Correlation of the Upper Cretaceous White Chalk (Turonian to Campanian) in the Anglo-Paris Basin

Using key lithological, biostratigraphic and geophysical borehole-log markers a correlation of the Upper Cretaceous Chalk stratigraphies across the whole Anglo-Paris Basin has been achieved. A common lithological marker bed stratigraphy applies and key fossil markers (inoceramids, Micraster and Echinocorys) are consistently related to the same lithological markers throughout the basin. The major lithological changes consistently occur at the same levels but are not necessarily equally strongly developed. The magnificent dip section along the French Channel coast between the Somme and the Seine, and the inland sections at Précy-sur-Oise and Verlin (Loiret) illustrate the influence of long-lived tectonic lines on Chalk sedimentation history recognised by:

(i) rapid thickness variations;

(ii) channel flooring hardgrounds and associated anomalous bedding dips:

(iii) stratigraphically anomalous infills of channels which may be metres to kilometres across;

(iv) redeposited chalks containing abundant Bathichnus paramoudrae;

(v) tectonically induced slumps and slides with flint and chalk shatter beds (palaeoseismic horizons).

These features are found along may axes including the Anticlinal du Bray at Précy and Dieppe, the Anticlinal de Margny-lès-Compiègne at Nourard le-Franc and Le Tréport (the Bresle Valley Axis) and the Fécamp and Verlin fault systems. The 'events' recognised along these axes link with similar events recognised in Sussex (e.g. Kingston Anticline), on Portsdown, at Culver Cliff, Isle of Wight (Sandown Pericline) and on the Weymouth Anticline (White Nothe). Such events are common in the high Turonian, low Coniacian, basal Santonian, and the low and mid Campanian. The recurrence of key marker beds dominated by a particular trace fossil association or sequence, Bathichnus-Thalassinoides suevicus-Zoophycos associated with major changes in lithology, micro and macro-fauna indicates more widespread 'oceanographic' cycles of transgression and regression related to Atlantic opening.