Volcanism and hydrothermal venting on a hot-spot ...
1
Volcanism and hydrothermal venting on a hot-spot influenced slow-spreading mid-ocean ridge Sofia Panasiuk 1 , Melissa O. Anderson 1 , Ármann Höskuldsson 2 , Fernando Martinez 3 , Dominik Pałgan 4 1 Department of Earth Sciences, University of Toronto, Canada 2 School of Engineering and Natural Sciences, University of Iceland, Iceland 3 SOEST, University of Hawai’i at Manoa, Honolulu, USA, 4 Institute of Oceanography, University of Gdańsk, Poland Introduction Results Methods Future Work Discussion Figure 1 Figure 2 Figure 4 Multibeam bathymetry compilation of the Reykjanes Ridge between 56 0 50’N and 58 0 20’N. Dataset is from the Marcus G. Langseth cruise (MGL1309) gridded at 50x50m resolution overlain on regional bathymetry (GMRT). The names of remnant fault zones (FZ), now non-transform offsets (NTOs) are indicated beside the respective FZ. • The Reykjanes Ridge (RR) is a slow spreading mid-ocean ridge (MOR) that extends ~1000 km south of Iceland (Fig. 1) • 37 Mya, the Reykjanes separated into transform-fault connected segments which have been eliminating from north to south • The evolution of the ridge has been influenced by basement depth gradients formed by the Iceland hotspot • The southern extent of the ridge is still actively deforming making it a prime area for current ridge dynamics studies (Fig. 1) • Near-continuous bathymetric data at grid resolutions from 50x50 m to 100x100 m has been collected over several research cruises • Unlike most MORs, this bathymetric data extends far off-axis, providing insights into to the evolution of the crust over time • The goal of this work is to investigate the tectonic and volcanic evolution of the RR through remote predictive geologic mapping • The work will allow for a reconstruction of the ridge's spreading history and an understanding of the ridge's geodynamic controls • This work will have implications for understanding the controls on the distribution of potential magmatic-hydrothermal systems along slow-spreading MORs Mapping guide with criteria for classification based on multibeam bathymetry and backscatter data. • The remote predictive geologic mapping approximated the technique used in other sea-floor environments (Klischies et al., 2017, Anderson et al., 2017). • Raw multibeam bathymetry data comes from the Marcus G. Langseth Cruise (MGL1309) at gridded resolution of 50x50 m • Bathymetry was rendered into ArcGIS and enhanced with hill shade and slope shade • Backscatter was used to determine relative ages of erupted crust • Moderate to high backscatter intensities represent newly erupted hummocky lava and sheet flow (Fig. 2) • Low backscatter intensities represent sedimented terrain • Linear features mapped include: major and minor faults, eruptive fissures and lineaments • Other features mapped include Axial Volcanic Ridges (AVRs), volcanic cones, flat-topped volcanoes, and cratered volcanoes Figure 3 Lineament density maps using equally weighed mapped linear features: major/minor faults, eruptive fissures, and lineaments. Both maps and features themselves are shown for comparison. Interpreted geology of the central segment of the MGL1309 survey between NTOs. In addition to the interpreted geology, figure 4a also shows major and minor faults. Figure 4b highlights point source volcanic features: volcanic cones, flat-topped volcanoes and cratered volcanoes. • A total of 4337 major faults, 4470 minor faults, 3862 eruptive fissures and 4200 lineaments were mapped across the study area • Features were binned according to their trend into 20-degree interval bins , and lineament density maps were calculated (Fig. 3) • Darker colored areas represent the highest lineament density and lighter tones represent the lowest lineament density • Almost 70% of all linear structures are oriented between 10 to 70 degrees azimuth (AVR long axis trends = 21 0 , axial valley trend = 40 0 ) • The region between two oppositely facing NTOs have few N/S trending structures compared to other zones corresponding to the same age (Fig 3a, 3b) • Linear structures in or near the axial valley are more N/S trending (Fig. 3a, 3b) compared to those off-axis which trend towards the NE/SW (Fig. 3c, 3d) • Structural trends typically dominating off-axis (30 – 70 degrees azimuth) are also found in the axial valley (Fig. 3c, 3d) • Consistent high lineament density locus in the center of the two oppositely facing NTOs (Fig. 3a, 3b, 3c) References 1. Anderson MO, Chadwick WW Jr, Hannington MD, Merle SG, Resing JA, Baker ET, Butterfield DA, Walker SL, Augustin N. Geological interpretation of volcanism and segmentation of the Mariana back-arc spreading center between 12.7°N and 18.3°N: GEOLOGY OF THE MARIANA BACK-ARC. Geochemistry, geophysics, geosystems: G(3). 