Temperature variability and paleo-ecological changes during the Cenomanian-Turonian Supergreenhouse
Final Report Abstract
Two scientific achievements are central to the results of this project: (1) Using high resolution single foraminifera stable isotope measurements of the Tanzanian Drilling Project (TDP), the mid-Cretaceous supergreenhouse conditions are proved to have lasted a prolonged period of time with a surprisingly low variability throughout the entire early-mid Turonian. Synchronously, significant cyclic sea-level changes are observed in the shallow-marine Cenomanian through Turonian material studied here. Correlation to the Western Interior Seaway supported by first indications of comparable cycles in the TDP material suggests that these sea-level cycles are global. A synthesis of this apparent controversy between uninterrupted warmth on the one hand and frequent sea-level fluctuations on the other hand will lead to a revised concept of the driver of sea-level fluctuation during greenhouse periods. (2) The exquisite preservation of the studied material allowed for a multitude of innovative paleontological investigations including (A) high-resolution combined optical microscopy and scanning electron microscope imaging of previously unknown wall-structural traits at unexpected detail of calcareous dinoflagellate cysts. This enabled a new understanding of the delicate primary biomineralization patterns and taxonomic revision of the studied genera, along with the discovery of new taxa. (B) Cathodoluminescence (CL) studies along with wall-chemical analyses including stable isotope measurement were used to characterize the diagenetically nonaltered stage: Intrinsic CL in both foraminifera and calcareous dinoflagellates, and elevated Mgcontents of calcareous dinoflagellates were discovered in the Tanzanian material. This study corroborates that some previously used morphological traits are the result of diagenetic alteration. The main potential for innovative future research based on the results of this project lies in the investigation of the shell-carbonate chemistry of TDP material which is likely to represent elemental concentration that directly reflect the ambient Cretaceous water chemistry.
Publications
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2010. Shell carbonate chemistry of Turonian pristine foraminifera from the Tanzania Drilling Project. Geological Society of America Abstracts with Programs, Vol. 42, No. 5, p. 175
Wendler, J., Wendler, I., Ehlinger, S.Q., MacLeod, K.G., Huber, B.T.
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2011. Drivers of cyclic sea level changes during the Cretaceous greenhouse: A new perspective from the Levant Platform. Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 376
Wendler, J., Meyers, S.R., Wendler, I., Vogt, C., Kuss, J.
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2011. Early evolutionary history of Tubulogenerina and Colomia, with new species from the Turonian of East Africa. Journal of Foraminiferal Research, 41 (4): 384-400
Wendler, I., Huber, B.T., MacLeod, K.G., Wendler, J.
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2011. Exceptionally preserved Turonian calcareous microflora from Tanzania: Implications of preservation on taxonomy. Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 427
Wendler, J., Wendler, I., Logan, M.A., Rose, T.R., Huber, B.T.
