No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Recent Deep-Sea Benthic Foraminifera from an Active Volcanic Area: First Insights around Nishinoshima, Northwest Pacific
ResearchGate has not been able to resolve any citations for this publication.
The island-forming Nishinoshima eruptions in the Ogasawara Islands, Japan, provide a rare opportunity to examine how the terrestrial part of Earth’s surface increases via volcanism. Here, the sequence of recent eruptive activity of Nishinoshima is described based on long-term geological and geochemical monitoring of eruptive products. Processes of island growth and temporal changes in the magma chemistry are discussed. The growth of Nishinoshima was sustained by the effusion of low-viscosity andesite lava flows since 2013. The lava flows spread radially with numerous branches, resulting in compound lava flows. Lava flows form the coherent base of the new volcanic edifice; however, pyroclastic eruptions further developed the subaerial volcanic edifice. The duration of three consecutive eruptive episodes decreased from 2 years to a week through the entire eruptive sequence, with a decreasing eruptive volume and discharge rate through time. However, the latest, fourth episode was the most intense and largest, with a magma discharge rate on the order of 10⁶ m³/day. The temporal change in the chemical composition of the magma indicates that more mafic magma was involved in the later episodes. The initial andesite magma with ∼60 wt% SiO2 changed to basaltic andesite magma with ∼55 wt% SiO2, including olivine phenocryst, during the last episode. The eruptive behavior and geochemical characteristics suggest that the 2013–2020 Nishinoshima eruption was fueled by magma resulting from the mixing of silicic and mafic components in a shallow reservoir and by magma episodically supplied from deeper reservoirs. The lava effusion and the occasional explosive eruptions, sustained by the discharge of magma caused by the interactions of these multiple magma reservoirs at different depths, contributed to the formation and growth of the new Nishinoshima volcanic island since 2013. Comparisons with several examples of island-forming eruptions in shallow seas indicate that a long-lasting voluminous lava effusion with a discharge rate on the order of at least 10⁴ m³/day (annual average) to 10⁵ m³/day (monthly average) is required for the formation and growth of a new volcanic island with a diameter on km-scale that can survive sea-wave erosion over the years.
en Nishinoshima, a submarine volcano in the Ogasawara Arc, approximately 1 000 km south of Tokyo, Japan, suddenly erupted in November 2013, after 40 years of dormancy. Olivine‐bearing phenocryst‐poor andesites found in older submarine lavas from the flanks of the volcano have been used to develop a model for the genesis of andesitic lavas from Nishinoshima. In this model, primary andesite magmas originate directly from the mantle as a result of shallow and hydrous melting of plagioclase peridotites. Thus, it only operates beneath Nishinoshima and submarine volcanoes in the Ogasawara Arc and other oceanic arcs, where the crust is thin. The primary magma compositions have changed from basalt, produced at considerable depth, to andesite, produced beneath the existing thinner crust at this location in the arc. This reflects the thermal and mechanical evolution of the mantle wedge and the overlying lithosphere. It is suggested that continental crust‐like andesitic magma builds up beneath submarine volcanoes on thin arc lithosphere today, and has built up beneath such volcanoes in the past. Andesites produced by this shallow and hydrous melting of the mantle could accumulate through collisions of plates to generate continental crust.
Abstract
ja 西之島は東京から 1 000 km 南に位置する, 小笠原弧の海底火山である. 2013 年 11 月, 西之島は 40 年ぶりに噴火した. 陸上と海底の調査により, 西之島海底火山の本体が安山岩であることが明らかとなり, 海底から採取された溶岩 (斑晶に乏しく, かんらん石を含有する安山岩) の分析からは, 安山岩マグマの新しい成因モデルが提示された. マントルの浅い部分 (30 km 以浅) は斜長石かんらん岩で構成され, この低圧マントルの含水下の部分融解により, 初生安山岩マグマが生成した. このマグマから, 主にかんらん石が結晶分別することによって, 西之島の安山岩マグマがつくられた. 一方, 西之島付近の古い時代の小海丘は玄武岩でできており, 初生マグマの組成が, 玄武岩質から安山岩質へと, 時間とともに変化したことも示された. すなわち, マントルの融解深度が地殻直下へと浅くなってきたことが示された. 地殻の薄い海洋島弧において生成された安山岩は, プレートの衝突帯で集積することにより, 大陸へと成長していく, と考えられる.