2017;18(6):2240–2274. 2. Eason DE, Dunn RA, Pablo Canales J, Sohn RA. Segment-scale variations in seafloor volcanic and tectonic processes from multibeam sonar imaging, Mid-Atlantic Ridge Rainbow region (35°45′-36°35′N): SEGMENT-SCALE VARIATIONS AT RAINBOW, MAR. Geochemistry, geophysics, geosystems: G(3). 2016;17(9):3560–3579. 3. Hey R, Martinez F, Höskuldsson Á, Benediktsdóttir Á. Propagating rift model for the V-shaped ridges south of Iceland: V-SHAPED RIDGES SOUTH OF ICELAND. Geochemistry, geophysics, geosystems: G(3). 2010;11(3). http:// dx.doi.org/10.1029/2009gc002865. doi:10.1029/2009gc002865 4. Hey R, Martinez F, Höskuldsson Á, Eason DE, Sleeper J, Thordarson S, Benediktsdóttir Á, Merkuryev S. Multibeam investigation of the active North Atlantic plate boundary reorganization tip. Earth and planetary science letters. 2016;435:115–123. 5. Klischies M, Petersen S, Devey CW. Geological mapping of the Menez Gwen segment at 37°50′N on the Mid-Atlantic Ridge: Implications for accretion mechanisms and associated hydrothermal activity at slow-spreading mid-ocean ridges. Marine geology. 2019;412:107–122. 6. Martinez F, Hey R, Höskuldsson Á. Reykjanes Ridge evolution: Effects of plate kinematics, small-scale upper mantle convection and a regional mantle gradient. Earth-science reviews. 2020;206(102956):102956 • Younger crust (on-axis terrain) is dominated by N/S trending structures and older crust (off-axis terrain) is dominated by NE/ SW trending structures • Significant number of structures exemplifying “older trends” in the on-axis terrain suggesting that older ridge dynamics may still influence modern spreading • The central segment has two kinks near the connections between the interpreted NTOs (Fig .4a, 4b). These kinks are also traced by the normal faults which stand-in as major ridge bounding faults • These faults regain their linearity off-axis means that the orientation of the axial valley has changed significantly • Brittle structures form in response to stress fields; a changing tectonic stress field could have caused the shift in orientation • There is preference for hummocky and pillow lava style volcanism with minimal point source volcanism in the central ridge segment between oppositely pointing NTOs • This segment also corresponds to the location of greatest lineament density (Fig. 3) • This region could be more magmatically robust and have higher crustal permeability • The gradually diverging NTOs could thin the crust, explaining the more magmatically focused center • This magmatically robust central segment offers the most potential for magmatic-hydrothermal systems Figure 5 Seismic event density mapping shows localities with higher earthquake occurrences, possible zones of higher tectonic dismemberment and higher crustal permeability (Data from Global CMT Project). The nature of the relationship between NTOs and the evolution of the recently reconstructed southern extent of the Reykjanes Ridge needs further study. To investigate the geodynamic control and interplay between NTO geometry, ridge deformation, and magmatically focused centers, the following work will be undertaken: • The geologic map of the central study area covers the Reykjanes Ridge’s axial valley between the Merlin and Morganore NTOs (Fig. 4) • The left North American plate appears more faulted and tectonically dismembered than the right Eurasian plate off-axis • Proximal off-axis faults on both plates shift orientation with the corresponding bend in the axial valley and resume a constant orientation off-axis • The southern Reykjanes axial valley is dominated by hummocky and pillow lava flows with abundant point source volcanism • A 16 km segment of the axial valley between the two oppositely facing NTOs is marked by an absence of significant point source volcanics The Reykjanes Ridge is still actively deforming despite having mostly reorganized back to its original linear geometry. This is evidenced by the orientation changes in linear structures progressively off-axis and variability in geomorphology along the axis. 1. Time correlated analysis of ridge segments and ridge bounding faults 2. Detailed mapping of Axial Volcanic Ridges and their morphological differences along the southern Reykjanes Ridge valley 3. Integrating multibeam bathymetry and backscatter data with other geophysical datasets, preliminary results (Fig. 5)
Transcript of Volcanism and hydrothermal venting on a hot-spot ...
