Eine neue hochauflösende Kompilation von stabilen Isotopendaten benthischer Foraminiferen im Zeitraum von 34 bis 75 Millionen Jahren vor Heute - für Atlantik und Pazifik.
Zusammenfassung der Projektergebnisse
The major goal of the project was to compile a high-resolution (<10kyr) deep-sea benthic foraminifer stable carbon and oxygen isotope reference section for both the Atlantic and Pacific Ocean spanning the interval from 75-34 Ma. Deep-sea carbon and oxygen isotope records have proven to be an invaluable archive of long-term changes in the Earth‘s carbon cycle, average global temperature and global ice volume fluctuations. In essence, it can represent the grid of global climate variability through time, needed for orientation to be able to determine and evaluate the role of processes driving Earth's climate in the past and future. On our way to develop such compilation, a tremendous effort generating new data, compiling and then synthesizing large data sets was performed. High-resolution geochemical and bio-magnetostratigraphic records were successfully combined and applied to build an accurate astronomically calibrated age model spanning the late Campanian to late Eocene (75-34 Ma). The implementation of the software tool Code for Ocean Drilling Data (CODD) developed by collaborator Dr. R. Wilkens (University of Hawai’i) has been proven as being critical for dealing with large data records including utilizing core images like data as THE tool of our project. The most valuable features of CODD is the ability to effectively correlate multiple records from multiple drill sites and perform astronomical tuning for our project. The major result of this project is the first ever high-fidelity, continuous and astronomically tuned deep-sea benthic foraminifera stable carbon and oxygen isotope reference record spanning the last 66 million years - the entire Cenozoic. This outcome is way beyond the initial objective to cover the late Campanian to late Eocene. Over the course of the project the perception developed that a global reference record spanning the entire Cenozoic is feasible and inevitable for past climate reconstructions. Discussions with J. C. Zachos played a major role in extending our efforts to also include whole of the Cenozoic. Therefore, we identified 14 of the best high-resolution ocean drilling records available, evaluated their composite splices and revised them where necessary, incorporated the new project benthic stable isotope data, and established a consistent astrochronology. The new ‘Cenozoic Global Reference benthic foraminifer carbon and oxygen Isotope Dataset’ (CENOGRID) provides a refined record with higher signal-to-noise ratio than previous benthic foraminifer stable isotope compilations, and much better coverage of the Paleocene, Eocene and late Miocene owing to newly available records. The CENOGRID will serve as an astronomically tuned high-definition stratigraphic reference of past global climate evolution. It documents on timescales of millions of years that Earth’s climate can be grouped into Hothouse, Warmhouse, Coolhouse and Icehouse states, each separated by transitions related to changing greenhouse gas levels and the growth of polar ice sheets. In addition to the new benthic reference record, our project produced a large geochemical data set of late Campanian and Maastrichtian age. Unexpectedly, we found persistent cyclic variation in geochemical data that allow to establish a new complete record for the Pacific Shatsky Rise Maastrichtian interval. We combined multiple records from the South Atlantic and correlated them on single cycle level (20 kyr) to the Pacific records. For the first time we could assemble a highly accurate age model synchronizing records from both oceans. New Osmium isotope data generated by J. Kuroda (University Toyko, Japan) as part of our project and new benthic foraminifer stable isotope data enable to document global climate change during the late Maastrichtian at unprecedented detail. Our results clearly show the causal relationship between the onset of massive volcanism of the Deccan Traps and global deep sea warming at 66.3 Ma. Longer bulk carbon isotope and X-ray fluorescence core scanning elemental concentration data, spanning the late Campanian and Maastrichtian, show that climate was dominated by low latitude climate processes. In collaboration with E. Griffith (Ohio State University, USA) new data reveal that the cyclic patterns in the sediment archives of the Pacific are cause by variations in surface ocean productivity paced by solar insolation variation, result of fluctuations in Earth's orbit around the sun. Despite the progress made we could not complete deep-sea benthic foraminifer stable carbon and oxygen isotope reference section for both the Atlantic and Pacific Ocean. A key interval from the Pacific’s late Eocene will be available soon from project partners at the National Oceanography Centre Southampton (NOCS). Then an isotope record from the Pacific of equally high-resolution as the Atlantic will be available for scientific examination spanning 75-34 Ma.
Projektbezogene Publikationen (Auswahl)
- 2017, A new high-resolution chronology for the late Maastrichtian warming event: Establishing robust temporal links with the onset of Deccan volcanism. Geology
Barnet, JSK, Littler, K, Kroon, D, Leng, MJ, Westerhold, T, Röhl, U and Zachos, JC
(Siehe online unter https://doi.org/10.1130/G39771.1) - 2019, A High-Fidelity Benthic Stable Isotope Record of Late Cretaceous–Early Eocene Climate Change and Carbon-Cycling. Paleoceanography and Paleoclimatology
Barnet, J. , Littler, K. , Westerhold, T. , Kroon, D. , Leng, M. , Bailey, I. , Röhl, U. and Zachos, J.
(Siehe online unter https://doi.org/10.1029/2019PA003556) - 2019, Astronomical time keeping of Earth history: An invaluable contribution of scientific ocean drilling. Oceanography, 32(1). 72-76
Littler, K., Westerhold, T., Drury, A.J., Liebrand, D., Lisiecki, L.E. and Pälike, H.
(Siehe online unter https://doi.org/10.5670/oceanog.2019.122) - 2019, Paleoenvironmental changes at ODP Site 702 (South Atlantic): anatomy of the Middle Eocene Climatic Optimum. Paleoceanography and Paleoclimatology, 34
Rivero-Cuesta, L., Westerhold, T., Agnini, C., Dallanave, E., Wilkens R. H. and Alegret, L.
(Siehe online unter https://doi.org/doi: 10.1029/2019PA003806) - 2019, The early to middle Eocene transition: an integrated calcareous nannofossil and stable isotope record from the Northwest Atlantic Ocean (IODP Site U1410). Paleoceanography and Paleoclimatology, 34
Cappelli, C. , Bown, P., Westerhold, T., Bohaty, S., de, Riu, M., Lobba, V., Yamamoto, Y. and Agnini, C.
(Siehe online unter https://doi.org/doi:10.1029/2019PA003686) - 2020, On impact and volcanism across the Cretaceous-Paleogene boundary. Science, 367, 266-272
Hull, P.M., Bornemann, A., Penman, D.E., Henehan, M.J., Norris, R.D., Wilson, P.A., Blum, P., Alegret, L., Batenburg, S.J., Bown, P.R., Bralower, T.J., Cournede, C., Deutsch, A., Donner, B., Friedrich, O., Jehle, S., Kim, H., Kroon, D., Lippert, P.C., Loroch, D., Moebius, I., Moriya, K., Peppe, D.J., Ravizza, G.E., Röhl, U., Schueth, J.D., Sepúlveda, J., Sexton, P.F., Sibert, E.C., Śliwińska, K.K., Summons, R.E., Thomas, E., Westerhold, T., Whiteside, J.H., Yamaguchi, T., Zachos, J.C.
(Siehe online unter https://doi.org/doi:10.1126/science.aay5055)
