Foraminiferal Analysis Research Articles

Faunal evidence of the 1755 Lisbon Tsunami in Gibraltar (S Iberian Peninsula)

This paper analyzes the first systematic faunal record of the 1755 Lisbon tsunami in the Mediterranean. On the basis of sedimentological and paleontological features, the sedimentary record of a core collected in Gibraltar was divided into six sedimentary facies, with a paleoenvironmental evolution from a shallow marine paleoenviroment to an increasingly restricted lagoon. This record includes a bioclastic layer deposited by the 1755 Lisbon tsunami and characterized by an erosive base, presence of basal rip-up clasts and abundant shell debris composed by marine and brackish molluscs. The paleoenvironmental reconstruction derived from the foraminiferal analysis is congruent with that inferred from the sedimentary and the macrofaunal reconstructions, with the introduction of brackish species into the innermost, intertidal areas of a confined lagoon. This paleontological record is the first faunal evidence of the 1755 Lisbon tsunami in the Mediterranean.

Upper-Cretaceous and Paleocene Biostratigraphy of Nkporo Shales, Calabar Flank, Southern Benue Trough

The present study Biostratigraphic (foraminiferal and palynological), paleoenvironment and paleoecological evaluations are aimed at interpreting the lithology, age, paleoenvironmental as well as the paleoecological condition of the deposited sediments newly exposed along Ikot Okpara Otopy, Southeastern Nigeria. Lithological descriptions of the samples reveal that this section is predominantly shale. This shale is dark grey to light brown, fossiliferous with minor occurrence of silts and sandstones. Foraminiferal analysis reveals a Paleocene interval within the Nkporo Formation for the first time. The sediments have low to moderate number of taxa with 96% benthic and 4% planktics, while a total of 196 microflora were recovered and identified. The microfloral species contain 60% of continental plants with 40% of marine counterparts. Key foraminiferal taxa used in this study include Bolivina afra, Bolivina explicata, Globigerina fringe and Haplophragmoides talokaense, while their microfloral counterparts encountered within the section include Cingulatisporites ornatus, Auriculidites reticulates Ephedripites ambonoides, Retidiporites magdalenensis, Synolocolporites marginatus, Constructipollenites ineffectus, Foveotriletes margaritae, Buttinia andreevi, Proxapertites operculatus, Zlivisporis blanensis and Paleocystodinium sp. These assemblages (Foraminiferal and Palynological) depict the deposition of these sediments during the Maastrichtian Paleocene age. The combination of lithologic and biostratigraphic data reveal paleoenvironment interpretation of the study section to range from marginal - shallow to Middle neritic paleo-water depths, while the paleoecological studies depicts a fluctuation in the salinity from brackish to marine settings deposited within a tropical to subtropical warm and humid climate.

Pollen Record Of Early/ Middle Miocene Boundary In The South Sumatra Basin

Early to Middle Miocene sediment obtained from three wells drilled in South Sumatera area has been evaluated for its micropaleontological content including foraminifera, calcareous nannoplankton and palynomorph. The boundary of Early/ Middle Miocene is clearly represented by zone N8/ N9 boundary based on foraminiferal analysis and zone NN4/ NN5 boundary on the basis of calcareous nannoplankton analysis. The rich assemblage of foraminifera and calcareous nannoplankton indicates the occurrence of marine sediment within the well sections. In addition, environmental markers of benthonic foraminifera suggest the occurrence of inner to middle neritic along the studied sections. Palynological analysis however, proves the high occurrence of pollen and spore along the marine successions situated in Early/ Middle Miocene boundary which is the first time to yield a good quality of palynological record. The Early/ Middle Miocene boundary is marked by low sea level in global sea level curve as indicated by significant decrease of foraminifera and calcareous nannoplankton. In addition, palynological record reflects climatic changes over N8/ N9 sediment marking Early/ Middle Miocene boundary with the declines of pollen assemblage suggesting seasonal/ dry climate condition. N8 sediment shows high abundance and diversity of palynomorphs including those of wet climate markers. Palynological assemblage drops gradually approaching foram zone N9/ N8 boundary, whilst seasonal climate indicators increase. On the other hand, palynological record recovers its assemblage over N9 sediment.