Vol
cani
sm a
nd h
ydro
ther
mal
ven
ting
on a
hot
-spo
t inf
luen
ced
slow
-spr
eadi
ng m
id-o
cean
ridg
eSo
fia P
anas
iuk1 , M
elis
sa O
. And
erso
n1 , Árm
ann
Hös
kuld
sson
2 , Fer
nand
o M
artin
ez3 , D
omin
ik P
ałga
n4
1 Dep
artm
ent o
f Ear
th S
cien
ces,
Uni
vers
ity o
f Tor
onto
, Can
ada
2 Sch
ool o
f Eng
inee
ring
and
Nat
ural
Sci
ence
s, U
nive
rsity
of I
cela
nd, I
cela
nd
3 SO
EST,
Uni
vers
ity o
f Haw
ai’i
at M
anoa
, Hon
olul
u, U
SA, 4
Inst
itute
of O
cean
ogra
phy,
Uni
vers
ity o
f Gda
ńsk,
Pol
and
Introd
uctio
nRe
sults
Met
hods
Futu
re W
ork
Disc
ussio
n
Figu
re 1
Figu
re 2
Figu
re 4
M
ultib
eam
bat
hym
etry
com
pila
tion
of th
e R
eykj
anes
Rid
ge b
etw
een
560 5
0’N
and
580 2
0’N
. Dat
aset
is fr
om th
e M
arcu
s G
. Lan
gset
h cr
uise
(MG
L130
9) g
ridde
d at
50x
50m
reso
lutio
n ov
erla
in o
n re
gion
al b
athy
met
ry (G
MR
T). T
he n
ames
of r
emna
nt
faul
t zon
es (F
Z), n
ow n
on-tr
ansf
orm
off
sets
(NTO
s) a
re in
dica
ted
besi
de th
e re
spec
tive
FZ.
•Th
e R
eykj
anes
Rid
ge (R
R) i
s a
slow
spr
eadi
ng m
id-o
cean
ridg
e (M
OR
) tha
t ext
ends
~10
00 k
m s
outh
of I
cela
nd (
Fig.
