Showing papers on "Foraminifera published in 2022"
TL;DR: In this article , the distribution of deep-water agglutinated foraminifera (DW AF) was analyzed within the Lates! Albian-earliest Turonian pelagic limestones of the famous Bottaccione standard section.
Abstract: Using semi-quantitative methods, the distribution of deep-water agglutinated foraminifera (DW AF) was analyzed within the Lates! Albian-earliest Turonian pelagic limestones of the famous Bottaccione standard section. The characteristic bathyal communities include forms of purely agglutinated "flysch-lype" assemblages and elements which are typical of Upper Cretaceous abyssal environments of the North Atlantic. Well-established planktonic foraminiferal and calcareous nannofossil zonations allowed to directly gauge the stratigraphic ranges of DW AF, contributing to a better chronostratigraphic calibration of a deep-water agglutinated foraminiferal zonation. Differences in ranges of sorne biostratigraphic marker species were observed. The distribution of morphogroups enabled us to interpret levels of oxygenation and organic input. The effects of the Cenomanian-Turonian boundary event (here represented by the ichtyolithic-bituminous radiolaritic Livello Bonarelli) on the DWAF were explored in detail. A major fauna! change in agglutinated foraminiferal communities consisting of a marked decrease in fauna! density and species richness was recognized in the middle of the Rotalipora cushmani Zone coinciding with a marked change in sedimentary regimes and related to extensive oxygen depletion on the sea bottom. The anoxic Livello Bonarelli
22 citations
TL;DR: A comprehensive list of 50 species and subspecies recognized among living planktonic foraminifera and evaluate their generic and suprageneric classifications is presented in this paper .
Abstract: Abstract. Applications of fossil shells of planktonic foraminifera
to decipher past environmental change and plankton evolution require a
robust operational taxonomy. In this respect, extant planktonic foraminifera
provide an opportunity for benchmarking the dominantly morphological species
concepts and classification of the group by considering ecological,
physiological and genetic characters. Although the basic framework of the
taxonomy of extant planktonic foraminifera has been stable for half a
century, many details have changed, not the least in light of genetic
evidence. In this contribution, we review the current taxonomy of living
planktonic foraminifera, presenting a comprehensive standard that emerged
from the meetings and consultations of the SCOR/IGBP Working Group 138
“Planktonic foraminifera and ocean changes”. We present a comprehensive
annotated list of 50 species and subspecies recognized among living
planktonic foraminifera and evaluate their generic and suprageneric
classification. As a result, we recommend replacing the commonly used names
Globorotalia menardii by G. cultrata and Globorotalia theyeri by G. eastropacia, recognize Globorotaloides oveyi as a neglected but valid living species, and
propose transferring the three extant species previously assigned to
Tenuitella into a separate genus, Tenuitellita. We review the status of types and designate
lectotypes for Globoturborotalita rubescens and Globigerinita uvula. We further provide an annotated list of synonyms and
other names that have been applied previously to living planktonic
foraminifera and outline the reasons for their exclusion. Finally, we
provide recommendations on how the presented classification scheme should be
used in operational taxonomy for the benefit of producing replicable and
interoperable census counts.
19 citations
TL;DR: In this article , the KIT boundary extinctions as a whole were caused by a complex scenario: the late Cretaceous changes in sea leve! as well as the increase of volcanic activity towards the boundary.
Abstract: lnvestigations at the K/T boundary section al Zumaya, northern Spain, underline the importance of this section in (1) establishing a Maastrichtian ammonite zonation and (2) in understanding "mass extinctions" in the fossil record. "Mass extinction" at the K/T boundary can be restricted to two groups of oceanic surface plankton, i.e. foraminifera and calcareous nannofloras. Ammonites and inoceramids exhibit a gradual decline through the late Cretaceous, as probably also do the Temperate belemnites and the bulk of involved vertebrales. Most of these groups disappear a long time before the boundary. Compared with the available environmental factors, the course of ammonite diversity through time perfectly parallels the course of global sea leve! changes. Times of high extinction rates (e.g. the era and system boundaries) coincide with times of maximum regressions, while the subsequent evolutionary radiations match with the new sea leve! rise. There is no need for any cosmic catastrophy to explain the decline of most invertebrate and vertebrate groups. oceanic surface at the boundary the following and changes were observed: minor (positive as well as negative) changes in boundary iridium and and changes in and strontium isotopes. these used to the Alvarez hypothesis of a cosmic impact at the boundary. they are easier explosive volvanicity which, on the other hand, might correlate also with the time-equivalen! magnetic reversals. of a series of comet showers. While most of the earlier Mesozoic major fauna! breaks can likewise be related with marine regressions, the KIT boundary extinctions as a whole were caused by a complex scenario: the late Cretaceous changes in sea leve! as well as the increase of volcanic activity towards the boundary.