Oligocene Palynological Zonation Scheme From East Java Sea

Systematic biostratigraphic analyses have been undertaken on the Oligocene clastic and carbonate Kujung Formation from the East Java Sea, North of Madura. The succession has been examined mainly using cutting samples in two wells, using a combination of foraminiferal, nannofossil and palynological analyses at regular spacing. Nannofossil analysis indicates that the Late Oligocene to basal Early Miocene succession is more or less complete, with zones NP24, NP25 and NN1 are all being well developed. In addition, the Early Oligocene is indentified by larger foraminifera indicating the Tc/ Td Letter Stage. Because the traditional palynological zonation of Morley (1978) does not work well in this area, the succession has been divided into broad assemblage zones, which appear to be controlled mainly by climate. These zones are OL-1, OL-2, OL-3, OL-4 and OL-5. Zone OL-1 is based essentially on the absence of seasonal climate and riparian elements, whilst zone OL-2 is characterized by the regular occurrence of seasonal climate elements, especially of Malvacipollis diversus. Zone OL-3 is indicated by common to abundant Dacrydium and Casuarina pollen, with a strong acme of dinoflagellate cysts dominated by Operculodinium spp. and Spiniferites spp., whereas zone OL-4 is marked by abundant Dacrydium and regular Casuarina pollen, but low representation of riparian elements. Finally, the youngest zone is OL-5 which is characterized by reduced Dacrydium and Casuarina pollen, and increased riparian elements. The above palynological zonation suggests climate change, which closely parallels the climate succession from West Java Sea (but with changes less pronounced). Therefore, this study provides a well dated Oligocene palynological zonation which can be applied across Java.

The influence of environmental conditions on the benthic foraminiferal distribution from the recent sediments of Lake Bardawil, Eastern Mediterranean Sea, Egypt

Lake Bardawil, similar to the other Mediterranean Egyptian lakes, is a unique wetland, separated from theMediterranean Seaby a narrowsandbarwith very restricted water exchange that allowed the development of a shallow-hypersaline lagoon. Late Pleistocene tectonics activities divided the lake into two main basins; the eastern and western basins. Twelve surface sediment samples were collected along the Lake and subjected to sediment texture and benthic foraminiferal analyses. In general, benthic foraminifera were abundant in the surface sediments of Lake Bardawil and were characterized by low diversity. The statistical analysis revealed two biotopes that distinguished between the eastern and western basins' environments. The eastern basin biotopes were characterized by fine bottom sediments with the predominance of salinity-tolerant assemblages, thus demonstrating hypersaline stressful restricted environment. The western biotope exhibited coarser bottom sediments associated with relatively narrow salinity-tolerant assemblages. This reflected sandy and less saline sediment of uncontaminated environments, as the western basin was exposed to active hydrodynamic regime that developed more magnitudes of water exchange with the Eastern Mediterranean Sea through the western inlet. Based on the results of this study, the biomonitoring of Lake Bardawil could be assessed by the analysis of its benthic foraminifera as a bioindicator tool that may help in the improvement of the Lake's conditions.

Foraminiferal patterns and palaeoenvironmental inferences from DEL-1 well, offshore Niger Delta