1)
•37
Mya
, the
Rey
kjan
es s
epar
ated
int
o tr
ansf
orm
-faul
t con
nect
ed s
egm
ents
whi
ch h
ave
been
elim
inat
ing
from
nor
th to
sou
th•
The
evol
utio
n of
the
ridge
has
bee
n in
fluen
ced
by b
asem
ent d
epth
gra
dien
ts fo
rmed
by
the
Icel
and
hots
pot
•Th
e so
uthe
rn e
xten
t of t
he ri
dge
is s
till
activ
ely
defo
rmin
g m
akin
g it
a pr
ime
area
for
cur
rent
rid
ge d
ynam
ics
stud
ies
(Fig
. 1)
•N
ear-c
ontin
uous
bat
hym
etric
dat
a at
grid
reso
lutio
ns fr
om 5
0x50
m to
100
x100
m h
as b
een
colle
cted
ove
r sev
eral
rese
arch
cru
ises
•
Unlik
e m
ost M
OR
s, th
is b
athy
met
ric d
ata
exte
nds
far o
ff-a
xis,
pro
vidi
ng in
sigh
ts in
to to
the
evol
utio
n of
the
crus
t ove
r tim
e •
The
goal
of t
his
wor
k is
to in
vest
igat
e th
e te
cton
ic a
nd v
olca
nic
evol
utio
n of
the
RR
thro
ugh
rem
ote
pred
ictiv
e ge
olog
ic m
appi
ng•
The
wor
k w
ill a
llow
for a
reco
nstr
uctio
n of
the
ridge
's s
prea
ding
his
tory
and
an
unde
rsta
ndin
g of
the
ridg
e's
geod
ynam
ic c
ontr
ols
•Th
is w
ork
will
hav
e im
plic
atio
ns fo
r und
erst
andi
ng th
e co
ntro
ls o
n th
e di
strib
utio
n of
pot
entia
l mag
mat
ic-h
ydro
ther
mal
sys
tem
s al
ong
slow
-spr
eadi
ng M
OR
s
Map
ping
gui
de w
ith c
riter
ia fo
r cla
ssifi
catio
n ba
sed
on m
ultib
eam
bath
ymet
ry a
nd b
acks
catt
er d
ata.
•Th
e re
mot
e pr
edic
tive
geol
ogic
map
ping
ap
prox
imat
ed th
e te
chni
que
used
in o
ther
se
a-flo
or e
nviro
nmen
ts (K
lisch
ies
et a
l.,
2017
, And
erso
n et
al.,
201
7).
•R
aw m
ultib
eam
bat
hym
etry
dat
a co
mes
fr
om th
e M
arcu
s G
. Lan
gset
h Cr
uise
(M
GL1
309)
at g
ridde
d re
solu
tion
of 5
0x50
m•
Bath
ymet
ry w
as re
nder
ed i
nto
ArcG
IS a
nd
enha
nced
with
hill
sh
ade
and
slop
e sh
ade
•Ba
cksc
atte
r was
use
d to
de
term
ine
rela
tive
ages
of
erup
ted
crus
t•
Mod
erat
e to
hi
gh
back
scat
ter i
nten
sitie
s re
pres
ent
new
ly
erup
ted
hum
moc
ky
lava
an
d sh
eet
flow
(Fig
. 2)
•Lo
w b
acks
catt
er
inte
nsiti
es
repr
esen
t se
dim
ente
d te
rrai
n •
Line
ar
feat
ures
m
appe
d in
clud
e: m
ajor
an
d m
inor
faul
ts,
erup
tive
fissu
res
and
linea
men
ts
•O
ther
fea
ture
s m
appe
d in
clud
e Ax
ial
Volc
anic
Rid
ges
(AVR
s),
volc
anic
con
es,
flat-t
oppe
d vo
lcan
oes,
and
cra
tere
d vo
lcan
oes
Figu
re 3
L
inea
men
t den
sity
map
s us
ing
equa
lly w
eigh
ed m
appe
d lin
ear
feat
ures
: m
ajor
/min
or
faul
ts, e
rupt
ive
fissu
res,
an
d lin
eam
ents
. Bot
h m
aps
and
feat
ures
the
mse
lves
are
sho
wn
for
com
paris
on.
Inte
rpre
ted
geol
ogy
of t
he c
entr
al s
egm
ent
of t
he M
GL1
309
surv
ey b
etw
een
NTO
s. In
add
ition
to th
e in
terp
rete
d ge
olog
y, fi
gure
4a
also
sho
ws
maj
or
and
min
or
faul
ts. F
igur
e 4b
hig
hlig
hts
poin
t so
urce
vol
cani
c fe
atur
es:
volc
anic
con
es,
flat-t
oppe
d vo
lcan
oes
and
crat
ered
vo
lcan
oes.
