Sedimentation at the Jurassic–Triassic boundary, south-west Barents Sea: indication of climate change - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 191

Barents basins to the west of Novaya Zemlya may
have restricted the sediment flux from the south-
east since the latest Triassic (Norian) (see maps in
Smelror et al . 2009). Such Early Jurassic reconfig-
uration of sediment supply can also be inferred
from western Svalbard, where marginal marine
sediment are sourced from the east, as opposed to
the westerly source recorded from Triassic strata
(Steel & Worsley, 1984; Smelror et al . 2009).
Analyses of uplift and denudation from apatite
fission tracks in onshore areas to the south of the
Barents shelf (eastern Finnmark and the Kola
Peninsula) are indicative of significant and rapid
Late Triassic to Early Jurassic uplift (Hendriks &
Andriessen, 2002; Hendriks, 2003). These obser-
vations are of importance for the understanding
of offshore sedimentation patterns, as they imply
some rejuvenation of the hinterlands at or near the
Triassic to Jurassic boundary, possibly influencing
the composition and calibre of sediment delivered
to the basins.
In the northern North Sea area, rifting in the
Viking Graben (Fig. 1) commenced during the
Late Permian to Early Triassic (e.g. Badley et al .,
1988; Færseth, 1996), with subsequent develop-
ment of a post-rift basin which accumulated more
than 2 km of predominantly terrestrial Triassic to
Early Jurassic strata (Lervik et al ., 1989; Nystuen
et al ., 1989; Steel & Ryseth, 1990). On the mid-
Norway shelf (e.g. Halten and Dønna terraces;
Fig. 1), initial extension may have commenced
during the Carboniferous and was followed by
Late Permian to Early Triassic rifting (Blystad et
al ., 1995; Marsh et al . 2009). Here, more than 3 km
of Triassic strata, including thick (400 m) halites
at the mid-Triassic level, have been documented
from wells and seismic data (Jacobsen & van Veen,
1984; Müller et al . 2005).
A Late Jurassic to Early Cretaceous rift climax
seems to have affected the entire Norwegian shelf
area from the North Sea (e.g. Badley et al ., 1988;
Færseth, 1996) and the mid-Norway shelf (Blystad
et al ., 1995; Marsh et al ., 2009) to the western
parts of the Barents Sea area (Gabrielsen et al .,
1990). This extensional phase was eventually fol-
lowed by regional post-rift subsidence, associated
with a general westwards shift of Cretaceous to
Cenozoic crustal extension to the Møre and Vøring
basins (Fig. 1) off the mid-Norway shelf (Doré,
1992; Doré et al . 1997) and to the deep Tromsø,
Bjørnøya and Sørvestsnaget basins in the western
margin of the Barents Sea (Figs 1 and 2A; Breivik
et al ., 1998; Ryseth et al ., 2003).

The present study is primarily related to the
Late Triassic to Early Jurassic (Late Carnian to
Sinemurian) succession in the Barents Sea, which
will be discussed in terms of depositional envi-
ronments and variations in sedimentary archi-
tecture, with some considerations of possible
palaeogeographic and climatic changes. A com-
parison of time-equivalent sedimentary facies
from the North Sea (Viking Graben) and the mid-
Norway shelf (Halten Terrace) is also included, to
provide some more detail to the possible regional
variation in the Late Triassic to Early Jurassic cli-
mates and on the possible climatic effects on
deposition.

TRIASSIC TO EARLY JURASSIC
CLIMATIC SETTINGS

During Triassic time, landmasses were concen-
trated into a single continent (Pangaea) and dis-
tributed around the equator, with continental
areas extending towards the poles (Golonka,
2007). During the Late Triassic, the North Sea area
was located at around 40º N and the Barents Sea
basins at approximately 50º N to 55° N (e.g. Ziegler
1988; Golonka, 2007; Worsley; 2008), with the
mid-Norway shelf in an intermediate position.
The Barents shelf bordered the Boral Sea during
the Triassic, whereas the North Sea area was
located well within the continental realm and
away from the Boral and Tethyan seas (Ziegler,
1988; McKie & Williams, 2009). Consequently, ter-
restrial strata are dominant in the Triassic of the
North Sea area (e.g. McKie & Williams, 2009)
whereas age-equivalent strata in the Barents Sea
area are characterised by intercalated marine and
terrestrial facies (e.g. Henriksen et al ., 2011).
Modelling of global Triassic climates (Sellwood &
Valdes, 2006) indicates that the continental posi-
tions between 40º N and 40º S (e.g. including the
current North Sea area and the mid-Norway shelf)
were generally warm, with sustained hot periods
during which temperatures may have exceeded
30 º C for most of the year. The Early Triassic may
have been one of the hottest phases in geological
time, with development of extensive calcretes
(soil carbonate), e.g. throughout Europe. Also,
during Middle and Late Triassic times, the equato-
rial zone was generally hot and dry, although with
a tendency towards more semi-arid conditions
during the Late Triassic (Sellwood & Valdes, 2006;
McKie & Williams, 2009).