Late Triassic to Early Jurassic climatic change, northern North Sea region: impact on alluvial architecture, palaeosols and clay mineralogy - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 62

North Sea as the Hegre Group and subdivided it
into the Teist, Lomvi and Lunde formations.
Nystuen et al . (1989) subsequently subdivided the
Lunde Formation into three informal members:
the lower, middle and upper Lunde members.
Lervik (2006) redefined the Lunde Formation to
comprise only the upper Lunde member of
Nystuen et al . (1989) and established the Alke
Formation, consisting of the previous lower and
middle Lunde members, located above the Lomvi
Formation (Fig. 2).
The Statfjord lithostratigraphic unit was origi-
nally given formation status and subdivided into
three members; in ascending order Raude, Eiriksson
and Nansen (Deegan & Scull, 1977). Vollset &
Doré (1984) redefined the lower boundary of the
Statfjord Formation (see below), but maintained
its formation status and the three formal members.
Lervik (2006) raised the rank of the Statfjord

GEOLOGICAL FRAMEWORK

Stratigraphy and lithology

The Norian to early Rhaetian Triassic Lunde
Formation and the late Rhaetian to earliest
Pliensbachian Statfjord Group (Figs 2 and 3) were
deposited in the northern part of a continental
basin that covered most of the present North Sea
area, until the region was transgressed in the Late
Sinemurian to Early Pliensbachian (Røe & Steel,
1985; Nystuen et al ., 1989; Steel & Ryseth, 1990;
Steel, 1993; Nystuen & Fält, 1995; Charnock et al .,
2001; Ryseth, 2001; Goldsmith et al ., 2003; Mckie
& Williams, 2009). The Lunde Formation was
defined originally as a part of the continental
Cormorant Formation by Deegan & Scull (1977).
Vollset & Doré (1984) redefined the Cormorant
Formation in the Norwegian sector of the northern

Chronostratigraphy Lithostratigraphy

Fossil
Documentation

SYSTEM SERIES STAGE AGE (Ma) DURATION GROUP FORMATION

PLIENS-
BACHIAN

6.6 DUNLIN AMUNDSEN

FORAMINIFERA/
OSTRACODS

189.6 ± 1.5

6.9

SINEMURIAN

NANSEN

LOWER

SPORES/
POLLEN

196.5 ± 1.0

EIRIKSSON

HETTANGIAN 3.1

199.6 ± 0.6

RAUDE

RHAETIAN

4.0

SPORES/
POLLEN

203.6 ± 1.5

LUNDE

NORIAN

12.9

UPPER

216.5 ± 2.0

SPORES/
POLLEN

CARNIAN

11.5

ALKE

228.0 ± 2.0

9.0

LADINIAN LOMVI

SPORES/
POLLEN MIDDLE

237.0 ± 2.0

ANISIAN TEIST

Fig. 2. Lithostratigraphy and chronostratigraphy of the Upper Triassic Hegre Group and the Lower Jurassic Statfjord and
Dunlin groups in the Norwegian sector of the northern North Sea region. Modified from Deegan & Scull (1977) and Lervik
(2006), with ages from Gradstein et al . (2004) and fossil documentation from Eide (1989) and Lervik et al . (1989).