Journal articles on the topic 'Planktic/planktonic foraminifera'
To see the other types of publications on this topic, follow the link: Planktic/planktonic foraminifera.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Planktic/planktonic foraminifera.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Wolfgring, Erik, and Michael Wagreich. "A quantitative look on northwestern Tethyan foraminiferal assemblages, Campanian Nierental Formation, Austria." PeerJ 4 (March 8, 2016): e1757. http://dx.doi.org/10.7717/peerj.1757.
Full textAbstract:
Deposits spanning theRadotruncana calcarataTaxon Range Zone at the Postalm section, Northern Calcareous Alps (Austria) are examined quantitatively for foraminiferal assemblages, especially the planktonic group. This study focuses on establishing a high resolution record spanning an 800 ka long stratigraphic interval from the active continental margin of the Penninic Ocean. The Postalm section displays reddish limestone- marl alternations representing precession cycles. For this study, 26 samples were taken bed by bed to allow a “per-precession-cycle” resolution (i.e., a minimum sample distance of ∼20 ka). Samples from limestones as well as from marls were examined for foraminiferal assemblages. Data suggest a typical, open marine Campanian foraminiferal community. The >63 µm fraction is dominated by opportunist taxa, i.e., members ofMuricohedbergellaand biserial planktic foraminifera.Archaeoglobigerinaand “Globigerinelloides” appear frequently and benthic foraminifera are very sparsely found. The share of globotruncanids, representing more complex morphotypes amongst planktonic foraminifera, is recorded with 5–10%. The state of preservation of foraminifera from the Postalm section is moderate to poor. Differences between samples from marls and samples from limestone are evident, but do not reveal evidence that there was an influence on the postdepositional microfossil communities. However, data from microfossils showing moderate to bad preservation can still offer valuable insight into the palaeoenvironment and biostratigraphy. Information gathered on the composition of the planktonic foraminiferal assemblage confirms a low-to-mid-latitude setting for the Postalm section. As well resolved records of Late Cretaceous foraminifera assemblages are rare, the examination of theRadotruncana calcarataTaxon Range Zone provides some insights into variations and short term changes during the very short period of 800 ka.
2
Stoykova, Kristalina, Sava Juranov, and Marin Ivanov. "Calibration of calraceous nannofossils and planktonic foraminifers’ zonation in the Lower and Middle Paleocene of Bulgaria." Geologica Balcanica 35, no. 1-2 (June 30, 2005): 3–9. http://dx.doi.org/10.52321/geolbalc.35.1-2.3.
Full textAbstract:
This study represents first attempt to juxtapose and correlate the zonal schemes of calcareous nannofossils and planktonic foraminifers in the Lower and Middle Paleocene of Bulgaria. The calibration of the two schemes is accomplished in the most complete and continuous sedimentary succession of Byala Fm., cropping out in the sections around the village of Goritsa, Varna District. In the Danian Stage the presence of NP1-NP4 nannofossil zones as well as of the planktic foraminifera zones Pα, P1a, P1b, P1c, P3a is documented. In despite of the scarce paleontological data, the presence of P0 zone in basal Danian and P2 zone in the upper Danian is suggested. In the Selandian Stage NP5 and respectively P3b zones are evidenced with exceptionally rich plankton associations. The upper part of the section is incomplete due to the overthrusting of Upper Cretaceous sediments. The most important bio-events in both group are calibrated, thus enable higher biostratigraphic resolution and accuracy of dating.
3
Broecker, Wallace S., Susan Trumbore, Georges Bonani, Willy Wölfli, and Millie Klas. "Anomalous AMS Radiocarbon Ages for Foraminifera from High-Deposition-Rate Ocean Sediments." Radiocarbon 31, no. 2 (1989): 157–62. http://dx.doi.org/10.1017/s0033822200044817.
Full textAbstract:
Radiocarbon ages on handpicked foraminifera from deep-sea cores are revealing that areas of rapid sediment accumulation are in some cases subject to hiatuses, reworking and perhaps secondary calcite deposition. We present here an extreme example of the impacts of such disturbances. The message is that if precise chronologies or meaningful benthic planktic age differences are to be obtained, then it is essential to document the reliability of radiocarbon ages by making both comparisons between coexisting species of planktonic foraminifera and detailed down-core sequences of measurements.
4
Saadu, Mariam B., Ayoola Y. Jimoh, Olabisi A. Adekeye, and Taofeeq A. Issa. "Biostratigraphy and Palaeoecological Studies of the Late Cretaceous-Tertiary Sediments in the Dahomey Basin, Nigeria." European Journal of Environment and Earth Sciences 3, no. 4 (July 25, 2022): 41–47. http://dx.doi.org/10.24018/ejgeo.2022.3.4.274.
Full textAbstract:
The Maastrichtian–Eocene sediments (mainly shales and limestones) penetrated by the Itori borehole and Ilaro boreholes in the Dahomey Basin were investigated for foraminiferal biostratigraphy and palaeoecological interpretation. These boreholes penetrated Araromi, Ewekoro, and Oshosun formations at varying depths. Selected shale sediments were subjected to foraminiferal analysis and many planktonic and benthic species of foraminifera (agglutinated and calcareous) were recovered from the Cretaceous interval of the penetrated boreholes. Twelve species of planktic foraminifera (Globalomalina planocompressa, G. pseudomenardii, Globigerina inaequispira, Acarinina cf.coalingenis, Acarinina nitida, Chiloguembelina cretacea, chiloguembelina subtriangularis, Orthokasrstenia sp., Hedbergella holmdelensis, Globigerina sp., Globigerinelloids asperus, Morozovella formosa formosa) and thirteen species of benthic i.e Bolivina sp., B. Crassicostata, , E. africana, Eponides psuedoelevatus, Gavelinella cf. guineana, Gavelinella pachysuturalis, Haplophragmiodes sp., Lenticulina cyprina, L. inornata, L. olokuni, L. psuedomamilligera, L. taylorensis, Nonionella communis, N. spissa, N. panamensis, Orthokarstenia sp., Planulina oyae) were identified. In general, benthic species of infauna deposit feeder and epifauna dominate the population. These species occupy a range of environments from dyoxic to anoxic, brackish water to marsh environment down to upper bathyal depth. Based on the abundant and stratigraphical distribution of the foraminiferal species, four biostratigraphic zones were recognized: Afrobolivina afra zone of late Maastrichtian, Globigerina zone of early Paleocene, Globalomalina pseudomenardii zone of late Paleocene and Morozovella formosa formosa zone of the early Eocene.
5
D’Onofrio, Roberta, Valeria Luciani, Gerald R. Dickens, Bridget S. Wade, and Sandra Kirtland Turner. "Demise of the Planktic Foraminifer Genus Morozovella during the Early Eocene Climatic Optimum: New Records from ODP Site 1258 (Demerara Rise, Western Equatorial Atlantic) and Site 1263 (Walvis Ridge, South Atlantic)." Geosciences 10, no. 3 (February 27, 2020): 88. http://dx.doi.org/10.3390/geosciences10030088.
Full textAbstract:
Here we present relative abundances of planktic foraminifera that span the Early Eocene Climatic Optimum (EECO) at Ocean Drilling Program (ODP) Site 1258 in the western equatorial Atlantic. The EECO (~53.3−49.1 Ma) represents peak Cenozoic warmth, probably related to high atmospheric CO2, and when planktic foraminifera, a dominant component of marine sediment, exhibit a major biotic response. Consistent with previous work, the relative abundance of the genus Morozovella, which dominated early Paleogene tropical-subtropical assemblages, markedly and permanently declined from a mean percentage of ~32% to less than ~7% at the beginning of the EECO. The distinct decrease in Morozovella abundance occurred at Site 1258 within ~20 kyr before a negative excursion in δ13C records known as the J event and which defines the beginning of EECO. Moreover, all morozovellid species except M. aragonensis dropped in abundance permanently at Site 1258, and this is related to a reduction in test-size. Comparing our data with that from other locations, the remarkable switch in planktonic foraminifera assemblages appears to have begun first with unfavourable environmental conditions near the Equator and then extended to higher latitudes. Several potential stressors may explain observations, including some combination of algal photosymbiont inhibition (bleaching), a sustained increase in temperature, or an extended decrease in pH.
6
Malak, Zaid A., Omar A. Al-Badrani, and Ezzat I. Al-Fandi. "Stratigraphic And Microfacies Study Of Upper Campanian - Lower Maastrichtian Succession (Shiranish Formation) In Bade Village, Bekhere Anticline, Kurdistan Region, Northern Iraq." Bulletin of the Geological Society of Malaysia 71 (May 31, 2021): 47–55. http://dx.doi.org/10.7186/bgsm71202104.
Full textAbstract:
The Upper Cretaceous Shiranish Formation outcropped close to Bade village and Bekhere anticline, Kurdistan region at northern Iraq and consists of alternating mixed tough grey limestone, marly limestone, marl beds interpreted as a middle - outer shelf – upper bathyal environments (basinal) depositional environment. Fifteen thin sections were studied under a polarized microscope to find out the petrographic component, fauna content, and for microfacies analysis. The major petrographic constituents are fossils, bioclastic grains, micrite matrix, and extraclast (quartz grains). Planktic foraminifera and nannofossils are the major particles within wackestone and packstone microfacies types. The planktonic foraminifera biozones from previous study (such as Globotruncana aegyptiaca, Gansserina gansseri, Racemiguembelina fructicosa, Plummerita hantkeninoides) and the recorded calcareous nannofossils biozones of Broinsonia parca, Reinhardtites levis, Arkhangelskiella cymbiformis, suggest a late Campanian to late Maastrichtian age.
7
Roy, T., F. Lombard, L. Bopp, and M. Gehlen. "Projected impacts of climate change and ocean acidification on the global biogeography of planktonic Foraminifera." Biogeosciences 12, no. 10 (May 19, 2015): 2873–89. http://dx.doi.org/10.5194/bg-12-2873-2015.