The present study shows the preliminary micropalaeontological
results obtained from surface samples collected during an Eurofleet
marine geological survey in the Terceira offshore (Azores Archipe -
lago, Portugal) carried out in September 2011.
Benthic foraminiferal assemblages were studied in order to
obtain a sea-floor ecological characterisation in natural stressed environments
like active volcanic area of the Azores Islands. Sediments
were collected at water depths ranging between 260 and 410 m and
consist of blackish, sand-sized glass shards, in which highly vesicular
to scoriaceous clasts prevail on fluidal striated fragments. All samples
were stained with Rose Bengal to determine living and dead assemblages.
The dominance of living specimens suggests that the first
generation of foraminiferal colonisers was found. Diversity index
(α-Fisher index), Faunal density and Foraminiferal Abnormality Index
(FAI) were calculated to assess the structure of the assemblage and the
degree of environmental stress. Living and dead assemblages are very
similar; they are very scarce but sufficiently diversified. The living
benthic assemblage is dominated by epi/shallow infaunal species
Angulogerina angulosa and typical infaunal taxa like Bolivina spp.
Subordinately other epifaunal (Ehrenbergina bradyi, Lenticulina spp.,
Quinqueloculina seminula, Stomatorbina concentrica) and agglutinated
species (Ammoglobigerina globigeriniformis, Eggerelloides scabrus,
Haplophragmoides canariensis, Spiroplectinella wrightii, Textularia
spp.) are also recorded. Significant frequencies of specimens showing
signs of test decalcification were found. These test alterations could be
due to hydrothermal fluids, since similar features were recorded in
foraminiferal specimens coming from other volcanic substrates in the
Aeolian Arc (Tyrrhenian Sea). The dominance of living and dead
A. angulosa specimens allows us to consider this species as opportunistic
pioneer taxon able to colonise stressed environments. This is
confirmed also by the highest values of FAI (>2%), recorded in most
of the samples, indicating a persisting environmental stress. Angulo -
gerina angulosa and Bolivina spp. are the species showing more abundant
deformed specimens (irregular development of chambers and
aberrant tests). On the basis of our observations, the recolonisation
process and the spatial distribution patterns are strongly influenced
by the sea bottom high hydrodynamic regime which is responsible for
volcanic deposit transport and depositional events. These conditions
may be reflected on the relationship between benthic foraminifers
and substrate features, which are mainly restricted to grain size, morphology
and texture of volcanic shards.
Deception Island, South Shetland Islands, Antarctica, was the site of volcanic eruptions in 1967, 1969 and 1970. These eruptions decimated much of the benthos in the island's caldera (Port Foster) and on its outer slopes. To study the effects on the foraminiferal fauna, approximately 250 bottom samples were collected during 5 successive austral summers following the last eruption. The mud substrate in Port Foster supports a low-diversity fauna dominated by Miliammina arenacea, Stainforthia fusiformis, Nonionella bradii, and Trochammina malovensis. Tongues of gravel and sand extend into Port Foster from the sites of recent eruptions. The island's coarse-grained outer slope has a more diverse fauna characterized by the Globocassidulina crassa plexus, Cribrostomoides jeffreysii, Rotaliammina ochracea, Trochammina malovensis, Rosalina globularis, Pseudoparrella exigua, Trifarina angulosa, and Cibicides lobatulus. Volcanic ashfall distributions and current transport in Port Foster delineate a transitional outer-bay subfacies where species associations and diversity of assemblages are intermediate between those of the inner-bay and outer-slope faunas. Turbidity and substratum grain-size are major controlling factors of foraminiferal distributions in the post-eruption environment. In the years following the eruptions, the foraminiferal fauna repopulated the devastated areas patchily and at different rates. Changes in the proportions of calcareous species suggest that volcanic activity may have affected the faunal composition in post-eruptive stages, although differential reproductive rates, faunal succession, a normal condition of dominance by agglutinated species, or selective dissolution of CaCO3 tests cannot be excluded as possibilities for the redundant alterations.