17 citations
TL;DR: The distribution of benthonic and planktonic foraminifera from a reference section in southern Israel is described in this article , where three foraminiferal tethyan chronozones, Globotruncana falsostuarti , Gansserina gansseri and Abathomphalus mayaroensis zones, are identified.
Abstract: Maastrichtian argillaceous chalks of the Ghareb Formation are widespread throughout Israel, both in exposures and in the subsurface. These strata contain a rich fauna of foraminifera and calcareous nannoplankton, allowing detailed biozonation of the sediments, which were deposited in a series of basins in an outer-shelf to upper-slope environment. The distribution of benthonic and planktonic foraminifera from a reference section in southern Israel is described. Three planktonic foraminiferal tethyan chronozones, the Globotruncana falsostuarti , Gansserina gansseri and Abathomphalus mayaroensis zones, are identified. The middle and upper parts of the Maastrichtian succession are fully recorded in the section. The common occurrence of Abathomphalus mayaroensis and Plummerita hantkeninoides at the top of the Maastrichtian strata indicate a continuous sedimentation till the Cretaceous/Tertiary boundary. The Maastrichtian beds in Israel vary in thickness from 0 to 200 m and reflect structures, controlled by the Syrian Are fold system, which evolved during pre- and syn-Maastrichtian times. Their isopach contours are in good agreement with present-day structural axes. The lithostratigraphy and tectonic events during the Maastrichtian in Israel are compared with those of other countries in the eastern Mediterranean
17 citations
TL;DR: In this article , the authors describe the hydroclimate evolution of the eastern Mediterranean Basin during the early Messinian (7.2 to 6.5 Ma) time interval based on analysis of a succession at Agios Myron (Crete, Greece).
15 citations
TL;DR: Foraminifera-bound nitrogen (N) isotopes have been used to show that water column denitrification in the eastern tropical North Pacific was greatly reduced during the Middle Miocene Climatic Optimum (MMCO) and the Early Eocene Climate Optimum(EECO) as mentioned in this paper .
Abstract: Dissolved oxygen (O2) is essential for most ocean ecosystems, fuelling organisms' respiration and facilitating the cycling of carbon and nutrients. Oxygen measurements have been interpreted to indicate that the ocean's oxygen-deficient zones (ODZs) are expanding under global warming1,2. However, models provide an unclear picture of future ODZ change in both the near term and the long term3-6. The paleoclimate record can help explore the possible range of ODZ changes in warmer-than-modern periods. Here we use foraminifera-bound nitrogen (N) isotopes to show that water-column denitrification in the eastern tropical North Pacific was greatly reduced during the Middle Miocene Climatic Optimum (MMCO) and the Early Eocene Climatic Optimum (EECO). Because denitrification is restricted to oxygen-poor waters, our results indicate that, in these two Cenozoic periods of sustained warmth, ODZs were contracted, not expanded. ODZ contraction may have arisen from a decrease in upwelling-fuelled biological productivity in the tropical Pacific, which would have reduced oxygen demand in the subsurface. Alternatively, invigoration of deep-water ventilation by the Southern Ocean may have weakened the ocean's 'biological carbon pump', which would have increased deep-ocean oxygen. The mechanism at play would have determined whether the ODZ contractions occurred in step with the warming or took centuries or millennia to develop. Thus, although our results from the Cenozoic do not necessarily apply to the near-term future, they might imply that global warming may eventually cause ODZ contraction.
14 citations
TL;DR: In this paper , the first data on the foraminiferal assemblages and ecology in Holocene surface sediments of the Campanian continental shelf, in the area off the Cilento promontory, was provided.
