The Ormen Lange turbidite systems: sedimentary architectures and sequence structure of sandy slope fans in a sediment-starved basin - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 618

Table 1. Muddy lithofacies; their characteristics and inferred depositional processes. The mudstones are given genetic names
to ease the cross-reference and readability of the text. Numbers in coloured boxes in left column refer to lithofacies coding in
Fig. 6. The width of individual core slabs is 10 centimetres.

Characteristics
BI & Diversity

Microfacies
Index

Core
Appearance

Depositional
Architecture Shale T ype Lithology

Pelagic Dark to dark grey,

rarely dark
greenish grey
claystones

High BI
Medium to Low
Diversity

High Extensive blankets

1

Hemi-pelagic Greyish and

greenish grey
claystones and
mudstones

Medium to High BI
Medium to High
Diversity

Medium
to High

Fairly extensive
blankets

Contouritic Green to grey

mudstones
and siltstones,
sometimes ripple
cross-laminated

Low to medium BI
Medium to High
Diversity

Low to
Medium

Lobate blankets to
patchy (erosional
remnants)

2

Turbiditic Grey and dark

grey mudstones
and siltstones,
laminated

Low BI
Low Diversity

Low Lobate blankets

The channel-belt association consists of ero-
sively based, commonly amalgamated bedsets
(Table 3; Figs 8A and 9) of stratified and cross-strat-
ified sandstones, ripple cross-laminated sandstone
lags, granule sandstones and shale-clast conglom-
erates, as well as interbedded turbiditic and rare
hemipelagic mudstones (see Tables 1 and 2 for
interpretations of lithofacies). Locally, also,
deformed and slumped strata are present. The bed-
sets normally form fining-upwards, or more rarely
coarsening-to-fining upwards motifs. These are,
based on the component facies, the mixture of
coarse and heterolithic lithologies, as well as the
vertical facies successions, interpreted to represent
submarine channel-fills (Clark & Pickering, 1996).
Such channel-fill motifs are common from sandy
submarine fan systems in a variety of settings
(Gardner & Borer, 2000; Gardner et al ., 2003;
Grecula et al ., 2003a; Milli et al ., 2007; O'Byrne
et al ., 2007; Sweet et al ., 2007), with individual
motifs representing single-storey channel-fills.
Basal boundary surface was probably concave
upwards and erosional, as inferred from borehole
dip-meter data. The common amalgamated character

of these compound motifs suggests that they
represent channel complexes (or storey sets; e.g.
Eschard et al ., 2003; Grecula et al ., 2003a; Euzen
et al ., 2007) at the outlet of slope tributary systems
(e.g. Johnson et al ., 2001; Decker et al ., 2004;
Gervais et al ., 2004, 2006; Hodgson et al ., 2007;
Deptuck et al ., 2008). Channel sinuosity (as inferred
from seismic data) is low (less than 1.2; e.g. see
Figs 10 and 11).
The channel-to-lobe transition/braided fan asso-
ciation comprises amalgamated and scoured bed-
sets (Table 3; Figs 8B and 9) of stratified and
cross-stratified sandstones, as well as rare shale-
clast conglomerates. The bedsets are embedded in
hemipelagic and/or contouritic mudstones, range
from a few to more than nine metres-thick and
define simple thinning-upward and fining-upward
motifs or more complex thickening-upwards and
coarsening-upwards to thinning-upwards and fin-
ing-upwards motifs. Interbedded claystones are
relatively uncommon. Erosive surfaces was again
concave upwards, although dipmeter data suggests
a more gentler relief compared to the boundary
surfaces of the proper channel storey fills (see