Med dical CT-i Thomas

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2ndd Deep-Water Circulation C
Congress, 10-1
12 Sept. 2014,, Ghent, Belgiium
Med
dical CT-iimages off contouriite cores: An onset to processsing and data
intterpretatiion
Thomas Vandorpe1, David
D
Van Ro
ooij1, Susanaa Lebreiro2, Belen
B
Alonso3, Anxo Menaa4, Veerle Cnu
udde1 and
5
Francisco Jaavier Hernan
ndez-Molina
1
2
3
4
5
Dpt. Geoloogy & Soil Science, Ghent Univerrsity, B-9000 Gheent, Belgium. Tho
[email protected]
@ugent.be; [email protected]
nt.be;
[email protected]
IGME, Maadrid, Spain. [email protected]
me.es
Instituto dee Ciencas del Maar, CSIC, Barcelo
ona, Spain. [email protected]
@icm.csic.es
Departameento de Xeocienccas, University off Vigo, Vigo, Spai
ain. [email protected]
uvigo.es
Departmennt of earth sciences, Royal Hollow
way University off London, London
n, UK. [email protected]
@rhul.ac.uk
Abstra
ract: Althoughh CT scans arre being usedd in scientific research sincce the late 19970’s, they arre only
recently being usedd in contouriite research. M
Mostly a verttical slice thrrough or an X
X-radiograph of the
sedim
ment core is shhown, not disp
playing the thhree-dimension
nal variationss within the seediment core. These
can bbe very imporrtant howeverr. This researrch attempts to
t discern components witthin the entirre core
basedd on their radiio-density valu
ues, using the 3D analysis software
s
“Mo
orpho+”, deveeloped by the UGCT
(Ghennt University Centre for X-Ray
X
Tomoggraphy). The abundance of
o each compponent is disp
played
througghout the seddiment core an
nd will be com
mpared to MSCL, XRF and grainsize datta in order to derive
what information is
i held within
n CT scans. B
By scanning muddy,
m
silty and
a sandy conntourite coress (both
compaacted and not)
t), a non-exhau
ustive referen ce set of CT scans
s
for conto
ourite cores w
will be created
d.
Key w
words: CT scanning, contou
urites, Gulf off Cádiz, MSCL
L, XRF.
den
nsity values histogram (Figg. 1), a measurre for changess
in density an
nd average atomic num
mber. Thesee
com
mponents are isolated and qquantified in comparison
c
too
thee total volume of interest.
CTION
INTRODUC
X-ray computed tom
mography (C
CT) is a nnondestructive ttechnique ennabling researrchers to obttain
information of the internal structure of an obj
bject
(Brabant et al. 2011). CT-images
C
in
n sediment ccore
sections mayy display featuures not visiblle with the naaked
eye or on core-picturees, such as distinct layyers,
bioturbation,, cracks, annd weatherin
ng effects ((e.g.
Dewanckele et al. 2014) and
a as such it is a tool whhich
has been useed to further improve coree interpretatioons.
CT imagery iin contourite research
r
is scaarce so far. Soome
authors (e.g. Rebesco et al.
a 2012 and Voigt
V
et al. 20013)
use X-radioggraphs, whichh do not take into account the
full 3D variaations within a core. Laterall variations aree of
high importaance and shouuld be taken in
nto account. T
This
research focuusses on seveeral contouritee cores from the
Alboran Seaa and the Gulf of Cádiz co
ontaining mudddy,
silty and sanndy intervals in order to assess
a
what exxtra
information can be obtaained from CT
C scans andd to
generate a prreliminary refference set of CT scans agaainst
which future cores can be compared.
FIG
GURE 1. Histogra
am of the radio-ddensity values in core GC01 (Gulff
of Cádiz).
C
The colou
urs in this histogra
ram correspond to
o those in Fig.2.
IN
NITIAL RESU
ULTS
The colourss within the vertical secttion (Fig. 2))
gen
nerally only show the coomponent wh
hich has thee
hig
ghest percenttage in that interval. Ho
owever otherr
com
mponents are not fully abseent within tho
ose zones, e.g..
bettween 2150 and 2550 cm
m the dominan
nt componentt
is the
t purple one while the liight blue com
mponent is nott
abssent (up to 20%).
2
There is as well an importantt
am
mount of the yellow
y
(up to 7.5%) component presentt
(Fiig. 2). Also although neverr really visiblle in the coree
image, the red co
omponent is nnever totally absent
a
and hass
som
metimes perceentages up to 55% (e.g. 900m
m, Fig. 2).