Full textAbstract:
Abstract. Planktonic Foraminifera are a major contributor to the deep carbonate flux and their microfossil deposits form one of the richest databases for reconstructing paleoenvironments, particularly through changes in their taxonomic and shell composition. Using an empirically based planktonic foraminifer model that incorporates three known major physiological drivers of their biogeography – temperature, food and light – we investigate (i) the global redistribution of planktonic Foraminifera under anthropogenic climate change and (ii) the alteration of the carbonate chemistry of foraminiferal habitat with ocean acidification. The present-day and future (2090–2100) 3-D distributions of Foraminifera are simulated using temperature, plankton biomass and light from an Earth system model forced with a historical and a future (IPCC A2) high CO2 emission scenario. Foraminiferal abundance and diversity are projected to decrease in the tropics and subpolar regions and increase in the subtropics and around the poles. Temperature is the dominant control on the future change in the biogeography of Foraminifera. Yet food availability acts to either reinforce or counteract the temperature-driven changes. In the tropics and subtropics the largely temperature-driven shift to depth is enhanced by the increased concentration of phytoplankton at depth. In the higher latitudes the food-driven response partly offsets the temperature-driven reduction both in the subsurface and across large geographical regions. The large-scale rearrangements in foraminiferal abundance and the reduction in the carbonate ion concentrations in the habitat range of planktonic foraminifers – from 10–30 μmol kg−1 in their polar and subpolar habitats to 30–70 μmol kg−1 in their subtropical and tropical habitats – would be expected to lead to changes in the marine carbonate flux. High-latitude species are most vulnerable to anthropogenic change: their abundance and available habitat decrease and up to 10% of the volume of their habitat drops below the calcite saturation horizon.
8
Roy, T., F. Lombard, L. Bopp, and M. Gehlen. "Projected impacts of climate change and ocean acidification on the global biogeography of planktonic foraminifera." Biogeosciences Discussions 11, no. 6 (June 30, 2014): 10083–121. http://dx.doi.org/10.5194/bgd-11-10083-2014.
Full textAbstract:
Abstract. Planktonic foraminifera are a major contributor to the deep carbonate-flux and the planktonic biomass of the global ocean. Their microfossil deposits form one of the richest databases for reconstructing paleoenvironments, particularly through changes in their taxonomic and shell composition. Using an empirically-based foraminifer model that incorporates three known major physiological drivers of foraminifer biogeography – temperature, food and light – we investigate (i) the global redistribution of planktonic foraminifera under anthropogenic climate change, and (ii) the alteration of the carbonate chemistry of foraminifer habitat with ocean acidification. The present-day and future (2090–2100) 3-D distributions of foraminifera are simulated using temperature, plankton biomass, and light from an Earth system model forced with historical and a future (IPCC A2) high CO2 emission scenario. The broadscale patterns of present day foraminifer biogeography are well reproduced. Foraminifer abundance and diversity are projected to decrease in the tropics and subpolar regions and increase in the subtropics and around the poles. In the tropics, the geographical shifts are driven by temperature, while the vertical shifts are driven by both temperature and food availability. In the high-latitudes, vertical shifts are driven by food availability, while geographical shifts are driven by both food availability and temperature. Changes in the marine carbon cycle would be expected in response to (i) the large-scale rearrangements in foraminifer abundance, and (ii) the reduction of the carbonate concentration in the habitat range of planktonic foraminifers: from 10–30 μmol kg−1 in the polar/subpolar regions to 30–70 μmol kg−1 in the subtropical/tropical regions. High-latitude species are most vulnerable to anthropogenic change: their abundance and available habitat decrease and up to 10% of their habitat drops below the calcite saturation horizon.
9
Salmon, K. H., P. Anand, P. F. Sexton, and M. Conte. "Upper ocean mixing controls the seasonality of planktonic foraminifer fluxes and associated strength of the carbonate pump in the oligotrophic North Atlantic." Biogeosciences 12, no. 1 (January 13, 2015): 223–35. http://dx.doi.org/10.5194/bg-12-223-2015.
Full textAbstract:
Abstract. Oligotrophic regions represent up to 75% of Earth's open-ocean environments. They are thus areas of major importance in understanding the plankton community dynamics and biogeochemical fluxes. Here we present fluxes of total planktonic foraminifera and 11 planktonic foraminifer species measured at the Oceanic Flux Program (OFP) time series site in the oligotrophic Sargasso Sea, subtropical western North Atlantic Ocean. Foraminifera flux was measured at 1500 m water depth, over two ~ 2.5-year intervals: 1998–2000 and 2007–2010. We find that foraminifera flux was closely correlated with total mass flux, carbonate and organic carbon fluxes. We show that the planktonic foraminifera flux increases approximately 5-fold during the winter–spring, contributing up to ~ 40% of the total carbonate flux. This was primarily driven by increased fluxes of deeper-dwelling globorotaliid species, which contributed up to 90% of the foraminiferal-derived carbonate during late winter–early spring. Interannual variability in total foraminifera flux, and in particular fluxes of the deep-dwelling species (Globorotalia truncatulinoides, Globorotalia hirsuta and Globorotalia inflata), was related to differences in seasonal mixed layer dynamics affecting the strength of the spring phytoplankton bloom and export flux, and by the passage of mesoscale eddies. As these heavily calcified, dense carbonate tests of deeper-dwelling species (3 times denser than surface dwellers) have greater sinking rates, this implies a high seasonality of the biological carbonate pump in oligotrophic oceanic regions. Our data suggest that climate cycles, such as the North Atlantic Oscillation, which modulates nutrient supply into the euphotic zone and the strength of the spring bloom, may also in turn modulate the production and flux of these heavily calcified deep-dwelling foraminifera by increasing their food supply, thereby intensifying the biological carbonate pump.
10
Salmon, K. H., P. Anand, P. F. Sexton, and M. Conte. "Upper ocean mixing controls the seasonality of planktonic foraminifer fluxes and associated strength of the carbonate pump in the oligotrophic North Atlantic." Biogeosciences Discussions 11, no. 8 (August 12, 2014): 12223–54. http://dx.doi.org/10.5194/bgd-11-12223-2014.
Full textAbstract:
Abstract. Oligotrophic regions represent up to 75% of Earth's open-ocean environments, and are typically characterized by nutrient-limited upper-ocean mixed layers. They are thus areas of major importance in understanding the plankton community dynamics and biogeochemical fluxes. Here we present fluxes of total planktonic foraminifera and eleven planktonic foraminifer species from a bi-weekly sediment trap time series in the oligotrophic Sargasso Sea, subtropical western North Atlantic Ocean at 1500 m water depth, over two ∼2.5 year intervals, 1998–2000 and 2007–2010. Foraminifera flux was closely correlated with total mass flux and with carbonate and organic carbon fluxes. We show that the planktonic foraminifera flux increases approximately five-fold during the winter–spring, contributing up to ∼40% of the total carbonate flux, driven primarily by increased fluxes of deeper dwelling ("globorotaliid") species. Interannual variability in total foraminifera flux, and in particular fluxes of the deep dwelling Globorotalia truncatulinoides, Globorotalia hirsuta, Globorotalia inflata, were related to differences in seasonal mixed layer dynamics affecting the strength of the spring phytoplankton bloom and export flux, and by the passage of mesoscale eddies. The heavily calcified, dense carbonate tests of deeper dwelling species (3 times denser than surface dwellers) can contribute up to 90% of the foraminiferal-derived carbonate in this region during late winter-early spring, implying a high seasonality of the biological carbonate pump in oligotrophic oceanic regions. Our data suggest that climate cycles, such as the North Atlantic Oscillation, that modulate the depth of the mixed layer, intensity of nutrient upwelling and primary production could also modulate the strength of the biological carbonate pump in the oligotrophic North Atlantic.
11
Benyamovskiy, V. N., and L. F. Kopaevich. "Coniacian-Campanian Alan-Kyr section of the Mountainous Crimea: biostratigraphy and palaebiogeography." Moscow University Bulletin. Series 4. Geology, no. 2 (April 28, 2016): 3–17. http://dx.doi.org/10.33623/0579-9406-2016-2-3-17.
Full textAbstract:
This article is a continuation of study of the reference section Alan Kyr (Central Crimea, Belogorsk region). Recorded the difference in age between complexes dating of radiolarians and planktonic foraminifera and benthic foraminifera. A likely explanation for this can be assumed that in the Crimea stratigraphically important taxa could appear before f few million years. Than on the platform where they could migrate during major global eustatic transgression in the early Campanian age. The article discusses the impact of paleobiogeographical aspect on taxonomic composition of foraminiferal zonal complexes as plankton and benthos.
12
Hernitz Kučenjak, Morana, Vlasta Premec Fućek, Renata Slavković, and Ivan Mesić. "Planktonic Foraminiferal Biostratigraphy of the Late Eocene and Oligocene in the Palmyride Area, Syria." Geologia Croatica 59, no. 1 (2006): 19–39. http://dx.doi.org/10.4154/gc.2006.02.
Full textAbstract:
Three deep exploration wells in the Palmyride area (Syria) have beendrilled through Oligocene and Eocene deposits. A detailed micropalaeontological investigation has been performed on the planktonic foraminiferal assemblage from drill cuttings. Standard planktonic foraminiferal zones from P15 to P22 (E15 to O6) have been identified.The test morphology and diversity of the foraminiferal assemblageindicate a general cooling trend during the late Eocene andOligocene. The specialized Eocene forms (K-mode life strategy) suchas turborotaliids, globigerinathekids and hantkeninids become extinctin the uppermost late Eocene. The Oligocene is characterized by thedominance of cooler, opportunistic planktonic foraminifera (r-modelife strategy), such as pseudohastigerinids, chiloguembelinids, globigerinids and tenuitellids. A very low number of benthic foraminiferain late Eocene cuttings implies sedimentation in a deep, open seaenvironment. A gradual increase of the benthic foraminiferal proportionthrough the Oligocene indicates shallowing of the sedimentaryenvironment.
13
Zarkogiannis, Stergios D., Assimina Antonarakou, Vincent Fernandez, P. Graham Mortyn, George Kontakiotis, Hara Drinia, and Mervyn Greaves. "Evidence of Stable Foraminifera Biomineralization during the Last Two Climate Cycles in the Tropical Atlantic Ocean." Journal of Marine Science and Engineering 8, no. 10 (September 24, 2020): 737. http://dx.doi.org/10.3390/jmse8100737.
Full textAbstract:
Planktonic foraminiferal biomineralization intensity, reflected by the weight of their shell calcite mass, affects global carbonate deposition and is known to follow climatic cycles by being increased during glacial stages and decreased during interglacial stages. Here, we measure the dissolution state and the mass of the shells of the planktonic foraminifera species Globigerina bulloides from a Tropical Eastern North Atlantic site over the last two glacial–interglacial climatic transitions, and we report no major changes in plankton calcite production with the atmospheric pCO2 variations. We attribute this consistency in foraminifera calcification to the climatic and hydrological stability of the tropical regions. However, we recorded increased shell masses midway through the penultimate deglaciation (Termination II). In order to elucidate the cause of the increased shell weights, we performed δ18O, Mg/Ca, and μCT measurements on the same shells from a number of samples surrounding this event. Compared with the lighter ones, we find that the foraminifera of increased weight are internally contaminated by sediment infilling and that their shell masses respond to local surface seawater density changes.