The following new taxa are established: Cribrilageninae subfam n.(for Cribrilagena R.W. Jones, 1984, Lagenidae) in the order Lagenida; Daucinoididae fam. n. (for Daucinoides de Klasz & Rerat, 1962) and Chrysalogoniinae subfam. n (for Chrysalogonium Schubert, 1908 and two other genera, Nodosariidae) in the order Nodosariida; Krebsininae subfam. n. (for Krebsina McCulloch, 1981, Polymorphinidae) in the order Polymorphinida; Turkmenellinae subfam. n. (for Turkmenella Bugrova, 1985) and Vribrolenticulininae subfam. n. (for Cribrolenticulina Haman, 1978 and Cribrorobulina Thalman, 1974) in the family Lenticulinidae, oeder Vaginulida. The superfamily PLeurostomellacea is upgraded to suborder (Pleurostomellina) and transferred from Rotaliiata to Nodosariata (Polymorphinida).
A comprehensive, but simple-to-use software package for executing a range of standard numerical analysis and operations used in quantitative paleontology has been developed. The program, called PAST (PAleontological STatistics), runs on standard Windows computers and is available free of charge. PAST integrates spreadsheettype data entry with univariate and multivariate statistics, curve fitting, time-series analysis, data plotting, and simple phylogenetic analysis. Many of the functions are specific to paleontology and ecology, and these functions are not found in standard, more extensive, statistical packages. PAST also includes fourteen case studies (data files and exercises) illustrating use of the program for paleontological problems, making it a complete educational package for courses in quantitative methods.
Taxonomy
A total of 563 species is listed from deep water (>50 m) from the New Zealand Exclusive Economic Zone (EEZ). The 347 most common or distinctive species are fully illustrated and their diagnostic features outlined. Two new species are described: Ammoscalaria georgescotti n. sp. and Spiroplectammina carteri n. sp. When used in combination with our twin publication on New Zealand’s shallow-water benthic foraminifera (Hayward et al. 1999), these two bulletins provide descriptive data and illustrations of the 504 most common and distinctive benthic foraminifera living in New Zealand marine and brackish environments.
Ecologic distribution of deep-water foraminifera
We use census counts (59,000 specimens) of 424 species in 264 samples to map the distribution of deep-sea (50-5000 m depth) benthic foraminifera around New Zealand. Using Q mode cluster analysis (chord similarity coefficient) of the full census data we identify 7 high-level ecologic associations (A-G), 6 of which can be further subdivided into 32 subassociations. The deepest association (A), dominated by Nuttallides umbonifera and Globocassidulina subglobosa occurs at mid-lower abyssal depths (>3500 m) east of New Zealand. The next deepest, C (Epistominella exigua - Alabaminella weddellensis), is widespread at lower bathyal – abyssal depths (>1200 m) off both sides of central and northern New Zealand, but does not extend into the subantarctic zone. Three bathyal associations are recognised, with D and E occurring right around New Zealand and B restricted to the subantarctic. Association D (Cassidulina carinata – A. weddellensis) is usually in deeper, less current-swept waters than E (Globocassidulina canalisuturata – Bolivina robusta). Association B (Trifarina angulosa – Ehrenbergina glabra) also occurs in deeper parts of the bathyal zone (900-2000 m) along the strong current-swept, south-eastern margin of the Campbell and Bounty Plateaux, beneath the Subantarctic Front. Associations F (Cassidulina carinata – Trifarina angulosa) and G (Cassidulina carinata – Bulimina marginata f. marginata) mostly occur at mid shelf-upper bathyal depths (50-600 m) around southern and northern New Zealand respectively, with the dividing line approximating the position of the Subtropical Front.
Q mode cluster analysis (Jaccard coefficient) of presence/absence data of the 424 species in the 264 samples allows the recognition of nine high-level associations (a-i), four of which are further subdivided into 13 subassociations. The distribution of these associations is similar, but not identical, to that based on the quantitative data, indicating that total species composition is just as important as the relative abundance of dominant species in defining these regions.
