Journal of Foraminiferal Research最新文献

{"title":"OCEAN ACIDIFICATION NOT LIKELY TO AFFECT THE SURVIVAL AND FITNESS OF TWO TEMPERATE BENTHIC FORAMINIFERAL SPECIES: RESULTS FROM CULTURE EXPERIMENTS","authors":"Anna McIntyre-Wressnig, J. Bernhard, J. Wit, D. McCorkle","doi":"10.2113/GSJFR.44.4.341","DOIUrl":"https://doi.org/10.2113/GSJFR.44.4.341","url":null,"abstract":"Specimens of Bolivina argentea and Bulimina marginata , two widely distributed temperate benthic foraminiferal species, were cultured at constant temperature and controlled p CO2 (ambient, 1000 ppmv, and 2000 ppmv) for six weeks to assess the effect of elevated atmospheric CO2 concentrations on survival and fitness using Adenosine Triphosphate (ATP) analyses and on shell microfabric using high-resolution SEM and image analysis. To characterize the carbonate chemistry of the incubation seawater, total alkalinity and dissolved inorganic carbon were measured approximately every two weeks. Survival and fitness were not directly affected by elevated p CO2 and the concomitant decrease in seawater pH and calcite saturation states (Ωc), even when seawater was undersaturated with respect to calcite. These results differ from some previous observations that ocean acidification can cause a variety of effects on benthic foraminifera, including test dissolution, decreased growth, and mottling (loss of symbiont color in symbiont-bearing species), suggesting that the benthic foraminiferal response to ocean acidification may be species specific. If so, this implies that ocean acidification may lead to ecological winners and losers even within the same taxonomic group.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.4.341","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ALLOPOLYMORPHINA N. GEN. (POLYMORPHINIDAE) FROM THE EARLIEST PLIOCENE OF FLINDERS ISLAND, TASMANIA","authors":"P. Quilty, J. Whitehead","doi":"10.2113/GSJFR.44.4.434","DOIUrl":"https://doi.org/10.2113/GSJFR.44.4.434","url":null,"abstract":"A new polymorphinid genus and species Allopolymorphina flindersi Quilty and Whitehead is defined from earliest Pliocene shallow-water, fully marine, calcareous sediments from eastern Flinders Island, northeast Tasmania, Tasman Sea. It is a large, elongate form up to 2.5 mm in length (holotype 1.85 mm), initially polymorphinid but changing early to uniserial frondicularine in later chambers. Specimens occur in most samples of this study, but not in others collected previously from the island. The thin source sequence comes from a previously unrecognized depositional event in outcrop in the western margin of the hydrocarbon-bearing Gippsland Basin of southeastern Australia. Deposition occurred during an interval of high sea level and major coastal onlap.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.4.434","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MOLECULAR PHYLOGENY OF CARTERINA SPICULOTESTA AND RELATED SPECIES FROM NEW CALEDONIA","authors":"J. Pawłowski, M. Holzmann, J. Debenay","doi":"10.2113/GSJFR.44.4.440","DOIUrl":"https://doi.org/10.2113/GSJFR.44.4.440","url":null,"abstract":"Carterina spiculotesta is a common tropical benthic foraminifer characterized by fusiform or rod-like calcareous spicules covering the surface of the test. Because of this peculiar wall feature, the genus Carterina was separated from other foraminifera and placed in its own suborder (Caterinina) or order (Carterinida). However, there is no agreement about the origin of Carterina spicules, which are considered either as being secreted by the foraminiferal cell or as agglutinated foreign particles; if the latter case, the genus was placed in the order Trochamminida. Here, we attempted to resolve this controversy by analysis of genetic data from various carterinids collected in New Caledonia. We obtained seven complete and 47 partial small subunit (SSU) rDNA sequences. Our results show that all specimens of spicule-bearing Carterina cluster together in a strongly supported clade. Sister to this clade are undetermined lineages of trochamminid morphospecies. Together with its sister groups, the Carterina clade forms an independent lineage at the base of Globothalamea within the paraphyletic radiation of textulariids and robertinids. Its exact phylogenetic position was difficult to establish because the used SSU rRNA genes lack resolution. As long as experimental data do not contradict the hypothesis of a secreted origin for Carterina spicules, we propose to retain the ordinal status of the Carterina clade, and consider it as one of the orders of the class Globothalamea. In view of our study, the diversity of this order may be much higher than traditionally accepted, including several genera and species, many of them new to science.