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Rhomboaster

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Journal Article
Published: 01 January 1996
Journal of Paleontology (1996) 70 (1): 7–22.
Journal Article
Journal: GeoArabia
Publisher: Gulf Petrolink
Published: 01 January 2014
GeoArabia (2014) 19 (1): 117–140.
... proposed. The oil shales studied contain abundant calcareous nannofossil taxa of Eocene age along with varying abundances of Maastrichtian and Paleocene taxa. The encountered marker species Rhomboaster cuspis, Tribrachiatus bramlettei, Tribrachiatus orthostylus, Discoaster lodoensis, Coccolithus crassus...
FIGURES | View All (18)
Series: GSA Special Papers
Published: 01 January 2007
DOI: 10.1130/2007.2424(04)
... the PETM, paying special attention to the quantitative determination of the changes undergone by the Rhomboaster spp. Discoaster araneus association (R-D); and (3) recovery of the ecosystem. In this study, we have revisited and conducted higher-resolution calcareous nannofossil quantitative analyses...
Journal Article
Published: 01 January 2007
Micropaleontology (2007) 53 (1-2): 127–144.
... by the first appearances of Discoaster araneus , Rhomboaster calcitrapa, R. bitrifida and R. cuspis . The Paleocene/Eocene boundary lies within the upper part of the Esna Formation. A very thin layer of conglomeratic chalk with no paleontological break is located between Zone NP9 and NP10. However, a very...
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Journal Article
Published: 01 January 2006
Micropaleontology (2006) 52 (3): 193–222.
... increase in abundance of Rhomboaster spp., a sharp increase of long-armed, asymmetrical discoasters, and a second shift of Coccolithus pelagicus/subpertusa . Immediately above the CIE-interval and continuing up to the top of the section, a gradual increase of Toweius spp. accompanied by a gradual decrease...
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Journal Article
Published: 01 June 2003
Micropaleontology (2003) 49 (Suppl_1): 41–59.
... foraminiferal excursion taxa are sporadic and the distinct Discoaster araneus-Rhomboaster spp. association is persistent throughout the CIE-interval. The quarry at Dababiya is in the process of becoming the stratotype for the Paleocene/Eocene boundary, formally defined by a lithostratigraphic horizon-the base...
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Journal Article
Published: 01 June 2003
Micropaleontology (2003) 49 (Suppl_1): 93–104.
... negative carbon isotope excursion of comparable magnitude to that recorded from Dababiya. Calcareous nannoplankton ( Rhomboaster spp.- Discoaster araneus association) and planktonic foraminiferal occurrences (the so-called excursion taxa) allow unambiguous determination of this isotopic excursion...
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Image
Stratigraphical distribution of the representatives of genera  Fasciculithu...
Published: 01 January 2006
TEXT-FIGURE 14 Stratigraphical distribution of the representatives of genera Fasciculithus, Discoaster, Toweius , Coccolithus , Rhomboaster and Tribrachiatus in the Paleocene-Eocene transition at Gebel Serai section.
Image
FIGURE 5 —Calcareous nannofossil and planktic foraminifera main bioevents, ...
in > PALAIOS
Published: 01 May 2009
- Toweius+Cocolithus pelagicus fraction. Abbreviated genus names include: C . = Coccolithus pelagicus ; D . = Discoaster ; R . = Rhomboaster ; S . = Sphenolithus ; F . = Fasciculithus ; A . = Acarinina ; G . = Globanomalina ; P . = Planorotalites . s.a. = short arms; l.a. = long arms; T = T
Image
(The scale bar for all photographs equal approximately to 2μm.  All figures...
Published: 01 January 2006
Rhomboaster sp, sample 57, Zone NP9b 33 Rhomboaster cuspis, sample 68, Zone NP9b 34–36 Rhomboaster spineus, Zone NP9b; 34, sample 57; 35, sample 60; 36, sample 61 37–38 Rhomboaster bitrifida , Zone NP9b; 37, sample 55; 38 sample 62 39–42 Tribrachiatus bramlettei , Zone NP10b; 39, sample 81; 40–42
Image
Figure 3. The columns to the far left show the lithology and nannofossil bi...
in > Geology
Published: 01 September 2006
of Rhomboaster / Tribrachiatus bramlettei and the NP10/NP11 boundary is approximated by the first occurrence of T. orthostylus . Stable-isotope, weight percent Corg and CaCO 3 , and TEX 86 raw data are plotted versus subsurface depth. The stable-isotope data are from analyses of Morozovella velascoensis
Image
(Scanning electron micrographs from Gebel Serai section)  1  Fasciculithus ...
