Showing papers on "Foraminifera published in 2021"
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TL;DR: In this paper, a series of 109climate model simulations using a unique set of paleogeographical reconstructions covering the entire Phanerozoic at the stage level was performed to investigate the robustness of these assumptions through geological time, and they found that the correlation between deep ocean temperatures and global mean surface temperatures is good for the Cenozoic, and thus the proxy data are reliable indicators for this time period, albeit with a standard error of 2'K.
Abstract: . Benthic oxygen isotope records are commonly used as a proxy for global mean
surface temperatures during the Late Cretaceous and Cenozoic, and the
resulting estimates have been extensively used in characterizing major
trends and transitions in the climate system and for analysing past climate
sensitivity. However, some fundamental assumptions governing this proxy have
rarely been tested. Two key assumptions are (a) benthic foraminiferal
temperatures are geographically well mixed and are linked to surface
high-latitude temperatures, and (b) surface high-latitude temperatures are well
correlated with global mean temperatures. To investigate the robustness of
these assumptions through geological time, we performed a series of 109
climate model simulations using a unique set of paleogeographical
reconstructions covering the entire Phanerozoic at the stage level. The
simulations have been run for at least 5000 model years to ensure that the
deep ocean is in dynamic equilibrium. We find that the correlation between
deep ocean temperatures and global mean surface temperatures is good for the
Cenozoic, and thus the proxy data are reliable indicators for this time
period, albeit with a standard error of 2 K. This uncertainty has not
normally been assessed and needs to be combined with other sources of
uncertainty when, for instance, estimating climate sensitivity based on
using δ18O measurements from benthic foraminifera. The
correlation between deep and global mean surface temperature becomes weaker
for pre-Cenozoic time periods (when the paleogeography is significantly
different from the present day). The reasons for the weaker correlation
include variability in the source region of the deep water (varying
hemispheres but also varying latitudes of sinking), the depth of ocean
overturning (some extreme warm climates have relatively shallow and sluggish
circulations weakening the link between the surface and deep ocean), and the
extent of polar amplification (e.g. ice albedo feedbacks). Deep ocean
sediments prior to the Cretaceous are rare, so extending the benthic foraminifera
proxy further into deeper time is problematic, but the model results
presented here would suggest that the deep ocean temperatures from such time
periods would probably be an unreliable indicator of global mean surface conditions.
39 citations
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32 citations
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university of lille1, University of Urbino2, University of Hamburg3, University of La Rochelle4, University of Nantes5, Rio de Janeiro State University6, Sapienza University of Rome7, University of the Basque Country8, National and Kapodistrian University of Athens9, National Research Council10, University of Göttingen11, Florida A&M University12, Shimane University13
TL;DR: In this article, benthic foraminifera from intertidal and transitional waters from the English Channel/European Atlantic coast and the Mediterranean Sea were assigned to five ecological groups using the weighted-averaging optimum with respect to TOC of each species.
25 citations
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TL;DR: In this article, the authors used a sample from the Integrated Ocean Discovery Program (IODP) Expedition 369 Site U1516 in the Mentelle Basin (eastern flank of the Naturaliste Plateau, Indian Ocean, SW Australia) to investigate the paleoceanographic changes across the Cenomanian-Turonian boundary interval and the Oceanic Anoxic Event 2 (OAE 2).
24 citations
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TL;DR: The Narmada Seaway began in India during the largest global sea-level transgression and Oceanic Anoxic Event 2 (OAE2) δ13C excursion during the late Cenomanian to early Turonian.
21 citations
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TL;DR: In this paper, the authors present the first compilation of quantitative data on deep-sea foraminifera at sites in all the world's oceans, aiming to build a unique, uniform database that allows comparison of deepsea faunal turnover across the uppermost Cretaceous through Paleogene.
21 citations
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01 Jun 2021TL;DR: In this article, geochemical proxies for temperature, salinity, seawater density and seawater carbonate systems parameters (pH, CO32−), nutrients, oxygen and water mass tracers are used to reconstruct the palaeoenvironment during periods of cold-water coral reef growth.
Abstract: Cold‐water coral (CWC) reefs and mounds are and have been biodiversity hotspots of the deep sea. As their occurrence depends on specific environmental parameters, gaining hindsight on changing ocean conditions under on‐going climate change is the key to a better understanding of CWC mound development through time. A convenient technique for reconstructing the palaeoenvironment during periods of CWC mound growth is by extracting geochemical proxies from biologically mediated carbonates. Here, the focus is on probably the two most abundant calcareous archives, that are, cold‐water Scleractinia and Foraminifera, with an overview of the geochemical proxies (selection) used in these aragonitic and calcitic skeletons from CWC mounds. A particular emphasis is set on constraining proxies for temperature, salinity, seawater density, seawater carbonate systems parameters (pH, CO32−), nutrients, oxygen and water mass tracers.