•A
tota
l of 4
337
maj
or fa
ults
, 447
0 m
inor
faul
ts, 3
862
erup
tive
fissu
res
and
4200
line
amen
ts w
ere
map
ped
acro
ss th
e st
udy
area
•Fe
atur
es w
ere
binn
ed a
ccor
ding
to th
eir t
rend
into
20-
degr
ee in
terv
al b
ins
, and
line
amen
t den
sity
map
s w
ere
calc
ulat
ed (F
ig. 3
)•
Dar
ker c
olor
ed a
reas
repr
esen
t the
hig
hest
line
amen
t den
sity
and
ligh
ter t
ones
repr
esen
t the
low
est l
inea
men
t den
sity
•
Alm
ost
70%
of
all
linea
r st
ruct
ures
are
orie
nted
bet
wee
n 10
to
70 d
egre
es a
zim
uth
(AVR
long
axi
s tr
ends
= 2
10 , ax
ial v
alle
y tr
end
= 40
0 )•
The
regi
on b
etw
een
two
oppo
site
ly fa
cing
NTO
s ha
ve fe
w N
/S tr
endi
ng s
truc
ture
s co
mpa
red
to o
ther
zon
es c
orre
spon
ding
to th
e sa
me
age
(Fig
3a,
3b)
•Li
near
str
uctu
res
in o
r nea
r the
axi
al v
alle
y ar
e m
ore
N/S
tren
ding
(Fig
. 3a,
3b)
com
pare
d to
thos
e of
f-axi
s w
hich
tren
d to
war
ds th
e N
E/SW
(Fig
. 3c,
3d)
•St
ruct
ural
tren
ds ty
pica
lly d
omin
atin
g of
f-axi
s (3
0 –
70 d
egre
es a
zim
uth)
are
als
o fo
und
in th
e ax
ial v
alle
y (F
ig. 3
c, 3
d)•
Cons
iste
nt h
igh
linea
men
t den
sity
locu
s in
the
cent
er o
f the
two
oppo
site
ly fa
cing
NTO
s (F
ig. 3
a, 3
b, 3
c)
References
1.An
ders
on M
O, C
hadw
ick
WW
Jr, H
anni
ngto
n M
D, M
erle
SG
, Res
ing
JA, B
aker
ET,
But
terf
ield
DA,
Wal
ker S
L, A
ugus
tin N
. G
eolo
gica
l int
erpr
etat
ion
of v
olca
nism
and
seg
men
tatio
n of
the
Mar
iana
bac
k-ar
c sp
read
ing
cent
er b
etw
een
12.7
°N a
nd 1
8.3°
N:
GEO
LOG
Y O
F TH
E M
ARIA
NA
BACK
-AR
C. G
eoch
emis
try,
geo
phys
ics,
geo
syst
ems:
G(3
). 20
17;1
8(6)
:224
0–22
74.
2.Ea
son
DE,
Dun
n R
A, P
ablo
Can
ales
J, S
ohn
RA.
Seg
men
t-sca
le v
aria
tions
in s
eaflo
or v
olca
nic
and
tect
onic
pro
cess
es fr
om
mul
tibea
m s
onar
imag
ing,
Mid
-Atla
ntic
Rid
ge R
ainb
ow re
gion
(35°
45′-3
6°35
′N):
SEG
MEN
T-SC
ALE
VAR
IATI
ON
S AT
RAI
NBO
W,
MAR
. Geo
chem
istr
y, g
eoph
ysic
s, g
eosy
stem
s: G
(3).
2016
;17(
9):3
560–
3579
.3.
Hey
R, M
artin
ez F
, Hös
kuld
sson
Á, B
ened
ikts
dótt
ir Á.
Pro
paga
ting
rift m
odel
for t
he V
-sha
ped
ridge
s so
uth
of Ic
elan
d: V
-SH
APED
R
IDG
ES S
OUT
H O
F IC
ELAN
D. G
eoch
emis
try,
geo
phys
ics,
geo
syst
ems:
G(3
). 20
10;1
1(3)
. htt
p://
dx.d
oi.o
rg/1
0.10
29/2
009g
c002
865.
doi
:10.