R-mode cluster analysis (Pearson product-moment correlation coefficient) of full census data for the 56 most common species allows the recognition of eight groups, whose distribution is most strongly linked to bathymetry and secondly to geography. Two abyssal-lower bathyal associations (dominated by Globocassidulina subglobosa and Trifarina angulosa) are most abundant off southern New Zealand; one from lower bathyal-abyssal depths (Epistominella exigua) occurs dominantly east of northern and central New Zealand; an outer shelf to mid bathyal association (Cassidulina carinata) is more common to the east and south than the west; and another from mid-lower bathyal depths (Uvigerina peregrina) dominantly occurs off the west coast of New Zealand. The remaining three are common all around New Zealand.
Canonical correspondence analysis was used to relate sample associations to a set of environmental "drivers" using the full census data. Bathyal and abyssal associations appear to be more strongly influenced by depth-related variables (e.g., bottom temperature, salinity, oxygen, carbon flux) and shallower associations by latitude-related differences in surface-water characteristics (e.g., temperature, surface phosphate, chlorophyll-a). Environmental variables that influence faunal patterns at abyssal and lower bathyal depths (Assocs. A-C) appear to be, in decreasing order: bottom current strength (mud percentage proxy), carbonate corrosiveness (fragmentation index and planktic % proxies), quality, quantity and seasonality of organic carbon flux to the sea floor (surface phosphate, sea surface temperature, spring and summer chlorophyll-a proxies), and possibly properties of bottom water masses (salinity proxy). Faunal patterns within bathyal associations (D, E) are most strongly influenced by organic carbon flux (surface phosphate proxy), bottom oxygen concentrations (bottom water measurements) and bottom current strength (mud percentage proxy). Latitude-related variables driving mid shelf-upper bathyal faunal patterns (Assocs. F, G) include water temperature and primary productivity in the overlying waters (chlorophyll-a and organic carbon flux proxies).
Species diversity
Based on calculations for individual samples, the species diversity (α, H) of New Zealand benthic foraminiferal faunas overall and at all depths down to mid abyssal (<3000 m) decreases from lower to higher latitudes. At lower abyssal depths (>3000 m) faunas from all regions have a similar range of species diversity. There are no consistent diversity or evenness trends related to depth. Faunal evenness (E) decreases from north to south around New Zealand with more dominance of opportunistic species in the south where nutrients and food supply are more seasonally pulsed.
Based on SHE analysis for biofacies identification (SHEBI), 16 communities were identified in the deep sea around New Zealand. The communities exhibit a north to south latitudinal trend with lnS, H and lnE decreasing to the south. In the north and in the south the communities show an increase in lnS and H with depth. There is no trend with depth in the east and west areas. The community structure in each community was compared using the log series as a null model. Each area exhibits a unique pattern of community structure. In the north-east, 4 communities are recognised and only one at mid-bathyal depths does not resemble a log series. In the west, 3 communities are identified and only the outer shelf does not resemble a log series. The east is very different, where 4 out of 5 communities do not resemble a log series with only the community at abyssal depths doing so. In the south, all 4 of the recognised communities resemble a log series. All abyssal communities resemble a log series and 5 of 6 communities deeper than 1300 m resemble a log series. The log series is characterised by a constant H and is interpreted as representing community stability.
Frequency of species occurrence
We found that the pattern of species occurrence in deep water and throughout New Zealand localities approximates a typical log series plot. As a consequence the vast majority of species occur rarely (37% of species occur in <2% of localities) and only a small number occur widely (4% occur in >50% of localities). Buliminid and rotaliid species and those that dominantly live in shallow water have the highest frequency of occurrence and carterinid, astrorhizid, lituolid, trochamminid and robertinid species the lowest occurrence frequency.
Species duration
We used the recorded regional stratigraphic ranges of 642 modern New Zealand species (both deep, shallow and brackish) to investigate species duration patterns. The percentage of extant species in each of the following orders having a New Zealand fossil record are: Carterinida 0%, Trochamminida 0%, Lituolida 5%, Astrorhizida 10%, Robertinida 20%, Spirillinida 22%, Textulariida 30%, Miliolida 36%, Lagenida 45%, Rotaliida 53%, and Buliminida 59%. Foraminifera that live dominantly in normal marine salinity, shallow (< 100 m) and deep (> 100 m) water have a similar proportion of species recorded fossil from New Zealand (38-42%), with a much lower proportion from brackish environments (11%), reflecting the poor fossil record from brackish settings.