The Miocene Epoch (23.3–5.3 Ma) represents a remarkable time in the Earth's geological history with significant palaeoclimatic and palaeoenvironmental relevance. In this study, microfossils recovered from the DEL-1 (4600–9460 ft) well in the western Detachment Fold Zone, offshore Niger Delta in the Gulf of Guinea were used to construe the age, palaeoenvironment, and palaeoecology of the penetrated successions. Standard foraminiferal analyses were carried out on one hundred and forty-eight (148) ditch cuttings retrieved from the studied interval following standard laboratory and identification procedures. Globigerinatella spp./Catapsydrax dissimilis Concurrent-range Zone (M3/N6), Fohsella birnageae Lowest Occurrence Subzone (M4b/N7), and Orbulina suturalis Lowest Occurrence Zone (M6/N9) of early to middle Miocene were identified. An overall progradational coastal and shelfal facies dominated by argillaceous and arenaceous sediment in the early and middle Miocene is construed, whereas interpreted palaeoenvironment of deposition indicates fluctuation between coastal deltaic, inner, middle, and outer neritic system with some fluvio-marine incursions between 4600 and 9460 ft intervals. The identified early Miocene succession is characterised by significantly high ecological parameters (diversity, evenness, richness), low salinity, and relatively high occurrence of foraminifera faunas compared to the middle Miocene. The relationships between the foraminiferal faunas and environmental factors suggest the local ecologic niche exhibits environmental heterogeneity that might have influenced even distribution of different microhabitat faunal preferences. Whereas the contributing influence of arenaceous sediment on the general dearth of microfossils in the upper section of the well cannot be neglected, the foraminiferal signatures reflect the ubiquitous middle Miocene carbonate crash event, and thus confirm its occurrence in the Gulf of Guinea.

Using past interglacial temperature maxima to explore transgressions in modern Maldivian coral and Amphistegina bleaching thresholds

Tropical corals and Amphistegina, an example genus of symbiont-bearing larger benthic foraminifera, are presently living close to their thermal bleaching thresholds. As such, these essential reef-building organisms are vulnerable to the future prospect of more frequent sea surface temperature (SST) extremes. Exploring the earth’s paleo-climatic record, including interglacials warmer than present, may provide insights into future oceanographic conditions. We analyse foraminiferal shell geochemical compositions, from Recent surface sediments and Marine Isotope stage (MIS) 9e and MIS11c aged sediments, from the International Ocean Discovery Program Expedition 359 Site U1467 drilled in the Inner Sea of the Maldives. We illustrate through traditional (pooled) geochemical analysis (δ18O, Mg/Ca) that tropical temperatures were indeed marginally warmer during MIS9e and MIS11c in comparison to the modern ocean. Individual foraminiferal analysis (IFA) from the Recent (representing the last few hundred years) and MIS9e samples shows SSTs occasionally breached the coral bleaching threshold similarly to the modern-day. Significantly, the number of transgressions was four times higher during MIS11c, a recognised analogue for a warmer modern world. This new knowledge and novel IFA insight and application is invaluable given thermal stress is already obvious today with an increasing number of bleaching events over the last few decades.

Late Pleistocene baldcypress (Taxodium distichum) forest deposit on the continental shelf of the northern Gulf of Mexico

Approximately 13 km south of Gulf Shores, Alabama (United States), divers found in situ baldcypress (Taxodium distichum) stumps 18 m below the ocean surface. These trees could have only lived when sea level fell during the Pleistocene subaerially exposing the tectonically stable continental shelf. Here we investigate the geophysical properties along with microfossil and stratigraphical analyses of sediment cores to understand the factors that lead to this wood’s preservation. The stumps are exposed in an elongated depression (~100 m long, ~1 m deep) nested in a trough of the northwest–southeast trending Holocene sand ridges and troughs with 2–5 m vertical relief and ~0.5 km wavelength. Radiocarbon ages of the wood were infinite thus optically stimulated luminescence (OSL) dating was used to constrain the site’s age. Below the Holocene sands (~0.1–4 m thick), separated by a regional erosional unconformity, are Late Pleistocene mud‐peat (72±8 ka OSL), mud‐sand (63±5, 73±6 ka OSL), and palaeosol (56±5 ka OSL) facies that grade laterally from west to east, respectively. Foraminiferal analysis reveals the location of the terrestrial‐marine transitional layer above the Pleistocene facies in an interbedded sand and mud facies (3940±30 (1σ) 14C a BP), which is part of a lower shoreface or marine‐dominated estuarine environment. The occurrence of palaeosol and swamp facies of broadly similar ages and elevation suggests the glacial landscape possessed topographic relief that allowed wood, mud and peats to be preserved for ~50 ka of subaerial exposure before transitioning to the modern marine environment. We hypothesize that rapid sea‐level rise occurring ~60 or ~40 ka ago provided opportunities for local flood‐plain aggradation to bury the swamp thus preserving the stumps and that other sites may exist in the northern Gulf of Mexico shelf.