Abstract: The present paper supplies the first data on the foraminiferal assemblages and ecology in Holocene surface sediments of the Campanian continental shelf, in the area off the Cilento promontory. Different types of assemblages have been distinguished and they have been related with parameters as depth, type of sediment and presence of alga! and plant remains. Our study has pointed out the strong prevalence of benthic species both in inf r alittoral and circalittoral samples and the absence of species that are extinct or indicative of particular paleoclimatic episodes. The age of the assemblages is therefore Holocene, with the exception of a group of foraminifers, presumably reworked, similar to microfaunas of Tyrrhenian age. The composition of the in relation with the known chemical-physical parameters (type of sediment, alga] and plant remains, fluvial input and water-depth) put evidence that: -there an almost perfect infralittoral and in the circalittoral zone, between type of sediment and the characteristic foraminiferal assemblages; infralittoral of epiphytic and the circalittoral zone the presence of epiphytic species, along with alga! remains, is probably dueto phenomena of transport from shallower levels. -the fluvial input, given by the rivers Solofrone and Alento, causes a sensible increase of euryhaline species, even if it has nota decisive effect on their global frequence. Finally some remarks are made on the ecological meaning of some species, that, for some of them, is not in agreement with what reported in previous papers.
14 citations
TL;DR: In this paper , the authors compared time averaging across five phyla of major carbonate producers co-occurring in a sediment core from the northern Adriatic Sea shelf, and found that despite different skeletal architecture, mineralogy, and life habit, all taxa showed very similar time averaging varying from ~1800 to ~3600 yr.
Abstract: Time averaging of fossil assemblages determines temporal precision of paleoecological and geochronological inferences. Taxonomic differences in intrinsic skeletal durability are expected to produce temporal mismatch between co-occurring species, but the importance of this effect is difficult to assess due to lack of direct estimates of time averaging for many higher taxa. Moreover, burial below the taphonomic active zone and early diagenetic processes may alleviate taxonomic differences in disintegration rates in subsurface sediments. We compared time averaging across five phyla of major carbonate producers co-occurring in a sediment core from the northern Adriatic Sea shelf. We dated individual bivalve shells, foraminiferal tests, tests and isolated plates of irregular and regular echinoids, crab claws, and fish otoliths. In spite of different skeletal architecture, mineralogy, and life habit, all taxa showed very similar time averaging varying from ~1800 to ~3600 yr (interquartile age ranges). Thus, remains of echinoids and crustaceans—two groups with multi-elemental skeletons assumed to have low preservation potential—can still undergo extensive age mixing comparable to that of the co-occurring mollusk shells. The median ages of taxa differed by as much as ~3700 yr, reflecting species-specific timing of seafloor colonization during the Holocene transgression. Our results are congruent with sequestration models invoking taphonomic processes that minimize durability differences among taxa. These processes together with temporal variability in skeletal production can overrule the effects of durability in determining temporal resolution of multi-taxic fossil assemblages.
13 citations
TL;DR: In the Igualada basin, Biplanispira, Pellatisipira, Heterostegina reticulate and Silvestriella are found together with other, larger foraminifera considered older than Priabonian as mentioned in this paper .
Abstract: The redescovery and exact location of Biplanisipira and abundant, free Pellatispira on the slopes of Puig Aguilera in the Igualada basin triggers the disscusion about the age of the first apperance of so many other genera considered so far as restricted to the Priabonian. In the Igualada basin, Biplanispira, Pellatisipira, Heterostegina reticulate and Silvestriella are found together with the other, larger foraminifera considered older than Priabonian. i.e. with Nummulites ptukhiani, Assilina schwageri and A. roselli . These latter species belong to lineages known to evolve constinuously from Lutetian to Pirabonian. The three representatives of the phyia concurrently indicate a Bartonian age of sediments yielding Pellatispira and its associates.
13 citations
TL;DR: A summary of the state of the art about their stratigraphic distribution and diversity across the Paleocene and Eocene epochs can be found in this article , where the authors suggest that their differentiation at the genus level was very rapid and reached its maximum in the upper Danian SBZ2, with a second peak during the Cuisian (=upper Ypresian).
Abstract: Rotaliids are one of the groups of larger foraminifera that quickly recolonized the shallow-water environments after the mass extinction at the end of the Cretaceous. Here we present a summary of the state of the art about their stratigraphic distribution and diversity across the Paleocene and Eocene epochs. Our data suggest that their differentiation at the genus level was very rapid and reached its maximum in the upper Danian SBZ2. Specific diversification, instead, culminated in the upper Thanetian SBZ4, with a second peak during the Cuisian (=upper Ypresian). Successively, the rotaliid diversity definitely declined, whereas other groups of larger foraminifera, and especially Alveolina and Nummulites, became more widespread and flourished with a large amount of species, up to the lower Bartonian SBZ17, when a final drop in rotaliid diversity is recorded. These major changes appear strictly linked to climate warming events such as Late Danian Event (LDE, generic diversification of rotaliids), Paleocene-Eocene Thermal Maximum (PETM, faunal turnover followed by abrupt decrease in both generic and specific diversity), Early Eocene Climatic Optimum (EECO, increase in number of K-strategists under oligotrophic conditions) and Middle Eocene Climatic Optimum (MECO, ultimate drop in diversity and competition with other larger foraminifera).