21 citations
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TL;DR: In this paper, the authors review the Miocene paleocenographic evolution of the Mediterranean starting from its Sr and Nd isotope records and discuss Mediterranean shallow-water carbonate production changes to identify the role of oceanographic conditions in controlling carbonate systems' evolution.
17 citations
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TL;DR: In this article, the authors use depth-stratified plankton tows to demonstrate that some species of planktic foraminifera are adapted to life in the heart of the pelagic oxygen minimum zone (OMZ).
Abstract: . Oxygen-depleted regions of the global ocean are rapidly expanding, with
important implications for global biogeochemical cycles. However, our
ability to make projections about the future of oxygen in the ocean is
limited by a lack of empirical data with which to test and constrain the
behavior of global climatic and oceanographic models. We use
depth-stratified plankton tows to demonstrate that some species of planktic
foraminifera are adapted to life in the heart of the pelagic oxygen minimum
zone (OMZ). In particular, we identify two species, Globorotaloides hexagonus and Hastigerina parapelagica, living within the
eastern tropical North Pacific OMZ. The tests of the former are preserved in
marine sediments and could be used to trace the extent and intensity of
low-oxygen pelagic habitats in the fossil record. Additional morphometric
analyses of G. hexagonus show that tests found in the lowest oxygen environments are
larger, more porous, less dense, and have more chambers in the final whorl.
The association of this species with the OMZ and the apparent plasticity of
its test in response to ambient oxygenation invites the use of G. hexagonus tests in
sediment cores as potential proxies for both the presence and intensity of
overlying OMZs.
16 citations
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TL;DR: In this article, the authors present multiproxy analyses, combining macro- and micropaleontological, as well as sediment compositional data to evaluate paleoenvironmental conditions during the deposition of sedimentary strata assigned to the Romualdo Formation.
15 citations
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TL;DR: It is found that the living benthic foraminiferal assemblage comprising of Epistominella umbonifera, Uvigerina auberiana, Reophax longicollis and Osangularia bengalensis is significantly affected only by %Corg in the sediment.
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TL;DR: In this article, carbon, oxygen, and strontium (87Sr/86Sr ratios) isotopic data of macrofossils (pacu and ray teeth, crab claws and oysters), and micro-fish (ostracods and foraminifera) from reported lower to lower upper Miocene sedimentary rocks of Western and Eastern Amazonian (Peru and Brazil), mainly from shallow-marine deposits were provided.
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TL;DR: This paper reconstructed the paleoceanographic evolution of the Japan Sea over the Pleistocene using benthic foraminiferal and organic geochemical records from sediment cores recovered at IODP Site U1426.
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TL;DR: In this article, the incorporation of bio-polymers and microplastics in selected benthic foraminiferal species by applying FTIR (Fourier Transform Infrared) microscopy was investigated.
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01 Feb 2021••
TL;DR: Foraminiferal taxa in the Clarion-Clipperton Zone (CCZ) have been studied extensively in the last few decades as discussed by the authors, with a large number of morphological and molecular taxa found in the CCZ.
Abstract: Benthic foraminiferal research in the North Pacific has a long history, with works published over a century ago providing important information about the taxonomy and distribution of morphospecies. These studies focused mainly on areas outside the Clarion-Clipperton Zone (CCZ). Our knowledge of foraminiferal faunas within the CCZ originates largely from recent baseline investigations related to likely future seabed mining of the polymetallic nodule deposits. These have revealed highly diverse assemblages of sediment-dwelling morphospecies among the meiofauna and macrofauna, as well as megafaunal xenophyophores and nodule-attached fauna. Morphological analyses have been complemented by metabarcoding studies that yielded even higher numbers of molecular species (Operational Taxonomic Units - OTUs). Monothalamids, the vast majority undescribed, constitute a substantial proportion of both morphological and molecular datasets, with multichambered agglutinated and calcareous foraminifera being less common. Their importance in this abyssal (>4000 m depth) habitat likely reflects food limitation combined with carbonate dissolution close to and below the carbonate compensation depth. Literature records, supported in a few cases by genetic data, suggest that many morphospecies found in the CCZ have wide geographical distributions across the Pacific abyss and in other oceans. At smaller spatial scales (several 100s of kilometers) there is a general uniformity in assemblage composition. Nevertheless, many morphospecies are too rare to conclude anything about their geographical distributions. Similarly, the part played by benthic foraminifera in CCZ ecosystems is largely a matter of speculation, although their abundance across different size classes suggests that it is significant. Meiofauna-sized taxa that consume freshly-deposited organic detritus may be important in carbon cycling, particularly at the shallower, more eutrophic eastern end of the CCZ. Megafaunal xenophyophores can provide habitat structure for other organisms, potentially enhancing benthic biodiversity. Foraminifera of all sizes could be among the earliest recolonisers of disturbed or redeposited sediments. Their potential contributions in terms of both ecology and biodiversity make these protists significant members of benthic communities in the CCZ.