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EFFECTS OF DIFFERENT POTENTIAL FOOD SOURCES ON UPPER-BATHYAL BENTHIC FORAMINIFERA: AN EXPERIMENT WITH PROPAGULES","authors":"C. Duffield, B. Edvardsen, W. Eikrem, E. Alve","doi":"10.2113/GSJFR.44.4.416","DOIUrl":"https://doi.org/10.2113/GSJFR.44.4.416","url":null,"abstract":"A propagule experiment was designed to investigate the effects of different food types and varying sediment depths on the survival and growth of upper-bathyal benthic foraminifera, collected from surface-sediment cores in Oslofjord, Norway. Sediment that passed through a 53-μm sieve was used in the experiment. Any foraminifera >63 μm at the end of the experiment had therefore grown, indicating at least tolerable living conditions. The experiment was arranged into four sub-experiments to test foraminiferal responses to a lack of food input, algal medium, sediment depth (1- vs. 2-cm depth), and different food types. Potential food sources included monospecific algal cultures (the green alga Dunaliella tertiolecta , the haptophyte Emiliania huxleyi , and the diatoms Chaetoceros sp. and cf. Navicula ), as well as phytoplankton and zooplankton from net hauls collected at the same sampling site. After six weeks all foraminiferal assemblages showed an increase in abundance, even those which were not fed. This suggests that most species (e.g., Textularia earlandi, Bathysiphon flexilis ) were feeding on microbes or detritus already in the sediment. However, the addition of certain phytodetritus increased the abundance, suggesting that some species (e.g., Epistominella vitrea ) are dependent on the input of this particular fresh phytodetritus. Conversely, certain types of detritus ( E. huxleyi and zooplankton) appear detrimental to most species, except Elphidium excavatum which appeared resistant to the treatments inimicable to other species. Leptohalysis catella was the only species observed to respond positively to net hauls dominated by dinoflagellates. For some species (e.g., Stainforthia fusiformis, Nonionella iridea ) the availability of a greater sediment depth stimulates growth more than the input of organic matter.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.4.416","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TRACING THERMOHALINE PROPERTIES AND PRODUCTIVITY OF SHELF-WATER MASSES USING THE STABLE ISOTOPIC COMPOSITION OF BENTHIC FORAMINIFERA","authors":"P. Eichler, K. Billups, H. Vital, J. Moraes","doi":"10.2113/GSJFR.44.4.352","DOIUrl":"https://doi.org/10.2113/GSJFR.44.4.352","url":null,"abstract":"We explored the applicability of stable isotopic ratios of nine foraminiferal species, four epifaunal (Pseudononion atlanticum, Cibicides fletcheri, Hoeglundina elegans, Hanzawaia boueana) and five infaunal (Angulogerina angulosa, Uvigerina peregrina, Buccella peruviana, Cassidulina subglobosa, Bulimina marginata), as environmental tracers on the southwest Atlantic continental shelf from samples collected along the Argentinean-Uruguayan-Brazilian Atlantic coast during austral winter 2003 and summer 2004. Linear regressions show that the stable isotopic composition of living foraminifera is associated with geographical and environmental variables (latitude, water depth, temperature, salinity, and dissolved silica). Multiple linear regressions show that the relevant variables in this study are latitude, salinity, and biogenic silica. There is a general trend of higher δ 18 O and lower δ 13 C values with increasing latitude, reflecting the influence of cooler water masses toward the south. Specifically, the δ 18 O data from U. peregrina, H. elegans, and P. atlanticum follow meridional temperature gradients with lower δ 18 O values in relatively warm Subtropical Shelf Water at the northernmost sites (27°S) and higher values in colder Sub-Antarctic Shelf Water at the southern sites (to 37°S). Angulogerina angulosa and P. atlanticum δ 18 O values correlate more strongly with salinity than temperature. Positive correlation of δ 13 C and water depth observed for some infaunal species indicates greater input of organic matter to the deeper-water benthos. In summer samples, however, this correlation between δ 13 C and water depth weakens, reflecting a less stratified water mass associated with upwelling. Results from this study support the application of these foraminifera to reconstructions of paleoenvironmental changes from sediment cores.