1029
/200
9gc0
0286
54.
Hey
R, M
artin
ez F
, Hös
kuld
sson
Á, E
ason
DE,
Sle
eper
J, T
hord
arso
n S,
Ben
edik
tsdó
ttir
Á, M
erku
ryev
S. M
ultib
eam
inve
stig
atio
n of
th
e ac
tive
Nor
th A
tlant
ic p
late
bou
ndar
y re
orga
niza
tion
tip. E
arth
and
pla
neta
ry s
cien
ce le
tter
s. 2
016;
435:
115–
123.
5.Kl
isch
ies
M, P
eter
sen
S, D
evey
CW
. Geo
logi
cal m
appi
ng o
f the
Men
ez G
wen
seg
men
t at 3
7°50
′N o
n th
e M
id-A
tlant
ic R
idge
: Im
plic
atio
ns fo
r acc
retio
n m
echa
nism
s an
d as
soci
ated
hyd
roth
erm
al a
ctiv
ity a
t slo
w-s
prea
ding
mid
-oce
an ri
dges
. Mar
ine
geol
ogy.
201
9;41
2:10
7–12
2.6.
Mar
tinez
F, H
ey R
, Hös
kuld
sson
Á. R
eykj
anes
Rid
ge e
volu
tion:
Eff
ects
of p
late
kin
emat
ics,
sm
all-s
cale
upp
er m
antle
con
vect
ion
and
a re
gion
al m
antle
gra
dien
t. Ea
rth-
scie
nce
revi
ews.
202
0;20
6(10
2956
):102
956
•Yo
unge
r cr
ust
(on-
axis
ter
rain
) is
dom
inat
ed b
y N
/S t
rend
ing
stru
ctur
es a
nd o
lder
cru
st (o
ff-a
xis
terr
ain)
is d
omin
ated
by
NE/
SW tr
endi
ng s
truc
ture
s•
Sign
ifica
nt n
umbe
r of s
truc
ture
s ex
empl
ifyin
g “o
lder
tren
ds” i
n th
e on
-axi
s te
rrai
n su
gges
ting
that
old
er r
idge
dyn
amic
s m
ay
still
inf
luen
ce m
oder
n sp
read
ing
•Th
e ce
ntra
l seg
men
t has
two
kink
s ne
ar th
e co
nnec
tions
bet
wee
n th
e in
terp
rete
d N
TOs
(Fig
.4a,
4b)
. The
se k
inks
are
als
o tr
aced
by
the
norm
al fa
ults
whi
ch s
tand
-in a
s m
ajor
rid
ge b
ound
ing
faul
ts•
Thes
e fa
ults
reg
ain
thei
r lin
earit
y of
f-axi
s m
eans
tha
t th
e or
ient
atio
n of
the
axia
l val
ley
has
chan
ged
sign
ifica
ntly
•Br
ittle
str
uctu
res
form
in re
spon
se to
str
ess
field
s; a
cha
ngin
g te
cton
ic s
tres
s fie
ld c
ould
hav
e ca
used
the
shift
in o
rient
atio
n •
Ther
e is
pre
fere
nce
for h
umm
ocky
and
pill
ow la
va s
tyle
vol
cani
sm w
ith m
inim
al p
oint
sou
rce
volc
anis
m in
the
cent
ral r
idge
se
gmen
t bet
wee
n op
posi
tely
poi
ntin
g N
TOs
•Th
is s
egm
ent a
lso
corr
espo
nds
to th
e lo
catio
n of
gre
ates
t lin
eam
ent
dens
ity (
Fig.
