity to some extent. In addition, we confirmed that the offshore area wasn’t the refuge for benthic foraminifera while the nearshore one had more resistance to moderate acidification. Calcareous species Protelphidium tuberculatum was the dominant species occupying on average 75% in all treatments and its shell diameter, weight and thickness showed a decrease, indicating the decrease of calcification of benthic foraminifera. A relationship between the weight of P. tuberculatum and pCO2 (R2 = 0.96) was established. Based on the present work, calcareous benthic foraminifera deposited 8.57 × 104 t calcium carbonate per year and this might reduce by nearly half and 90% under 800 and 1200 ppm scenarios, which indicates a biocalcification crisis under ongoing OA. This work shows an analogy for palaeoceanic OA and also provides new insights into the sediment of calcium carbonate in the future.

Holocene Glaucony from the Guadiana Shelf, Northern Gulf of Cadiz (SW Iberia): New Genetic Insights in a Sequence Stratigraphy Context

Glaucony occurrences have been reported both from exposed transgressive and overlying highstand system tracts. However, its occurrences within highstand deposits are often invoked as the result of underlying condensed section reworking. Detailed textural, mineralogical and geochemical reports of glaucony grains in highstand deposits remain elusive. The northern Gulf of Cadiz shelf (SW Iberia) offers a unique opportunity to investigate late Holocene glaucony authigenesis in a well-documented time-stratigraphic context, where transgressive deposits are locally exposed on the seafloor and are laterally draped by highstand muddy deposits. In this study, glaucony grains extracted from a core retrieved from a highstand muddy depocenter off the Guadiana River were investigated by means of digital microscopy, X-ray diffraction (XRD), and electron microscopic methods (FESEM-EDX and TEM-HRTEM). To better constrain the glaucony origin (autochthonous vs. allochthonous) in highstand muddy deposits, glaucony grains from surficial samples—taken from exposed transgressive deposits—were also investigated. Glauconitization in the studied core can be largely attributed to the replacement of faecal pellets from c. ~4.2–1.0 cal. ka BP. Both XRD and TEM-HRTEM analyses indicate that glaucony consists mainly of an R1, with a minor presence of R0, smectite-rich (nontronite) glauconite-smectite mixed-layer silicate, made up of 35–75% glauconitic layers and 65–25% of interstratified smectite layers. At the mineral lattice level, minor individual 7Å layers (berthierine) were also identified by HRTEM. Shallow radial cracks at the pellet surface, along with globular and vermiform-like biomorphic to low packing density lamellar-flaky nanostructures, mineralogical properties, and K-poor content (average 0.4 atoms p.f.u.) indicate a scarcely mature glauconitization process, attesting to formation of the grains in situ (autochthonous). Glaucony grains from exposed transgressive deposits, i.e., in the tests of calcareous benthic foraminifera, do not share a genetic relationship with the grains investigated in the highstand deposits, thus supporting the autochthonous origin of glaucony within the highstand deposits. Our combined dataset provides evidence of a multiphase history for autochthonous glaucony formation in the Guadiana shelf, as its genesis is traced to both transgressive and highstand conditions. While eustatic sea-level changes favoured glaucony formation under transgressive conditions, factors such as protracted low sediment supply and the establishment of a strong nutrient-rich upwelling system in the study area promoted glaucony development during late Holocene highstand conditions.

Renewal of planktonic foraminifera diversity after the Cretaceous Paleogene mass extinction by benthic colonizers

The biotic crisis following the end-Cretaceous asteroid impact resulted in a dramatic renewal of pelagic biodiversity. Considering the severe and immediate effect of the asteroid impact on the pelagic environment, it is remarkable that some of the most affected pelagic groups, like the planktonic foraminifera, survived at all. Here we queried a surface ocean metabarcoding dataset to show that calcareous benthic foraminifera of the clade Globothalamea are able to disperse actively in the plankton, and we show using molecular clock phylogeny that the modern planktonic clades originated from different benthic ancestors that colonized the plankton after the end-Cretaceous crisis. We conclude that the diversity of planktonic foraminifera has been the result of a constant leakage of benthic foraminifera diversity into the plankton, continuously refueling the planktonic niche, and challenge the classical interpretation of the fossil record that suggests that Mesozoic planktonic foraminifera gave rise to the modern communities.