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British Antarctic Survey1, University of Cambridge2, Leipzig University3, National Oceanography Centre, Southampton4, Royal Holloway, University of London5, University of Exeter6, University of South Florida St. Petersburg7, Alfred Wegener Institute for Polar and Marine Research8, University of Florida9, Durham University10
TL;DR: In this paper, the authors presented data from new sediment cores recovered on cruise JR298 from seven continental rise sites west of the Antarctic Peninsula and in the Bellingshausen Sea with the objectives to constrain RPI-based age models, and investigate the depositional history at these locations.
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TL;DR: The Carboniferous-Earliest Permian Biodiversification Event (CPBE) as discussed by the authors is a marine biodiversification event that lasted 41.2 Myr from the middle Visean to the late Asselian, with species number increasing by 246%.
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01 May 2021
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TL;DR: In this paper, the authors compared two foraminiferal-based biotic indices, namely the Foram-AMBI and Foram Stress Index (FSI), to evaluate the ecological quality status (EcoQS) of marine benthic systems.
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TL;DR: In this paper, the authors investigate the paleoenvironment near the southwestern edge of the seaway during OAE2 by integrating microfossil and geochemical records from the lower beds of the Mancos Shale at Carthage, New Mexico, USA.
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TL;DR: In this paper, a sediment core collected at the Hallett Ridge (1800m of depth), where significant occurrences of calcareous planktonic and benthic foraminifera allow to document the first evidence of the deglaciation after the Last Glacial Maximum (LGM) at about 20.2
Abstract: . During the Late Pleistocene–Holocene, the Ross Sea Ice Shelf exhibited
strong spatial variability in relation to the atmospheric and oceanographic
climatic variations. Despite being thoroughly investigated, the timing of
the ice sheet retreat from the outer continental shelf since the Last
Glacial Maximum (LGM) still remains controversial, mainly due to a lack of
sediment cores with a robust chronostratigraphy. For this reason, the recent
recovery of sediments containing a continuous occurrence of calcareous
foraminifera provides the important opportunity to create a reliable age
model and document the early deglacial phase in particular. Here we present
a multiproxy study from a sediment core collected at the Hallett Ridge (1800 m of depth), where significant occurrences of calcareous planktonic and benthic
foraminifera allow us to document the first evidence of the deglaciation
after the LGM at about 20.2 ka. Our results suggest that the
co-occurrence of large Neogloboquadrina pachyderma tests and abundant juvenile forms reflects the
beginning of open-water conditions and coverage of seasonal sea ice. Our
multiproxy approach based on diatoms, silicoflagellates, carbon and oxygen
stable isotopes on N. pachyderma, sediment texture, and geochemistry indicates that
abrupt warming occurred at approximately 17.8 ka, followed by a period of
increasing biological productivity. During the Holocene, the exclusive
dominance of agglutinated benthic foraminifera suggests that dissolution was
the main controlling factor on calcareous test accumulation and preservation.
Diatoms and silicoflagellates show that ocean conditions were variable
during the middle Holocene and the beginning of the Neoglacial period at
around 4 ka. In the Neoglacial, an increase in sand content testifies to
a strengthening of bottom-water currents, supported by an increase in the
abundance of the tycopelagic fossil diatom Paralia sulcata transported from the coastal
regions, while an increase in ice-rafted debris suggests more glacial
transport by icebergs.
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TL;DR: The results show that the relationship between planktonic foraminifera shell size and abundance or sea surface temperature are either absent or weaker than previously reported for other regions and that in central Mediterranean assemblages’ size may be mainly related to nutrient availability.
