Supervisors: Sasha Turchyn (Earth Sciences) and Sigal Abromovich (Ben Gurion University)
Importance of the area of research:
66 Million years ago, the second largest environmental catastrophe in Earth history occurred at the Cretaceous-Paleogene (K-Pg) Boundary. It is now widely recognized, however, that there were a myriad of climatic fluctuations and biotic changes prior to the K-Pg boundary crisis. This calls for a more in-depth understanding of the global ecosystem and the paleoenvironments during the last 20 million years preceding the boundary, known as the Senonian when the environmental conditions may have begun to deteriorate as well as the boundary event itself. The Senonian was a time of vast environmental change: the lengthy warm, stable climate of the middle Cretaceous led to an increasingly cooler climate, interrupted by periodic transient warming episodes. Apart from carbon and oxygen isotopes, little geochemistry over this key time interval has been done.
Changes in the oxygenation state of the ocean-atmosphere system are notoriously difficult to reconstruct, but one powerful tool would be to reconstruct the marine sulfur cycle over this time interval. Marine sulfate is sensitive to changes in the oxygen content of the oceans. Sulfate is preserved in the shells of foraminifera, and analytical advances in the Department of Earth Sciences mean that small amounts of sulfur can be analysed in foraminifera. Newly drilled boreholes of an oil shale and phosphate sequence that were taken at 2010 in the Shefela basin, Israel provide continuous core records across the entire Senonian and across the boundary. This represents a unique opportunity for exploring this period using pristine fossils with very high sulfur content.
What the student will do:
The student will travel to Israel and select samples with Dr. Abramovich, who has access to the drill core. The samples will be sieved and picked at the University of Cambridge and sulfur isotope analysis will be done in house. This can be coupled to more traditional analysis of these samples (bulk rock geochemisty and isotope geochemistry). Finally, the results will be analysed numerically, both to couple into Dr. Abramovich’s past work on faunal abundances through the Senonian and to explore the coupled response of the biogeochemical sulfur cycle leading up to the K-Pg boundary and after, during the prolonged recovery. The analyses will take place on the laser coupled to the MC-ICP-MS as well as on the gas source mass spectrometer. Development of the measurement of mass independent sulfur isotopes will be made on the gas source mass spectrometer to look for evidence of the extra-terrestrial impactor at the boundary.
Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.
Friedrich., O., Norris, R.D. and, Brbacher J. 2012. Evolution of middle to Late Cretaceous oceans—A 55 m.y. record of Earth’s temperature and carbon cycle. Geology 40, 107–110.
Meilijson, A., Ashckenazi-Polivoda, S., Ron-Yankovich, L., Illner, P., Alsenz, H., Speijer, R.P., Almogi-Labin, A., Feinstein, S., Berner, Z., Püttmann, W., and Abramovich, S., (2014). Chronostratigraphy of the Upper Cretaceous high productivity sequence of the southern Tethys, Israel. Cretaceous Research. 50, 187-213.
Alsenz, H., Illner, P., Ashckenazi-Polivoda, S., Meilijson, Abramovich, S., Feinstein, S., Almogi-Labin, A., Berner., Z., and Püttmann, W., 2015. Geochemical evidence for the link between sulfate reduction, sulfide oxidation and phosphate accumulation in a late Cretaceous upwelling system. Geochemical Transactions, 16, 2.
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