Stratigraphy and Paleoenvironment(s) of the Late Cretaceous deposits in Ohafia area, Afikpo Basin, Southeastern Nigeria

Lithofacies and biofacies data extracted from three outcropping sections of Nkporo and Mamu Formations’ sediments in Ohafia area were used for paleoenvironmental and sequence stratigraphic interpretations. The five (5) lithofacies distinguished from the sections were Dark-Grey to Black Shale Facies (A), Oolitic Limestone Facies (B), Calcareous Siltstone Facies (C), Sandstone Facies (D) and Heterolithic Facies (E). The attributes of these lithofacies, including lithotype, rootlets, bioturbation, reducing conditions and microfossil contents, were used to discriminate the units into various environments of deposition and paleodepths. The oolithic limestone facies for instance was interpreted as deposits in shallow coastal areas with high turbulence, especially, in warm shallow marine environments. Paleobathymetry of the lithofacies ranged from non-marine through coastal deltaic, shallow inner neritic, inner neritic to middle neritic paleodepths. Micropalaeontological analysis of the sediments revealed a complete absence of planktonic foraminifera while agglutinated benthic assemblages (dominated by Haplophragmoides spp., Textularia spp. and Anomalinoides spp.), calcareous benthic foraminifera (Gavelinella guineana and Planulina nacatochensis), Gastropods, Ostracods, and Arenaceous indeterminate were recovered. The recognition of Bolivina afra-Haplophragmoides talokaense assemblage zone in the Mamu Formation conferred Maastrichtian age to the deposits. The presence of palynological assemblages like the Adallussiella polymorpha were used to assign Late Campanian age for the Nkporo Formation. Sequence stratigraphic analysis using the integration of foraminiferal, paleontological and lithofacies data identified two incomplete depositional sequences. The first sequence identified in the Nkporo Formation, comprised a Highstand systems tract (HST) bounded at the top by a sequence boundary (SB) dated 75 Ma. The SB also marked the beginning of the second depositional sequence that occurred in the successions of the Mamu Formation and comprised of Transgressive systems tract (TST), bounded at the top by a maximum flooding surface (MFS) dated 69.8 Ma. The results of this study have indicated the presence marker beds and constrained stratigraphic surfaces which can be used to map the identified play elements (source, reservoirs, traps and seals) in the study area. The surfaces are thus essential ingredients in basin-wide correlations for improved hydrocarbon exploration and development in the Afikpo and other adjoining inland basins of Nigeria.

Unilocular calcareous benthic foraminifera from the deep-sea sediments of the Bay of Bengal

Benthic foraminifera, predominantly marine unicellular organisms, are abundant and diverse. Their tests with intricate and varied surface ornamentation make them unique and fascinating organisms. Among them, Unilocular calcareous benthic foraminifera have always been the least explored group due to their less frequent occurrence and small, fragile tests. Hence, a study on the unilocular foraminifera was conducted by collecting a core (4.15 m long deep-sea core of 12.7 cm diameter) sample from the deep-sea environment (3083 m depth) of the Bay of Bengal on the Research Vessel MGS Sagar. This study describes the vertical distribution of unilocular foraminifera, assesses their community structure, provides illustrated taxonomic descriptions and reports new records from the Indian waters. Twenty-five species belonging to seven genera, two families and one suborder were recorded, of which eight species are new reports from the Indian waters. The total abundance of the Unilocular foraminifera was 219 number/gram (9% of the total foraminifera abundance) Fissurina (77), Oolina (46) Parafissurina (28) and Lagena (28) were the most abundant genera. Vertical distribution of the unilocular species showed a decreasing trend with 19 species in the 0–100 cm to three species in the 301–415 cm of the core sample. Shannon Weiner diversity index (H’) values ranged between 0 and 3.75, with the highest of 3.75 recorded at the 138–140 cm layer. Pielou’s species evenness (J’) values ranged from 0.82 to 1, and species dominance ranged from 0 to 0.5. Results of the analysis of similarity proved a significant variation in the species composition of unilocular benthic foraminifera between various depth layers of the core. Systematic descriptions of this taxa have also been included in the present study. This study is thus expected to fill the gap in knowledge of this lesser-known group of benthic foraminifera from the Indian waters.