10 citations
TL;DR: In this paper , an integrative analysis of macroinvertebrates (decapods, gastropods, and bivalves) and microfossils collected in the Romualdo Formation, south-central Araripe Basin, is presented.
TL;DR: In this article , a considerably revised taxonomy and phylogeny for Albian-Maastrichtian planispiral planktonic foraminiferal species that have traditionally been included in Globigerinelloides is presented.
Abstract: We propose a considerably revised taxonomy and phylogeny for Albian-Maastrichtian planispiral planktonic foraminiferal species that have traditionally been included in Globigerinelloides. The revised taxonomy is necessary because of a ~6 m.y. gap between the extinction of planispiral species during the late Aptian and the next younger occurrence of planispiral species in the middle Albian. Our stratophenetic taxonomic groupings utilize ontogenetic morphometric data, shell wall ultrastructure, and general morphologic features observed from Scanning Electron Microscope and X-radiograph images of primary type specimens and globally distributed hypotype specimens. The planispiral lineage Laeviella n. gen., whose type species is La. bentonensis (Morrow), first appeared in the middle Albian and is postulated to have evolved from the evolutionary series Ticinella primula Luterbacher-Laviella primuloides n. sp. Laeviella is characterized as having a smooth to finely pustulose wall texture and a moderate chamber size increase rate. Two additional species, La. tururensis (Bronnimann) and La. bollii (Pessagno), are included in Laeviella with the youngest species of the genus, La. bollii, becoming extinct during the late Campanian. Planohedbergella, with Plh. aspera (Ehrenberg) as its type species, is revised to include 10 species that show a wide variation in chamber arrangement, wall microstructure and test morphology, but all have a moderately to coarsely pustulose wall texture on some or most final whorl chambers. Its stratigraphic range is from the late Albian-Cretaceous/Paleogene boundary. The oldest species is Plh. ultramicra (Subbotina), which evolved from Planomalina pulchella Todd and Low during the late Albian. Planohedbergella circularis n. sp. is described as a new late Campanian-Maastrichtian species representing forms with evolute coiling, a large number of final whorl chambers, and a slow chamber size increase rate. Polycamerella n. gen. is described as a monospecific genus, with Po. tardata n. sp. as the type species. It is a small, biapertural form with a very slow chamber expansion rate and a stratigraphic range from the late Campanian-Maastrichtian. The ancestor of Po. tardata, is tentatively identified as Plh. ultramicra.
TL;DR: The Plenus Cold Event (PCE) temporarily interrupted the supergreenhouse conditions exacerbated during much of the Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE 2) as discussed by the authors, and evidence for changes in the biogeography of planktonic organisms are limited to the equatorward migration of the dinoflagellate cysts grouped in the Cyclonephelium compactum-membraniphorum morphological plexus.
TL;DR: In this article , the authors use global abundance and biogeographic data, combined with depth habitat reconstructions, to determine the environmental mechanisms behind speciation in two groups of pelagic microfossils over the past 15 Myr.
Abstract: Abstract. The fossil record of marine microplankton provides insights into the evolutionary drivers which led to the origin of modern deep-water plankton, one of the largest components of ocean biomass. We use global abundance and biogeographic data, combined with depth habitat reconstructions, to determine the environmental mechanisms behind speciation in two groups of pelagic microfossils over the past 15 Myr. We compare our microfossil datasets with water column profiles simulated in an Earth system model. We show that deep-living planktonic foraminiferal (zooplankton) and calcareous nannofossil (mixotroph phytoplankton) species were virtually absent globally during the peak of the middle Miocene warmth. The evolution of deep-dwelling planktonic foraminifera started from subpolar–mid-latitude species, during late Miocene cooling, via allopatry. Deep-dwelling species subsequently spread towards lower latitudes and further diversified via depth sympatry, establishing modern communities stratified hundreds of metres down the water column. Similarly, sub-euphotic zone specialist calcareous nannofossils become a major component of tropical and sub-tropical assemblages during the latest Miocene to early Pliocene. Our model simulations suggest that increased organic matter and oxygen availability for planktonic foraminifera, and increased nutrients and light penetration for nannoplankton, favoured the evolution of new deep-water niches. These conditions resulted from global cooling and the associated increase in the efficiency of the biological pump over the last 15 Myr.