14
Morard, Raphaël, Franck Lejzerowicz, Kate F. Darling, Béatrice Lecroq-Bennet, Mikkel Winther Pedersen, Ludovic Orlando, Jan Pawlowski, Stefan Mulitza, Colomban de Vargas, and Michal Kucera. "Planktonic foraminifera-derived environmental DNA extracted from abyssal sediments preserves patterns of plankton macroecology." Biogeosciences 14, no. 11 (June 6, 2017): 2741–54. http://dx.doi.org/10.5194/bg-14-2741-2017.
Full textAbstract:
Abstract. Deep-sea sediments constitute a unique archive of ocean change, fueled by a permanent rain of mineral and organic remains from the surface ocean. Until now, paleo-ecological analyses of this archive have been mostly based on information from taxa leaving fossils. In theory, environmental DNA (eDNA) in the sediment has the potential to provide information on non-fossilized taxa, allowing more comprehensive interpretations of the fossil record. Yet, the process controlling the transport and deposition of eDNA onto the sediment and the extent to which it preserves the features of past oceanic biota remains unknown. Planktonic foraminifera are the ideal taxa to allow an assessment of the eDNA signal modification during deposition because their fossils are well preserved in the sediment and their morphological taxonomy is documented by DNA barcodes. Specifically, we re-analyze foraminiferal-specific metabarcodes from 31 deep-sea sediment samples, which were shown to contain a small fraction of sequences from planktonic foraminifera. We confirm that the largest portion of the metabarcode originates from benthic bottom-dwelling foraminifera, representing the in situ community, but a small portion (< 10 %) of the metabarcodes can be unambiguously assigned to planktonic taxa. These organisms live exclusively in the surface ocean and the recovered barcodes thus represent an allochthonous component deposited with the rain of organic remains from the surface ocean. We take advantage of the planktonic foraminifera portion of the metabarcodes to establish to what extent the structure of the surface ocean biota is preserved in sedimentary eDNA. We show that planktonic foraminifera DNA is preserved in a range of marine sediment types, the composition of the recovered eDNA metabarcode is replicable and that both the similarity structure and the diversity pattern are preserved. Our results suggest that sedimentary eDNA could preserve the ecological structure of the entire pelagic community, including non-fossilized taxa, thus opening new avenues for paleoceanographic and paleoecological studies.
15
Petró, Sandro M., María A. G. Pivel, and João C. Coimbra. "Foraminiferal Solubility Rankings: a Contribution To the Search For Consensus." Journal of Foraminiferal Research 48, no. 4 (October 29, 2018): 301–13. http://dx.doi.org/10.2113/gsjfr.48.4.301.
Full textAbstract:
Abstract Factors intrinsic to foraminiferal tests result in different degrees of susceptibility to dissolution. Differential resistance to dissolution among planktonic foraminifera has been studied in several regions, but no previous work has been reported for the western South Atlantic. The goal of this research was to develop a dissolution susceptibility ranking for planktonic foraminifera from the western South Atlantic Ocean, to compare the solubility between benthic and planktonic foraminifera, and to evaluate changes in the oxygen isotopic signal (δ18O) associated with dissolution. Two experiments were carried out by immersing tests in acetic acid or distilled water for 200 days. Our comparison revealed that tests of planktonic foraminifera were more resistant to dissolution than the benthic species tested, which has implications for use of the planktonic/benthic ratio (P/B) as a preservation proxy. Solubility of tests is directly proportional to the Mg content in the calcite structure, which varies widely across benthic taxa but is consistently low in planktonics. The δ18O increased during dissolution, probably due to the preferential dissolution of the internal chambers, making the remaining calcite progressively reflect the composition of the last chambers. Our solubility ranking for planktonic foraminifera agreed in part with rankings for foraminifera from other regions. Neogloboquadrina pachyderma and Globorotalia inflata proved to be resistant species; Globigerinella calida, Globigerinella siphonifera, Globorotalia hirsuta, Candeina nitida, and Trilobatus trilobus were moderately resistant; and Globorotalia fimbriata and Orbulina universa were most susceptible to dissolution. Presence and condition of benthic genera such as Quinqueloculina, Hoeglundina and Bulimina, and the planktonic species O. universa can be used to indicate limited dissolution in paleoceanographic studies. Small variations in the dissolution index may also reflect oceanographic changes that influence the composition of the tests, indicating the importance of regional solubility rankings, such as this study for the western South Atlantic.
16
Fang, Peiyue, Bo Xu, Brian T. Huber, Shijia Liu, Youhua Zhu, and Hui Luo. "Late Campanian to early Maastrichtian planktonic foraminiferal assemblages from Cretaceous oceanic red beds (CORBs) in the Yongla section, Gyangze, southern Tibet." Micropaleontology 66, no. 2 (2020): 85–102. http://dx.doi.org/10.47894/mpal.66.2.01.
Full textAbstract:
Well-preserved and abundant planktonic foraminifera have been recovered from limestones of the Cretaceous oceanic red beds (CORBs) from the Yongla section in Gyangze, southern Tibet. This foraminiferal assemblage is dominated by species of Contusotruncana, Globotruncana, and Globotruncanita. The assemblage contains 21 species belonging to 7 genera and suggests a late Campanian to early Maastrichtian age, which permits amore precise age constraint for CORBs in the Gyangze area. This planktonic assemblage provides an important biostratigraphic datum for the correlations of theCORBs in theHimalayan region of the northern Tethys. The interval yielding foraminifers in the Yongla section may be the youngest known CORB in the Gyangze area.
17
Kalanat, Behnaz, Mohammad Vahidinia, Hossein Vaziri-Moghaddam, and Mohamad Hossein Mahmudy-Gharaie. "Planktonic foraminiferal turnover across the Cenomanian – Turonian boundary (OAE2) in the northeast of the Tethys realm, Kopet-Dagh Basin." Geologica Carpathica 67, no. 5 (October 1, 2016): 451–62. http://dx.doi.org/10.1515/geoca-2016-0028.
Full textAbstract:
Abstract Two Late Cenomanian – Early Turonian (C–T) intervals of the eastern part of the Kopet-Dagh basin, NE Iran have been investigated to evaluate the response of planktonic foraminifera to the geological event OAE2. The Gharesu and Taherabad sections with the thicknesses of 30 m and 22.5 m are composed of shale and marl interbedded with glauconitic sandstone. Three biozones Rotalipora cushmani, Whiteinella archaeocretacea and Helvetoglobotruncana helvetica were recognized based on study of planktonic foraminifera, in these sections. We observed the patterns of planktonic foraminiferal assemblage changes around the C–T boundary and divided this succession into several successive intervals. This study confirms that OAE2 was a long term event. A gradual perturbation in the study successions starts in the interval 1 with low abundance and diversity of planktonic foraminifera. An enhanced oxygen minimum zone (OMZ) occurs in the interval 3 which coincides with a temporary absence of planktonic foraminifera and sedimentation of framboidal pyrite. High diversity of planktonic foraminifera and appearance of new genera in the interval 5 indicate return of normal conditions to the basin. A significant short-term sea surface temperature cooling is also indicated by planktonic foraminiferal turnover and carbonate contents in the interval 2 which is comparable with other parts of the Tethys Ocean, Boreal sea and Atlantic region.
18
Ando, Atsushi, Brian T. Huber, and Kenneth G. MacLeod. "Depth-habitat reorganization of planktonic foraminifera across the Albian/Cenomanian boundary." Paleobiology 36, no. 3 (2010): 357–73. http://dx.doi.org/10.1666/09027.1.
Full textAbstract:
New mid-Cretaceous stable isotope (δ18O and δ13C) records of multiple planktonic foraminiferal species and coexisting coccoliths from Blake Nose (western North Atlantic) document a major depth-ecology reorganization of planktonic foraminifera. Across the Albian/Cenomanian boundary, deep-dwellingPraeglobotruncana stephaniandRotalipora globotruncanoidesadapted to living at a shallower depth, while, at the same time, the population of surface-dwellingParacostellagerina libycadeclined. Subsequently, the opportunistic speciesHedbergella delrioensisshifted to a deep environment, and the deep-dwelling formsRotalipora montsalvensisandRotalipora reichelifirst appeared. The primary paleoenvironmental cause of the observed changes in planktonic adaptive strategies is uncertain, yet their coincidence with an earliest Cenomanian cooling trend reported elsewhere implicates the importance of reduced upper-ocean stratification. Although there has been an implicit assumption that the species-specific depth habitats of fossil planktonic foraminifera were invariant through time, planktonic paleoecology is a potential variable. Accordingly, the possibility of evolutionary changes in planktonic foraminiferal depth ecology should be a primary consideration (along with other environmental parameters) in paleoceanographic interpretations of foraminiferal stable isotope data.
19
Pracht, Hilde, Brett Metcalfe, and Frank J. C. Peeters. "Oxygen isotope composition of the final chamber of planktic foraminifera provides evidence of vertical migration and depth-integrated growth." Biogeosciences 16, no. 2 (February 1, 2019): 643–61. http://dx.doi.org/10.5194/bg-16-643-2019.
Full textAbstract:
Abstract. The translation of the original seawater signal (i.e. ambient temperature and δ18Osw) into distinct chambers of a single shell of a foraminifer during calcification can influence our interpretation of surface ocean conditions of the past, when based upon oxygen and carbon stable isotope geochemistry. In this study three different hypotheses were tested to gain more insight into biological and ecological processes that influence the resultant composition of stable isotopes of oxygen (δ18O) in the shells of planktonic foraminifera. These hypotheses were related to the shell size; the differences in isotopic composition between the final chamber and the remaining shell; and the differences between different species. Shells of Trilobatus sacculifer, Globigerinoides ruber white and Neogloboquadrina dutertrei were picked from the top of multi-core GS07-150-24, of modern age, offshore of north-eastern Brazil (3∘46.474′ S, 37∘03.849′ W) and analysed for single-shell and single-chamber stable isotope analysis. We show that the mean value of δ18O of the final chambers (δ18OF) is 0.2 ‰ ± 0.4 ‰ (1σ) higher than the mean value δ18O of the test minus the final chamber (δ18O<F) of T. sacculifer. The formation of the final chamber happens at temperatures that are approximately 1 ∘C cooler than the chambers formed prior, suggesting both ontogenetic depth migration to deeper water and a potential offset from the surface signal. Furthermore, we show that there is no statistical difference in the δ18Osacculifer values of shells of three different size classes of T. sacculifer, although the pattern between the different size classes indicates depth migration during the life and growth of T. sacculifer. Comparison of vital effect corrected δ18Oshell between T. sacculifer, G. ruber white and N. dutertrei suggests that G. ruber has a slightly shallower depth habitat (∼90–120 m) compared to the other two species (∼100–130 m). Disentangling depth vs. seasonal habitat is complicated given the commonality between isotope values from similar depths but different seasons; for instance, the same average isotope value will have a shallower depth habitat in May than September. Calculation of seasonal-depth habitat was therefore tested. Our results highlight the complicated nature of interpreting oxygen isotopes even for the modern record.