BIOSTRATIGRAPHY AND SEDIMENTARY ENVIRONMENTS OF THE LOWER/UPPER CRETACEOUS BOUNDARY DEPOSITS BY SMALL FORAMINIFERA (PIENINY KLIPPEN BELT, UKRAINIAN CARPATHIANS)

The Pieniny Klippen Belt extends 600 km from the Slovakian Carpathians to the Romanian Carpathians. The Pieniny KIippen Belt narrows in the Ukrainian Carpathians. It is called the Pieniny Zone here. The Cretaceous succession of the Pieniny KIippen Belt in the Ukrainian Carpathians consists of the upper part of the Svalyava Formation (Titonian- Neocomian), Tyssalo Formation (Aptian-Senomanian), Puchov Formation (Turonian-Maastrichtian) and Yarmuta Formation (Maastrichtian). This succession is overlapped by the Eocene Vylhivchyk Formation with angular uncomformity. The Lower/Upper Cretaceuous boundary sediments of the Pieniny KIippen Belt in the Ukrainian Carpathians is located in the Tyssalo Formation. The paper presents the results of the analysis of foraminifera from the marls of the Tysalo Formation developed in the Tysalo tract, in the sections of the Tereblya and Luzhanka rivers, in the quarries of Perechyn and Pryborzhavske villages (Transcarpathians region). 27 species of foraminifera were identified in this study in the age range of Late Albian — earliest Turonian including 15 planktonic species and 4 benthic species. The biostratigraphic succession of foraminiferal subdivisions ranging from late Albian to Senomanian is identified. Upper Albian-Senomanian sediments of the Tyssalo Formation are divided into three lithological members. The lower member consists of black limestones and marls with dark grey limestones which correspond to early Late Albian. The middle member is represented by gray and gray-green marls with gray siltstones and sandstones which correspond to middle Late Albian. The upper member consists of light green-gray marls with pink marls which correspond to late Late Albian-Senomanian. The Hedbergella gaultina Zone (late Late Albian), Pseudothalmanninella ticinensis Zone (middle Late Albian) and Parathalmanninella appeninica Zone (late Late Albian) were identified in the Tyssalo Formation both by previous researchers and in the material presented. The layers with Thalmanninella globotruncanoides (early Senomanian), Thalmanninella reicheli Zone (middle Senomanian) and Rotalipora cushmani Zone (later Senomanian) are established in the Tyssalo Formation for the first time. The Lower/Upper Cretaceous boundary corresponds to the boundary between the Parathalmanninella appeninica Zone and the layers with Thalmanninella globotruncanoides, which are not found in the same section due to the intense deformation of the deposits in the Pieniny KIippen Belt. Changes in the generic composition of planktonic foraminifera in the boundary deposits of the Lower and Upper Cretaceous of the Tysalo Formation are gradual, from the dominance of small Biglobigerinella, Globigerinelloides, Hedbergella, Ticinella in the Upper Albian to the bloom of large complex-built Pseudothalmanninella, Rotalipora, Thalmanninella, Parathalmanninella, Praeglobotruncana Pseudothalmanninella, Rotalipora, Thalmanninella, Parathalmanninella, Praeglobotruncana in the Senomanian. The black marls of the lower member contain pyritized foraminifers, so it can be assumed that they were formed in oxygen-deficient botton-water conditions (early Late Albian). In the middle member change in the color of sediments from black to gray and green and the presence of calcareous benthic foraminifera belonging to genera Parella, Anomalina, Pleurostomella, Gavelinella indicate an improvement in oxygen conditions in bottom waters (middle Late Albian). The marl of the upper member is dominated by (70-100% of associations) planktonic foraminifera mainly from the genera Parathalmanninella, Rotalipora, Thalmanninella, Praeglobotruncana, which indicates the depth of the middle batial (late Late Albian-Senomanian).

