De Haas, H.

Martins, I.X.

Van Rooij, D.

Vandorpe, T.

Open Marine Archive

 
 
 
 
Obstacle
1 Dpt. Geolo
2 Departmen
Henk.de.H
3 Instituto H
 
 
Abstra
drifts 
Cádiz)
mud v
Escarp
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An An
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LADC
Duick
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water
 
Key w
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INTRODUC
 
The nort
attention due
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the Mediterr
339 Scientist
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southern Gul
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et al., 2005
obstacle-rela
volcano field
drifts and 
oceanograph
 
MATERIAL
 
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Thom
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aas@nioz.nl 
ídrográfico Lisbo
ct: This stud
at water dept
.The drift sys
olcanoes (e.g
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ated at the b
tarctic Interm
ce of Medite
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P data indica
 drift experie
ience an east
mass. 
ords: obstacl
raphy, LACD
TION 
hern Gulf of
 to IODP E
contourite de
anean Outflow
s, 2012). The
urite system
y Llave et 
f of Cádiz, so
udied, althou
ud volcanoes
). This stud
ted drift syst
 (Fig. 1). A
their relation
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 AND MET
high-resoluti
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 1002 mult
 order to de
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 Deep-Water 
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. Gemini M
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 Cádiz is re
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positional sy
 Water (MO
 temporal and
 has been de
al. (2011).  
uth of the St
gh diapiric ri
 are present (
y focuses o
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 to the pa
f this research
HODS 
on, single c
 (>1500km), 
n 2002 and
ibeam datase
scribe the dri
seismic pro
CO geophy
lying a band
mplitude corr
he El Arraich
 CTD data 
mperature 
Circulation C
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Gu
e1, David Va
sity, B-9000 Ghe
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ophysical evi
0 and 800 me
cted by local
ud Volcano) 
 the foot of t
aternary, wit
 origin is infe
ow Water cou
nadsky drift)
ce of slow (<
al west to ea
direction, imp
ts, Antarctic I
ceiving a lot
9 which dril
stem created 
W) (Expedit
 lateral variat
scribed in gr
In contrast, 
rait of Gibral
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Van Rensber
n several sm
El Araiche m
of the differ
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. 
hannel, spark
obtained dur
 2013), and
t (700km²) h
ft system at 
files have b
sical Radex
pass and sw
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and salin
 
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2 Sept. 2014,
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k De Haas2
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search, 1790 AB 
existence of a
 Arraiche Mu
g. uplift of rid
ter corals (e.
k Escarpmen
ange around
riving mecha
stantiated. Li
an Outflow
om currents i
tion, while t
t two could p
Water, El Ara
tp://www.nod
 displayed in
D (SeaBird 
CP 300kHz)
paign “COM
 
SULTS AND
 
The multibe
eral importan
ge, numerou
lcano) and ch
URE 1. Multibe
ication of the thr
icate the positio
ctions in them. 
tom current stren
 Ghent, Belgi
ud Volca
and Inês Ma
ugent.be, David
Den Burg, The N
t least three 
d Volcano fie
ges) and by t
g. at the foo
t has been st
the Mid-Plei
nism for this 
kewise, at the
Water is cur
n the moats of
he Renard an
ossibly origi
iche Mud Vol
c.noaa.gov/O
 Ocean Data 
SBE19) and
 data acquire
IC” were als
 DISCUSSI
am data (Fig
t features: th
s mud volc
annels on the
am bathymetric m
ee observed drif
n of the differe
The black arrows
gth, derived from
um 
no field, 
rtins3 
.VanRooij@UG
etherlands. 
different con
ld (southern G
he presence o
t of the Pen 
udied in deta
stocene Revo
drift system a
 two more no
rently not p
 the drifts. Th
d Vernadsky
nate from the
cano Field, s
C5/WOD/pr_
View (http://
 LADCP (T
d during the 
o used in this 
ON 
. 1) show the
e Renard an
anoes (e.g. 
 seabed in the
ap of the El Ar
t systems. The l
nt moats and th
 show the direc
 the preliminary
Southern
ent.be 
tourite 
ulf of 
f both 
Duick 
il and 
lution. 
nd the 
rthern 
resent. 
e Pen 
 drifts 
 same 
eismic 
wod.html) 
odv.awi.de/).
eledyne RDI
2013 Belgica
study.  
 presence of
d Vernadsky
Gemini Mud
 area.  
raiche area with
ight blue arrows
e inferred flow
tion and relative
 LADCP data. 
 
