Depositional evolution and structural synthesis of the B marker (limestone) member, Whiterose formation, Jeanne d'Arc, offshore Newfoundland

Noseworthy, Dianne (2003) Depositional evolution and structural synthesis of the B marker (limestone) member, Whiterose formation, Jeanne d'Arc, offshore Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

The discrepancy in the correlation of lithostratigraphy and seismic stratigraphy of the B Marker (limestone) Member on the eastern flank of the Hibernia oilfield is studied using available 3d seismic profiles and the log data from 16 wells across the Jeanne d'Arc Basin. Unlike the previous studies which suggested that the B Marker was deposited as a time synchronous lithology across basin, detailed seismic stratigraphic and well analysis revealed that the marker was in fact deposited as a mildly diachronous unit. Four seismic traces (S1-S4) are recognized within the stratigraphic range of the proposed B Marker seismic event. A Carbonate Ramp Facies Model is proposed, incorporating these traces, for the basin-wide sedimentation of the B Marker which explains in a precise manner, the notable lithological variations of the marker in various exploration wells across the Jeanne d'Arc Basin. The B Marker was deposited during a relative rise of base level within the basin, coincident with a rise of global sea level during the Valanginian. This deposition is summarized by four discrete events (S1-S4). S1 marks the end of a phase of regression in the basin, and beginning of a transgressive phase of marine deposition. Limestone deposited during S1 was confined to a narrow E-W trending belt in the northern portion of the basin. During S2 landward migration of the shoreline southward, caused the deposition of shale over a wider E-W trending belt of limestone in the north. During S3 a very broad E-W trending belt of oolitic limestone blanketed the southern shallow shelf, and shingled above thin-bedded limestones (in S1 and S2). This geometry is interpreted as a subtle depositional hinge zone, which migrated south because of the stick slip on a master fault and uplift on structural culminations in the southern areas of the basin. This resulted in the lateral gradation of B Marker limestone into sandstone further north, during ensuing transgression from S1 to S3. S4 marks the peak of transgression within the basin, and in the widest coverage of the deeper shelf across basin.

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