Project EARTH-09-SPH1 Major environmental changes during the mid by uuk44760


									                         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.


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.

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