Project EARTH-09-SPH1 Major environmental changes during the mid-Cretaceous: integrated sequence stratigraphy, chemostratigraphy, and modelling of the Aptian and Albian Earth system. Supervisors: Steve Hesselbo (Oxford) & Christian Bjerrum (Copenhagen) Major Mid-Cretaceous palaeo-environmental changes are now well-known from the results of investigations into deep-water and oceanic depositional settings. In particular, the Aptian–Albian interval was characterized by at least one major Oceanic Anoxic Event – the so-called Selli Event1 – but other somewhat less intense anoxic events are also known from this time2. The record of Aptian– Albian environmental change in relatively near-shore siliciclastic depositional settings is relatively poorly explored, partly because of the difficulty of determining precise ages based on biostratigraphy. However, the occurrence of significant perturbations in the global carbon-cycle during the Aptian and Albian allow the possibility of high-resolution correlation with deep marine successions using terrestrial carbon-isotope stratigraphy3,4. In the proposed project a refined technique for correlation using residues from palynological preparations will be used to greatly enhance knowledge of the palaeoenvironmental changes and their origins, as determined from the Aptian and Albian sedimentary succession of southern England, and especially to clarify any relationship between sea-level change and cyclic variations in biospheric carbon-isotope ratios. Results will then be used to test and refine numerical models of carbon and phosphorous cycles processes as they relate to sea-level change5. The project will include fieldwork, laboratory analysis, and physical modelling, and will be based at Oxford but include visits to Copenhagen. References: 1. Arthur, M.A., Jenkyns, H.C., Brumsack, H., Schlanger, S.O., 1990. Stratigraphy, geochemistry, and paleoceanography of organic carbon-rich Cretaceous sequences. In: Ginsburg, R.N., Beaudoin, B. (Eds.), Cretaceous Resources, Events and Rhythms. Kluwer Academic, Dordrecht, pp. 75–119. NATO AS1 Series C, 304 1990. 2. Herrle, J.O., Kössler, P., Friedrich, O., Erlenkeuser, H., Hemleben, C., 2004. High resolution carbon isotope records of the Aptian to lower Albian from SE France and the Mazagan Plateau (DSDP Site 545). A stratigraphic tool for paleoceanographic and paleobiologic reconstruction. Earth and Planetary Science Letters 218, 149–161. 3. Gröcke, D.R., Hesselbo, S.P., & Jenkyns, H.C. 1999. Carbon isotope composition of Lower Cretaceous fossil wood: ocean–atmosphere chemistry and relation to sea-level change. Geology, 27, 155-158. 4. Hesselbo, S.P., Jenkyns, H.C., Duarte, L.V., Oliveira, L.C.V. 2007. Carbon- isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal). Earth and Planetary Science Letters, 253, 455-470, doi: 10.1016/j.epsl.2006.11.009.
Pages to are hidden for
"Project EARTH-09-SPH1 Major environmental changes during the mid"Please download to view full document