Calcareous nannofossil changes across the Middle Eocene Climatic Optimum from IODP Site U1410 (NW Atlantic): Preliminary result

2014 ◽  
Vol 31 ◽  
pp. 7-8
Author(s):  
Claudia Agnini ◽  
Alice Costa
Keyword(s):  
Middle Eocene ◽  
Calcareous Nannofossil ◽  
Climatic Optimum

Changes in calcareous nannofossil assemblages during the Middle Eocene Climatic Optimum: Clues from the central-western Tethys (Alano section, NE Italy)

2011 ◽  
Vol 81 (1-2) ◽  
pp. 22-31 ◽  
Author(s):  
Federica Toffanin ◽  
Claudia Agnini ◽  
Eliana Fornaciari ◽  
Domenico Rio ◽  
Luca Giusberti ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Calcareous Nannofossil ◽  
Western Tethys ◽  
Ne Italy ◽  
Climatic Optimum

scholarly journals Impact of the Middle Eocene Climatic Optimum (MECO) on Foraminiferal and Calcareous Nannofossil Assemblages in the Neo-Tethyan Baskil Section (Eastern Turkey): Paleoenvironmental and Paleoclimatic Reconstructions

2021 ◽  
Vol 11 (23) ◽  
pp. 11339
Author(s):  
Roberta D’Onofrio ◽  
Amr S. Zaky ◽  
Fabrizio Frontalini ◽  
Valeria Luciani ◽  
Rita Catanzariti ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Middle Eocene ◽  
Marine Biota ◽  
Partial Recovery ◽  
Calcareous Nannofossil ◽  
Eastern Turkey ◽  
Cooling Trend ◽  
Climatic Optimum

The Middle Eocene Climatic Optimum (MECO; ~40 Ma), which interrupted for ~500–600 kyr the long-term cooling trend culminating at the Eocene/Oligocene boundary, still requires a comprehensive understanding of the biotic resilience. Here we present a high-resolution integrated foraminiferal and calcareous nannofossil study across the MECO from the expanded and continuous Tethyan Baskil section (eastern Turkey) that offers a complete magneto-biostratigraphic and geochemical framework. The five MECO phases identified reveal a transition from oligotrophic (pre-MECO) to eu-mesotrophic conditions, possibly related to accelerated hydrological cycle, during the initial MECO and MECO δ13C negative excursion phases. The MECO WARMING PEAK phase, marking the highest carbonate dissolution interval, records the most striking biotic changes, such as peak in warm and eutrophic nannofossils, virtual disappearance of the oligotrophic planktic foraminiferal large Acarinina and Morozovelloides, and peak in eutrophic deep dwellers Subbotina. Benthic foraminifera suggest in this phase an improvement in the quality of organic matter to the seafloor. The post-MECO phase shows only a partial recovery of the pre-event conditions. Large Acarinina and Morozovelloides did not recover their abundance, possibly due to cooler conditions in this phase. Our reconstruction reveals how paleoenvironment and marine biota from the studied Neo-Tethyan setting reacted to the MECO perturbations.

‘Bleaching’ of Photosymbionts in Planktic Foraminifera During the Middle Eocene Climatic Optimum

2014 ◽  
Vol 13 ◽  
pp. 141-141
Author(s):  
Kirsty M. Edgar ◽  
Stephen M. Bohaty ◽  
Samantha J. Gibbs ◽  
Philip F. Sexton ◽  
Richard D. Norris ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Planktic Foraminifera ◽  
Climatic Optimum

scholarly journals Harmful algae and export production collapse in the equatorial Atlantic during the zenith of Middle Eocene Climatic Optimum warmth

Geology ◽  
2019 ◽  
Vol 47 (3) ◽  
pp. 247-250 ◽  
Author(s):  
Margot J. Cramwinckel ◽  
Robin van der Ploeg ◽  
Peter K. Bijl ◽  
Francien Peterse ◽  
Steven M. Bohaty ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Harmful Algae ◽  
Equatorial Atlantic ◽  
Export Production ◽  
Climatic Optimum

scholarly journals Calcareous nannofossil biostratigraphy of Eocene oil shales from central Jordan