Published: 01 January 2006
pulcher, sample 65, Zone NP9b 12 Discoaster mohleri, distal view, sample 7, Zone NP7/8 13–14 Discoaster multiradiatus, sample 39, Zone NP9a 15 Discoaster binodosus, sample 39, Zone NP9a 16 Discoaster aegyptiacus, sample 55, Zone NP9b 17 Rhomboaster cuspis, sample 55, Zone NP9b 18
Series: Geological Society, London, Special Reports
Published: 01 January 2016
DOI: 10.1144/SR27.21
EISBN: 9781862397071
.... 1984 ); the absence of Rhomboaster and Tribrachiatus, and the presence of F. tympaniformis, would indicate Subzone NP9a (latest Thanetian). However, the records of Discoaster mohleri and D. riedelii (Zone NP8 or older) are anomalous. The possibility that all of these are reworked cannot be discounted...
Journal Article
Journal: PALAIOS
Published: 01 May 2009
PALAIOS (2009) 24 (5): 318–328.
...- Toweius+Cocolithus pelagicus fraction. Abbreviated genus names include: C . = Coccolithus pelagicus ; D . = Discoaster ; R . = Rhomboaster ; S . = Sphenolithus ; F . = Fasciculithus ; A . = Acarinina ; G . = Globanomalina ; P . = Planorotalites . s.a. = short arms; l.a. = long arms; T = T...
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Journal Article
Published: 01 September 2000
Journal of the Geological Society (2000) 157 (5): 929–941.
... of this species from upper Zone NP9 through Zone NP14. A size increase is also observed in this study. The base of Zone NP10, the Rhomboaster bramlettei Zone of Martini (1971), is defined by the first appearance of the nominate species. In recent papers there has been an unresolved controversy about...
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Journal Article
Published: 20 April 2018
Journal of Foraminiferal Research (2018) 48 (2): 100–120.
...–61.00 m (OS–01) and 48.70–47.05 m (OS–28) were assigned to biozone NP9a based upon the presence of Discoaster multiradiatus . The boundary between the biozones NP9a/NP9b is defined by the first occurrence (FO) of the calcareous nannofossil taxa Discoaster araneus and Rhomboaster cuspis . Biozone...
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Journal Article
Published: 01 June 2003
Micropaleontology (2003) 49 (Suppl_1): 15–40.
... negative shift in the carbon isotope of ~3.5% occurs within Zone P5 across the NP9/NP10 zonal boundary. A major turnover in the calcareous nannofossils is recorded by these authors across the P/E boundary involving the LO of Rhomboaster cuspis, R. spineus, Tribrachiatus bramlettei, D. mahmoudi . All...
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Journal Article
Journal: Paleobiology
Published: 22 August 2013
Paleobiology (2013) 39 (4): 628–647.
..., Neochiastozygus, Cruciplacolithus, Ellipsolithus, Neococcolithes, Pontosphaera, and Rhomboaster , increase in abundance during the onset of the PETM ( Gibbs et al. 2006b ). Nannofossil assemblage data through the PETM were compiled from studies completed at seven localities spanning multiple environments...
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Series: Geological Society, London, Special Reports
Published: 01 January 2016
DOI: 10.1144/SR27.20
EISBN: 9781862397071
... below seafloor (mbsf). Core subdivisions are numbered from the top (e.g. Core 32.3). CIE, carbon isotope excursion; P, planktonic foraminiferid zones. Planktonic foraminiferid zones are from Aubry et al. (1996) . F., Fasciculithus; R., Rhomboaster; T.; Tribrachiatus. Fig. 176. The Faroe...
Journal Article
Published: 01 September 2007
Journal of Paleontology (2007) 81 (5): 1020–1030.
... protists, calcareous nannoplankton species of unusual morphology (the Rhomboaster — Discoaster araneus association) proliferated in the Atlantic and Tethys Oceans ( Aubry and Requirand, 2000 ; Kahn and Aubry, 2004 ). The dinoflagellate record indicates an interruption of normal ecological conditions...
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