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.4.352","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BENTHIC FORAMINIFERA OF THE WESTERN GULF OF MAINE 60 YEARS LATER: A PILOT STUDY COMPARING CHANGES IN SPECIES DISTRIBUTIONS","authors":"S. A. Nathan, R. Leckie, S. Mabee","doi":"10.2113/GSJFR.44.3.230","DOIUrl":"https://doi.org/10.2113/GSJFR.44.3.230","url":null,"abstract":"The Merrimack River paleo-delta formed during the late Pleistocene as post-glacial rebound produced a local low stand in sea level. Subsequent sea-level rise drowned and eroded the paleo-delta, which is now reworked by a variety of processes. This study used benthic foraminifera as a biotic and environmental proxy to evaluate the sand and gravel resources of the paleo-delta. Nineteen box-core sediment samples were collected from the paleo-delta along two east–west depth transects east of the Merrimack River mouth and off Plum Island, Massachusetts. From these samples, 62 species of benthic foraminifera were identified. When compared with distribution studies published over 60 years ago, some species have shifted landward in their distributions (e.g., Adercotryma glomeratum, Cibicides lobatulus, Reophax curtus, Trochammina squamata), while a few exhibited wider and more distal occurrences (e.g., Elphidium excavatum and Elphidium subarcticum). These differences point to variations in the Merrimack River outflow and its effects upon water column nutrient delivery, productivity, and organic matter flux over the past six decades. Other mitigating factors affecting benthic foraminiferal distributions may include increased seafloor disturbance from strong winter storms or fishing activity. Species richness and evenness peak at the delta break, coincident with low species dominance at about 50-m depth. Q-mode cluster analyses show three distinct assemblages: ‘‘shallow’’ (#30-m water depth), ‘‘deep’’ ($40 m), and ‘‘delta edge’’ (,50 m). There are no apparent correlations between foraminiferal distributions and deltaic bedforms or sediment type. This implies that foraminiferal distributions are controlled by other environmental variables other than grain size, such as food availability.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.3.230","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ALPHA AND BETA DIVERSITY OF FORAMINIFERA THAT ENCRUST THE ANTARCTIC SCALLOP ADAMUSSIUM COLBECKI: ECOLOGICAL CONNECTIVITY AMONG SHELLS AND BETWEEN SITES","authors":"D. Radford, S. Walker, S. Bowser","doi":"10.2113/GSJFR.44.3.255","DOIUrl":"https://doi.org/10.2113/GSJFR.44.3.255","url":null,"abstract":"Benthic foraminifera are ubiquitous marine organisms in Antarctica, but little is known about their ecology despite their importance as climate-change proxies. A fundamental question remains unanswered: is foraminiferal diversity highly localized and similar to reports for Antarctic benthic invertebrates? If so, high endemism would result driven by dispersal limitation with little connectivity among sites. To answer this question, the composition, abundance, spatial distribution and alpha (α) and beta (β) diversity of foraminiferal species that encrust living shells of the Antarctic scallop Adamussium colbecki were compared within and between two sites located 30-km apart in McMurdo Sound, Ross Sea, Antarctica: Bay of Sails (BOS), an open coastal region with annual sea-ice cover, and Explorers Cove (EC), a protected embayment with multiannual sea-ice cover. Foraminiferal community structure differed between the sites, generated by variations in species abundance, turnover of rare species, and heterogeneity in species composition between top and bottom valves. Foraminifera were significantly more common on the scallop’s auricles, perhaps driven by nutrients generated by the scallop. Calcareous taxa were significantly more abundant at EC despite lower seawater pH, while agglutinated taxa were significantly more abundant at BOS. Alpha diversity (species richness, Shannon H , e H ) was higher at BOS than at EC and is similar to deep-sea diversity reported for Caribbean encrusting foraminifera. Based on Shannon H , foraminifera at EC may represent a stressed community dominated by Cibicides antarcticus , while those at BOS may represent a transitional