Geoscience Reference
In-Depth Information
production of sediments belonging to sequences
J-1 and J-2 and sub-sequence K-2.1.
During basin configuration 2, both the North
Sea area and the hinterlands were probably
exposed to only minor tectonic activity, as indi-
cated by the prolonged existence of the Chalk Sea,
gradually extending northwards in the northern
North Sea throughout Late Cretaceous (Surlyk
et al
., 2003). However, we propose that the cou-
pled source-to-sink relationship as seen during
basin configuration 1 also functioned during basin
configuration 2. This interpretation is based on
the assumption that the tectonic influence in the
North Sea area was negligible during the Late
Cretaceous, where subsidence were mainly caused
by sediment loading and thermal cooling (e.g.
Gabrielsen
et al
., 2001; Kyrkjebø
et al
., 2001). As
this occurred without any simultaneous uplift of
the basin margins, although subsequent to denu-
dation and transgression of parts of the hinter-
lands, we suggest that the North Sea area and
present adjacent landmasses were stable during
basin configuration 2.
A coupled source-to-sink relationship is also
suggested for basin configuration 3. This is evi-
dent from the rapid subsidence of the North Sea
Basin, with palaeo-water-depths up to 600 metres,
as recorded by Jordt
et al
. (1995), Kjennerud
et al
.
(2001) and Kyrkjebø
et al
. (2001), simultaneously
with uplift of the East Shetland Platform and the
north-western parts of southern Norway (Faleide
et al
., 2002). The uplifted hinterlands acted as
source areas for sediments belonging to sequences
CSS-1 and CSS-2. Several uplift mechanisms have
been proposed to explain this tectonodynamic
process: transient thermal uplift due to buoyancy
of the lithosphere when heated by the Icelandic
Plume (e.g. Sleep, 1990; Clift & Turner, 1998),
uplift due to mantle fluid flow (e.g. Nadin
et al
.,
1995, 1997) and underplating, giving rise to a
permanent isostatic uplift (e.g. Brodie & White,
1994; Clift, 1999). However, although the coupled
source-to-sink relationship is well established,
further work is necessary to constrain the pro-
cesses which acted on the basin configuration
during Late Palaeocene to Eocene time.
A vast increase in sediment input, sourced from
southern Norway in Early Oligocene, combined
with development of diachronous accommoda-
tion space in the North Sea area, is a strong indica-
tion of coupled source-to-sink dynamics also for
basin configuration 4. Although a climatic change
at the Eocene-Oligocene boundary triggered an
increase in erosion and run-off in the hinterland
(Huuse
et al
., 2001), this cannot explain the for-
mation of contemporaneous sub-basins and migra-
tion of their depocentres throughout the Oligocene
and Neogene, as discussed above. The basin sub-
sidence, as recorded throughout the Cenozoic,
probably was related to lithospheric flexuring, as
the southern Norwegian landmasses were uplifted.
However, as mentioned above, the mechanism of
such coupled crustal processes is still not con-
strained. The reader is referred to Faleide
et al
.
(2002) and Anell
et al
. (2009) for a review of the
discussion.
CONCLUSIONS
As illustrated in this study, sedimentation in the
study area was related to four main different basin
configurations when basin configuration and
uplift of the hinterlands during Late Mesozoic and
Cenozoic times are concerned, namely the Late
Jurassic to Early Cretaceous (basin configuration
1), the Late Cretaceous to Early Palaeocene (basin
configuration 2), the configuration influenced by
break-up and initial opening of the NE Atlantic
(Late Palaeocene-Eocene; basin configuration 3)
and, finally, the last phase of uplift of South
Norway, which was initiated in the Oligocene
(basin configuration 4).
1
This way of separating the basin configura-
tions from each other implies that the latest
syn-rift and the early post-rift phases are
incorporated in basin configuration 1 and that
basin configuration 2 coincides with the late
post-rift phase.
2
A coupled source-to-sink dynamic is revealed
from the close relationship between diachro-
nous development of accommodation space in
the North Sea area and uplift of hinterlands
throughout the Late Mesozoic and Cenozoic.
3
The late syn-rift to early post-rift phases (basin
configuration 1), is characterised by terrige-
nous erosional material that was trapped in
depocentres located between topographical
highs, both in the northern and eastern North
Sea basinal areas.
4
The eastern topographic highs were located in
parts of southern Norway (Fig. 14A) and at the
Lista Fault Blocks south of the Sorgenfrei
Search WWH ::
Custom Search