197 research outputs found
The new and reinstated genera of agglutinated foraminifera published between 1986 and 1996
In the 10 years following the publication of "Foraminiferal Genera and their Classification"
by Loeblich & Tappan (1987), some 91 new genera of agglutinated foraminifera have been
proposed by various authors. Additionally, at least four of the genera listed by Loeblich &
Tappan as junior synonyms have been resurrected by subsequent authors. This
compilation is an attempt at bringing together the nomenclatorial changes to the
agglutinated foraminiferal genera that have appeared in the accessible literature
The utility of deep-water agglutinated Foraminiferal acmes for correlating Eocene to Oligocene abyssal sediments in the North Atlantic and Western Tethys
Quantitative analysis of Deep-water Agglutinated Foraminifera (DWAF) assemblages from key ODP sites in the North Atlantic reveal the presence of stratigraphically-significant abundance maxima, that may be useful for correlating sedimentary sequences deposited beneath the CCD. The DWAF record from ODP Hole 647A in the Labrador Sea was re-studied and abundances were recalculated by excluding calcareous benthic foraminifera. This hole is a key locality, as it provides direct calibration of the DWAF biostratigraphy to the standard chronostratigraphy. Eight DWAF acmes are recognised in the Eocene to lower Oligocene at Site 647 and at other North Atlantic and Norwegian Sea sites. These are: The Paleocene-Eocene Thermal Maximum (PETM) Glomospira Acme, a lower Eocene N. excelsa acme, an early/middle Eocene Glomospira Acme, a Karrerulina acme, a middle Eocene Reticulophragmium amplectens acme, a middle/late Eocene Spiroplecta- mmina acme, a latest Eocene-early Oligocene Ammodiscus latus acme, and an early Oligocene Spirosigmoilinella acme. Some of these acmes can be correlated with similar events occurring at onshore localities in the Western Tethys (northern Spain, Moroccan Rif, Italian Appenines, Western Carpathians). The occurrence of these DWAF acmes is caused by variations in the trophic continuum which is a consequence of the profound climatic and oceanographic changes that took place in the deep ocean during the Eocene and early Oligocene
The Year 2000 classification of the agglutinated foraminifera
A reclassification of the agglutinated foraminifera (subclass Textulariia) is presented, consisting of four
orders, 17 suborders, 27 superfamilies, 107 families, 125 subfamilies, and containing a total of 747
valid genera. One order (the Loftusiida Kaminski & Mikhalevich), five suborders (the Verneuilinina
Mikhalevich & Kaminski, Nezzazatina, Loftusiina Kaminski & Mikhalevich, Biokovinina, and
Orbitolinina), two families (the Syrianidae and the Debarinidae) and five subfamilies (the
Polychasmininae, Praesphaerammininae Kaminski & Mikhalevich, Flatschkofeliinae, Gerochellinae
and the Scythiolininae Neagu) are new. The classification is modified from the suprageneric scheme
used by Loeblich & Tappan (1992), and incorporates all the new genera described up to and including
the year 2000. The major differences from the Loeblich & Tappan classification are (1) the use of
suborders within the hierarchical classification scheme (2) use of a modified Mikhalevich (1995)
suprageneric scheme for the Astrorhizida (3) transfer of the Ammodiscacea to the Astrorhizida (4)
restriction of the Lituolida to forms with simple wall structure (5) supression of the order
Trochamminida, and (6) inclusion of the Carterinida within the Trochamminacea (7) use of the new
order Loftusiida for forms with complex inner structures (8) broadening the definition of the
Textulariida to include perforate forms that are initially uniserial or planispiral. Numerous minor
corrections have been made based on the recent literature
The new and reinstated genera of agglutinated foraminifera published between 1996 and 2000
During the four year period since the previous International Workshop on Agglutinated
Foraminifera, some 33 genera of agglutinated foraminifera have been described as new, and an
additional six genera have been reinstated by various authors. This brings the total number of new
and reinstated genera to 121 since the publication of âForaminiferal Genera and their Classificationâ
by Loeblich & Tappan (1987)
Sediment disturbance caused by a suspension-feeding tubular agglutinated foraminifer
We report the occurrence of in-situ sediment disturbance caused by a specimen of Rhabdammina
observed in life position on the 1991 Mt. Pinatubo ash layer in the abyssal South China Sea. The
specimen extracts sediment grains from the ash layer to build its agglutinated test, causing a
depression, or âmoatâ to form around the base of the specimen. We suspect that such fine-scale
disturbance caused by large, erect tubular foraminifera is a common feature of the fossil record in
deep-sea settings
Evidence for vertical motility in Campanian deep-water agglutinated foraminifera: The Furlo volcanic ash layer
Evidence for vertical motility has been observed among six Campanian deep-water agglutinated foraminiferal species from the Furlo Bentonite in the Umbria-Marche Basin, Ital