An Overview of Oligocene to Recent Sediments of the Western Pacific Warm Pool (WPWP) (International Ocean Discovery Program-IODP Exp. 363) Using Warm and Cool Foraminiferal Species

We use the excellent sediment recovery of International Ocean Discovery Program (IODP) Exp. 363, in the Western Pacific Warm Pool (WPWP) to assess down-core variations in the abundance of warm versus cool benthic foraminiferal species through a warm benthic foraminifers (WBF) curve. The total percentage of the “warm” shallower species group (Laticarinina pauperata, Cibicidoides kullenbergi, C. robertsonianus, Cibicidoides sp., Hoeglundina elegans, and Bulimina aculeata) and of the “cool” species group from deep waters (Pyrgo murrhina, Planulina wuellerstorfi, Uvigerina peregrina, and Globobulimina hoeglundi, Hopkinsina pacifica) at all sites is used to assess paleo temporal and spatial variations in preservation and marine temperature. Our study sites span water depths ranging from 875 m to 3421 m and our results indicate that well-preserved living and fossil foraminifera characterize mudline and core sediments at all water depths attesting the wide environmental tolerance of these species to temperature and pressure. Using magneto-and biostratigraphy datum, these sediments are of Oligocene age. Our low-resolution study showed that with the exception of core 1486B which the linear tendency of warmer species is toward cool sediments in old times, all of them show that older sediments indicate warmer periods than today, which is expected from Miocene to Recent. Our results provide evidence for the preservation potential of deeply buried sediments, which has implications on climate reconstructions based on the population dynamics of calcareous benthic foraminifera.

Living (stained) calcareous benthic foraminiferal assemblages ([formula omitted]) in a coastal upwelling zone of the Humboldt Current System, Northern Chile ([formula omitted]S)

In coastal upwelling ecosystems, understanding of environmental factors regulating the structure of benthic foraminiferal communities is fundamental to enhance our knowledge of their ecology and to validate their use in palaeoceanographic studies. In this study, we assess the influence of organic matter (quantity/quality) and subsurface oxygenation on living (stained) calcareous benthic foraminifera inhabiting a coastal upwelling ecosystem influenced by Oxygen Minimum Zone (OMZ) off Inglesa Bay, Northern Chile. Benthic foraminifera and their environment (i.e. biochemical/elemental sediment composition and subsurface water column oxygenation) were sampled along a transect perpendicular to the coastline consisting of three stations (30, 70 and 120 m) and covering two seasons (winter and summer). The geochemical composition of surface sediments and subsurface oxygenation reveal a typical pattern of marine ecosystems associated with coastal upwelling centers influenced by OMZ. Forty-seven species of living calcareous benthic foraminifera were identified, in which Bolivinella seminuda, Buliminella elegantissima, Bulimina marginata, and Nonionella miocenica were found as the most abundant species. Total abundance increases remarkably with depth while taxonomic richness and evenness decrease. Multivariate analyses show three benthic foraminiferal associations strongly linked to nutritive organic matter and subsurface oxygenation, regardless of the sampling period. Assemblages “A” (22 species, 4 dominant) and “C” (5 species, 1 dominant) are associated with the shallow (30 m) and deep (120 m) station, and present contrasting subsurface oxygenation and organic matter content. Assemblage “B” (19 species, 3 dominant) is associated with the intermediate station (70 m) characterized by mixed subsurface oxygenation and organic matter content. Our results suggest that local environment conditions (i.e. OMZ intensity, organic matter quality/quantity) govern the structure and composition of the living calcareous benthic foraminiferal assemblages of Inglesa Bay. Such assemblages have similarities and differences with other benthic foraminifera assemblages found in other coastal upwelling ecosystems impinged by an OMZ.

Lithostratigraphic revision and biostratigraphy of Upper Hauterivian–Barremian strata from the Kugmallit Trough, Mackenzie Delta, Northwest Territories