Of the 249 extant species with recorded fossil ranges in New Zealand: 3% first appeared in the Cretaceous, 1% in Paleocene, 10% in Eocene, 16% in Oligocene, 47% in Miocene, 14% in Pliocene and 9% in Pleistocene. These species have a mean partial species duration of 20 million years, comparable with a mean of 21 myrs for benthic foraminifera from the Atlantic margin of north America. There is no major difference in the timings of first appearances nor mean partial species durations between deep- and shallow-water-dwelling species.
Eighty-one percent of commonly occurring species (in >25% of localities) have a fossil record (mean species duration 21 myrs) compared with 14% of rarely occurring species (mean species duration 24 myrs). Sixty percent of endemic species (mean species duration 13 myrs) have a New Zealand fossil record compared with 43% of cosmopolitan species (mean species duration in NZ of 24 myrs) – the reverse of North American Atlantic coast data. This indicates that endemic species have been more common in New Zealand waters than in the North Atlantic, possibly a reflection of New Zealand’s isolation.
Biogeography
Sixty-four percent of the 642 extant New Zealand benthic foraminiferal species (both deep, shallow and brackish) have a cosmopolitan distribution, compared with 9% (52 spp) endemic to New Zealand and a further 8% to each of the South-west Pacific (including Australia), West Pacific and Pacific regions. A slightly greater proportion of deep-water (>100 m) species (69%) have a cosmopolitan distribution than do shallower-water (<100 m) species (55%), with brackish species (92%) having the highest proportion. Just 3% of deep-water species (Sigmoilopsis finlayi, Siphonaperta crassa, Spiroloculina novozelandica, Ruakituria pseudorobusta, Jullienella zealandica) are endemic to New Zealand, but 16% of shallow-water species are.
Our analyses of species presence/absence data suggest that the benthic foraminiferal biogeography around New Zealand differs at different depths and in different water masses. Five provinces can be recognised in our shallowest faunas (inner-mid shelf) and these correspond well with those identified from molluscs. At mid-outer shelf and upper bathyal depths, only 2 provinces can be identified. With increasing depth, greater subdivision is again possible, with 3 provinces recognisable at mid-lower bathyal depths and 4 at abyssal depths. Twenty-four percent (mostly common species) of all 424 species in our quantitative deep-water data set occur in all four regions - north, west, east and south of New Zealand - 17% are restricted to the north, 16% to the east, 8% to the south and just 4% to the west. The main faunal differences between regions are in the numerous rarely occurring species.
Paleoenvironmental assessment
There are many environmental drivers of the modern ecologic distribution of foraminifera and these vary from place to place. In this and previous shallow-water studies of modern foraminifera we have been able to correlate the strength of some of these environmental variables with the relative abundance of various taxa or associations. These correlations can be used to provide estimates of the paleoenvironments in which fossil foraminiferal faunas accumulated that are of value to geological, paleoclimatic and paleoceanographic studies. This uniformitarian approach is most applicable to Quaternary and Neogene faunas but far less reliable further back in time in the Paleogene and Cretaceous.
Planktic foraminiferal percentages and the relative abundance of different planktic species (census counts) can be used to estimate oceanicity, paleo-sea surface temperature and to give an indication of water depth. The composition of benthic foraminiferal faunas by order may provide a general indication of the past environment, but the relative abundance of benthic genera or species and the recognition of faunal associations allow more detailed environmental assessments. In the deep sea these are predominantly of water depth, seasonal or sustained carbon flux, strong bottom currents, bottom oxygen concentrations or exposure to carbonate corrosive bottom waters. In shallow or brackish environments these are predominantly water depth, tidal elevation, salinity, water temperature and exposure to water turbulence. Although depth is not a driver of foraminiferal distribution, a number of environmental variables show general trends with respect to depth, which allow depth estimates to be extracted from faunal composition data. Charts and tables summarising the depth distribution around New Zealand of a number of genera and species are provided to assist in paleodepth assessments. At bathyal depths we have identified c.60 benthic genera and species that appear to have distinct upper depth limits to their distribution and these provide an additional method to help refine paleodepth estimates of Neogene deep-sea faunas.
A method for rapid paleoenvironmental assessments of fossil New Zealand Neogene faunas is outlined, based on a quick estimate of planktic foraminiferal percentage, benthic foraminiferal composition and identification of dominant benthic taxa.