community. Within-site β-diversity was high, spurred by the turnover of rare species between top and bottom valves, which acted as separate microhabitats. Higher β-diversity at BOS suggests that foraminiferal dispersal and recruitment were more localized than at EC. Additive partitioning revealed that encrusting diversity was mostly held at the local level, and that BOS and EC have high connectivity, similar to deep-sea communities. The Antarctic endemicity of these protists is questionable, and is in stark contrast to Antarctic invertebrates with high within- and between-site diversity. Therefore, Antarctic encrusting foraminifera appear to be influenced primarily by niche-based processes, rather than dispersal limitation. Indeed, habitat islands, such as carbonate shells, are essential for generating Antarctic diversity, and are integral for the conservation of Antarctica’s unique polar ecosystem.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.3.255","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LIVING (STAINED) DEEP-SEA FORAMINIFERA OFF HACHINOHE (NE JAPAN, WESTERN PACIFIC): ENVIRONMENTAL INTERPLAY IN OXYGEN-DEPLETED ECOSYSTEMS","authors":"C. Fontanier, Pauline Duros, T. Toyofuku, K. Oguri, K. Koho, R. Buscail, A. Grémare, O. Radakovitch, B. Deflandre, L. Nooijer, Sabrina Bichon, S. Goubet, A. Ivanovsky, Gérard Chabaud, C. Menniti, Gert, Jan Reichart, H. Kitazato","doi":"10.2113/GSJFR.44.3.281","DOIUrl":"https://doi.org/10.2113/GSJFR.44.3.281","url":null,"abstract":"Live (Rose-Bengal stained) deep-sea foraminiferal faunas have been studied at five stations between 500–2000-m depth along the NE Japanese margin (western Pacific) to understand how complex environmental conditions (e.g., oxygen depletion, organic matter) control their structure (i.e., diversity, standing stocks, and microhabitats). All stations are characterized by silty sediments with no evidence of recent physical disturbances. The three stations located between 760–1250 m are bathed by dysoxic bottom waters ( 2.2% DW), only the oxygen-depleted sites are characterized by higher concentrations of sugars, lipids, and enzymatically hydrolysable amino acids (EHAA). Sedimentary contents in chlorophyllic pigments decrease with water depth without any major change in their freshness (i.e., [Chl a/(Chl a + Pheo a)] ratios). Both Uvigerina akitaensis and Bolivina spissa are restricted to the stations bathed by dysoxic waters, proving their oxygen-depletion tolerance. In such conditions, both phytophagous taxa are obviously able to take advantage of labile organic compounds (e.g., lipids and EHAA) contained in phytodetritus. Nonionella stella and Rutherfordoides cornuta survive in oxygen-depleted environments probably via alternative metabolic pathways (e.g., denitrification ability) and a large flexibility in trophic requirements. At stations where oxygen availability is higher (i.e., >70 μmol/L in bottom water) and where bioavailable organic compounds are slightly less abundant, diversity indices remain low, and more competitive species (e.g., Uvigerina curticosta, U. cf. U. graciliformis, Nonionella globosa, Nonionellina labradorica, and Elphidium batialis) are dominant.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.3.281","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"“MONOSPECIFIC” AND NEAR-MONOSPECIFIC BENTHIC FORAMINIFERAL FAUNAS, NEW ZEALAND","authors":"B. Hayward","doi":"10.2113/GSJFR.44.3.300","DOIUrl":"https://doi.org/10.2113/GSJFR.44.3.300","url":null,"abstract":"Thirteen benthic foraminiferal species dominate modern “monospecific” faunas (dead faunas with >80% of one species in >63-μm samples) in New Zealand. These faunas occur in sheltered, often brackish, intertidal or shallow-subtidal environments, never deeper than 25 m. None occurs along exposed coasts or in the open ocean. Seven agglutinated species ( Entzia macrescens , Haplophragmoides wilberti , H. manilaensis , Miliammina fusca , M. obliqua , Trochammina inflata , Trochamminita salsa ) dominate “monospecific” faunas in salt marshes with varying salinity and elevational ranges. All but H. manilaensis have been recorded comprising 99–100% of at least one fauna. A further six species ( Ammobaculites exiguus , Ammonia aoteana , Ammotium fragile , Elphidium excavatum clavatum , E. williamsoni , E. gunteri ) dominate “monospecific” faunas in unvegetated intertidal and shallow-subtidal ( Amb. exiguus faunas are inferred to have been produced by dissolution of calcareous