Foraminifera assemblages in the eastern part of the Stetten-section from the Karpatian of the Korneuburg Basin

Der Baubeginn der Umfahrungsstraße "S1" bei Stetten (Niederösterreich) bot die einmalige Gelegenheit, ein 2,5 Kilometer umfassendes Profil durch große Teile des Korneuburger Beckens (Karpat) zu untersuchen. 2 Profile mit 9 Abschnitten wurden aufgenommen und 186 Proben auf den Bestand an Foraminiferen und Ostracoden untersucht. Die vorliegende Arbeit behandelt den Bestand an Foraminiferen und deren Vergesellschaftungen. Sie gibt einen Überblick über die Taxonomie, wie auch über die faunistische Zusammensetzung und Paläo-Ökologie der Ablagerungen des Ostprofiles (mit den Teilabschnitten A, F und E). Repräsentativ für die Flachwasserfauna ist die Gattung Ammonia gemeinsam mit einigen wenigen anderen Vertretern benthischer Arten. Die im ökologischen Spektrum tiefer anzusiedelnden Abschnitte werden von Vergesellschaftungen, die einen hohen Anteil an der benthischen Gattung Bulimina aufweisen, sowie einigen planktonischen Taxa, wie Cassigerinella oder Globorotalia, dominiert. Ökologisch aussagekräftige Faunengemeinschaften ermöglichten die Ableitung einer Tiefenzonierung der untersuchten Abschnitte. Diese Art der Analyse basiert ausschließlich auf dem Vorkommen benthischer Foraminiferen und deren Tiefenreichweite. Die Ergebnisse zeigen Paläo-Tiefen zwischen 0 und 40 Metern Wassertiefe - kennzeichnen also durchwegs Flachwasser. Weiters wurden im Zuge dieser Arbeit Ost- und West- Abschnitte anhand der vorkommender Fossilvergesellschaftungen und lithologischer Daten korreliert.The construction of the bypass road "S1" (Schnellstrasse 1) at Stetten (Lower Austria) gave a unique opportunity to study an approximately 2.5 km long east-west transect through large parts of the Karpatian Korneuburg Basin. 9 sections in two profiles have been recorded and combined. Over 186 samples were examined for foraminifera and ostracods. This work deals with the foraminifers and gives an overview on taxonomy and the faunal composition in general. The main focus is on the palaeoenvironment of the deposits in the eastern part of the profile (with sections A, F and E) especially. The foraminiferal assemblage spectrum is dominated by the genus Ammonia and a few other shallow water benthic species on the shallow end of the ecological spectrum. The "deep" water communities contain large numbers of the benthic genus Bulimina and several planktic taxa, such as Cassigerinella or Globorotalia. After the identification of distinct ecological groups, an estimation of palaeo-water-depths was conducted. This analysis, which is based on the abundance data of recent benthic foraminifera and their depth distribution, gives a signal for a generally very shallow water depth. The mean depth values fluctuate between 0 and 40 metres. Furthermore, the results of the assemblage analyses allow a direct correlation of the western part with the eastern part of the section via peak occurrences of certain taxa and lithological structures

Morphological variations in Cycloclypeus carpenteri: Multiple embryos and multiple equatorial layers

In this work, 17 specimens of Cycloclypeus carpenteri have been analysed by means of microCT scanning. It has been observed that many specimens possess multiple embryos, multiple nepionts and some tests show more than one equatorial layer. The diameter of each proloculus has been measured, and it seems that they are very variable even within the same specimen, therefore questioning the long known theory that schizonts have smaller proloculi than gamonts and also questioning the fact that proloculi in the same species should all have comparable size. Whenever the nepionts are positioned on different planes, thus creating an angle between them, this angle has a significant correlation to the angle connecting different equatorial layers. T-shaped connections are located at the junction between two equatorial layers; these junctions are made by a chamberlet, which possesses an unusually higher number of apertures, resembling the chamberlet structure of the genus Spiroclypeus

Late Cretaceous Paleoceanographic Evolution and the Onset of Cooling in the Santonian at Southern High Latitudes (IODP Site U1513, SE Indian Ocean)

The latest Cenomanian to Santonian sedimentary record recovered at IODP Expedition 369 Site U1513 in the Mentelle Basin (SE Indian Ocean, paleolatitude 60°S at 85 Ma) is studied to interpret the paleoceanographic evolution in the Southern Hemisphere. The planktonic foraminiferal assemblage changes, the depth ecology preferences of different species, and the surface and seafloor temperature inferred from the stable isotopic values measured on foraminiferal tests provide meaningful information to the understanding of the Late Cretaceous climate. The hothouse climate during the Turonian-Santonian, characterized by weak latitudinal temperature gradients and high atmospheric CO2 concentrations, is followed by a progressive cooling during the Campanian. At Site U1513 the beginning of this climatic transition is nicely recorded within the Santonian, as indicated by an ∼1‰ increase in δ18O values of planktonic foraminifera suggesting a decline in surface water paleotemperatures of 4°C. The onset of cooling is mirrored by changes in the planktonic foraminiferal assemblages including extinctions among surface and deep dwellers, appearances and diversification of newly evolving taxa, and changes from predominantly epifaunal oxic to infaunal dysoxic/ suboxic taxa among co-occurring benthic foraminifera. Overall, the data presented here document an interval in the Santonian during which the rate of southern high latitude cooling increased. Both surface and bottom waters were affected, although the cooling signal is more evident in the data for surface waters. This pattern of cooling ascribes the deterioration of the Late Cretaceous climate to decreased CO2 in the atmosphere and changes in the oceanic circulation correlated with enhanced meridional circulation

