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High-resolution seismic and sequence stratigraphy of the Upper Jurassic deposits of the Boulonnais (northern France)

Abstract:

Very high-resolution seismic data were obtained from a Kimmeridgian-Tithonian submarine series located off the Boulonnais (northern France). The data were compared with high-resolution sequence stratigraphic results obtained on the same formations cropping out on the adjacent coastal cliffs. The seismic data provide better defined geometrical relationships between the sequences and the surfaces ('toplap', 'downlap') than the ones identified in the field. Based on the identification of downlap and toplap surfaces, one of the major contributions of the seismic data is to point out that the sandstone bodies isolated in offshore shales are sharp-based shoreface deposits induced by forced regression.