20
Karmini, Mimin, and H. Yuniarto. "BIOSTRATIGRAFI FORAMINIFERA KUARTER PADA BOR INTI MD 982152 DAN 982155 DARI SAMUDRA HINDIA." JURNAL GEOLOGI KELAUTAN 11, no. 2 (February 16, 2016): 55. http://dx.doi.org/10.32693/jgk.11.2.2013.231.
Full textAbstract:
Dari bor inti pada EKSPEDISI IMAGES, di Samudra Hindia, telah diteliti sebanyak 21 percontoh sedimen dari lokasi MD 982152, dan 29 buah dari lokasi MD 982155 untuk kepentingan biostratigrafi berdasarkan analisis foraminifera plankton dalam interval 1,5 meter.
Pada kedua penampang bor inti tersebut hanya dijumpai satu zona foraminifera plankton Kuarter, yaitu Zona Globorotalia truncatulinoides. Untuk MD 982152, zona ini bisa dibagi ke dalam dua subzona, yakni Subzona-subzona Globorotalia crassaformis hessi dan Globigerinella calida, sedangkan untuk MD 982155, zona tersebut bisa dibagi lagi ke dalam tiga subzona, yakni Subzona-subzona Globorotalia crassaformis hessi Globigerinella calida, dan Beella digitata.
Kejadian yang signifikan di kedua penampang itu adalah Datum Pemunculan Pertama dari Globigerinella calida dan Pemunculan Akhir dari Globorotalia crassaformis hessi. Pada MD 982155, dijumpai Pemunculan Pertama dari Beella digitata.
Kata kunci: foraminifera plankton, Kuarter, biostratigrafi, Samudra Hindia.
From IMAGES Expedition in Indian Ocean, 21 samples from MD 982152, and 29 samples from MD 982155 had been studied for the purpose of biostratigraphy based on planktonic foraminifera within 1,5 meter interval.
In both sections, only one Quaternary zone is found, namely Globorotalia truncatulinoides Zone. For MD 982152, that zone can be subdivided into two interval subzones e.g. Globorotalia crassaformis hessi and Globigerinella calida calida. However, in MD 982155 Globorotalia truncatulinoides Zone can be subdivided into three subzones namely, Globorotalia crassaformis hessi, Globigerinella calida calida, and Beella digitata Subzones.
The planktonic foraminifera event revealed in both sections are the First Appearance Datum (FAD) of Globigerinella calida calida and the Last Appearance (LAD) of Globorotalia crassaformis hessi. In MD 982155 the FAD of Beella digitata is found.
Keywords: planktonic foraminifera, Quaternary, biostratigraphy, Indian Ocean.
21
Babazadeh, Seyed Ahmad, and Dominique Cluzel. "Biostratigraphy and paleoenvironmental significance of Paleogene foraminiferal assemblages from Dashte Zari area in High Zagros, West Iran." Revista Brasileira de Paleontologia 25, no. 3 (November 26, 2022): 189–207. http://dx.doi.org/10.4072/rbp.2022.3.03.
Full textAbstract:
The Paleogene carbonate deposits of Pabdeh and Jahrum formations are widespread from the northwest (Dashte Zari area) to the southwest of the Shahrekord region in the High Zagros Mountains of Iran and record the lateral and upward transition from open marine into the shallow water environment. The Pabdeh Formation shows a succession of open marine pelagic and hemipelagic limestone, argillaceous limestone, and argillaceous chert. It consists of planktonic wackestone, pellet-planktonic wackestone, mudstone with planktonic foraminifera, and radiolarian siliceous wackestone, which accumulated within the Zagros Foreland Basin. The planktonic foraminifers are assigned to the Late Paleocene–Late Eocene and correspond to subtropical and tropical Zones P4b–E15. The Jahrum Formation is represented by bioclast-bearing limestone and calcarenite. It consists of benthic foraminiferal wackestone, benthic foraminiferal-red algal packstone, and bioclast-intraclast packstone deposited in a shallow platform environment. The Jahrum Formation is inter-fingered in the upper part of the Pabdeh Formation and finally overlies it conformably during the Bartonian–Priabonian. Shallowing and off-lap relationships record basin shrinking, while repeated inter-fingering signals moderate tectonic subsidence. Both formations are disconformably covered by the Late Oligocene–Miocene Asmari Formation. Keywords: biostratigraphy, Pabdeh Formation, Zagros, Paleogene, Iran.
22
Brummer, Geert-Jan A., and Michal Kučera. "Taxonomic review of living planktonic foraminifera." Journal of Micropalaeontology 41, no. 1 (March 11, 2022): 29–74. http://dx.doi.org/10.5194/jm-41-29-2022.
Full textAbstract:
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.
23
Galeotti, Simone, Eugenia Angori, Rodolfo Coccioni, Gabriella Ferrari, Bruno Galbrun, Simonetta Monechi, Isabella Premoli Silva, Robert Speijer, and Bruno Turi. "Integrated stratigraphy across the Paleocene/Eocene boundary in the Contessa Road section, Gubbio (central Italy)." Bulletin de la Société Géologique de France 171, no. 3 (May 1, 2000): 355–65. http://dx.doi.org/10.2113/171.3.355.
Full textAbstract:
Abstract An integrated stratigraphic study of the upper Paleocene to lower Eocene Scaglia limestones of the Contessa Road section has allowed us to identify the classical markers of the Paleocene-Eocene transition. The section provides a good magnetostratigraphic record as well as a continuous calcareous nannofossil and foraminiferal biostratigraphy. A negative Carbon Isotopic Excursion (CIE) occurs in the lower part of Chron C24r. The calibration to calcareous plankton zonation indicates that the CIE occurs in the lowermost part of calcareous nannofossil Zone NP10 and the upper part of Zone CP8, that is in the planktonic foraminiferal Zone P5. In the same stratigraphic interval, a distinct turnover in the calcareous benthic foraminifera and a sharp change in the Deep Water Agglutinated Foraminiferal (DWAF) assemblages have been recognised. The record of DWAF, however, indicates a gradual initiation of such a change beginning some 150 k.y. before the CIE and BEE.
24
Boscolo-Galazzo, Flavia, Amy Jones, Tom Dunkley Jones, Katherine A. Crichton, Bridget S. Wade, and Paul N. Pearson. "Late Neogene evolution of modern deep-dwelling plankton." Biogeosciences 19, no. 3 (February 8, 2022): 743–62. http://dx.doi.org/10.5194/bg-19-743-2022.
Full textAbstract:
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.
25
Burke, Janet E., Willem Renema, Michael J. Henehan, Leanne E. Elder, Catherine V. Davis, Amy E. Maas, Gavin L. Foster, Ralf Schiebel, and Pincelli M. Hull. "Factors influencing test porosity in planktonic foraminifera." Biogeosciences 15, no. 21 (November 7, 2018): 6607–19. http://dx.doi.org/10.5194/bg-15-6607-2018.
Full textAbstract:
Abstract. The clustering of mitochondria near pores in the test walls of foraminifera suggests that these perforations play a critical role in metabolic gas exchange. As such, pore measurements could provide a novel means of tracking changes in metabolic rate in the fossil record. However, in planktonic foraminifera, variation in average pore area, density, and porosity (the total percentage of a test wall that is open pore space) have been variously attributed to environmental, biological, and taxonomic drivers, complicating such an interpretation. Here we examine the environmental, biological, and evolutionary determinants of pore characteristics in 718 individuals, representing 17 morphospecies of planktonic foraminifera from 6 core tops in the North Atlantic. Using random forest models, we find that porosity is primarily correlated to test surface area, test volume, and habitat temperature, key factors in determining metabolic rates. In order to test if this correlation arose spuriously through the association of cryptic species with distinct biomes, we cultured Globigerinoides ruber in three different temperature conditions, and found that porosity increased with temperature. Crucially, these results show that porosity can be plastic: changing in response to environmental drivers within the lifetime of an individual foraminifer. This demonstrates the potential of porosity as a proxy for foraminiferal metabolic rates, with significance for interpreting geochemical data and the physiology of foraminifera in non-analog environments. It also highlights the importance of phenotypic plasticity (i.e., ecophenotypy) in accounting for some aspects of morphological variation in the modern and fossil record.
26
Carreno, Analuisa L., J. Ledesma-Vazquez, C. F. Hernandez-Perez, and F. R. Gio-Argaez. "Microfossils from the Early Pliocene Carmen Formation, Monserrat Island, Baja California Sur, Mexico." Micropaleontology 61, no. 3 (2015): 199–225. http://dx.doi.org/10.47894/mpal.61.3.07.
Full textAbstract:
A stratigraphic section measured in the northern area of Monserrat Island, Baja California Sur, yielded abundant moderate to well-preserved benthic foraminifers, rare planktonic foraminifers, calcareous nannoplankton, and ostracods. Based on both planktonic microfossils, relative age situates the base of the section from the Uppermost Miocene to Lower Pliocene, while the top is Upper Zanclean (around 5.06-3.3 Ma). The abundant benthic foraminifer assemblage is characterized by small tests and a few dominant species, i.e. Bolivinella seminuda, Brizalina subadvena and Brizalina interjuncta. The foraminifers are characterized as low-oxygen-related biofacies; the absence of heavily calcified fauna suggests that oxygen concentration of the bottom water was <0.3 ml/L. The presence of abundant pristine foraminiferal tests typical of an upper bathyal biofacies such as Planulina ornata, along with features considered as adaptations to low-oxygen conditions, suggest that the upper limit of the oxygen minimum zone was shallow, at a water depth of probably around 150m.
