--> ABSTRACT: Evaluation of Jurassic Eustatic Cycles. The Results of the Sequence Stratigraphy of European Basins Project, by T. Jacquin and P. C. Graciansky; #91021 (2010)

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Evaluation of Jurassic Eustatic Cycles. The Results of the Sequence Stratigraphy of European Basins Project

JACQUIN, THIERRY, and PIERRE C. GRACIANSKY

Two critical points affect the credibility of global coastal on lap and sea level curves (1) the accuracy of the biostratigraphic calibration in support of the geochronology of sequence-cycle charts, (2) the evaluation of the different orders of sea level cycles. The first point has been the purpose of a regional compilation project, documenting Mesozoic sequences occurring within European Basins in a broad range of depositional and structural settings. More than 1000 well logs, from mid-Norway to SE France, have been calibrated to a precise biostratigraphic framework, and tied to age-controlled outcrop data where available. The result is an accurate sequence cycle chart, where the geochronology of most of third-order sequences can be shown at the resolution of the biostratigraphic tools. These age informations are an essential part of the stratigraphic forward-modeling techniques. The second point cannot be directly observed on the geological data base, which only allows the quantification of relative sea level changes, resulting from the effects of tectonic subsidence, sediment loading and compaction. These last two parameters can be easily separated. To separate eustasy from tectonic effects, it is necessary to backstrip various sections. By comparison of different accommodation curves documenting the Jurassic succession of several European Basins, a common signal interpreted as being induced by eustasy can be extracted. This signal was tested with PHIL, a 2D stratigraphic forward, modeling program, to reproduce the observed stratal geometries. This technique has been applied to realize its full potential to the time interval of the BRENT in the North Sea (Toarcian-Bajocian) and its European equivalents.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.