Pliocene and Pleistocene chronostratigraphy and paleoenvironment of the Central Arctic Ocean, using deep water agglutinated foraminifera
Deep-water agglutinated foraminifera (DWAF) were studied from Cores PS2177-5, PS2200-5, PS2212-3 and PS2185-6; from the R/V POLARSTERN ARK-VIII/3 Cruise in the central Arctic Ocean. The sediments were non-calcareous containing a sparse assemblage of eleven DWAF species. A chronostratigraphic framework is presented for Cores PS2200-5 and PS2185-6. Paleoenvironmental data suggests a bathyal environment (2000-4000m) affected by water masses in the Arctic Ocean. The taxonomy of all of the DWAF found is presented and illustrated. A new species of the Family Trochamminidae; Trochammina lomonosovensis n. sp. is described and illustrated
What, if anything, is a Paratrochamminoides? A key to the morphology of the Cretaceous to Cenozoic species of Conglophragmium and Paratrochamminoides (Foraminifera)
We present a review of the current taxonomical status of the genus Paratrochamminoides Soliman,
1972. We recognise five main subgroups of this genus based upon the following modes of coiling:
trochospiral, streptospiral, glomospiral, triloculine or milioline, and thalmannamminiform. Species
that display streptospiral coiling and an interiomarginal aperture are placed in the genus
Conglophragmium BermĂșdez & Rivero, 1963, whereas the genus Paratrochamminoides is here
understood to encompass all other coiling modes. The morphological characters of 23 named and
unnamed species that we recognise as belonging to Paratrochamminoides and Conglophragmium are
presented in tabular form. Of these, 22 are considered here to be valid species. Emended descriptions
are provided for both genera, and diagnoses are given for each of the species
Valanginian to Barremian Benthic Foraminifera from ODP Site 766 (Leg 123, Indian Ocean)
A Valanginian to Barremian bathyal foraminiferal assemblage (118 taxa belonging to 51 genera) is documented from ODP Site 766, drilled near the foot of the Exmouth Plateau off northwest Australia. The majority of taxa are cosmopolitan species previously described from the boreal assemblages of northern Europe and the northern margins of the Tethys, but 32 taxa could not be assigned to previously described species and are left in open nomenclature. The chronostratigraphy of this section is based upon nannofossils, palynomorphs, and radiolarians. The foraminiferal succession is divided into four assemblages based on the first and last occurrences of characteristic benthic foraminifera: 1) An upper Valanginian Lenticulina ouachensis - Textularia bettenstaedti assemblage with Ammodiscus tenuissimus, Bulbobaculites sp., and Aaptotoichus clavellatus. The last occurrences of these taxa are observed near the transition between the Valanginian and Hauterivian. 2) A lower Hauterivian assemblage is characterized by Lenticulina heiermanni and Saracenaria forticosta. 3) An upper Hauterivian assemblage contains Planularia crepidularis, Patellina subcretacea, and Reinholdella hofkeri. A major faunal discontinuity is observed at the top of this assemblage between Cores 766A-32R and 766A-30R, probably associated with a depositional gap between the late Hauterivian and the Barremian. 4) The overlying Barremian assemblage is characterized by Gavelinella barremiana, Glomospira spp., and Pseudogaudryinella sp. This record enables long-distance comparisons of the stratigraphic ranges of benthic foraminiferal species in the austral bioprovince with their reported ranges in the North Atlantic region and the northern Tethys. Although the assemblages at Site 766 consist of ca. 74% cosmopolitan species, they differ from Tethyan assemblages in the rarity or absence of index taxa such as Praedorothia spp., Lenticulina nodosa and L. eichenbergi, as well as ornamented, palmate morphotypes such as Citharina spp., Flabellina spp., and Frondicularia spp. They differ from the typical boreal assemblages by the lack of diverse agglutinated taxa. As a result, benthic foraminiferal zonations established for the Lower Cretaceous of the northern Tethys and Tethyan DSDP sites could not be applied at Site 766. Taxonomic and biostratigraphic differences at Site 766 support the existence of a taxonomically distinct Early Cretaceous austral bioprovince
Tubular agglutinated foraminifera as indicators of organic carbon flux
The dimensions of tubular agglutinated foraminifera such as Rhizammina and Rhabdammina respond
in a predictable manner to changes in the flux of organic carbon to the sea floor. In both the modern
western North Atlantic and in an ancient example (the K/T boundary in Gubbio), the slender,
finely-grained tubes (<100 ÎŒm diameter) dominate in oligotrophic regimes, whereas in eutrophic
regimes the abundance of tubes is higher, and the mean and standard deviation of the tube
diameter increases. Large tubes (> 500 ÎŒm) are present only when organic flux is comparatively
high. Although our observations are at present not directly calibrated to primary productivity
levels, we maintain that the potential for using tubular agglutinated foraminifera does exist
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