27
Grigoratou, Maria, Fanny M. Monteiro, Daniela N. Schmidt, Jamie D. Wilson, Ben A. Ward, and Andy Ridgwell. "A trait-based modelling approach to planktonic foraminifera ecology." Biogeosciences 16, no. 7 (April 10, 2019): 1469–92. http://dx.doi.org/10.5194/bg-16-1469-2019.
Full textAbstract:
Abstract. Despite the important role of planktonic foraminifera in regulating the ocean carbonate production and their unrivalled value in reconstructing paleoenvironments, our knowledge on their ecology is limited. A variety of observational techniques such as plankton tows, sediment traps and experiments have contributed to our understanding of foraminifera ecology. But, fundamental questions around costs and benefits of calcification and the effect of nutrients, temperature and ecosystem structure on these organisms remain unanswered. To tackle these questions, we take a novel mechanistic approach to study planktonic foraminifera ecology based on trait theory. We develop a zero-dimensional (0-D) trait-based model to account for the biomass of prolocular (20 µm) and adult (160 µm) stages of non-spinose foraminifera species and investigate their potential interactions with phytoplankton and other zooplankton under different temperature and nutrient regimes. Building on the costs and benefits of calcification, we model two ecosystem structures to explore the effect of resource competition and temperature on planktonic foraminifera biomass. By constraining the model results with ocean biomass estimations of planktonic foraminifera, we estimate that the energetic cost of calcification could be about 10 %–50 % and 10 %–40 % for prolocular and adult stages respectively. Our result suggest that the shell provides protection against processes other than predation (e.g. pathogen invasion). We propose that the low standing biomass of planktonic foraminifera plays a key role in their survival from predation, along with their shell protection. Our model suggests a shift from temperature as a main regulator of foraminifera biomass in the early developmental stage to resource competition for adult biomass.
28
Aurahs, Ralf, Markus GÖker, Guido W. Grimm, Vera Hemleben, Christoph Hemleben, Ralf Schiebel, and Michal Kučera. "Using the Multiple Analysis Approach to Reconstruct Phylogenetic Relationships among Planktonic Foraminifera from Highly Divergent and Length-polymorphic SSU rDNA Sequences." Bioinformatics and Biology Insights 3 (January 2009): BBI.S3334. http://dx.doi.org/10.4137/bbi.s3334.
Full textAbstract:
The high sequence divergence within the small subunit ribosomal RNA gene (SSU rDNA) of foraminifera makes it difficult to establish the homology of individual nucleotides across taxa. Alignment-based approaches so far relied on time-consuming manual alignments and discarded up to 50% of the sequenced nucleotides prior to phylogenetic inference. Here, we investigate the potential of the multiple analysis approach to infer a molecular phylogeny of all modern planktonic foraminiferal taxa by using a matrix of 146 new and 153 previously published SSU rDNA sequences. Our multiple analysis approach is based on eleven different automated alignments, analysed separately under the maximum likelihood criterion. The high degree of congruence between the phylogenies derived from our novel approach, traditional manually homologized culled alignments and the fossil record indicates that poorly resolved nucleotide homology does not represent the most significant obstacle when exploring the phylogenetic structure of the SSU rDNA in planktonic foraminifera. We show that approaches designed to extract phylogenetically valuable signals from complete sequences show more promise to resolve the backbone of the planktonic foraminifer tree than attempts to establish strictly homologous base calls in a manual alignment.
29
Roche, Didier M., Claire Waelbroeck, Brett Metcalfe, and Thibaut Caley. "FAME (v1.0): a simple module to simulate the effect of planktonic foraminifer species-specific habitat on their oxygen isotopic content." Geoscientific Model Development 11, no. 9 (September 3, 2018): 3587–603. http://dx.doi.org/10.5194/gmd-11-3587-2018.
Full textAbstract:
Abstract. The oxygen-18 to oxygen-16 ratio recorded in fossil planktonic foraminifer shells has been used for over 50 years in many geoscience applications. However, different planktonic foraminifer species generally yield distinct signals, as a consequence of their specific living habitats in the water column and along the year. This complexity is usually not taken into account in model–data integration studies. To overcome this shortcoming, we developed the Foraminifers As Modeled Entities (FAME) module. The module predicts the presence or absence of commonly used planktonic foraminifers and their oxygen-18 values. It is only forced by hydrographic data and uses a very limited number of parameters, almost all derived from culture experiments. FAME performance is evaluated using the Multiproxy Approach for the Reconstruction of the Glacial Ocean surface (MARGO) Late Holocene planktonic foraminifer calcite oxygen-18 and abundance datasets. The application of FAME to a simple cooling scenario demonstrates its utility to predict changes in planktonic foraminifer oxygen-18 to oxygen-16 ratio in response to changing climatic conditions.
30
Bragina, L. G., N. Yu Bragin, L. F. Kopaevich, and V. N. Beniamovsky. "SANTONIAN RADIOLARIANS AND FORAMINIFERS FROM BREŽĐE SECTION, WESTERN SERBIA." Moscow University Bulletin. Series 4. Geology, no. 3 (June 28, 2018): 12–24. http://dx.doi.org/10.33623/0579-9406-2018-3-12-24.
Full textAbstract:
New data on the radiolarians and foraminifers (planktonic and benthic) from the lower part of Struganik limestones (Brežđe Section, Western Serbia) were presented. Radiolarian data show the presence of Afens perapediensis Zone (uppermost Santonian) [Bragina, 2016]. Planktonic foraminifers are represented by abundant Marginotruncana (extinct in latest Santonian) and Globotruncana linneiana (d’Orbigny) (appear in early Santonian). Radiolarian and planktonic and benthic foraminiferal data agree with one another.
31
Bordiga, M., J. Henderiks, F. Tori, S. Monechi, R. Fenero, and E. Thomas. "The Eocene–Oligocene transition at ODP Site 1263, Atlantic Ocean: decreases in nannoplankton size and abundance and correlation with benthic foraminiferal assemblages." Climate of the Past Discussions 11, no. 3 (May 7, 2015): 1615–64. http://dx.doi.org/10.5194/cpd-11-1615-2015.
Full textAbstract:
Abstract. The biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene–Oligocene transition (~34.8–32.7 Ma) was investigated at high resolution at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, South East Atlantic Ocean), and compared with a lower resolution benthic foraminiferal record. During this time interval, the global climate which had been warm during the Eocene, under high levels of atmospheric CO2 (pCO2), transitioned into the cooler climate of the Oligocene, with overall lower pCO2. At Site 1263, the absolute nannofossil abundance (coccoliths per gram of sediment; N g−1) and the mean coccolith size decreased distinctly across the E–O boundary (EOB; 33.89 Ma), mainly due to a sharp decline in abundance of large-sized Reticulofenestra and Dictyococcites, within ~53 kyr. Since carbonate dissolution did not vary much across the EOB, the decrease in abundance and size of nannofossils may highlight an overall decrease in their export production, which could have led to an increased ratio of organic to inorganic carbon (calcite) burial, as well as variations in the food availability for benthic foraminifers. The benthic foraminiferal assemblage data show the global decline in abundance of rectilinear species with complex apertures in the latest Eocene (~34.5 Ma), potentially reflecting changes in the food source, thus phytoplankton, followed by transient increased abundance of species indicative of seasonal delivery of food to the sea floor (Epistominella spp.; ~34.04–33.54 Ma), with a short peak in overall food delivery at the EOB (buliminid taxa; ~33.9 Ma). After Oi-1 (starting at ~33.4 Ma), a high abundance of Nuttallides umbonifera indicates the presence of more corrosive bottom waters, possibly combined with less food arriving at the sea floor. The most important signals in the planktonic and benthic communities, i.e. the marked decrease of large reticulofenestrids, extinctions of planktonic foraminifer species and more pronounced seasonal influx of organic matter, preceded the major expansion of the Antarctic ice sheet (Oi-1) by ~440 kyr. During Oi-1, our data show no major change in nannofossil abundance or assemblage composition occurred at Site 1263, although benthic foraminifera indicate more corrosive bottom waters following this event. Marine plankton thus showed high sensitivity to fast-changing conditions, possibly enhanced but pulsed nutrient supply, during the early onset of latest Eocene-earliest Oligocene climate change, or to a threshold in these changes (e.g. pCO2 decline, high-latitude cooling and ocean circulation).
32
Smith, Andrew J., Stephen J. Gallagher, Malcolm Wallace, Guy Holdgate, Jim Daniels, and Jock Keene. "The Recent temperate foraminiferal biofacies of the Gippsland Shelf: an analogue for Neogene environmental analyses in southeastern Australia." Journal of Micropalaeontology 20, no. 2 (December 1, 2001): 127–42. http://dx.doi.org/10.1144/jm.20.2.127.
Full textAbstract:
Abstract. This study describes the foraminiferal biofacies of a temperate stenohaline shelf and associated euryhaline marine lakes of Gippsland in southeast Australia. The study incorporates facies analyses and interpretations of three types of foraminiferal distributional data: forms alive at the time of collection, recently dead forms and relict forms. Four principal biofacies types occur: (1) the euryhaline marine Gippsland Lakes silts and sands; (2) inner shelf medium to coarse quartz-rich sands and bioclastic silty sands; (3) medium shelf bryozoan-rich bioclastic silt and silty sand; (4) outer shelf bryozoan- and plankton-rich silts and fine sands.The euryhaline marine Gippsland Lakes silts and sands contain abundant Ammonia beccarii and Eggerella, with minor Quinqueloculina, Elphidium and Discorbinella. The Gippsland inner shelf biofacies (0–50 m depths) consists of medium to coarse quartz-rich sands and bioclastic silty sand. Abundant living, relict and recently dead miliolids occur in the inner shelf with rare planktonic forms. Common planktonic foraminifera, with Cibicides, Parrellina, Elphidium and Lenticulina and relict forms occur in the bryozoan-rich bioclastic silt and silty sand of the Gippsland middle shelf (50–100 m depth). Bryozoan and plankton-rich silts and fine sand occur in the outer shelf to upper slope facies (100–300 m) below swell wave base on the Gippsland Shelf. A diverse fauna with common textulariids, Uvigerina, Bulimina, Anomalinoides and Astrononion and rare relict forms, occurs in this biofacies. Planktonic foraminifera and Uvigerina are most abundant at the shelf break due to local upwelling at the head of the Bass Canyon.Estimates of faunal production rates from live/dead ratios and full assemblage data suggest that the fauna of the Gippsland Shelf has not been significantly reworked by wave and/or bioturbation processes. Most relict foraminifera occur in the inner shelf, with minor relict forms in the middle to outer shelf. This pattern is similar to other shelf regions in Australia, where shelf areas were exposed during Pleistocene lowstand times, principally reworking pre-existing inner to middle shelf faunas. Correspondence analyses of the foraminiferal data yield a clear depth-related distribution of the faunal assemblage data. Most of the modern Gippsland Shelf fauna are cosmopolitan species and nearly a third are (semi-)endemic taxa suitable for regional palaeo-environmental studies. From biostratigraphic studies it is clear that the modern Gippsland foraminiferal assemblage evolved since Early Miocene times, with most elements present by the Late Miocene. Hence, the Recent Gippsland Shelf foraminiferal biofacies distribution is a good analogue for Neogene palaeo-environmental studies in the region. The longer ranging pre-Miocene mixture of epifaunal and infaunal taxa are deeper shelf cosmopolitan forms and are inferred to be more conservative since they evolved in relatively lower stress environments, typifying mesotrophic to eutrophic conditions compared to inner shelf epifaunal forms with ecological niches markedly affected by sea-level and temperature fluctuations in zones of constant wave action, in oligotrophic environments.The foraminiferal and facies analogues of this study on the Gippsland Shelf can be used for palaeo-environmental analyses of the Gippsland and Otway Neogene sedimentary successions. Such improvements will lead ultimately to a better understanding of the evolution of the neritic realm in southeastern Australia, an area facing the evolving Southern Ocean during the Cenozoic.