GeoArabia ◽  
2014 ◽  
Vol 19 (1) ◽  
pp. 117-140 ◽  
Author(s):  
Mohammad Alqudah ◽  
Mohammad Ali Hussein ◽  
Olaf G. Podlaha ◽  
Sander van den Boorn ◽  
Sadat Kolonic ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Tectonic Setting ◽  
Planktonic Foraminifera ◽  
Calcareous Nannofossil ◽  
Current Analysis ◽  
Accommodation Space ◽  
Central Jordan ◽  
Age Model ◽  
Calcareous Nannofossil Biostratigraphy ◽  
Oil Shales

ABSTRACT Cretaceous and Paleogene marls, rich in total organic carbon, are widespread throughout Jordan and adjoining areas. Based on planktonic foraminifera these oil shales have been assigned a late Campanian–Paleocene age in previous studies. For the current analysis a total of 283 smear slides from five wells in central Jordan have been investigated for calcareous nannofossil biostratigraphy. Findings suggest a much more differentiated age model of the oil shales than previously 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, Discoaster sublodoensis, Nannotetrina quadrata, Reticulofenestra umbilicus and Chiasmolithus solitus, indicate an Early to Middle Eocene age, while the presence of Maastrichtian and Paleocene forms suggests major reworking. The presence of Cretaceous taxa reflects either subaerial erosive input from the hinterland or submarine reworking of Cretaceous strata within the basin. The highly variable amount of reworked material and associated deposition rates in the basin may represent changes in the tectonic setting during the Eocene. We propose that the high abundances of Cretaceous and Paleocene taxa reflect an increase in accommodation space by active graben flank movements. A dominance of Eocene taxa, on the other hand, indicates either periods of little accommodation space due to graben infill or inversion-type movements of the graben itself. In any case, the youngest Eocene and autochthonous taxa represent shallower or low topography graben phases.

Rise and fall of rotaliids in the Paleocene-Eocene: the influence of climate and trophic competition

2021 ◽  
Author(s):  
Andrea Benedetti ◽  
Cesare Andrea Papazzoni ◽  
Francesca Romana Bosellini
Keyword(s):  
Middle Eocene ◽  
Ecological Niches ◽  
Trophic Conditions ◽  
Significant Drop ◽  
Abrupt Decrease ◽  
Faunal Turnover ◽  
Number Of Species ◽  
Early Eocene Climatic Optimum ◽  
Climatic Optimum ◽  
Larger Foraminifers

<p>It is largely accepted that climate plays a pivotal role in the diversification of shallow-water communities, with special regards to larger foraminifera (LF), also because increase of surface water temperatures is often accompanied by change in trophic conditions. The shift from widespread eutrophic to oligotrophic conditions in shallow seas probably contributed to the LF differentiation during Paleocene-Eocene times. However, there are few recent attempts to quantify the changes in biodiversity and to correlate them with the global climatic events of the Paleogene. We concentrated our attention on the group of rotaliids, resilient taxa that partially survived after the mass extinction occurred at the end of the Cretaceous.</p><p>Our data show that their differentiation at genus level was very rapid, reaching its maximum already in the late Danian SB2 Zone. Specific diversification, instead, culminated in late Thanetian SB4 Zone. A second peak in specific diversity is recorded during the Cuisian (upper part of the Ypresian), then rotaliid diversity steadily declined, as long as other groups of larger foraminifers, especially <em>Alveolina </em>and <em>Nummulites</em>, became more competitive and proliferated with a large number of species up to the Bartonian SB17 Zone, when a significant drop in rotaliid biodiversity is recorded.</p><p>Differently to other taxonomic groups, i.e., alveolinids and nummulitids, for which a single genus during the whole Eocene generated numerous species, rotaliid genera are usually characterized by a low number of species, possibly due to the re-opening of ecological niches after the abrupt decrease of diversity that followed the PETM event. The competition with other K-strategist LF probably contributed to the decline of rotaliids in the middle Eocene up to the MECO event, where a last dramatic drop is recorded.</p><p>The major changes appear strictly linked to warming events such as the Late Danian Event (LDE, starting of the generic diversification of rotaliids), Paleocene Eocene Termal Maximum (PETM, faunal turnover followed by abrupt decrease in both generic and specific diversity), Early Eocene Climatic Optimum (EECO, increase in number of K-strategists under widespread oligotrophic conditions) and Middle Eocene Climatic Optimum (MECO, ultimate drop in diversity and competition with other larger foraminifers).</p><p>This study was funded by the Italian Ministry of Education and Research (MIUR), funds PRIN 2017: project “Biota resilience to global change: biomineralization of planktic and benthic calcifiers in the past, present and future” (prot. 2017RX9XXY).</p>

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