Geoscience Reference
In-Depth Information
Climatic
Conditions
GDE/
Basin Type
Sediment
Supply
Rift Episodes
Active Faults
Subsidence
Latitude
Very high
to
High
(but variable)
?
Dry?
Restricted
shelfal sea
Minimal
(but variable)
54°N
Shelfal sea
Intermediate
(but variable)
C
Melke Fm
Very low
(but variable)
B
Garn Fm
B
Wet
Low
Rifted
shelfal strait
Low
52°N
?
Not Fm
A
Ile Fm
Intermediate
?
Shelfal
strait
Intermediate
T
Ror-Tofte Fms
High
Tilje Fm
Marine
embayment
P
Wet
High
50°N
Very high
Delta plain
S
Very high
Åre Fm
Humid
H
Floodplain
High
?
?
Dry
Shelfal
Marginal marine
Delta-plain
Flood-plain
Tectonic History
Palaeoclimatic conditions
Depositional setting
Fig. 3.
Tectonostratigraphic summary chart for the Jurassic of the Halten Terrace area, mid Norway.
these controlling factors impact the resultant
sequence architecture.
Mid-Norway shelf areas formed the two opposing,
or conjugate, margins of this seaway. The Halten
and Dønna Terraces then combined with the
Trøndelag Platform to form a wide platform area
along the eastern rift margin.
During the late Middle to Late Jurassic rifting,
the Halten and Dønna Terraces were structurally
separated from the rift-marginal Trøndelag
Platform to the east by the Frøya High and the
Nordland Ridge (Withjack
et al
., 1989; Brekke,
2000; Færseth & Lien, 2002; Mosar
et al
., 2002).
The Halten and Dønna Terraces were variably
tilted eastwards and separated from the deep
Late Jurassic basins to the west by a series of
structural highs along the Klakk Fault Complex,
such as the Sklinna Ridge and a series of smaller,
downfaulted terraces and sub-platforms to the
north (Fig. 2). it was during this rift episode
that the area attained its present structural
configuration.
Geological setting & Early to Middle Jurassic
semi-regional geological evolution
The Halten Terrace (Blystad
et al
., 1995), located
on the Mid-Norway shelf between 64°N and 65°N
and 6°E and 8°E, formed the eastern margin and
sub-platform area of the Mesozoic Norwegian-
Greenland Sea Rift-basin (Fig. 2). The Halten
Terrace together with its northward extension, the
Dønna Terrace, both formed in response to two
rifting episodes; during the Permo-Triassic and
the Late Jurassic (Roberts
et al
., 1999; Brekke,
2000; Færseth & Lien, 2002; Mosar
et al
., 2002).
The intervening Early to Middle Jurassic period
was less tectonically active compared to both the
preceding Middle to Late Triassic and succeeding
Late Jurassic rift episodes, although some struc-
turing also prevailed during this period (Fig. 3;
Marsh
et al
., 2010).
During the Early and Middle Jurassic, the
Norwegian-Greenland Sea rift evolved from a sub-
siding alluvial-fluvial, south-westward-draining
basin to a narrow shelfal strait or epicontinental
seaway, connecting the Boreal Sea to the north
with the Tethys Sea to the south (Figs 3, 4 and 5;
Nøttvedt
et al
., 2008). The East Greenland and
Early to Middle Jurassic structuring &
basin setting
The Lower to Middle Jurassic of the Norwegian-
Greenland Sea rift-basin forms the post-rift unit
to the underlying Permo-Triassic and the pre-
rift strata to the overlying Upper Jurassic syn-rift
succession (Færseth & Lien, 2002). Previous
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