33
Davis, Catherine V., Tessa M. Hill, Ann D. Russell, Brian Gaylord, and Jaime Jahncke. "Seasonality in planktic foraminifera of the central California coastal upwelling region." Biogeosciences 13, no. 18 (September 16, 2016): 5139–50. http://dx.doi.org/10.5194/bg-13-5139-2016.
Full textAbstract:
Abstract. The close association between planktic foraminiferal assemblages and local hydrography make foraminifera invaluable proxies for environmental conditions. Modern foraminiferal seasonality is important for interpreting fossil distributions and shell geochemistry as paleoclimate proxies. Understanding this seasonality in an active upwelling area is also critical for anticipating which species may be vulnerable to future changes in upwelling intensity and ocean acidification. Two years (2012–2014) of plankton tows, along with conductivity–temperature–depth profiles and carbonate chemistry measurements taken along the north-central California shelf, offer new insights into the seasonal dynamics of planktic foraminifera in a seasonal coastal upwelling regime. This study finds an upwelling affinity for Neogloboquadrina pachyderma as well as a seasonal and upwelling associated alternation between dominance of N. pachyderma and Neogloboquadrina incompta, consistent with previous observations. Globigerina bulloides, however, shows a strong affinity for non-upwelled waters, in contrast to findings in Southern California where the species is often associated with upwelling. We also find an apparent lunar periodicity in the abundances of all species and document the presence of foraminifera even at very low saturation states of calcite.
34
Georgescu, Marius Dan. "SantonianCampanian planktonic foraminifera in the New Jersey coastal plain and their distribution related to the relative sea-level changes." Canadian Journal of Earth Sciences 43, no. 1 (January 1, 2006): 101–20. http://dx.doi.org/10.1139/e05-090.
Full textAbstract:
The Upper Cretaceous (SantonianCampanian) sediments of the New Jersey coastal plain subsurface yielded rich planktonic foraminiferal assemblages at certain stratigraphic levels in three wells: Ocean Drilling Program (ODP) Leg 174AX at Bass River and Ancora sites and a United States Geological Survey borehole in Freehold. Relative sea-level fluctuations can be recognized by following the presence or absence and amounts of two groups of planktonic foraminifers, the shallow water and deep water faunas. The former consists of globular-chambered species, while the complicated tests showing keels, heavy ornamentation and elaborated umbilical structures are confined to the latter. The Merchantville (late Santonian) and Marshalltown (early late Campanian) formations, which represent transgressive system tracts, show the richest and most diverse planktonic foraminiferal assemblages. In the highstand system tracts, represented by the Woodbury (early Campanian), lower Englishtown (middle Campanian), Wenonah (late Campanian), and Mount Laurel (late Campanian) respectively, a gradual decrease in the planktonic foraminiferal diversity and richness was observed. Planktonic foraminiferal peaks of lower amplitude are recorded in the proximity of the minor flooding surfaces. A five-fold planktonic foraminiferal zonal framework for the Santonian-Campanian stratigraphic interval is proposed. Paleobathymetry strongly influenced the planktonic foraminiferal distribution and biostratigraphic resolution.
35
Tapia, Raúl, Sze Ling Ho, Hui-Yu Wang, Jeroen Groeneveld, and Mahyar Mohtadi. "Contrasting vertical distributions of recent planktic foraminifera off Indonesia during the southeast monsoon: implications for paleoceanographic reconstructions." Biogeosciences 19, no. 13 (July 7, 2022): 3185–208. http://dx.doi.org/10.5194/bg-19-3185-2022.
Full textAbstract:
Abstract. Planktic foraminifera are widely used in paleoceanographic and paleoclimatic studies. The accuracy of such reconstructions depends on our understanding of the organisms' ecology. Here we report on field observations of planktic foraminiferal abundances (>150 µm) from five depth intervals between 0–500 m water depth at 37 sites in the eastern tropical Indian Ocean. The total planktic foraminiferal assemblage here comprises 29 morphospecies, with 11 morphospecies accounting for 90 % of the total assemblage. Both species composition and dominance in the net samples are broadly consistent with the published data from the corresponding surface sediments. The abundance and vertical distribution of planktic foraminifera are low offshore western Sumatra and increase towards offshore southern Java and the Lesser Sunda Islands (LSI). Average living depth of Trilobatus trilobus, Globigerinoides ruber, and Globigerina bulloides increases eastward, while that of Neogloboquadrina dutertrei, Pulleniatina obliquiloculata, and Globorotalia menardii remains constant. We interpret the overall zonal and vertical distribution patterns in planktic foraminiferal abundances as a response to the contrasting upper-water-column conditions during the southeast monsoon, i.e., oligotrophic and stratified offshore Sumatra (non-upwelling) vs. eutrophic and well mixed offshore Java–LSI (upwelling). Overall, the inferred habitat depths of selected planktic foraminifera species show a good agreement with those from sediment trap samples and from surface sediments off Sumatra, but not with those from surface sediments off Java–LSI. The discrepancy might stem from the different temporal coverage of these sample types. Our findings highlight the need to consider how foraminiferal assemblages and ecology vary on shorter timescales, i.e., from “snapshots” of the water column captured by a plankton net to seasonal and interannual variability as recorded in sediment traps, and how these changes are transferred and preserved in deep-sea sediments.
36
Leckie, R. Mark, Robert W. Scott, Timothy J. Bralower, and William V. Sliter. "Relationship between sequence boundaries and the evolutionary history of planktonic foraminifera, calcareous nannofossils, and reef communities in the mid-Cretaceous (Barremian-Cenomanian)." Paleontological Society Special Publications 6 (1992): 179. http://dx.doi.org/10.1017/s2475262200007395.
Full textAbstract:
Planktonic foraminifera first evolved in the middle Jurassic but did not experience a major radiation until the mid-Cretaceous. The mid-Barremian to late Aptian was characterized by a steady increase in species richness and by the appearance of new morphological forms including planispiral coiling, clavate and radially elongate chambers, and culminating in the first appearance of taxa with complex apertural structures and the keeled morphotype in late Aptian time. This broad interval of radiation was abruptly ended by evolutionary turnover and low diversification rates in the latest Aptian and early Albian prior to a second explosive episode of radiation in the middle and late Albian. The evolutionary history of mid-Cretaceous calcareous nannofossils generally parallels the trends observed in planktonic foraminifera, although the latest Aptian-early Albian turnover event is not as pronounced. Reef communities in the Caribbean/Gulf of Mexico and Mediterranean provinces show a change in dominance from coral-algal-rudist reefs in the Barremian-early Albian to rudist domiance by the late Albian time. These changes in calcareous plankton and reef communities are related to complex oceanographic changes of the mid-Cretaceous including structure of the upper water column, productivity, sea level, atmospheric and oceanographic circulation, and changes in the chemistry of the ocean.Changes in eustatic sea level influenced many of these factors including nutrient delivery to the oceans, climate, sites and rates of deep water formation, and ocean chemistry. What is the relationship between changes in sea level, as expressed by major seismic sequence boundaries, and the changes observed in marine biota? We have compared major changes of eustatic sea level within this interval of generally rising global sea level (Scott et al., 1988), with equivalent sequence boundaries (Haq et al., 1988) and the records of calcareous plankton (Roth, 1987; Leckie, 1989) and reef communities (Scott, 1988). What is most striking about these relationships is the apparent lack of direct correlation between sequence boundaries and turnover events in the marine biota. The calcareous plankton alternate in phase between relatively high rates of diversification and low rates of diversification, with the major sequence boundaries falling within intervals of change rather than at intervals of change. However, we acknowledge the potential of missing or condensed intervals in deep sea settings which may influence the record of evolutionary rates (e.g., Loutit, et al., 1988). Only the basal Albian sequence boundary appears to correlate with a major turnover event in the planktonic foraminifera, and the rapid change in Gulf Coast reef communites between the middle and upper Albian may correlate with a eustatic sea level change and a major sequence boundary. Based on high-resolution calcareous nannofossil, planktonic foraminiferal, sedimentologic, and geochemical data of Bralower et al. (submitted), the lower Aptian, basal Albian, and lower upper Albian sequence boundaries appear to correlate more closely with widespread oceanic dysoxic/anoxic events OAE1a, OAE1b, and OAE1c, respectively. The correlations between evolutionary events, anoxic events, and sequence boundaries must be considered tentative at this time because major disparities exist between the correlation of calcareous plankton zones and mid-Cretaceous chronostratigraphic units used by Haq et al. (1988) and Bralower et al. (submitted).
37
LeKieffre, Charlotte, Howard J. Spero, Jennifer S. Fehrenbacher, Ann D. Russell, Haojia Ren, Emmanuelle Geslin, and Anders Meibom. "Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts." Proceedings of the Royal Society B: Biological Sciences 287, no. 1929 (June 17, 2020): 20200620. http://dx.doi.org/10.1098/rspb.2020.0620.