Abstract The Kipnik Formation, named herein, is defined from the Late Hauterivian to Barremian Kugmallit Trough in the Mackenzie Delta, Arctic Canada. The trough was formed by extensional tectonics associated with the opening of the Canada Basin and was infilled by kilometre-thick accumulations of clastic sediments. Samples from the Kugmallit Trough are known only from two exploration wells – Shell Kipnik O-20 and Gulf Mobil Ogruknang M-31. Examination of palynomorphs, foraminifera, and ostracods from cuttings of these wells, integrated with regional subsurface and outcrop correlations, indicated that the existing subsurface stratigraphic interpretations [Upper Jurassic to Barremian] of the Kugmallit Trough were in need of revision. The revised Upper Hauterivian–Barremian succession thus consists of the Siku, Kipnik (new), and Mount Goodenough formations. The Siku and Kipnik formations are known only from the subsurface, but the Mt. Goodenough Formation is widespread and was deposited over a regional unconformity. The Siku to Kipnik deposition is a large-scale transgressive-regressive succession that represents deposition during a period of initial subsidence (transgression) followed by uplift and erosion (regression). The shale dominant Siku Formation contains a distinctive unnamed foraminiferal assemblage that consists of agglutinated species typical of offshore or deeper water. Ostracods of the Siku Formation are contained in the informal Galliaecytheridea postsinuata zone, which is confined to the Siku Formation. Ostracods of the G. postsinuata zone suggest shelf environments. The Kipnik Formation is sand-dominant with thin beds of shale, siltstone and coal. Agglutinated foraminifera occur sparsely because of coarse, rapid sedimentation. Inner shelf environments are suggested by the foraminifera. The lower half of the Mount Goodenough Formation is shale-dominant and the upper half consists of intercalated shale and sandstone. Foraminifera and ostracods occur abundantly in the Mt. Goodenough subsurface and outcrops of the Richardson Mountains. The foraminiferal Convallina mcneili Zone of Barremian age occurs in the Mt. -Goodenough Formation and its composition of agglutinated and calcareous benthic foraminifera suggests outer shelf or deeper environments. Ostracods of the Mt. Goodenough Formation in subsurface and outcrop are assigned to the informal Clithrocytheridea spp. zone. Ostracods suggest an outer shelf or deeper-water environment. Palynomorphs indicate that the Siku Formation is Late Hauterivian, the Kipnik Formation is probably latest Hauterivian to Early Barremian, and the Mount Goodenough Formation is Barremian.

Foraminiferal analysis and paleoenvironments of sediments in well -Aa, deepwater offshore, Niger Delta, Nigeria

Foraminiferal analysis was carried out on twenty five (25) ditch cutting samples from well -AA, offsore Niger Delta covering a depth interval of 9000ft-11025f. The study was aimed at age deduction, zoning the well, and interpreting the paleoenvironment of deposition. Lithostratigraphic description carried out on the sample revealed that the bulk lithofacies constitute shale with streaks of sand (fine-medium) between 9170ft - 9210ft and 9360ft -9380ft. The entire analysed interval was barren of planktonic foraminifera while depth 9960ft revealed a spot occurrence of Lagena spp,representing the only calcareous benthic foraminifera recovered in the entire interval. Few to common occurrences of deepwater agglutinated foraminifera were found in the well, dominated by some species of Haplophragmoides spp and Haplophragmoides narivaensis. Other foraminifera with rare and scattered occurrence includes, Cribrostomides spp, Bathysiphon spp, Troahammina spp, Cyclammina spp, Cyclammina cancellata, Valvulina spp, and Glomospira spp. The only microfaunal associated accessory recovered is ostracod at depth 1080ft. The analysed intervals was assigned a Middle – Late Miocene (N17 and older age) based on the FDO of Haplophragmoides narivaensis. The environment of deposition is based on the distribution of typical deep water arenaeceous foraminifera species recovered in the study. The predominance of the arenaeceous forms over calcareous forms suggest outer shelf environment of deposition.
 Keywords: Foraminifera, Palaeoenvironment, Niger delta, Biostratigraphy.

Paleocene agglutinated foraminifera from Jabal Mundassa, Al Ain area, United Arab Emirates

The Paleocene succession of Jabal Mundassa, Al Ain area, United Arab Emirates (UAE) contains prolific and well-preserved species of agglutinates, planktic and calcareous benthic foraminifera at the Danian/Selandian (D/S) transition. This succession is considered as the only one that has Danian sediments in the Al Ain area. The present study is deals with the taxonomy, palaeogeography and stratigraphic distribution of twenty-six agglutinated benthic species at Jabal Mundassa and other Paleocene outcrops localities in the Tethys

Upper Cretaceous and Early Paleogene Smaller Calcareous Benthic Foraminifera from Cauvery Basin, Southeast India

Smaller calcareous benthic foraminiferal fauna consists of 198 species with observed stratigraphic ranges from upper Cretaceous to early Paleogene are documented from Cauvery Basin. One species has been described as new species. This compilation is based on well cutting samples of 17 exploratory wells from sub-surface litho units Kamalapuram Formation of early Eocene — Paleocene age and the underlying Porto Nova and Nannilam Formation of Maestrichtian — Campanian age. Several representatives of Nodosariids, Gyroidinoidids and Gavelinellids were found with extended stratigraphic ranges crossing K/T boundary. Nearly 40 benthic species became extinct at the end of Paleocene as reported among deep sea benthics elsewhere. The record of high diversity of benthic species, moderately high percentage of planktic forms associated with several of deep water organic walled agglutinated benthic species indicates sediments at this time interval are deep water shelf and slope deposits in the basin.

