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(A)
(B)
Barents Sea
humid
Pangaea
60
humid
Migration of
higher latitude
precipitation?
semi-arid
30
arid
Tethys
0
Playa
Fluvial
30
Marine
Halite
60
semi-arid
90
0
90
Central
North
Sea
(C)
Barents Sea
Southern Permian Basin
Tethys
arid
R
Summer
monsoon
N
dryer
wetter
C
L
A
O
Te thys
Fig. 21.
Regional climatic setting of the central North Sea. (A) Late Triassic distribution of climatic belts across the northern
hemisphere of Pangaea (with the region of little or no winter precipitation highlighted in white; after Sellwood & Valdes,
2006). The region from the Barents Sea to Tethys traverses a zone of southward increasing aridity. (B) Regional distribution
of fluvial and playa facies during the Early Carnian (after McKie & Williams, 2009; Müller
et al
., 2005). This facies
distribution is also broadly representative of the Middle Triassic (excluding the period of Muschelkalk flooding) and
illustrates that the central North Sea area remained part of a latitudinal region which sustained fluvial activity across the
North Sea and Atlantic basins, whilst to the south the basins were increasingly playa dominated and evaporitic. During
arid periods the Skagerrak Formation shale members record expansion of these playa facies into the central North Sea, but
during pluvial episodes vegetated alluvial systems expanded off the basin-flanking catchments. This may have been driven
by intensified monsoon activity, but could also reflect a contribution from the southward migration of higher latitude
precipitation. However, southward migration is difficult to reconcile with increased runoff during warming (Fig. 18)
when the reverse situation might be expected. In addition, the Barents Sea climate record at higher latitude (C) shows
limited coherence with the records to the south to support either synchronous movement or expansion/contraction of
climate zones. Curve sources as per Fig. 18, Barents Sea curve based on hygrophyte vs. xerophyte palynological data
documented by Hochuli & Vigran (2010).
systems extending northwards from the central
North Sea, into the northern North Sea and west-
ward into the north Atlantic region (McKie &
Williams, 2009) and the presence of generally
wetter conditions through the boreal and polar
regions (Golonka
et al
., 1994; Ziegler
et al
., 2003;
Hochuli & Vigran, 2010) it could be argued that
the central North Sea area was more influenced by
the southward migration of mid-latitude precipi-
tation (given that the fluvial catchments were not
large enough to traverse climatic zones). However,
fluvial expansion appears to have occurred inde-
pendently of Boreal trends of wettening and drying
(Fig. 21C), with the Ladinian expansion of the
Joanne Sandstone Member occurring during
pronounced Boreal drying. Such differences in
climate trends, together with the similarity to the
climate record to the south, would tend to favour
a predominantly Tethyan origin for the precipita-
tion which drove fluvial expansion. The develop-
ment of pluvial conditions during warming episodes
might also be expected to be characterised by a
northward migration of mid-latitude precipitation
rather than southward expansion. However, dry
season runoff may have been episodically aug-
mented by northern sources in the Anisian and
Carnian when all regions appear to have been
wetter. The fluvial systems remained terminal and
flood-dominated throughout, suggesting domi-
nance of seasonal monsoon precipitation, but with
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