components. A further 17 species dominate modern near-monospecific faunas (50–80% of one species), 11 at depths Six species dominate “monospecific” early Miocene faunas in northern New Zealand: Elphidium crispum in a sheltered gravel beach; Nonionella novozealandica in a deep-water (50–100 m), possibly dysoxic harbour; and three larger, more robust species ( Amphistegina aucklandica, Lepidocyclina orakiensis, Miogypsina intermedia ) in current- or wave-concentrated beach or shallow-marine deposits. The only bathyal or abyssal “monospecific” fauna is dominated by Amphimorphinella butonensis occurring in a fossil hydrocarbon seep setting. Many of the modern “monospecific” faunas (especially those in salt marshes) are cosmopolitan, whilst most of the fossil and some of the modern faunas are endemic to the New Zealand region. These high-dominance faunas are produced by taphonomic and ecological processes. Taphonomic causes include wave or current concentration by winnowing or transport in high energy, shallow-marine environments and carbonate dissolution in low pH, brackish, salt marsh or deep-sea settings. Ecological drivers include highly specific adaptations that allow species to outcompete all others in stressful (intertidal), strongly variable (high-tidal brackish), or unusual (hydrocarbon seep) environments. Sometimes high test productivity of opportunistic species may result in near-monospecific faunas.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.3.300","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ORTHOPHRAGMINIDS (FORAMINIFERA) ACROSS THE PALEOCENE–EOCENE TRANSITION FROM NORTH AFRICA: TAXONOMY, BIOSTRATIGRAPHY, AND PALEOBIOGEOGRAPHIC IMPLICATIONS","authors":"E. Özcan, C. Scheibner, K. Boukhalfa","doi":"10.2113/GSJFR.44.3.203","DOIUrl":"https://doi.org/10.2113/GSJFR.44.3.203","url":null,"abstract":"The platform margin and slope deposits in Galala, Egypt, record a larger benthic foraminiferal turnover (LFT), previously proposed to coincide with the Paleocene-Eocene (P/E) boundary based on the negative carbon isotope excursion (CIE) consistent with the Paleocene-Eocene Thermal Maximum (PETM). The LFT in these deposits was established on the basis of supposed synchronous first appearances of such taxa as Alveolina , Nummulites , and Orbitolites at or around the P/E boundary, although the response of orthophragminids, assigned only to the genus Discocyclina , was not studied. The orthophragminids in the late Paleocene–early Eocene interval in some of these deposits (sections B3, D5, D6, and D8) are represented by species of Discocyclina Gumbel, Orbitoclypeus Silvestri, and Nemkovella Less, reported for the first time from the southern margin of the Tethys. The Thanetian orthophragminids consist of Orbitoclypeus multiplicatus , O. schopeni , Discocyclina seunesi , and D. tenuis , while assemblages in the early Eocene are characterized by Discocyclina archiaci , D. dispansa , Orbitoclypeus schopeni , and Nemkovella stockari , suggesting a significant change in composition through the sections. The assemblages below and above the P/E boundary, only recorded in sections B3 and D8, mark the orthophragminid zones OZ 1B and 3, respectively. The OZ 2, correlated to shallow benthic zones SBZ 5 and 6 in the basal part of the Eocene and recognized by the first appearance of asterocyclinids, nemkovellids, and some ribbed orbitoclypeid species in northern Tethyan platforms, was not found. This may suggest either a hiatus, recorded previously in section D8 based on calcareous plankton, across the P/E transition in section B3 or an artifact of sampling. Consequently, our data raise some doubts about the aforementioned compositional changes related to the LFT and P/E boundary. We discovered an advanced developmental stage of N. stockari ( N. stockari bejaensis n. subsp.) from a new section in Tunisia. This subspecies seems to be a key taxon for the early Eocene of the southern Tethyan platforms and extends the geographic and stratigraphic range of the species. We conclude that orthophragminids at Galala bear a close resemblance to those in the northern Tethyan platforms, especially assemblages from Turkey.","PeriodicalId":54832,"journal":{"name":"Journal of Foraminiferal Research","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2014-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSJFR.44.3.203","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68287253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}