EARLY TITHONIAN DEEP-WATER COLONIZATION BY BENTHIC FORAMINIFERA IN THE MAGURA BASIN (PIENINY KLIPPEN BELT, WESTERN CARPATHIANS): A CLUE TO THE ORIGINS OF DEEP-WATER FORAMINIFERA.

Deep-water benthic foraminifera were reported from lower Tithonian abyssal deposits lying above a barren interval of radiolarites in the Magura Basin (Western Carpathians). The analysis of morphogroups shows that the assemblage is represented by increased globular chambered morphogroups of both agglutinated and calcareous benthic foraminifera and planoconvex calcareous benthic foraminifera. The composition of the benthic foraminiferal assemblage points to a stressed setting particularly occurring in environments with increased organic flux and depleted oxygen in bottom and pore waters, as indicated by the scarcity of strictly epifaunal agglutinated foraminifera and the absence of strictly epifaunal calcareous benthic foraminifera. The assemblage is compared with Oxfordian – Tithonian assemblages reported from deep-water facies and shelf assemblages from the Boreal, Tethys and Atlantic realms.

Benthic foraminiferal paleoecology of the Maastrichtian succession at the Kharga Oasis, Western Desert, Egypt

The present work deals with the benthic foraminiferal investigations and analyses of the Maastrichtian succession from two sections in the Kharga Oasis (Naqb El-Rufuf and Gabal Teir), to evaluate the prevailing paleobathymetric and paleoenvironmental conditions. Three benthic foraminiferal assemblages have been distinguished by the R-mode cluster analysis. The first two clusters are dominated by simple-walled and complex-walled non-calcareous agglutinated foraminifera, respectively; while the third assemblage is characterized by calcareous agglutinated and calcareous benthic foraminiferal species. The Q-mode Detrended Correspondence Analysis (DCA) of the studied samples indicates five main groups designated as five biofacies (IV), each with a characteristic faunal structure. The overall dominance of the non-calcareous agglutinated foraminifera and the sporadic occurrence of the calcareous benthic foraminifera suggest deposition in a shallow water environment of restricted brackish, lagoonal, and littoral setting with occasional marine incursions. The distribution of the identified benthic foraminiferal species suggests deposition under oxygen-depleted conditions with high organic matter flux. Surficial epifaunal taxa dominate the benthic assemblages at certain intervals suggesting episodes of stagnation and elevated position of the redox boundary relative to the water/sediment interface.

Novel biomineralization strategy in calcareous foraminifera

This work shows that calcareous benthic foraminifera are capable of agglutinating sedimentary particles also. In particular, we focus on Melonis barleeanus. Traditionally considered a calcareous species, our data revealed the presence of minute (~3 μm) sedimentary particles (silicate grains) inside the chamber walls of the examined shells. These particles were arranged in a definitive and systematic pattern, and the similar grain chemical characterization and size suggested a relatively high degree of selectivity in both modern and fossil specimens. Based on these results, we propose that M. barleeanus is capable of agglutinating sedimentary particles during the formation of a new chamber. The analysis of other calcareous foraminiferal species (e.g., Cassidulina neoteretis, Lobatula lobatula, Nonionella stella) did not reveal the presence of silicate grains in the shell of the specimens analyzed confirming this to be a characteristic of M. barleeanus. Considering that the isotopic and chemical composition of this species is widely used in paleoclimatic and paleoceanographic reconstructions, we used a mixing model to better constrain the influence of sedimentary particles on M. barleeanus δ18O data. Our model showed that the calcite δ18O would increase by ~0.9–2‰ if 10 wt% of feldspars (i.e., anorthite, albite, orthoclase) and quartz, respectively, were included in the analyzed shell. Based on these results, we emphasize that it is of paramount importance to consider M. barleeanus unusual biomineralization strategy during the interpretation of geological records and to investigate the presence of similar processes in other calcareous foraminiferal species.