The Neogene stratigraphy of the glaciated European margin from Lofoten to Porcupine

The stratigraphic-range chart in Fig. 7 depicts a combination of 13 boreholes and wells that are taken as key sources of stratigraphic information for the establishment of the unified stratigraphic framework (Fig. 6). These data enable the calibration and correlation of the megasequences and their bounding, regional unconformities as defined in this atlas (Fig. 8, Fig. 9, and Fig. 10). The sites were chosen from the more extensive stratigraphic-range charts constructed for each individual Work Package area (North Sea Fan–Vøring; Faroe–Shetland; Rockall–Porcupine) presented in Fig. 11, Fig 12, and Fig. 13. Collectively, they provide a stratigraphic transect along the entire NW European Atlantic margin for the area under consideration in this atlas.

From the stratigraphic-range chart, the following key points are noted with regard to the age assignment of the megasequence boundaries:

• A late early Pliocene unconformity can be identified throughout most of the study area, extending from the shelves into the adjacent deep-water basins. This unconformity forms the main intra-Neogene boundary that subdivides the Neogene succession into Miocene–lower Pliocene and lower Pliocene–Holocene megasequences. Biostratigraphic information shows a common overlap interval that tentatively infers that the hiatus may be assigned to the NN14/15 nannofossil biozone, at about 4Ma. Where an unconformity has not been reported, e.g. DSDP site 610 and well 164/25-2, due largely to sampling gaps, seismic evidence supports either a hiatus or a marked change in the style of sedimentation. The only area within this study where no hiatus has been identified is the outer part of the Vøring Margin. However, whilst ODP site 642 suggests a conformable boundary this coincides with a marked lithological change (Fig. 11).

• The Miocene–lower Pliocene megasequence is preserved as a punctuated record. Although there are indications of a mid-Miocene break, regional correlation remains unattainable at present, partly through restricted development and partly due to the quality and resolution of biostratigraphic and seismic data. Despite the variable preservation of the succession, this megasequence is generally separated from the underlying Palaeogene section by an unconformity, albeit with indications of diachroneity locally across the Oligocene–Miocene boundary. In the northern Rockall Trough, there is a significant hiatus with the lower Miocene record largely absent. Whilst no hiatus is reported from well 214/4-1 in the Faroe-Shetland Channel, regional data support an erosional break (Fig. 12). In the central and southern Rockall Trough, the assignment of the late early–early mid-Miocene basinal reflective zone that is C20 is borne out of a problem identifying the base of the Neogene in the southern half of this basin. Megasequence definition in this area may require some revision and/or refinement if and when more data become available. Further information on the C20 boundary can be found in WP3 and WP3 Statigraphic Range.  

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