TL;DR: This work explores the genetic variability of both the 18S and COI markers in 22 benthic foraminiferal morphospecies and suggests the use of a set of sequences to describe species showing intra-genomic variability additionally to using multiple markers.
Abstract: Traditional morphological methods for species identification are highly time consuming, especially for small organisms, such as Foraminifera, a group of shell-building microbial eukaryotes. To analyze large amounts of samples more efficiently, species identification methods have extended to molecular tools in the last few decades. Although a wide range of phyla have good markers available, for Foraminifera only one hypervariable marker from the ribosomal region (18S) is widely used. Recently a new mitochondrial marker cytochrome oxidase subunit 1 (COI) has been sequenced. Here we investigate whether this marker has a higher potential for species identification compared to the ribosomal marker. We explore the genetic variability of both the 18S and COI markers in 22 benthic foraminiferal morphospecies (orders Miliolida and Rotaliida). Using single-cell DNA, the genetic variability within specimens (intra) and between specimens (inter) of each species was assessed using next-generation sequencing. Amplification success rate was twice as high for COI (151/200 specimens) than for 18S (73/200 specimens). The COI marker showed greatly decreased intra- and inter-specimen variability compared to 18S in six out of seven selected species. The 18S phylogenetic reconstruction fails to adequately cluster multiple species together in contrast to COI. Additionally, the COI marker helped recognize misclassified specimens difficult to morphologically identify to the species level. Integrative taxonomy, combining morphological and molecular characteristics, provides a robust picture of the foraminiferal species diversity. Finally, we suggest the use of a set of sequences (two or more) to describe species showing intra-genomic variability additionally to using multiple markers. Our findings highlight the potential of the newly discovered mitochondrial marker for molecular species identification and metabarcoding purposes.
TL;DR: In this paper , the authors proposed a transfer function to convert EBFOI vales directly into DO values, increasing efficiency by up to 38% on modern samples and applied to fossil datasets, providing a major improvement in defining and reconstructing marine oxygen levels and eutrophication.
Abstract: Marine oxygen minimum zones (OMZs) trap greenhouse gases, reduce livable habitats, a critical factor for these changes is the amount of dissolved oxygen (DO). The frequently used tool to reconstruct DO values, the Benthic Foraminifera Oxygen Index (BFOI), showed major shortcomings and lacks effectiveness. Therefore, we enhanced the BFOI and introduce enhanced BFOI (EBFOI) formulas by using all available data benthic foraminifers provide, calculating the whole livable habitat of benthic foraminifers, including bottom water oxygenation (BWO) and pore water oxygenation (PWO). Further, we introduce for the first time a transfer function to convert EBFOI vales directly into DO values, increasing efficiency by up to 38%. All formulas are calibrated on modern samples and applied to fossil datasets. Our new approach provides a major improvement in defining and reconstructing marine oxygen levels and eutrophication, by, providing a new toolset for understanding past changes and tracking actual and predicted future expanding OMZs.
TL;DR: In this article , a review of the application of benthic foraminifera as proxies in the (paleo)ecological characterization of different habitats of marine caves is presented.
Abstract: Marine caves are characterized by wide environmental variability for the interaction between marine and continental processes. Their conditions may be defined as extreme for inhabiting organisms due to the enclosed morphology, lack of light, and scarcity of nutrients. Therefore, it is necessary to identify reliable ecological indicators for describing and assessing environmental conditions in these habitats even more than elsewhere. This review aims to provide the state of art related to the application of benthic foraminifera as proxies in the (paleo)ecological characterization of different habitats of marine caves. Special attention was addressed to a research project focused on Mediterranean marine caves with different characteristics, such as extent, morphology, freshwater influence, salinity, sediment type, oxygenation, and organic matter supply. This review aims to illustrate the reliability of foraminifera as an ecological and paleoecological indicator in these habitats. They respond to various environmental conditions with different assemblages corresponding to a very detailed habitat partitioning. Because marine caves may be considered natural laboratories for environmental variability, the results of these studies may be interpreted in the perspective of the global variability to understand the environmental drivers of future changes in marine systems.
