Geoscientists have tended to view the Mesozoic as a long ice-free time of global greenhouse warmth, but there is increasing awareness that the warm climate may have been interrupted by cooler periods and ice buildup. The ancient Dinaric Platform, Croatia is 7 km thick carbonate platform like the Bahamas. However because of uplift, its superb sedimentary record of global climate change is exposed at the surface and can be studied without deep drilling. The shallow water platform recorded many of the sea level fluctuations of the 50 million year Late Jurassic and Early Cretaceous (150 to 100 million years ago), and can be used to define greenhouse times when the earth lacked ice sheets and sea levels underwent many small sea level fluctuations, and times of transition when the earth had moderate sized ice sheets, and fewer, but larger sea level changes (waxing and waning of small ice sheets). The project will document the frequency and magnitude of sea level and climate change from the sedimentary succession. Fossils, and Sr isotopes will be used to date the succession and stable isotopes of carbon and oxygen will be used to document changes in biologic production, burial of organic carbon, and possible waxing and waning of small ice sheets. Estimates of sea level changes will be made using computer simulations of the stratigraphy, which will allow us to greatly refine the climate changes during this time period. The project should increase our understanding of global climate change during times of global greenhouse, and mode of transitions into cooler phases.