Foraminiferal Biozonation of Late Eocene - Early Oligocene sediments of BC-1 well, Onshore, Western Niger Delta Basin, Nigeria

Foraminiferal analysis was carried out on forty (40) ditch cutting samples from BC-1 well in the Onshore, Western Niger Delta at depth intervals of 5590 ft. - 8300 ft. Lithologic description of the samples together with the gamma ray log analytical data indicated the presence of four lithostratigraphic units composed of shale, sandstone, sandy shale and shaly sand corresponding to the continental Benin and paralic Agbada Formations. A total of twelve (12) species defined into eleven (11) genera, six (6) subfamilies and eleven (11) families were recovered. Benthonic and planktonic foraminiferal species constitute approximately 82 % and 18 % respectively. The calcareous benthics make up 44.4 % while the arenaceous benthics representing 37.7% of the total foraminiferal assemblages. Foraminiferal index marker species - Globorotalia opima nana, Nonion oyae, Cassigerinella chipollensis and Spiroplectammina wrightiirevealed that the age of the studied well is from Late Eocene - Early Oligocene epoch. This indicated that both the planktonic and benthonic foraminiferal recovered from the well contained the transition between the Priabonian and the Rupelian age. Three (3) informal foraminiferal zone were established - Nonion oyae zone, Cassigerinella chipollensis zone and undiagnostic zone. The zones compares with foraminiferal markers species whose stratigraphic ranges are well established in the Niger Delta and globally.
 Keyword: Lithostratigraphic units, Agbada Formation, Eocene, Oligocene and Biozone.

Discerning Changes in High‐Frequency Climate Variability Using Geochemical Populations of Individual Foraminifera

AbstractIndividual foraminiferal analysis (IFA) has proven to be a useful tool in reconstructing the amplitude of high‐frequency climate signals such as the annual cycle and the El Niño‐Southern Oscillation (ENSO). However, using IFA to evaluate past changes in climate variability is complicated by many factors including geographic location, foraminiferal ecology, methods of sample processing, and the influence of multiple, superimposed high‐frequency climate signals. Robust statistical tools and rigorous uncertainty analysis are therefore required to ensure the reliability of IFA‐based interpretations of paleoclimatic change. Here, we present a new proxy system model—called the Quantile Analysis of Temperature using Individual Foraminiferal Analyses (QUANTIFA)—that combines methods for assessing IFA detection sensitivity with analytical tools for processing and interpreting IFA data to standardize and streamline reconstructions employing IFA‐Mg/Ca measurements. Model exercises with simulated and real IFA data demonstrate that the dominant signal retained by IFA populations is largely determined by the annual‐to‐interannual ratio of climate variability at a given location and depth and can be impacted by seasonal biases in foraminiferal productivity. In addition, our exercises reveal that extreme quantiles can be reliable indicators of past changes in climate variability, are often more sensitive to climate change than quantiles within the distributional interior, and can be used to distinguish changes in interannual phenomena like ENSO from seasonality. Altogether, QUANTIFA provides a useful tool for modeling IFA uncertainties and processing IFA data that can be leveraged to establish a history of past climate variability.

Foraminiferal biostratigraphy and paleoenvironmental analysis of the sediments penetrated by Sahaiawei-1 well in the Northern Delta Depobelt, Niger Delta Basin