The Soufrière Hills Volcano, on the island of Montserrat, has an eruption history spanning over 2 million years. During this time the volcano has undergone multiple eruptions with intervening periods of low activity or dormancy. The most recent activity began in 1995 and has seen a series of major eruptive events. One of the most recent of these, and the focus of this study, occurred on the 20th May 2006. This major dome collapse produced 90 million m3 of volcanic material in only 3 hours, propelling ash clouds through the air and pyroclastic flows down the side of the volcano and into the sea. In this study of benthic foraminifera, cores from four sites off-shore Montserrat are analysed, including those collected from a location within the path of the 2006 ash cloud, around 10 km west of the Montserrat coast. In this area, one core contained 6-7 cm of ash overlying hemipelagic sediments. Volcanic ash is present in two distinct layers, one 3 cm layer produced by the 2006 eruption and the other, 3-4 cm layer, from an earlier eruption in 2003. Other cores were collected from areas unaffected by recent ash fall deposits and provide a base line for comparisons within the affected areas. To the east and south-east of Montserrat there is a different situation as this is the direction of travel of massive pyroclastic flows down the Tar Valley and the impact on the sea floor is more dramatic. There are also two extinct volcanic centres that allow the investigation of sea floor re-colonization on different time scales. The sites to the west of Montserrat record rapid colonization by benthic foraminifera of opportunistic taxa, comparable to that seen near Mt Pinatubo in the South China Sea while the sites to the east record a slower pattern of re-colonization by a wider spectrum of taxa, similar to that recorded at Deception Island in the Southern Ocean, with different benthic taxa performing the pioneering role.
Abstract
The new, atypical aragonitic foraminifer Tubulastella comans gen. et sp. nov. is described from the Late Triassic of Panthalassa (Wallowa terrane, north-east Oregon, USA). This rectilinear, undivided tubular form is closely related to ‘Coptocampylodon? rhaeticus’, a Rhaetian incertae sedis commonly found in the western Tethys. Morphologically and structurally distinct from other aragonitic foraminifers, Tubulastella comans gen. et sp. nov. and T. rhaetica gen. et comb. nov. are part of an independent aragonitic lineage, here embodied by the family Tubulastellidae fam. nov. To understand the origination and taxonomic affinity of this unique taxon, a comparative study between Tubulastella and the calcitic syzraniid foraminifer Rectostipulina is carried out. Although these forms differ in wall composition, they present identical constructional patterns, providing evidence of their close phylogenetic relationship. The existence of an aragonitic branch in Nodosariata evolution deeply challenges current foraminiferal classifications and evolutionary hypotheses. We here propose to limit the class Nodosariata to a monophyletic group of bi- to plurilocular foraminifers originating from a Silurian earlandiid ancestor, and the order Nodosariida to a monophyletic lineage of primarily single-layered built foraminifers, which takes root in the Middle Pennsylvanian. This new classification reflects an evolutionary transition from calcitic to aragonitic walls, as documented in other shelled organisms, and definitively excludes calcitic unilocular foraminifers (i.e. Ellipsolagenidae and Lagenidae) from the class Nodosariata.
1. From Baffin’s Bay, between 76° 30' and 74° 45' North Latitude. These specimens are derived from seven deep-sea soundings made during one of the Arctic Expeditions under Sir Edward Parry. These soundings were confided to us by Professor Huxley, of the Museum of Practical Geology, Jermyn Street, to which Institution they had been given in April 1853 by Mr. J. W. Lowry, who received them of Mr. Fisher, Assistant-Surgeon in the Expedition alluded to. The Foraminifera obtained by us from these soundings are tabulated in Tables I., IV., and VII. This material from the “Arctic Province” of Naturalists is but scanty. None of the Foraminifera here obtained are numerous, except Polystomella striatopunctata , Nonionina Scwpha , Truncatulina lobatu , and Cassidulina lœvigata ; the first two of which are at home in Arctic waters : and none have attained here a large size except lituolœ . The material from 150 fathoms yielded these relatively large and numerous specimens.
