EGU General Assembly 2020
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Faunal and environmental changes through the Cretaceous-Paleogene boundary (K-Pg) linked with Deccan Volcanism: evidence from the Neo-Tethys, Turkey

Ali Uygar Karabeyoglu1, Thierry Adatte1, Valentin Lorenzo1, Jorge Spangenberg2, Sevinç Özkan Altıner3, and Demir Altıner3
Ali Uygar Karabeyoglu et al.
  • 1ISTE, Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland, (,
  • 2IDYST, Institute of Surface Dynamics, University of Lausanne, Lausanne, Switzerland (
  • 3Department of Geological Engineering, Middle East Technical University, Çankaya/Ankara, Turkey (

Recent multi-disciplinary efforts demonstrate a correlation between continental flood basalt (CFB) volcanism and major environmental catastrophes associated with four out of the five largest Phanerozoic mass extinctions. Unique among these is the end-Cretaceous mass extinction, which is potentially coincident with both the Chicxulub bolide impact and the Deccan volcanism. Among these two drivers, the role of the Deccan volcanism is crucial in order to decipher if there is a causal relationship between volcanism and environmental stress, and if so, how stressed the environment was during the latest Maastrichtian. To assess the cause-and-effect relationship between Deccan volcanism and climate change and mass extinctions, high-resolution biostratigraphy, quantitative species analysis coupled with geochemical measurements have been performed on complete sections of Mudurnu-Göynük and Haymana basins (Turkey).

In both basins Maastrichtian sedimentation is characterized by monotonous mudstones, which sharply in turn to marl-calcareous mudstone alternations in the earliest Danian. Detailed quantitative study on planktonic foraminifera of the Haymana Basin revealed that planktonic foraminiferal community in the latest Maastrichtian is dominated by ecological generalists with small, simple morphologies (e.g., Heterohelix, Globigerinelloides, Guembelitria). Among them low oxygen tolerant Heterohelix globulosa is the most dominant taxa and their abundance changing with the presence of stress marker Guembelitria cretacea. In all sections, the K/Pg boundary itself is characterized by 2-3 mm thick reddish oxidized layer which corresponds to sudden annihilation of large, ornamented ecological specialists (e.g., Globotruncana, Rugoglobigerina, Racemiguembelina). Right after the boundary, there is an acme of calcareous dinoflagellate cysts (Thoracosphaera) and a surge of Guembelitria cretacea indicate ecosystem collapse in post-K/Pg environment.

On the other hand, detailed quantitative analysis shows a systematic reduction in the species richness throughout the Plummerita hantkeninoides Zone corresponding to the final 150 kyr of the Cretaceous. Proliferations of the Guembelitria cretacea through late Maastrichtian is known as an indicator of high terrigenous influx; therefore, enhanced food resources. The high sedimentation rates observed in all the studied sections might be linked to increased greenhouse conditions due to Deccan volcanism leading to enhanced weathering. Overall, our multiproxy approach including quantitative biostratigraphy and geochemical analyses highlights the influence of the Deccan volcanism by releasing high amounts of atmospheric CO2 and SO2, leading to the climatic changes and associated biotic stress, which predisposed faunas to eventual extinction at the K/Pg boundary.

How to cite: Karabeyoglu, A. U., Adatte, T., Lorenzo, V., Spangenberg, J., Özkan Altıner, S., and Altıner, D.: Faunal and environmental changes through the Cretaceous-Paleogene boundary (K-Pg) linked with Deccan Volcanism: evidence from the Neo-Tethys, Turkey, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2002,, 2020.


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displays version 3 – uploaded on 06 May 2020, no comments
Some additions made of the representation of foraminifera.
displays version 2 – uploaded on 04 May 2020
More material field photos added. Issues more clarified.
  • CC1: Comment on EGU2020-2002, Andressa Alves, 04 May 2020

    Dear Ali,

    Firstly, I would like to congratulate you on your work.

    I've been work with calcareous nannofossils from early Danian, I would like to know if you found any different responses from other sections, such as El Kef and Agost, as you are in a more Bathial environment. How is the morphological aspect before and after of the foraminifera assemblage? Do they present any different ornamentation?



    All the best

    • AC1: Reply to CC1, Ali Uygar Karabeyoglu, 04 May 2020

      Dear Andressa,

      Thank you. Regarding to echinoid fecal pellets peaks, they have been observed from the New Jersey Coast (Esmeray-Senlet et al. 2017, EPSL). Some peak has been observed within the P. hantkeninoides Zone some of them are in P0 and Pα. During the P.hantkenionoides planktonic foraminifera shows aberrant morphologies (e.g., abnormal tests, distortion of coiling (especially in Heterohelix), abnormal chambers and ultimate chambers). Interestingly, these features are not evident in trochospiral forms (e.g. globotruncanids). After the K-Pg these effects are not observed. Yet, there is a very much of Lilliput Effect happened on survivors (e.g. Guembelitria, Heterohelix) and the benthics.

      All the best,


displays version 1 – uploaded on 27 Apr 2020, no comments