[N] 2004 Rapid changes in Cretaceous climate
Paytan, A.Kastner,M., Campbell, D. and Thiemens, M.H. (2004) Seawater Sulfur Isotope Fluctuations in the Cretaceous Science Vol 304 Iss. 5677,5161
Abstract: The exogenic sulfur cycle is tightly coupled with the carbon and oxygen cycles, and therefore a central component of Earth\\\'s biogeochemistry. Here we present a high-resolution record of the sulfur isotopic composition of seawater sulfate for the Cretaceous. The general enrichment of isotopically light sulfur that prevailed during the Cretaceous may have been due to increased volcanic and hydrothermal activity. Two excursions toward isotopically lighter sulfur represent periods of lower rates of pyrite burial, implying a shift in the location of organic carbon burial to terrestrial or open-ocean settings. The concurrent changes in seawater sulfur and inorganic carbon isotopic compositions imply short-term variability in atmospheric oxygen partial pressure.
More info: According to Adina Paytan, an assistant professor of geological and environmental sciences at Stanford the planet during the Cretaceous was very different from today, the climate was extremely warm and global sea levels were significantly higher. Co-principal investigator of the study Miriam Kastner, a professor of earth sciences at UCSD’s Scripps Institution of Oceanography notes that the Cretaceous was a time when there were no glaciers in either the Arctic or Antarctic. Acoording to Mark H. Thiemens, dean of UCSD’s Division of Physical Sciences and also a co-author of the paper the Cretaceous was a period of extremes. Between 120 million to 105 million years ago, and from 95 million to 80 million years ago, the fraction of sulfur-34 dipped even more precipitously, suggesting a sharp reduction in the amount of organic matter buried in the ocean and used by sulfate-reducing bacteria. The conclusion of the scientist is that these changes in the productivity of ocean life suggest that the Earth’s atmosphere may have gone through fluctuations in the amount of available oxygen and that there might have been more rapid climatic changes than known untill now in the atmosphere of the Cretaceous.