 
 
 
 
 
 
 
 
 
 
 
 
2nd Deep-Water Circulation Congress, 10-12 Sept. 2014, Ghent, Belgium 
 
 
 
 
[74]
Based on the location of the drifts, the moats and the 
coriolis deflection, the directions of the bottom currents 
are inferred (light blue in Fig. 1). These are compared to 
preliminary LADCP-results, acquired during the June 
2013 Belgica campaign (indicated by the black arrows 
in Fig. 1). The highest bottom current velocities (about 
8-10cm.s-1) are recorded just north of the Renard ridge. 
South of the Gemini mud volcano, velocities exceeding 
5cm.s-1 are recorded. Except for the Vernadsky drift, the 
inferred direction of bottom currents agree nicely with 
those observed in the LADCP data. 
 
The seismic stratigraphy of the Pen Duick drift 
consists of 5 units: the lower 2 are affected by the uplift 
of the Pen Duick Escarpment (PDE) and the upper 4 
units are intersected with mud extrusions from the 
nearby Gemini Mud Volcano (Fig. 2). The Pen Duick 
drift consists of a pre-contourite (hemi-)pelagic phase, a 
phase with sheeted drift deposits (2.6Ma to 0.92Ma) and 
a phase with mounded drift deposits (920ka till recent). 
Within unit 3 (920 – 575ka), three small (<50ms TWT) 
mounds are present, resembling cold-water corals 
(Vandorpe et al. 2014). 
 
 
 
FIGURE 2. Preliminary result of a LACDP profile in the Renard drift 
(35°22.856’N and 6°50.726’W) at a water depth of 745m. 
 
The chronostratigraphy of the Pen Duick drift differs 
from MOW-controlled drifts in the Northern Gulf of 
Cádiz (Llave et al., 2011) and the Le Danois area, Bay 
of Biscay (Van Rooij et al., 2010). Also, the CTD data 
do not indicate the presence of MOW at the foot of the 
PDE (Vandorpe et al., 2014). Both observations indicate 
that MOW is not involved in the build-up of the drift. 
Antarctic Intermediate Water (AAIW) is proven to be 
present in the area (e.g. Vandorpe et al., 2014) and 
could be intensified by the deflection against the Gemini 
Mud Volcano and the PDE. The Renard and Vernadsky 
drifts are not necessarily influenced by the same bottom 
currents as those responsible for creating the Pen Duick 
drift due to the contrasting direction (west- versus 
eastwards) of the bottom currents. Although, a 
secondary flow pattern around the complex topography 
of the Renard Ridge is also a possibility (Martins et al. 
2014). Which bottom currents and which water mass are 
involved in the build-up of the Renard and Vernadsky 
drifts is the aim of this ongoing research. 
 
CONCLUSIONS 
 
The El Arraiche mud volcano field yields several 
examples of obstacle-related drift deposits. The Pen 
Duick drift is probably created by the deflection of 
AAIW against two topographies. The Renard and 
Vernadsky drift are not necessarily influenced by the 
same water mass as LADCP data indicate a different 
current compared to the Pen Duick drift, but a complex 
flow pattern around the Renard Ridge cannot be 
excluded. 
 
ACKNOWLEDGEMENTS 
 
The authors would like to thank the FWO for 
financing this research (KaN Contourite-3D) and the 
captain and crew of the R/V Belgica. 
 
REFERENCES 
 
Expedition 339 Scientists, 2012. Mediterranean 
outflow: environmental significance of the 
Mediterranean Outflow Water and its global 
implications, Integrated Ocean Drilling Project 
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Llave, E., Matias, H., Hernández-Molina, F., Ercilla, G., 
Stow, D., Medialdea, T., 2011. Pliocene–Quaternary 
contourites along the northern Gulf of Cadiz margin: 
sedimentary stacking pattern and regional 
distribution. Geo-Marine Letters 31, 377-390. 
Martins, I. & Vitorino, J., 2014. A physical 
oceanography contribution to understand the 
processes affecting El-Arraiche Mud Volcano field 
(NW Moroccan Margin). 2nd Deep-Water 
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Obstacle-related contourite drifts in the El Araiche Mud Volcano field, Southern Gulf of Cádiz

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