Full textAbstract:
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk 15 N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with 13 C-enriched inorganic carbon, 15 N-nitrate, and 15 N-ammonium, as well as a 13 C- and 15 N- enriched heterotrophic food source, followed by TEM (transmission electron microscopy) coupled to NanoSIMS (nanoscale secondary ion mass spectrometry) isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of 15 N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with 15 N-ammonium, indicating efficient ammonium assimilation. Only weak 15 N-assimilation was observed after incubation with 15 N-nitrate. Feeding foraminifers with 13 C- and 15 N-labelled food resulted in dinoflagellates that were labelled with 15 N, thereby confirming the transfer of 15 N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based palaeoceanographic reconstructions, as they show that δ 15 N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates.
38
Sokolova, E. A. "The crucial boundaries in the development of the late cretaceous biota of plankton foraminifers in the southern part of the Indian ocean." Океанология 59, no. 6 (December 22, 2019): 1074–85. http://dx.doi.org/10.31857/s0030-15745961074-1085.
Full textAbstract:
The article analyzes own data on the species composition of shells of planktonic foraminifera from the Upper Cretaceous sediments of the Indian Oceans, as well as from the sections of the offshore seas of Australia. The species of planktonic foraminifera are grouped and arranged in a climatic series. An analysis of the change in the systematic composition of foraminifers made it possible to distinguish periods of extreme and intermediate climatic states in the Late Cretaceous.
39
Jenkins, D. G., D. Curry, B. M. Funnell, and J. E. Whittaker. "Planktonic foraminifera from the Pliocene Coralline Crag of Suffolk, Eastern England." Journal of Micropalaeontology 7, no. 1 (May 1, 1988): 1–10. http://dx.doi.org/10.1144/jm.7.1.1.
Full textAbstract:
Abstract. Nine species of planktonic foraminifera have recently been identified from the Coralline Crag of Suffolk, Eastern England. Stratigraphically important species include Globorotalia puncticulata (Deshayes) and Neogloboquadrina atlantica (Berggren) whose joint ranges, based on evidence from the North Atlantic, indicate an age for the deposit of between c. 4.2 and 2.3 Ma; other published evidence suggests that it may not be younger than c. 3.4 Ma. The low planktonic foraminiferal species diversity is interpreted as being due to a combination of factors, including the shallow water nature of the Coralline Crag, which would preclude deeper water species of planktonic foraminifera, and the possibility that the source of the fauna was from relatively high latitudes of the North Atlantic via the northern entrance to the North Sea. The planktonic foraminifera recorded indicate that the water temperature of the sea was within the range 10–18°C.The Coralline Crag contains very rich Lusitanian faunas of gastropod and bivalve molluscs, bryozoans, ostracods and benthic foraminifera.
40
Lupi, Claudia, Valeria Luciani, and Miriam Cobianchi. "Integrated calcareous nannofossil and planktonic foraminiferal bioevents of the last 1.07 Ma: a case study from the East New Zealand Pacific Ocean." Micropaleontology 54, no. 5 (2008): 463–76. http://dx.doi.org/10.47894/mpal.54.5.05.
Full textAbstract:
The core MD97-2114 (42°22.32’S; 171°20.42’W) on the northern slope of the submarine Chatham Rise (east of New Zealand, 1935m water depth), is a significant case-study for the improvement of the resolution of the mid-late Pleistocene integrated calcareous nannofossil and planktonic foraminiferal biostratigraphy. Quantitative data of calcareous nannofossils and planktonic foraminifera, well preserved and abundant throughout the core, are correlated with magnetostratigraphy and oxygen isotope stratigraphy and indicate that the studied core contains a sedimentary record of the past ca. 1.07 Ma. Several standard nannofossil events were documented and their correlation with Marine Isotope Stages (MIS) is consistent with previous calibrations. Moreover, some subsidiary events are here recorded thus improving the biostratigraphic resolution. The identification of one standard and a number of additional foraminiferal bioevents have been achieved by using climatically/ ecologically controlled entries/exits or variations in abundance. The integrated scheme obtained includes 17 bioevents, calibrated with magneto-isotope stratigraphy, and provides a biostratigraphic resolution of ca 63kyr. The bioevents of the two investigated groups of calcareous plankton appear closely spaced in two selected intervals in the lower part of the core, placed at the middle-lower part of the Brunhes Chron and at the top of the Jaramillo Subchron. The implications for the recognition of the chronostratigraphic lower-middle and middle-upper Pleistocene boundaries are discussed.
41
Pearson, Paul N. "Oxygen Isotopes in Foraminifera: Overview and Historical Review." Paleontological Society Papers 18 (November 2012): 1–38. http://dx.doi.org/10.1017/s1089332600002539.
Full textAbstract:
Foraminiferal tests are a common component of many marine sediments. The oxygen isotope ratio (δ18O) of test calcite is frequently used to reconstruct aspects of their life environment. The δ18O depends mainly on the isotope ratio of the water it is precipitated from, the temperature of calcification, and, to a lesser extent, the carbonate ion concentration. Foraminifera and other organisms can potentially preserve their original isotope ratio for many millions of years, although diagenetic processes can alter the ratios. Work on oxygen isotope ratios of foraminifera was instrumental in the discovery of the orbital theory of the ice ages and continues to be widely used in the study of rapid climate change. Compilations of deep sea benthic foraminifer oxygen isotopes have revealed the long history of global climate change over the past 100 million years. Planktonic foraminifer oxygen isotopes are used to investigate the history of past sea surface temperatures, revealing the extent of past ‘greenhouse’ warming and global sea surface temperatures.
42
Triantaphyllou, M. V., A. Antonarakou, H. Drinia, M. D. Dimiza, G. Kontakiotis, E. Tsolakis, and G. Theodorou. "HIGH RESOLUTION BIOSTRATIGRAPHY AND PALEOECOLOGY OF THE EARLY PLIOCENE SUCCESSION OF PISSOURI BASIN (CYPRUS ISLAND)." Bulletin of the Geological Society of Greece 43, no. 2 (January 23, 2017): 763. http://dx.doi.org/10.12681/bgsg.11242.
Full textAbstract:
The Pissouri basin (Cyprus Island) corresponds to a small tectonically controlled depression elongated NNW-SSE and widening southward in the direction of the deep Mediterranean domain. In the centre of the basin, the section Pissouri South, about 100 m thick, consists of well-preserved cyclic marine sediments including laminated brownish layers alternating with grey homogeneous marls. Plankton biostratigraphy (calcareous nannofossil and planktonic foraminifera) revealed a remarkable number of biovents bracketing the Zanclean-Piacenzian boundary. In particular the Highest Occurrence (HO) of Reticulofenestra pseudoumbilicus suggests the presence of NN14/15-NN16 nannofossil biozone boundary, dated at 3.84 Ma. Additionally the defined planktonic foraminiferal MPL3-MPL4a and MPL4a-MPL4b zone boundaries point to ages between 3.81 and 3.57 Ma, in Pissouri North section. Zanclean/Piacenzian boundary (3.6 Ma) is placed at 75.8 m from the base of the section, considering Discoaster pentaradiatus top paracme (3.61 Ma) and Globorotalia crassaformis first influx (3.6 Ma) bioevents. The cyclically developed sapropelic layers around the Zanclean – Piacenzian boundary suggest a climate characterized by a period of warm temperate conditions and a highly stratified water column that occurred at times of precession minima.
43
Trommer, G., M. Siccha, E. J. Rohling, K. Grant, M. T. J. van der Meer, S. Schouten, U. Baranowski, and M. Kucera. "Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial." Climate of the Past Discussions 7, no. 2 (April 8, 2011): 1195–233. http://dx.doi.org/10.5194/cpd-7-1195-2011.
Full textAbstract:
Abstract. This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktonic foraminiferal fauna following high salinities during MIS 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktonic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea SST increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktonic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktonic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.
44
Ozdínová, Silvia, and Ján Soták. "Oligocene-Early Miocene Planktonic Microbiostratigraphy and Paleoenvironments of the South Slovakian Basin (Lučenec Depression)." Geologica Carpathica 65, no. 5 (January 31, 2015): 451–70. http://dx.doi.org/10.1515/geoca-2015-0005.
Full textAbstract:
Abstract Oligocene and Lower Miocene sediments of the Lučenec Depression were studied to demonstrate the planktonic bioevents and climatic proxies from the Číž Formation (Rupelian) and Lučenec Formation (Chattian-Aquitanian) on the basis of quantitative analyses of foraminifers and calcareous nannofossils. The oldest nannofossil assemblages of the Číž Formation belonged to the NP23 Zone and were dominated by Reticulofenestra ornata known for preference of temperate eutrophic water conditions. An increase in bioproductivity was documented by abundant large-sized planktonic foraminifers (e.g. Turborotalia ampliapertura, Paragloborotalia nana, Subbotina gortanii) and epifaunal to shal-low-infaunal benthic species. The middle part of the Číž Formation reveals a lowstand progradation of deltaic sediments of the Rapovce Member. There, the planktonic foraminifers are impoverished in both size and diversity, containing mostly tenuitellid and cassigerinellid species, probably as a result of decreased salinity and increased anoxia in the Tard Clay. Contrary of this, the benthic foraminifers are rich, mainly the infaunal forms of uvigerinid species. They probably proliferated due to a high organic flux from riverine input. Open marine conditions were restored in the upper part of the Číž Formation above the lowest occurrence (LO) of Cyclicargolithus abisectus on the NP23-NP24 zone boundary. The transitional interval between the Číž and Lučenec formations (O5/O6 - NP24/25) was approximated by the HOs of Paragloborotalia opima and Sphenolithus distentus and the LOs of Globigerinoides primordius and Pontosphaera enormis. Benthic foraminifera of the Lučenec Formation indicate a high productivity and oxygen-deplected environ-ments. The Oligocene-Miocene boundary in the Lučenec Formation was appointed by the HOs of Helicospahera recta and Dictyococcites bisectus. Foraminiferal markers of this boundary were established from the HO of Globigerina ciperoensis and the LO of G. ottnangiensis. The highest nannofossil dating in the Lučenec Formation is recorded by the LOs of Helicosphaera mediterranea (NN1 Zone) and Discoaster druggi (NN2 Zone). The uppermost part of the Lučenec Formation contained many Paratethys benthic foraminifera, such as Uvigerina posthantkeni.
45
Boukhary, Mohamed, Mohamed El Amin Bassiouni, Bahay Issawi, Safaa Sharabi, and Hesham Mansour. "Maastrichtian–Early Paleogene Ostracoda from the Kharga Oasis and the Nile Valley, Egypt." Micropaleontology 59, no. 2-3 (2013): 223–48. http://dx.doi.org/10.47894/mpal.59.2.11.