Foraminifera biostratigraphy and paleoenvironmental analysis of the sediments penetrated by Sahaiawei-1 Well in the Northern Delta Depobelt, Niger Delta Basin was carried out in order to determine the foraminifera biozonation, age, paleobathymetry, depositional environment and paleo-oxygen condition of the well. The total foraminifera population recovered was two thousand, three hundred and sixty five (2365), with planktic foraminifera constituting one hundred and fifty four (154) forms, while calcareous benthic and agglutinated benthic foraminifera recovered accounted for two thousand, one hundred and sixty two (2162) and fourty nine (49) of the total foraminifera population respectively. The total foraminifera species recovered was fifty nine (59); planktic accounted for twenty (20) foraminifera species, while calcareous and agglutinated benthic foraminifera accounted for thirty one (31) and eight (8) foraminifera species respectively. Five benthic foramineferabiozones were identified: lumped P7-P13, P5-P6/P7, lumped P3-P4, lumped P1-P2 and M18 Zones of Blow (1969, 1979). The result of the analysis indicates that the entire analysed interval (1800ft – 10680ft) was deposited during the Late Maastrichtian to Late Eocene epoch. The depositional environments of the Well varied from littoral, marginal, shallow and deep marine environments.
 Keywords: Biozonation, Calcareous, Arenaceous, Agglutinated, Hyposaline Marshes, Hyposaline Shelf Sea

Foraminiferal analysis of AE-1 well, Agbada formation Onshore, Western Niger Delta Basin: Implication for biozonation and age dating

Foraminiferal and sedimentological analysis was carried out using ditch cutting samples from intervals 2700 ft. - 10,185 ft. in AE-1 well. The samples were composited at 60 ft. into ninety four (94) ditch cutting samples. The standard micropaleontological sample procedures to recover the foraminiferal biofacies assemblages was utilized, followed by analysis and interpretation of the obtained results. The sedimentological analysis reveals five lithofacies - sandstone, sandy shale, shaly sand, mudstone and sandy clay which constitute part of the Agbada Formation of the Niger Delta. The foraminiferal fauna recovered from the samples studied comprised of twenty four species grouped into nineteen genera from niniteen families and nineteen subfamilies. A few number of miscellaneous microfossils such as Ostracoda, Holothuroidea and Echinoderm remains were recovered. The total count of foraminiferal defined from this well is four hundred and nineteen (419). The planktic foraminiferal count was two hundred and forty two (242) (57.8 % of the total count) while the benthics foraminiferal count was one hundred and seventy seven (177) (42.2 % of the total count). Among the benthic forms, the calcareous consists of one hundred and forty nine forms (149) (33.4 % of the total benthic count) while the agglutinating benthic forms were thirty seven (37) (8.8 % of the total benthic count). One (1) planktic (Chiloguembelinacubensis) and three (3) benthic (Eponidesberthelotianus, Hanzawaiastratonii and Nonionellaauris) informal foraminiferal zones were established in the well. The age of the AE-1 well sediments has been interpreted to belong to Early Oligocene - Early Miocene in comparism with foraminiferal markers species whose stratigraphic ranges are well established in the Niger Delta and globally. This inferred the presence of the Rupelian - Burdigalian sediments in the Niger Delta.
 Keywords: Foraminiferal, Biozone, Age, Rupelian, Burdigalian.

Glacier and ocean variability in Ata Sund, west Greenland, since 1400 CE

To improve knowledge of marine-terminating glaciers in western Greenland, marine sediment cores from the Ata Sund fjord system, hosting two outlet glaciers, Eqip Sermia and Kangilerngata Sermia, were investigated. The main objective was to reconstruct glacial activity and paleoceanographic conditions during the past 600 years. Ice-rafted debris (IRD) was quantified by wet-sieving sediment samples and by using a computed tomography scan. Variability in relative bottom water temperatures in the fjord was reconstructed using foraminiferal analysis. On the basis of this, three periods of distinct glacial regimes were identified: Period 1 (1380–1810 CE), which covers the culmination of the Little Ice Age (LIA) and is interpreted as having advanced glaciers with high IRD content. Period 2 (1810–1920 CE), the end of the LIA, which was characterised by a lowering of the glaciers’ calving flux in response to climate cooling. During Period 3 (1920–2014 CE), both glaciers retreated substantially to their present-day extent. The bottom water temperature started to decrease just before Period 2 and remained relatively low until just before the end of Period 3. This is interpreted as a local response to increased glacial meltwater input. Our study was compared with a study in Disko Bay, nearby Jakobshavn Glacier and the result shows that both of these Greenlandic marine-terminating glaciers are responding to large-scale climate change. However, the specific imprint on the glaciers and the different fjord waters in front of them result in contrasting glacial responses and sediment archives in their respective fjords.

