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 78

The palaeosols were formed as soils beneath distinct
land surfaces and reflect breaks in sedimentation
and erosion and the intensity and duration of
pedogenic processes. Representative core photo-
graphs of mudrocks and palaeosols are presented
in Fig. 10. The relative frequency of mudrock
facies in the LF and LSG, PA1 to 4, is shown in
Fig. 11.
Pedocomplexes are vertically stacked individual
palaeosol horizons and are compound, composite,

or cumulative (Fig. 11). Compound and in part
composite, pedocomplexes commonly represent
weakly developed palaeosols formed during rather
frequent, episodic aggradation of the floodplain.
Cumulative pedocomplexes represent better devel-
oped palaeosols associated with lower rates of
floodplain aggradation, longer periods of non-
deposition and continuous pedogenesis (Marriott &
Wright, 1993; Wright & Marriott, 1996; Kraus &
Aslan, 1999).

(A) (C)

Mud cracks

Root hole

(B)

Oxidised
cracks

Fig. 10. Core photographs of mudrocks and
palaeosol types in the Lunde Formation. (A)
Sub-vertical stacked carbonate nodules
which represent rhizocretions (2548.7 m
RkB, well 34/4-4). (B) Several hierarchies
of peds defined by slickensides. Pedogenic
mud aggregates postdate the slickensides
(2524.5 m RkB, well 34/7A-9H). (C) Sand-
filled desiccation cracks filled in with sand
from overlying sand bed have been oxidised
and later mottled by reduction of iron-
oxide in the uppermost part. Both wells
from the Snorre Field. Scale bars are 5 cm.
From Müller et al . (2004).

Ped surfaces