A system is proposed for the Foraminifera, which are considered to be a subtype including seven classes (Lagynata, Astrorhizata, Miliolata, Spirillinata, Nodosariata, Rotaliata, and Globigerinata), eight subclasses, and 63 orders. The system is based on the priority of the body plan as compared to the test wall ultrastructure. A conclusion has been drawn that the evolution of the test wall proceeded independently and in parallel in different phylogenetic branches (classes) of the Foraminifera from the organic type to the agglutinated and secretional type, with increasing orderliness of all structural elements of the latter in higher representatives of the classes Spirillinata, Nodosariata, Rotaliata, and Globigerinata. Lower subclasses of the classes Miliolata, Spirillinata, Nodosariata, and Rotaliata have an agglutinated and microgranular wall (Schlumbergerinana, Ammodiscana, Hormosinana, and Textulariana, respectively), Paleozoic forms have been considered in a common system with living forms.
Volume 1 contains the text of the treatise, and volume 2, 847 plates. Of the 3620 validly proposed generic taxa of Foraminiferida considered 2455 genera are recognised, described and illustrated, 960 regarded as synonyms, 208 considered systematically unrecognisable, 16 too late for detailed inclusion. They are placed in 12 suborders, 74 superfamilies, 296 families, 302 subfamilies. A systematic index is included. The systematic arrangement of genera is alphabetical within the various subfamily or family categories, and the family group taxa within the suborders are arranged in order of presumed evolutionary sequence or increasing complexity. Descriptions are generally focused on test morphology, both external and internal, but some information concerning the living organism is summarized for the few that are known. Geologic range is given to the level of the geologic series of epoch, and known geographic occurrence and a limited amount of ecologic information is included. In view of the very large number of taxa considered, morphologic descriptions are as concise as possible, consistent with the inclusion of the available information. Morphologic terms used are defined in a glossary, in which reference also is given to other terms proposed by various writers. -from Authors
The distribution of Holocene benthic foraminifer species in bottom sediments in the Izu-Bonin Arc region of the northwestern Pacific Ocean has been investigated on the basis of 23 samples recovered from depths between 1100 and 4100 m. The benthic foraminifer faunas identified can be grouped into four species assemblages corresponding to four bathymetric zones. The dominance of such an agglutinated foraminifer as Rhabdamminella sp. characterizes the abyssal zone, whereas assemblages devoid of calcareous foraminifers distinguish the zone deeper than the carbonate compensation depth (CCD). The occurrence of Bulimina aculeata d'Orbigny enables the recognition of the following three bathymetric zones: the lower bathyal zone, the lower middle bathyal zone and the upper middle bathyal zone. To estimate Quaternary and Pliocene paleobathymetry in the Izu-Bonin region, three water-depth indexes will work well: 3700 m for the CCD, 2300 m for the deepest habitat of B. aculeata, and 1600 m for the shallowest habitat of B. aculeata. -from Authors
Nine new species of benthic foraminifera are described from sediments of the southwest Pacific Ocean. All are bathyal to abyssal in their distribution. Two of them, Globocassidulina hooperi n. sp. and Pseudoparrella parca n. sp., are particularly significant because their occurrence is limited to abyssal depths, coincident with the distribution of Antarctic Bottom Water and its close derivatives. The other species to be described are Ammobaculites paradoxus, Globulotuba scrippsi, Turrilina hadra, Schackoinella favoculcita, Heronallenia cursa, and Nonion belfordi. -from Author
The circulation nature in the Subarctic Gyre in the North Pacific, and the water mass modification processes found there are discussed. The circulation path penetrates well inside the Bering Sea, and a part of the water enters into the Okhotsk Sea. The water masses are modified significantly in and near these marginal seas. The Oyashio Water is shown to be formed by mixing between the East Kamchatka Current Water and the Okhotsk Sea Water. The freshest water in the intermediate layers is found in the Okhotsk Sea, and appears to play important role in the formation of the North Pacific Intermediate Water.