Full textAbstract:
The present work deals with the stratigraphy, lithological characteristics, planktonic foraminiferal zonation and the ostracods of the Upper Cretaceous (Maastrichtian) - Paleocene rocks in the Kharga Oasis and the lower paleogene of Gebel Dandara section, Nile Valley, Egypt. The planktonic foraminifera and ostracods were obtained from twostratigraphic sections:Ain Dabadib and N. AinAmurfrom the area NorthWest of the Kharga Oasis, Egypt. Thirty seven planktonic foraminiferal and twelve ostracod species were identified, among the latter, 1 genus: Aegyptoleberis Boukhary, Bassiouni and Sharabi n.gen. (Type species: Cythereis coronata Esker 1968) and 2 species: Cytheropteron dakhlaensis Boukhary and Bassiouni n.sp., and Ordonyia dabadibensis Boukhary and Sharabi n. sp., from the Late Paleocene are believed to be new. Among the association, there are species which are identical with those described from Tunisia by Esker (1968) and Said (1978) and from Jordan by Bassiouni (1971). The planktonic foraminifera were used for the biostratigraphic control. Future studies may prove these ostracod assemblages to be of index value and valid for the Mesogean Paleocene in the neritic provinces in North Africa and Middle East.
46
Missiaen, L., L. Wacker, B. C. Lougheed, L. Skinner, I. Hajdas, J. Nouet, S. Pichat, and C. Waelbroeck. "Radiocarbon Dating of Small-sized Foraminifer Samples: Insights into Marine sediment Mixing." Radiocarbon 62, no. 2 (March 9, 2020): 313–33. http://dx.doi.org/10.1017/rdc.2020.13.
Full textAbstract:
ABSTRACTRadiocarbon (14C) can be used to build absolute chronologies and reconstruct ocean ventilation over the last 40 ka. Sample size requirements have restricted 14C measurements in marine cores with low foraminifer content, impeding 14C-based studies focused on abrupt climate events. Recent developments have demonstrated that small-sized foraminifer samples can now be dated using a gas introduction system at the cost of a small decrease in precision. We explore the potential of gas measurements on benthic and planktonic foraminifers from core SU90-08 (43°03′1″N, 30°02′5″W, 3080 m). Gas measurements are accurate, reproducible within 2σ uncertainty and comparable to graphite measurements. Both techniques yield negative 14C benthic-planktonic (B-P) age-offsets after Heinrich event 1. We argue that negative B-P ages result from bioturbation and changes in foraminifer abundances, with the chance of negative B-P especially increased when the 14C age gradient between the deep and surface waters is decreased. Small-sized 14C measurements seem to capture the variance of the foraminifera age distribution, revealing the active mixing in those archives. Sediment deposition and mixing effects possibly pose a greater obstacle for past 14C-based dating and ocean ventilation reconstructions than the measurement precision itself, particularly in relatively low sedimentation rate settings.
47
Drinia, H., Α. Antonarakou, N. Tsaparas, M. D. Dermitzakis, and G. Kontakiotis. "FORAMINIFERAL RECORD OF ENVIRONMENTAL CHANGES: PREEVAPORITIC DIATOMACEOUS SEDIMENTS FROM GAVDOS ISLAND, SOUTHERN GREECE." Bulletin of the Geological Society of Greece 36, no. 2 (July 23, 2018): 782. http://dx.doi.org/10.12681/bgsg.16817.
Full textAbstract:
The Messinian pre-evaporitic sedimentary succession of Gavdos island (Metochia section) is a nearly uninterrupted succession of marine sediments, dominated by finely laminated diatomaceous sediments, which are cyclically alternating with marlstone and white limestone beds. The purpose of this study is to analyze in detail the benthic and planktonic foraminiferal microfauna preserved in the sediments of this section. The qualitative and quantitative analysis of the planktonic foraminifera fauna allowed the recognition of seven bioevents, which have been astronomically dated for the Mediterranean. The base of the diatomitic succession in Gavdos Island is dated at 6.696 Myr, whereas its top at 6.0 Myr. Our results suggest that two environmental parameters are the most important factors that control the community structure of the benthic foraminiferal fauna: the food availability and oxygen concentration. In addition, local upwelling phenomena evidenced by signals from the benthic foraminifera and the distribution pattern of the planktonic G. bulloides may have played a role in the faunal density and composition
48
Lam, Adriane R., and R. Mark Leckie. "Late Neogene and Quaternary diversity and taxonomy of subtropical to temperate planktic foraminifera across the Kuroshio Current Extension, northwest Pacific Ocean." Micropaleontology 66, no. 3 (2020): 177–268. http://dx.doi.org/10.47894/mpal.66.3.01.
Full textAbstract:
Patterns of diversity in the modern planktic foraminifera indicate a latitudinal diversity gradient (LDG), which peaks in the mid-latitude regions. Plankton distributional patterns are oftenmost strongly associated with temperature and are expected to change in response to expanded tropical water masses. Defining the underlying causes of climatic and oceanographic processes, however, requires detailed, local-scale diversity curves and evolutionary metrics, as well as solid taxonomic concepts of planktic foraminifera, to test the oceanographic processes driving evolution ofmarine plankton. Currently, diversity estimates for the planktic foraminifera are mainly based on global datasets skewed towards tropical to subtropical sites and conducted at coarse resolutions that hamper investigations of evolutionary processes, especially for short-lived climate perturbations. Here, we present 10-kyr resolution diversity curves and 25-kyr resolution local first appearance and extirpation rates of planktic foraminifera for four Ocean Drilling Program sites that extend from the temperate northern edge of the modern-day position of the Kuroshio Current Extension (KCE) to the tropics. We provide an updated taxonomic review of late Neogene planktic foraminiferal species from within the influence of the KCE. These data allow for investigations of the western Pacific LDG and patterns of evolution through the late Neogene in response to tectonic and climate events. Our results indicate that a mid-latitude diversity peak has been prominent in the western Pacific since at least 12.1Ma, with highest diversity generally on the northern edge of the KCE. These data contradict previous studies indicating highest diversity is located +/- 20 degrees, as our data reveal highest diversity for the planktic foraminifera at +/- 35 degrees N likely due to strong seasonality. Development of the modern North Pacific gyre system due to closure of the Central American Seaway and constriction of the Indonesian Throughflow increased the LDG between the tropics and the northernmost site, likely in response to KCE intensification. Diversity was only slightly affected during the mid-Piacenzian Warm Period (approx. 3.2-2.9Ma),with diversity gradients between the equatorial site and southernmost mid-latitude sites becoming similar, perhaps indicating a weaker thermal gradient developing in the northwest Pacific as the KCE and warmer waters were displaced northwards.With intensification of Northern Hemisphere glaciation came a decrease in diversity at the northernmost site, hypothesized to be caused by subtropical gyre constriction and southward displacement of subpolar surface waters. The beginning of the mid-Pleistocene transition marks an increase in diversity gradients, especially between the northernmost and tropical sites. A detailed taxonomic evaluation of planktic foraminiferal species has led to synonymization of what we consider regional morphological variants, as well as revised taxonomic concepts of key subtropical to temperate late Neogene planktic foraminifera. Scanning electron micrographs capture the morphological variability within a species concept for the first time in great detail for this part of the world ocean. These data and updated taxonomic concepts provide a framework for future studies to link evolutionary patterns with high-resolution geochemical and sedimentological data to further interpret localized drivers of diversification in the planktic foraminifera.
49
Shahin, Abdalla, and Sharif Elbaz. "Foraminiferal biostratigraphy, paleoenvironment and paleobiogeography of Cenomanian–Lower Turonian shallow marine carbonate platform in west central Sinai, Egypt." Micropaleontology 59, no. 2-3 (2013): 249–83. http://dx.doi.org/10.47894/mpal.59.2.12.
Full textAbstract:
The Cenomanian-Early Turonian succession exposed in west central Sinai was carefully studied for their foraminiferal content. Lithostratigraphically, this carbonate platform interval in the studied area include the Raha Formation (Early-Middle Cenomanian) andAbu Qada Formation (Late Cenomanian–Early Turonian). One hundred and one species belonging to 69 genera and 41 families are identified. Out of this content, 86 species belong to benthic foraminifera, and 16 belong to the planktonic ones. One larger benthic foraminiferal species namely Biconcava ribbata Shahin (n. sp.) is considered here as new species. Four large benthic foraminiferal zones and one planktonic foraminiferal zone are recognized and correlatedwith their equivalents inside and outside Egypt. The successive last and first appearances of most large agglutinated and porcellaneous benthic foraminifera refer to successive bioevents. The Heterohelix shift below the Cenomanian-Turonian boundary is an excellent biomarker for global event correlation for oxygen minimum zone.Also the scarcity or even the disappearance of larger benthic foraminifera in this interval can be interpreted as the final stages of the Late Cenomanian-Early Turonian Oceanic Anoxic Event 2. The wide paleobiogeographic distribution of the recorded larger foraminifera reveals that there was a strong affinity and direct connection all over the Tethyan Realm.
50
Vishnevskaya, V. S., L. F. Kopaevich, V. N. Benyamovsky, and M. N. Ovechkina. "CORRELATION OF THE UPPER CRETACEOUS ZONAL SCHEMES OF THE EASTERN EUROPEAN PLATFORM ON FORAMINIFERS, RADIOLARIES AND NANNOPLANKTON." Moscow University Bulletin. Series 4. Geology, no. 1 (February 28, 2018): 26–35. http://dx.doi.org/10.33623/0579-9406-2018-1-26-35.
Full textAbstract:
This article proposes a composite biostratigraphical scheme for the Upper Cretaceous of the East European Platform on the basis of the distribution in the sections of three groups of microfossils–foraminifers, both planktonic and benthic, radiolarians and nannoplankton. Most of the stages and subsustages boundaries are confirmed by macropalaeontological data. The most divided units are on benthic foraminifers and nannoplankton. The diversity of these microfossils and their constant presence in the sections made it possible to identify zones and subzones, while it is possible to subdivide only the beds by planktonic foraminifers and radiolarians. The most favorable stages in the development of plankton biota can be considered the Turonian-Coniacian interval, when the basins of the East European Platform felt the intensive influence of the warm waters of the Tethys ocean. The global Campanian coooling is clearly recorded, reflecting on the taxonomic diversity of all microfossil groups.