Late Maastrichtian-early Danian sea-level changes at Gebel Tawil Shihaq in Central Jordan: Implications of chemostratigraphy and foraminiferal biostratigraphy

Integrated foraminiferal and geochemical analyses of the upper Maastrichtian-lower Danian succession of the Gebel Tawil Shihaq section in the Central Jordan Plateau has been conducted to interpret the nature of that succession within a sequence stratigraphic context. The studied succession covers the interval of the CF4-P1c planktonic foraminiferal zones. The incorporation of foraminiferal and geochemical proxies led to the recognition of four 3rd order depositional sequences, three in the Maastrichtian (M-Sq1, M-Sq2, and M-Sq3) and one in the Danian (D-Sq1). These depositional sequences are bounded by four sequence boundaries, detected based on abrupt faunal (e.g., zonal interruption, foraminiferal turnover) and geochemical (e.g., dolomitization, Sr/Ca and nearby Ti/Al maxima, Mn and CaCO3 minima) shifts. Based on the paleodepth variation revealed from the foraminiferal analyses and the consistent behavior of the different geochemical proxies, a relative sea-level curve was established and consequently, the systems tracts of each depositional sequence were recognized. The development of the inferred relative sea-level curve reveals the twofold control of both global sea-level changes and regional tectonics. The latter resulted in amalgamation and elimination or modification of some sea-level cycles relative to the previously recognized eustatic schemes. At the Cretaceous/Paleogene (K/Pg) boundary, a highly agitated phosphatized event bed is intercalated and exposes distinctive unique lithological, geochemical, and biostratigraphical characteristics denoting a long-lasting period of non-deposition and erosion commonly interrelated to the tectonic impact of the Syrian Arc Orogeny (SAO).

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.

The Maastrichtian–Danian transition in the northern Farafra Oasis, Western Desert (Egypt): Implications from foraminiferal paleobathymetry and paleoenvironmental reconstructions

Two exposed sections of the Lower/Upper Maastrichtian to Danian at northern and northeastern Farafra Oasis, Western Desert (Egypt) namely, the Farafra–Ain Dalla road and the Ain Maqfi sections have been analyzed for their planktonic and benthonic foraminifera to constrain the biostratigraphy and infer the paleoenvironmental conditions. Lithostratigraphically, the successions of the present study are classified into the Khoman Chalk and the Dakhla Shale. Biostratigraphically, six planktonic foraminiferal zones; Gansserina gansseri, Racemiguembelina powelli and Plummerita reicheli of the Maastrichtian as well as the Praemurica inconstans (P1c), Praemurica uncinata (P2) and Morozovella angulata (P3a) of the Danian are recognized. A detailed quantitative benthonic foraminiferal analysis has been performed and yields a total of 172 identified benthonic foraminiferal species belonging to 62 different genera. The various foraminiferal parameters as well as cluster analysis provide good information about the paleoenvironmental conditions and sea–level fluctuations across the Maastrichtian–Danian transition. The Maastrichtian revealed outer neritic shelf with slightly shallowing conditions recorded only at the Ain Maqfi section, well oxygenated conditions with low organic matter influx coupled with sea–level rise. During the Maastrichtian–Danian transition, a paleoenvironmental shift to inner-shallow middle neritic shelf, low oxygenated conditions with moderate organic matter influx coupled with sea–level fall is interpreted. This transition is characterized by a major hiatus due to absences of Guembelitria cretacea (P0), Parvularugoglobigerina eugubina (Pα), Parasubbotina pseudobulloides (P1a) and Subbotina triloculinoides (P1b) zones and subzones. It is well marked in the field by an irregular contact and conglomeratic phosphatic dolostone bed at the Farafra-Ain Dalla road section while the disconformity surface can be detected by planktonic foraminifera in the Ain Maqfi section. The lowermost Danian is phosphatic argillaceous chalky limestone with intensive reworking. Low oxygen and/or relatively high–moderate organic matter influx within inner–middle neritic shelf paleoenvironmental conditions can be reconstructed for the lowermost Danian associated with a slight increase in sea–level during the Praemurica inconstans (P1c) zone. The uppermost Danian reflected very well oxygenated conditions and/or low organic matter influx in middle–outer neritic shelf conditions associated with sea–level rise during ages of the planktonic foraminiferal zones P2–P3a.