TL;DR: In this paper , the benthic foraminifer Ammonia beccarii precipitates its calcite at a rate of ∼24 ± 4 nmol/cm2/min.
TL;DR: A caprinid rudist association with Amphitriscoelus waringi Harris and Hodson, Praecaprina sp. cf. C. douvi/lei Paquier and Offneria sp. is reported from Turitzio, State of Michoacán, Mexico as discussed by the authors .
Abstract: A caprinid rudist association with Amphitriscoelus waringi Harris and Hodson, Praecaprina sp. cf. ? P. pennyi Harris and Hodson, Caprina sp. cf. C. douvi/lei Paquier and ?Offneria sp. is reported from Turitzio, State of Michoacán, México. It occurs together with the foraminifera Palorbitolina lenticularis (Blumenbach), ChojJatel/a decipiens Schlumberger and Everticyclammina sp. and the algae Delojf r el/a quercifoliipora Granier and Michaud, Marine/la /ugeoni Pfender and Arabicodium sp. The study of tha embryonic apparatusses of the specimens of Palorbitolina from this locality indicates an earliest Aptian age for that population. The presence of Amphitriscoelus and the other associated caprinids in México, constitutes evidence supporting the biotic homogeneity of the Caribbean Province during the Early Cretaceous.
TL;DR: In this article , the Cretaceous pelagic carbonate succession was studied in the Chutair Section, Sulaiman Range, representing part of the eastern Tethys for the paleoenvironment and bio-sequence stratigraphy.
Abstract: The Cretaceous pelagic carbonate succession, i.e., Goru Formation was studied in the Chutair Section, Sulaiman Range, representing part of the eastern Tethys for the paleoenvironment and bio-sequence stratigraphy. Eight planktonic foraminiferal biozones are identified which include: 1. Muricohedbergella planispira Interval Zone; 2. Ticinella primula Interval Zone; 3. Biticinella breggiensis Interval Zone; 4. Rotalipora appenninica Interval Zone; 5. Rotalipora cushmani Total Range Zone; 6. Whiteinella archeocretacea Partial Range Zone; 7. Helvetoglobotruncana helvetica Total Range Zone; and 8. Marginotruncana sigali Partial Range Zone representing Albian-Turonian age. The petrographic studies revealed five microfacies: 1. Radiolarians-rich wacke-packestone microfacies; 2. Radiolarians-rich wackestone microfacies; 3. Planktonic foraminiferal wacke-packestone microfacies; 4. Planktonic foraminiferal wackestone microfacies; and 5. Planktonic foraminiferal packestone microfacies; indicating deposition of the Goru Formation in outer-ramp to deep basinal settings. Based on the facies variations and planktonic foraminiferal biozones, the 2nd and 3rd order cycles are identified, which further include six transgressive and five regressive system tracts. The sea level curve of the Goru Formation showed fluctuation between outer-ramp and deep-basin, showing the overall transgression in the 2nd order cycle in the study area, which coincides with Global Sea Level Curve; however, the 3rd order cycle represents the local tectonic control during deposition of the strata.
TL;DR: In this paper , isotopic signatures (δ13C and δ18O) of living foraminifera from methane-charged sediments reflect incorporation of methane-derived carbon.
Abstract: Fossil benthic foraminifera are used to trace past methane release linked to climate change. However, it is still debated whether isotopic signatures of living foraminifera from methane-charged sediments reflect incorporation of methane-derived carbon. A deeper understanding of isotopic signatures of living benthic foraminifera from methane-rich environments will help to improve reconstructions of methane release in the past and better predict the impact of future climate warming on methane seepage. Here, we present isotopic signatures (δ13C and δ18O) of foraminiferal calcite together with biogeochemical data from Arctic seep environments from c. 1200 m water depth, Vestnesa Ridge, 79° N, Fram Strait. Lowest δ13C values were recorded in shells of Melonis barleeanus, - 5.2‰ in live specimens and - 6.5‰ in empty shells, from sediments dominated by aerobic (MOx) and anaerobic oxidation of methane (AOM), respectively. Our data indicate that foraminifera actively incorporate methane-derived carbon when living in sediments with moderate seepage activity, while in sediments with high seepage activity the poisonous sulfidic environment leads to death of the foraminifera and an overgrowth of their empty shells by methane-derived authigenic carbonates. We propose that the incorporation of methane-derived carbon in living foraminifera occurs via feeding on methanotrophic bacteria and/or incorporation of ambient dissolved inorganic carbon.