A revised classification is presented for the Foraminiferida, combining the results of our research with various partial or more inclusive reclassifications that have appeared during the past two decades. The total 591 suprageneric taxa used herein for the Order Foraminiferida include 12 suborders, 63 superfamilies, 253 families and 263 subfamilies. New taxa proposed herein are the suborder Robertinina, the families Abadehellidae, Bolivinoididae, Bronnimanniidae, Coleitidae, Dryorhizopsidae, Dusenburyinidae, Earlandinitidae, Eocristellariidae, Globanomalinidae, Globuligerinidae, Globorotalitidae, Hippocrepinellidae, Hospitellidae, Hyperamminoididae, Linderinidae, Lituotubidae, Oridorsalidae, Pachyphloiidae, Palaeospiroplectamminidae, Pannellainidae, Paratikhinellidae, Partisaniidae, Polysaccamminidae, Praebuliminidae, Thomasinellidae, Valvulinellidae and Virgulinellidae, and the subfamilies Ammoastutinae, Ashbrookiinae, Bykoviellinae, Cuneatinae, Cyclopsinellinae, Endostaffellinae, Eohastigerinellinae, Halyphyseminae, Hergottellinae, Koskinobigenerininae, Lingulinopsinae, Louisettitinae, Novalesiinae, Orthoplectinae, Palmerinellinae, Pernerininae, Planctostomatinae, Shepheardellinae, Siphogenerininae, Siphoninoidinae, Textularioidinae and Torresininae. Family group taxa that are changed in rank (new status) herein are the superfamilies Acervulinacea, Coscinophragmatacea, Cyclolinacea, Geinitzinacea, Glabratellacea, Hyperamminacea, Ptychocladiacea, Robuloidacea, Siphoninacea and Squamulinacea, the families Alfredinidae, Bathysiphonidae, Cyclolinidae, Dictyopsellidae, Discamminidae, Discorbinellidae, Dorothiidae, Elhasaellidae, Globigerinitidae, Orbitopsellidae, Pulleniatinidae, Reussellidae, Robuloididae, and Stainforthiidae and the subfamilies Placentulininae and Semitextulariinae. Brief definitions are given herein for all recognized suprageneric taxa within the Foraminiferida. The synonymy listed for these suprageneric taxa includes only those taxa based on included genera. An index to recognized suprageneric taxa is included.
An up-to-date atlas of an important fossil and living group, with the Natural History Museum.
Deep-sea benthic foraminifera have played a central role in biostratigraphic, paleoecological, and paleoceanographical research for over a century. These single–celled marine protists are important because of their geographic ubiquity, distinction morphologies and rapid evolutionary rates, their abundance and diversity deep–sea sediments, and because of their utility as indicators of environmental conditions both at and below the sediment–water interface. In addition, stable isotopic data obtained from deep–sea benthic foraminiferal tests provide paleoceanographers with environmental information that is proving to be of major significance in studies of global climatic change.
This work collects together, for the first time, new morphological descriptions, taxonomic placements, stratigraphic occurrence data, geographical distribution summaries, and palaeoecological information, along with state-of-the-art colour photomicrographs (most taken in reflected light, just as you would see them using light microscopy), of 300 common deep-sea benthic foraminifera species spanning the interval from Jurassic - Recent. This volume is intended as a reference and research resource for post-graduate students in micropalaeontology, geological professionals (stratigraphers, paleontologists, paleoecologists, palaeoceanographers), taxonomists, and evolutionary (paleo)biologists.
The limitations of a traditional morphology-based classification of Foraminifera have been demonstrated by molecular phylogenetic studies for several years now. Despite the accumulation of molecular data, no alternative higher-level taxonomic system incorporating these data has been proposed yet. Here, we present a new supraordinal classification of Foraminifera based on an updated SSU rDNA phylogeny completed with the description of major morphological trends in the evolution of this group. According to the new system, multi-chambered orders are grouped in two new classes: Tubothalamea and Globothalamea. Naked and single-chambered Foraminifera possessing agglutinated or organic-walled tests are arranged into a paraphyletic assemblage of “monothalamids”. The new system maintains some multi-chambered calcareous orders, such as Rotaliida, Miliolida, Robertinida and Spirillinida, although their definitions have been modified in some cases to include agglutinated taxa. The representatives of the planktonic order Globigerinida are tentatively included in the order Rotaliida. The agglutinated Textulariida are probably paraphyletic. The position of the order Lagenida is uncertain because reliable molecular data are only available for one species. The new classification system separates orders or families, which differ in basic chamber shapes, prevailing mode of coiling and distance between successive apertures. It appears that these features correspond better to the main evolutionary trends in Foraminifera than wall composition and structure, both used in traditional classification.