The oldest stage of the Outer Carpathian evolution in the light of Oxfordian\u2013Kimmeridgian exotic clast studies (southern Poland)

In the Late Jurassic, the rifting process led to the disintegration of the southern margin of the North European Platform and to the opening of the Outer Carpathian flysch basin sedimentary system. The initial sediments accumulated in the northern part of the basin are related to both the destruction and resedimentation of older platform deposits. Since the sedimentary succession of this pre-flysch phase was consumed by the Miocene subduction, its only traces are represented, nowadays, by clasts preserved as exotics in the succeeding flysch deposits. Our analysis of foraminifers as well as calcareous and organic dinoflagellate cysts found in these exotics confirms the Oxfordian–early Kimmeridgian timing of the platform phase that preceded the opening of the flysch basin. The exotics are represented by three main facies types: sponge–microbial limestones, oncoid–intraclastic–Crescentiella limestones and fine-grained, biodetrital limestones with Saccocoma. These deposits are related to mid-ramp to outer-ramp settings. The land influence was rather weak, and these sedimentary settings were dominated by pelagic/hemipelagic accumulation. The studied facies are similar to facies types widely distributed over the northern shelf area of the Western Tethys (e.g., extra-Carpathian southern Poland, Carpathian Foredeep basement, southern Germany). In turn, coeval strata known from the part of the Magura Basin and of the Penninic–Pieninic Ocean, which were situated in more southern part of the Tethys, yielded different microfacies reflecting significant differences between the sedimentary settings of the study area and its southern extensions.

Influence of the Holocene relative sea level on the coastal plain of Sepetiba Bay (Southeast Brazil)

This work analyzes the results of the SP2 core (50.30 m length) collected in the coastal plain of Sepetiba Bay (SB; SE Brazil), 2 km away from the Guandu River mouth (latitude 22° 55′S, longitude 43° 46′W). It aims to study the influence of the Holocene relative sea level (RSL) on the coastal plain of SB. After description, the SP2 core was sampled at every 5 cm for grain size, geochemical, mineralogical and foraminiferal analyses. Four radiocarbon dates obtained in the first 18 m were modulated with Bayesian statistics. The SP2 core is composed of basement rocks, gneisses (50.30–43.80 m); river sediments (43.80–21.00 m) up to about ≈ 5.0 kyr BP; a sediment package marked by sudden textural and compositional changes, accumulated between ≈ 5.0 and 4.7 kyr BP; muddy sediments deposited between 4.7 and 0.8 kyr BP (18.80–3.35 m) with intercalations of sandy levels; an upper part of disturbed embankment sediments used for the implantation of Santa Cruz Thermoelectric Power Plant. The fluvial sands accumulated before ≈ 5.0 kyr BP were deposited before the maximum Mid-Holocene relative sea level. They were probably eroded and transported by the drainage network of the N region of SB, namely by the Guandu River. Between ≈ 4.5 and 3.5 kyr BP, the foraminiferal abundance and assemblage composition indicate that the study site was a shallow marine environment, due to the Mid-Holocene relative sea-level highstands (MHSLH). Between ≈ 3.5 and 3.0 kyr BP, the sediment accumulation rate (SAR) was the lowest of the last ≈ 5 kyr BP and the study site was exposed to subaerial weathering processes, in a scenario of the relative sea-level drop. A new phase of marine influence was recorded between ≈ 3.0 and 1.9 kyr BP, associated with the highest SAR of this record, up to ≈ 27.4 m/kyr BP. Between ≈ 1.9 and 1.8 kyr BP, the study site was under subaerial weathering processes. Since then the SAR reduced significantly to a mean value of ≈ 4.5 m/kyr and, between ≈ 1.8 and 0.8 kyr BP, the study site was again under the marine influence. Foraminifera were not found, after ≈ 0.8 kyr BP, in the SP2 core. However, the occurrence of a shallow marine environment was identified in another core, between ≈ 1.4 and 0.35 kyr BP, in the Guaratiba Mangrove, NE of SB. The results of the SP2 core suggest that MHSLH left a striking record in the study area, although some of the identified environmental changes are probably related to adjustments of the lower course of Guandu River and tidal channels and variations in the configuration of sandy littoral strands. The growth of a barrier–island system, the Marambaia barrier island, since the last ≈ 8–7.5 kyr BP may also have induced changes in the study area.