Biotic and Paleoceanographic Changes Across the Late Cretaceous Oceanic Anoxic Event 2 in the Southern High Latitudes (IODP Sites U1513 and U1516, SE Indian Ocean)

Oceanic Anoxic Event 2, spanning the Cenomanian/Turonian boundary (93.9 Ma), was an episode of major perturbations in the global carbon cycle. To investigate the response of biota and the paleoceanographic conditions across this event, we present data from International Ocean Discovery Program sites U1513 and U1516 in the Mentelle Basin (offshore SW Australia; paleolatitude 59°–60°S in the mid-Cretaceous) that register the first complete records of OAE 2 at southern high latitudes. Calcareous nannofossils provide a reliable bio-chronostratigraphic framework. The distribution and abundance patterns of planktonic and benthic foraminifera, radiolaria, and calcispheres permit interpretation of the dynamics of the water mass stratification and provide support for the paleobathymetric reconstruction of the two sites, with Site U1513 located northwest of the Mentelle Basin depocenter and at a deeper depth than Site U1516. The lower OAE 2 interval is characterized by reduced water mass stratification with alternating episodes of enhanced surface water productivity and variations of the thickness of the mixed layer as indicated by the fluctuations in abundance of the intermediate dwelling planktonic foraminifera. The middle OAE 2 interval contains lithologies composed almost entirely of radiolaria reflecting extremely high marine productivity; the low CaCO3 content is consistent with marked shoaling of the Carbonate Compensation Depth and ocean acidification because of CaCO3 undersaturation. Conditions moderated after deposition of the silica-rich, CaCO3-poor rocks as reflected by the microfossil changes indicating a relatively stable water column although episodes of enhanced eutrophy did continue into the lower Turonian at Site U1516

Turonian and Coniacian benthic foraminiferal abundance data of IODP Site 369-U1513

This dataset documents the results of a biostratigraphic assessment of the benthic foraminiferal record at International Ocean Discovery Program (IODP) Site U1513 in the Mentelle Basin (southeast Indian Ocean, offshore western Australia), yielding a Turonian through Santonian deep water benthic foraminiferal assemblage. Predominantly calcareous deep water benthic foraminifera are recovered, whereas agglutinated benthic taxa show a rare occurrence and epifaunal benthic foraminifera make up ~50% of the total assemblage during the Turonian to Santonian. The most frequently recorded taxa are gavelinellids and gyroidinoids and according to taxa identified, we can inferr a distal, bathyal depositional environment. Two distinct benthic foraminiferal associations, the Gavelinella berthelini association and the Notoplanulina rakauroana association, were identified in the 160 m-thick succession, and together they yield over 190 taxa

A quantitative look on northwestern Tethyan foraminiferal assemblages, Campanian Nierental Formation, Austria

Deposits spanning the Radotruncana calcarata Taxon 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 of Muricohedbergella and biserial planktic foraminifera. Archaeoglobigerina and “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 the Radotruncana calcarata Taxon Range Zone provides some insights into variations and short term changes during the very short period of 800 ka

Cenomanian/Turonian benthic foraminiferal abundance data of IODP Site U1516, Mentelle Basin, Indian Ocean

This dataset documents benthic foraminiferal assemblage data of International Ocean Discovery Program (IODP) Expedition 369 Site U1516 during the Oceanic Anoxic Event 2 (OAE 2) in the southern high latitudes (absolute abundance in the 125-300μm fraction). Benthic foraminiferal assemblages indicate a distal, outer neritic to upper bathyal depositional environment. The record of the OAE 2 is characterized by an interval of low carbonate content which involves a prominent positive Carbon Isotope Excursion (CIE). Benthic foraminiferal data documented in this dataset present assemblage changes during the pre OAE 2 (478.5 m - 475.12 m), pre max-CIE (474.38 m – 471.12 m), low CaCO3 (470.36 m – 467.96 m), and post low CaCO3 intervals (467.27 m – 459.72 m). During the pre OAE2 and pre max-CIE intervals, calcareous deep-water gavelinellids, lingulogavelinellids and gyroidinids are dominant. The low CaCO3 interval records a decline in benthic foraminiferal abundance and the post low CaCO3 interval is characterized by a distinct repopulation event