L AND METHODS
MATERIAL
Over 5 m
meters of sediment core GC01 (northhern
Gulf of Caddíz) were sccanned with the SOMAT
TON
definition fflash scannerr of the Ghent
G
Univerrsity
hospital. A 120kV step and
a rotation time of 1 secoond
were set by w
which a x andd y-resolution of 0.2mm andd zresolution off 0.6mm wass obtained. The
T images w
were
reconstructedd using thee “J37s meedium smoooth”
algorithm. T
The analyticall software paackage Morphho+
(Brabant et al., 2011) from the Ceentre for X--ray
Tomographyy of the Ghentt University was
w used in orrder
to discern ddifferent com
mponents baseed on the raddio-
Based on the abunddance of th
he differentt
com
mponents, at least 14 unitss can be distin
nguished (Fig..
2). These unitss almost exaactly match XRF-definedd
[129]
2ndd Deep-Water Circulation C
Congress, 10-1
12 Sept. 2014,, Ghent, Belgiium
zones (cfr. F
Fe/Ca and Si//Al curves in Fig. 2). Zonne 2
(green box in Fig. 2) consists
c
mosttly of the grreen
component and correlattes with Si/A
Al values. T
The
variation of tthe other CT--components can
c however still
be used in oorder to derivee intra-zone variations.
v
In this
case the redd component,, indicating very
v
high raddiodensity valuees still shows a lot of variaation. It has too be
noted that X
XRF measuress the chemical compositionn of
the top millim
metre of a spllit core, which
h may not be the
same throughhout the entirre horizontal slice of the ccore
this measurinng point reprresents. A CT
T scan measuures
the radio dennsity of that entire
e
horizonttal slice and m
may
as a result ppotentially revveal more infformation on the
core.
RE
EFERENCES
S
Braabant, L., Vlassenbroeck, JJ., De Witte, Y.,
Y Cnudde,
V., Boone, M.N.,
M
Dewancckele, J., Van Hoorebeke,
H
L., 2011. Thrree-Dimension
onal Analysis of
o HighResolution X-Ray
X
Compuuted Tomograp
phy with
Morpho+. Miscroscopy
M
annd Microanaly
ysis 17 (2):
252-263.
Deewanckele, J., De Kock, T., Fronteau, G.,, Derluyn, H.,
Vontobel, M.,
M Dierckx, L.., Van Hooreb
beke, L.,
Jacobs, P., Cnudde,
C
V., 20014 Neutron raadiography
and X-ray co
omputed tomoography for qu
uantifying
weathering and
a water uptaake processes inside porouss
limestone used as buildingg material. Maaterials
characterizattion 88: 86-999.
Reebesco, M., Wåhlin, A., Labberg, J.S., Sch
hauer, U.,
Beszczynskaa-Möller, A., L
Lucchi, R.G..,, Noormets,
R., Accettella, D., Zarayskkaya, Y., Diviiacco, P., in
press Quaternary contouritite drifts of thee Western
Spitsbergen margin.
m
Deepp Sea Research
h Part I:
Oceanograph
hic Research PPapers, 79: 15
56-168.
Vo
oigt, I., Hen
nrich, R., PPreu, B.M., Piola, A.R.,,
Hanebuth, T.J.J., Schwenkk, T., Chiessii, C.M., 2013..
A submarin
ne canyon aas a climate archive —
Interaction of
o the Antarctiic Intermediatte Water withh
the Mar del Plata Canyyon (Southwest Atlantic)..
Marine Geollogy 341: 46-557.
RESEARCH
FUTURE R
Further ccomparisons to XRF, MSC
CL and grain-ssize
data will be carried out to
t find out what
w
the differrent
components represent annd how they can be usedd to
further interppret contouritte cores. To achieve
a
this ggoal,
contourite ssections from
m various settings will be
scanned in order to com
mpile an initiial reference set
against whichh future scanss can be compared.
LEDGEMEN
NTS
ACKNOWL
The authhors acknowleedge FWO grrant “Contourrite3D” for finan
ancing this prooject, and Pro
of. Dr. E. Achhten
and Claire Scchepens (Radiiology unit, UZ
U Gent).
FIGURE 2. Variation of the com
mponents (percen
ntages) and XRF- measured Fe/Ca and Si/Al throug
ghout sediment coore GC01. The grrey component is
v
section th
hrough the core is given on the rig
ght. The black horrizontal lines delilineate 14 zones based
b
on the CT
not displayed iin the graphs. A vertical
data. Zone 2 iss indicated in greeen because it sho
ows a good correllation between th
he green compone
ent and the Si/Al ddata. Also the purple component
and the Fe/Ca
Ca data display the same trends.
[130]
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