Quantitative Middle Eocene benthic foraminiferal biofacies from west-central Sinai, Egypt: Implications to paleobathymetry and sequence stratigraphy

Abstract The basinal depositional architecture, paleobathymetry and paleoproductivity assessment of west central Sinai (Egypt) lacks robust sequence stratigraphic framework inferred in conjunction with changes in benthic foraminiferal biofacies. Sinai is an economically important region for hydrocarbon exploration, hence understanding its depositional architecture is fundamental. For this, the planktic foraminifera biostratigraphy is done first to date the strata exposed at Wadi Nukhul, and then, the quantitative benthic foraminiferal biofacies are evaluated to infer changes in paleobathymetry and paleoproductivity. Five Eocene planktic biozones identified (E7b to E11), spanning 48.6 to 40.4 Ma are identified along with five 3rd order depositional sequences bounded by four sequence boundaries. Quantitative (Rotated factor analysis) benthic foraminiferal analysis revealed seven benthic foraminifera biofacies (A to F) suggesting a meso- to eutrophic, outer neritic, moderate to low oxygenated bottom waters, dominated largely by benthic foraminifera taxa, Bulimina, Uvigerina, Bolivina and Lenticulina. Exception to this trend is the presence of biofacies B (Discorbis ciperensis-Lenticulina cuvillieri) at the top of the Thebes Formation that reflects well‑oxygenated bottom waters straddling the middle to outer neritic depth boundary. The inferred relative sea level gradually decreases throughout the studied section (from bottom to top) and is consistent with a gradual global decline. Of interest is the possible identification of the Middle Eocene Climatic Optimum (~40.5–40 Ma), a global warming event that in the present study, encompasses the Uvigerina mediterranea-Spiroloculina esnaensis biofacies (Biofacies A) suggesting the presence of mesotrophic but moderately well‑oxygenated bottom waters at outer neritic depths. The base of the Thebes Formation is marked by the presence of an Oxygen Minimum Zone.

Modern foraminiferal assemblages in northern Nares Strait, Petermann Fjord, and beneath Petermann ice tongue, NW Greenland

ABSTRACT Calving events of Petermann Glacier, northwest Greenland, in 2010 and 2012 reduced the length of its ice tongue by c. 25 km, allowing exploration of newly uncovered seafloor during the Petermann 2015 Expedition. This article presents the results of foraminiferal analysis and environmental data from thirteen surface sediment samples in northern Nares Strait and Petermann Fjord, including beneath the modern ice tongue. This is the first study of living foraminifera beneath an arctic ice tongue and the first modern foraminiferal data from this area. Modern assemblages were studied to constrain species environmental preferences and to improve paleoenvironmental interpretations of foraminiferal assemblages. Sub–ice tongue assemblages differed greatly from those at all other sites, with very low faunal abundances and being dominated by agglutinated fauna, likely reflecting low food supply under the ice tongue. Fjord fauna were comprised of 80 percent or more calcareous species. Notably, Elphidium clavatum is absent beneath the ice tongue although it is dominant in the fjord. Increasing primary productivity associated with the transition to mobile sea ice, diminishing influence of the Petermann Glacier meltwater with distance from the grounding line, and increased influence of south-flowing currents in Nares Strait are the important controls on the faunal assemblages.