Subsidence patterns in western margin basins: evidence from the Faeroe–Shetland Basin

Abstract

Anomalously high rates of Paleocene tectonic subsidence have been documented from a number of basins on the NW European continental shelf. This period of accelerated subsidence occurs during what is conventionally regarded as the post-rift phase of basin development. It cannot, therefore, be explained by theoretical models of basin formation in which the post-rift subsidence is driven only by the decay of the thermal anomaly generated during active extension. The Faeroe-Shetland Basin developed as a major Cretaceous depocentre, with Late Cretaceous times in particular characterized by extremely high rates of tectonic subsidence. Subsidence rates on the flanks of the basin slowed dramatically into Paleocene times as a major mid-Paleocene unconformity developed across the eastern side of the basin. Wells from the basin centre, on the other hand, show extremely high and accelerating rates of Late Paleocene subsidence associated with normal faulting. These high rates of observed tectonic subsidence lasted for less than 5 Ma and cannot easily be explained in terms of fluctuations in sediment supply rates or eustatic sea-level. This simultaneous flank uplift and basin centre subsidence acceleration is the same age as both the anomalous Paleocene subsidence reported from other nearby basins, and the oldest magmatism associated with the proto-Icelandic plume. Subsidence behaviour returned to normal, across the entire basin, at the same time as continental break-up was achieved between Greenland and Northwest Europe. This suggests that there is a link between regional tectonics and the anomalous Paleocene subsidence patterns observed in this and other basins on the NW European continental shelf.

Episodic Cenozoic tectonism and the development of the NW European ‘passive’ continental margin

“…19 in Barton and Wood, 1984;cf. Cloetingh et al, 1990;Gradstein et al, 1994) and is also observed in wells from the Faroe-Shetland Basin (Turner and Scrutton, 1993) and the Porcupine Basin (Tate et al, 1993), in all areas corresponding to a few hundred metres of water-loaded subsidence. Along the Norwegian margin, the acceleration of subsidence is evident in the few published burial history curves (e.g.…”

“…However there is no evidence of extension where subsidence analyses are supported by tectono-stratigraphic analyses (e.g. Tate et al, 1993;Turner and Scrutton, 1993;Jones et al, 2001). The onset of the subsidence episode appears to have been slightly diachronous, beginning in the late Paleocene in the Faroe-Shetland and northern North Sea basins, i.e.…”

“…In the northern North Sea and Faroe-Shetland basins, backstripped wells indicate an acceleration of subsidence in the late Paleocene to early Eocene (Joy, 1992;Turner and Scrutton, 1993;White and Latin, 1993;Hall and White, 1994), estimated to correspond to 300-500 m of water-loaded subsidence over 10-20 Ma (Hall and White, 1994). The subsidence episode has been inferred to follow a Paleocene phase of transient uplift, of comparable magnitude based on assumed Late Cretaceous water depths of O500 m (Nadin et al, 1997).…”

Indicators of hot fluid migration in sedimentary basins: evidence from the UK Atlantic Margin

“…The large volumes of igneous material emplaced during this event appear to have had no regional-scale effect on geothermal gradients (Holmes et al 1999), but localized effects are both predicted (Turner & Scrutton 1993) and observed (Parnell et al 1999). Hot fluid migration may produce several recordable features in rocks, including the alteration of matrix and cement phases and the deposition of new minerals during cooling (which, in turn, may trap syn-flow fluids).…”

Tectonism and volcanism at the southeast Greenland rifted margin: a record of plume impact and later continental rupture

“…Around the boundary between the Lower and Upper Paleocene (Danian/Selandian boundary, 61 Ma; Berggren et al, 1995), a number of basins within the northern North Sea and the Faeroe-Shetland channel record uplift of source areas and of the shallow, marginal parts of the basins while the deeper parts of the basin subsided without any clear evidence for tectonic extension (e.g., Turner and Scrutton, 1993). Based on facies developments (e.g., Maureen Formation), trace-minerals (Knox and Morton, 1988) and correlation with published ages for the British Tertiary volcanism and the Faeroes (Mussett, 1986;Mussett et al, 1988;Waagstein, 1988;Pearson et al, 1996) this regional basin inversion has been interpreted as reflecting uplift in conjunction with initial North Atlantic Tertiary Igneous Province (NAIP) activity at approximately 61 Ma (Galloway et al, 1993;Den Hartog Jarger et al, 1993;O'Connor and Walker, 1993;Morton et al, 1993).…”