TL;DR: In this article , the authors focused on the Lower Turonian Abu Roash-F Member from the prolific Abu Gharadig field, Western Desert, Egypt which consists of argillaceous and bioclastic limestones.
TL;DR: The mass of well-preserved calcite in planktonic foraminifera shells provides an indication of the calcification potential of the surface ocean as discussed by the authors , which suggests a depth regulating function for plankton calcification, not dictated by water column acidity.
Abstract: The mass of well-preserved calcite in planktonic foraminifera shells provides an indication of the calcification potential of the surface ocean. Here we report the shell weight of 8 different abundant planktonic foraminifera species from a set of core-to sediments along the Mid-Atlantic Ridge. The analyses showed that near the equator, foraminifera shells of equivalent size weigh on average 1/3 less than those from the middle latitudes. The carbonate preservation state of the samples was assessed by high resolution X-ray microcomputed tomographic analyses of Globigerinoides ruber and Globorotalia truncatulinoides specimens. The specimen preservation was deemed good and does not overall explain the observed shell mass variations. However, G. ruber shell weights might be to some extent compromised by residual fine debris internal contamination. Deep dwelling species possess heavier tests than their surface-dwelling counterparts, suggesting that the weight of the foraminifera shells changes as a function of the depth habitat. Ambient seawater carbonate chemistry of declining carbonate ion concentration with depth cannot account for this interspecies difference. The results suggest a depth regulating function for plankton calcification, which is not dictated by water column acidity.
TL;DR: This article used geochemical fingerprinting to show that carbonate mud cannot be derived from the breakdown and mixing of any combination of known carbonate grains or skeletal sources, rather, mud represents a distinct seawater precipitate.
Abstract: Significance The Bahama Banks produce huge volumes of carbonate mud. These sediments represent a major sink in the modern carbon cycle, and likely an even larger sink in the ancient carbon cycle. Yet, it is still debated where and how carbonate mud is formed. We use geochemical fingerprinting to show that mud cannot be derived from the breakdown and mixing of any combination of known carbonate grains or skeletal sources. Rather, mud represents a distinct seawater precipitate. We use ancient sedimentary and modern oceanographic evidence to show that high seawater alkalinity is required to produce carbonate mud. Finally, we illustrate how the size and strength of the shallow carbonate factory plays a first-order control in setting global pCO2 and climate.
TL;DR: In this article , three different Standard Microfacies types (SMF) have been observed, corresponding to two different depositional environments (Facies Zones or FZ) of a platform progradation.
Abstract: Field investigation, Microfacies analysis, and biostratigraphy have been carried out in the central parts of the Ionian Basin (Aetoloakarnania area, Western Greece) in order to decipher the depositional environments that developed during the accumulation of the Upper Cretaceous to Eocene carbonate succession. Three different Standard Microfacies types (SMF) have been observed, corresponding to two different depositional environments (Facies Zones or FZ) of a platform progradation. The three SMF types which occur in the study area during the Upper Cretaceous to Eocene are: 1. SMF 3 that includes mudstone/wackestone with planktic foraminifera and radiolaria, corresponding to toe-of-slope (FZ: 3), 2. SMF 4, which can be classified as polymict clast-supported microbreccia, indicating a toe-of-slope-slope environment (FZ: 4) and 3. SMF 5 which is characterized by allochthonous bioclastic breccia and components deriving from adjacent platforms and which reflects a slope environment. Microfacies analysis provided evidence of a change in the origin of sedimentary components and biota showing the transition from toe-of-slope to slope, as well as a change in organism distribution.
TL;DR: In this article , the authors examined surface sediment samples from the Labrador Sea to the Iceland-Faroe-Shetland Channel (IFSC) for planktic foraminifera distribution along a latitudinal transect at 59.50°N.