Abstract: Studies of the spatial distribution and size of modern planktonic foraminifera are still lacking in the Mediterranean Sea. In this study, 17 core-top sediments collected from a north-south transect along the central Mediterranean have been analyzed for planktonic foraminiferal content, in terms of their distributional pattern and intraspecific size variability. Among the analyzed planktonic foraminiferal species, Globigerina bulloides and Globigerinoides ruber (w) were the most abundant, presenting an antagonistic behavior and an overall decreasing trend in their average size values from Adriatic to Ionian sub-basins. Intraspecific differences have been also documented for G. ruber (w), with the dominant sensu stricto morphotype to present generally higher frequencies and more constant shell sizes than sensu lato. The greater size variability of the latter is possibly related to its adaptation in particular hydrographic conditions based on its depth habitat preference and ecological characteristics to reach the (sub)optimum growth conditions. The rest of the species occur in minor percentages and show on average 11% increase with decreasing latitude characterized by distinct species-specific size variations along the transect. Our results show that the relationship between planktonic foraminifera shell size and abundance or sea surface temperature are either absent or weaker than previously reported for other regions and that in central Mediterranean assemblages’ size may be mainly related to nutrient availability. Besides the environmental parameters (sea surface temperature, primary productivity, water depth, stratification), the possible hidden cryptic diversity, still lingers to be consistently determined, could give a better understanding of the geographic and morphological differentiation within the Mediterranean planktonic populations.
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TL;DR: In this paper, a paleoenvironmental, paleoclimatic and paleoceanographic reconstruction of the early Danian from the Caravaca section, Spain, one of the most complete and continuous K-PgB sections worldwide is presented.
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TL;DR: In this paper, the authors investigated the Aptian-lower Albian microfossil association present in the Romualdo Formation, Araripe Basin, Pernambuco State, northeastern Brazil.
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TL;DR: In this paper, a study of the paleoenvironmental evolution of the middle Eocene platforms recognized in the westernmost Tethys has been carried out in the well-exposed mid-Eocene succession from Sierra Espuna-Mula basin (Betic Cordillera, S Spain).
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TL;DR: Triton as mentioned in this paper is a large-scale dataset of planktonic foraminifera from ocean floor sediments, which contains >500,000 records and is four times larger than the previous largest database, Neptune.
Abstract: Planktonic foraminifera are a major constituent of ocean floor sediments, and thus have one of the most complete fossil records of any organism. Expeditions to sample these sediments have produced large amounts of spatiotemporal occurrence records throughout the Cenozoic, but no single source exists to house these data. We have therefore created a comprehensive dataset that integrates numerous sources for spatiotemporal records of planktonic foraminifera. This new dataset, Triton, contains >500,000 records and is four times larger than the previous largest database, Neptune. To ensure comparability among data sources, we have cleaned all records using a unified set of taxonomic concepts and have converted age data to the GTS 2020 timescale. Where ages were not absolute (e.g. based on biostratigraphic or magnetostratigraphic zones), we have used generalised additive models to produce continuous estimates. This dataset is an excellent resource for macroecological and macroevolutionary studies, particularly for investigating how species responded to past climatic changes.
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TL;DR: Foraminifera are important components of tropical marine benthic ecosystems and their recovery pattern from the end-Permian mass extinction can yield insights into the Mesozoic history of this group as discussed by the authors.
Abstract: Abstract. Foraminifera are important components of tropical marine benthic ecosystems and their recovery pattern from the end-Permian mass extinction can yield insights into the Mesozoic history of this group. Here we report the calcareous and agglutinated foraminifera recovered from five measured stratigraphic sections on the Great Bank of Guizhou, an uppermost Permian to Upper Triassic isolated carbonate platform in the Nanpanjiang Basin, south China. The material contains >100 Triassic species, including three that are newly described (Arenovidalina weii n. sp., Meandrospira? enosi n. sp., and Spinoendotebanella lehrmanni n. gen., n. sp.), ranging from Griesbachian (Induan) to Cordevolian (Carnian) age. The species belong to the classes Miliolata, Textulariata, Fusulinata, Nodosariata, and to an unknown class housing all aragonitic forms of the orders Involutinida and Robertinida. Based on previously established conodont zones and carbon isotope chemostratigraphy, the Griesbachian (early Induan) through Illyrian (late Anisian) interval has been subdivided into 12 foraminiferal zones and two unnamed intervals devoid of foraminifera. Following the extinction at the Permian-Triassic boundary, habitable ecological niches of Griesbachian age were invaded by disaster taxa that subsequently became extinct during the Dienerian (late Induan) and left no younger descendants. The disaster taxa were replaced by Lazarus taxa with Permian origins, which were then decimated by the Smithian-Spathian (mid-Olenekian) boundary crisis. The tempo of recovery appears to have been modulated by environmental changes during the Griesbachian through Smithian that involved both climate change and expansion of anoxic ocean bottom waters. Uninterrupted and lasting recovery of benthic foraminifera did not begin until the Spathian.