3)
•Th
is r
egio
n co
uld
be m
ore
mag
mat
ical
ly r
obus
t an
d ha
ve h
ighe
r cr
usta
l pe
rmea
bilit
y •
The
grad
ually
div
ergi
ng N
TOs
coul
d th
in th
e cr
ust,
expl
aini
ng th
e m
ore
mag
mat
ical
ly fo
cuse
d ce
nter
•Th
is m
agm
atic
ally
robu
st c
entr
al s
egm
ent o
ffer
s th
e m
ost p
oten
tial f
or m
agm
atic
-hyd
roth
erm
al s
yste
ms
Fi
gure
5
Seis
mic
eve
nt d
ensi
ty m
appi
ng s
how
s lo
calit
ies
with
hi
gher
ea
rthq
uake
oc
curr
ence
s, p
ossi
ble
zone
s of
hi
gher
tec
toni
c di
smem
berm
ent
and
high
er c
rust
al p
erm
eabi
lity
(Dat
a fr
om G
loba
l CM
T Pr
ojec
t).
The
natu
re o
f th
e re
latio
nshi
p be
twee
n N
TOs
and
the
evol
utio
n of
the
rec
ently
rec
onst
ruct
ed s
outh
ern
exte
nt o
f th
e R
eykj
anes
Rid
ge
need
s fu
rthe
r st
udy.
To
in
vest
igat
e th
e ge
odyn
amic
co
ntro
l an
d in
terp
lay
betw
een
NTO
ge
omet
ry,
ridge
de
form
atio
n,
and
mag
mat
ical
ly f
ocus
ed c
ente
rs, t
he fo
llow
ing
wor
k w
ill b
e un
dert
aken
:
• T
he g
eolo
gic
map
of t
he c
entr
al s
tudy
are
a co
vers
the
Rey
kjan
es R
idge
’s a
xial
val
ley
betw
een
the
Mer
lin a
nd M
orga
nore
NTO
s (F
ig. 4
)•
The
left
Nor
th A
mer
ican
pla
te a
ppea
rs m
ore
faul
ted
and
tect
onic
ally
dis
mem
bere
d th
an th
e rig
ht E
uras
ian
plat
e of
f-axi
s •
Pro
xim
al o
ff-a
xis
faul
ts o
n bo
th p
late
s sh
ift o
rient
atio
n w
ith th
e co
rres
pond
ing
bend
in th
e ax
ial v
alle
y an
d re
sum
e a
cons
tant
orie
ntat
ion
off-a
xis
• T
he s
outh
ern
Rey
kjan
es a
xial
val
ley
is d
omin
ated
by
hum
moc
ky a
nd p
illow
lava
flow
s w
ith a
bund
ant p
oint
sou
rce
volc
anis
m
• A
16
km s
egm
ent o
f the
axi
al v
alle
y be
twee
n th
e tw
o op
posi
tely
faci
ng N
TOs
is m
arke
d by
an
abse
nce
of s
igni
fican
t poi
nt s
ourc
e vo
lcan
ics
The
Rey
kjan
es R
idge
is s
till a
ctiv
ely
defo
rmin
g de
spite
hav
ing
mos
tly re
orga
nize
d ba
ck to
its
orig
inal
line
ar g
eom
etry
. Thi
s is
evi
denc
ed
by th
e or
ient
atio
n ch
ange
s in
line
ar s
truc
ture
s pr
ogre
ssiv
ely
off-a
xis
and
varia
bilit
y in
geo
mor
phol
ogy
alon
g th
e ax
is.
1. T
ime
corr
elat
ed a
naly
sis
of ri
dge
segm
ents
and
ridg
e bo
undi
ng fa
ults
2. D
etai
led
map
ping
of A
xial
Vol
cani
c Rid
ges
and
thei
r mor
phol
ogic
al
diff
eren
ces
alon
g th
e so
uthe
rn R
eykj
anes
R
idge
val
ley
3. In
tegr
atin
g m
ultib
eam
bat
hym
etry
and
ba
cksc
atte
r dat
a w
ith o
ther
geo
phys
ical
da
tase
ts, p
relim
inar
y re
sults
(Fig
. 5)