Abstract: The subpolar North Atlantic (SPNA) Ocean has complex hydrography, and moderates the global climate through the Atlantic Meridional Overturning Circulation (AMOC). The surface water mass dynamics in SPNA and the upper limb of AMOC, govern the plankton distribution. Specifically, the habitat of modern planktic foraminifera is strongly affected by the SPNA hydrography. In the present study, 25 surface sediment samples from the Labrador Sea to the Iceland-Faroe-Shetland Channel (IFSC) were examined for planktic foraminifera distribution along a latitudinal transect at 59.50°N. The planktic foraminifera distribution followed the transition in water mass structure in the study area from the Sub-Arctic water in the west to the warm North Atlantic water in the east. Temperature and salinity are two dominant ecological factors controlling planktic foraminifera assemblages in the region. This hydrographic contrast was also reflected in the ratio of Neogloboquadrina pachyderma/Neogloboquadrina incompta along the transect. Based on the cluster analysis, the planktic foraminifera assemblages could be assigned to three groups. A cold/polar group in the Labrador Sea, a mixed (both cold and warm) group in the Irminger Sea and IFSC, and a warmer temperate group in the eastern part of the transect were represented by different planktic foraminifera assemblages. Additionally, a decrease in Globorotalia inflata in the eastern transect and an increase in Turborotalita quinqueloba in the Iceland basin and Irminger Sea was observed in our study when compared with the published dataset. From this, we suggest a shift in planktic assemblages in the SPNA. The present study on the distribution of modern planktic foraminifera can help paleoceanographic reconstructions in the SPNA ocean.
TL;DR: The Eocene Peñicas (Almería) and Harania (Málaga) stratigraphic sections from the Malaguide Complex (Betic Cordillera, South Spain) belonging to the Mesomediterranean Microplate from the westernmost Tethys (about-35°N and 0° to 5°E according to the Eocene coordinates) have been studied as discussed by the authors .
TL;DR: Metagenomic analysis found taxonomic groups missed by amplicon sequencing and identified trends in abundance of fungi and protists in metagenomes from the Eastern Tropical North and South Pacific ODZs and compared these data to the oxic Hawaii Ocean Time-series in the North Pacific.
Abstract: Ocean oxygen deficient zones (ODZs) host 30-50% of marine N2 production. Cyanobacteria photosynthesizing in the ODZ create a secondary chlorophyll maximum and provide organic matter to N2 producing bacteria. This chlorophyll maximum is thought to occur due to reduced grazing in anoxic waters. We first examine ODZ protists with long amplicon reads. We then use non-primer-based methods to examine the composition and relative abundance of protists in metagenomes from the Eastern Tropical North and South Pacific ODZs and compare these data to the oxic Hawaii Ocean Time-series in the North Pacific. We identify and quantify protists in proportion to the total microbial community. From metagenomic data, we see a large drop in abundance of fungi and protists such as choanoflagellates, radiolarians, cercozoa and ciliates in the ODZs but not in the oxic mesopelagic at HOT. Diplonemid euglenozoa were the only protists that increased in the ODZ. Dinoflagellates and foraminifera reads were also present in the ODZ though less abundant compared to oxic waters. Denitrification has been found in foraminifera but not yet in dinoflagellates. DNA techniques cannot separate dinoflagellate cells and cysts. Metagenomic analysis found taxonomic groups missed by amplicon sequencing and identified trends in abundance. This article is protected by copyright. All rights reserved.
TL;DR: In this article , the upper Aptian planktonic foraminifera assemblages recorded in the post-salt section of the Santos, Campos and Espírito Santo Brazilian marginal basins are described and interpreted in terms of biostratigraphy and relative ages.
TL;DR: In this paper , isotopic signatures (δ13C and δ18O) of living foraminifera from methane-charged sediments reflect incorporation of methane-derived carbon.
Abstract: Fossil benthic foraminifera are used to trace past methane release linked to climate change. However, it is still debated whether isotopic signatures of living foraminifera from methane-charged sediments reflect incorporation of methane-derived carbon. A deeper understanding of isotopic signatures of living benthic foraminifera from methane-rich environments will help to improve reconstructions of methane release in the past and better predict the impact of future climate warming on methane seepage. Here, we present isotopic signatures (δ13C and δ18O) of foraminiferal calcite together with biogeochemical data from Arctic seep environments from c. 1200 m water depth, Vestnesa Ridge, 79° N, Fram Strait. Lowest δ13C values were recorded in shells of Melonis barleeanus, - 5.2‰ in live specimens and - 6.5‰ in empty shells, from sediments dominated by aerobic (MOx) and anaerobic oxidation of methane (AOM), respectively. Our data indicate that foraminifera actively incorporate methane-derived carbon when living in sediments with moderate seepage activity, while in sediments with high seepage activity the poisonous sulfidic environment leads to death of the foraminifera and an overgrowth of their empty shells by methane-derived authigenic carbonates. We propose that the incorporation of methane-derived carbon in living foraminifera occurs via feeding on methanotrophic bacteria and/or incorporation of ambient dissolved inorganic carbon.