MARINER Mid-Atlantic Ridge INtegrated Experiments at Rainbow
R/V Marcus G. Langseth MGL1305April 10 - May 19, 2013
J. Pablo CanalesWoods Hole Oceanographic Institution
Ryuta Arai (Univ. Hawaii; JAMSTEC)Michele Paulatto (GéoAzur, Univ. Nice Sophia Antipolis)Greg Horning (MIT/WHOI JP)
Florent Szitkar (IPG Paris; GEOMAR)Maja Fabeta (Nat. Univ. Ireland)Omar Benazzouz (Univ. Aveiro)Eva Kakone (Univ. Hawaii)Hannes Griesche (Univ. Münster)Chris McHugh (Coastal Carolina Univ.)
Robert DunnUniversity of Hawaii
Rob SohnWoods Hole Oceanographic Institution
MARINER Mid-Atlantic Ridge INtegrated Experiments at Rainbow
R/V Marcus G. Langseth MGL1305April 10 - May 19, 2013
What are the relationships between magmatism, faulting, substrate lithology, and hydrothermal circulation at Rainbow?
- 3D active-source OBS seismic tomography (~30km x 80km)
- Long-streamer (8 km) 2D Multichannel Seismic profiling
- Network of 15 OBSs for 9-month passive monitoring
- Multibeam bathymetry and backscatter echosounding
- Gravity and Magnetics
−42˚ −40˚ −38˚ −36˚ −34˚ −32˚ −30˚ −28˚ −26˚28˚
30˚
32˚
34˚
36˚
38˚
40˚
42˚
44˚
−6000 −4000 −2000 0Depth (m)
0 100 200
km
a)
−34˚20' −34˚10' −34˚00' −33˚50' −33˚40' −33˚30'
35˚50'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
0 10 20
km
1000 2000 3000Depth (m)
b)
Mid-Atla
ntic Ridge
Experiment siteRainbow
Azorestriple junction
S. A
MA
R
AM
AR
Min
or N
AM
AR
Min
or S
AM
AR
Rainbow massif
22 mm/yr
Pot of Gold massif
Clurichaun massifbasins
basins
Paulatto et al., G3, 2015
Oceanographer
Kane
Hayes
Atlantis
Azores Is.
RAINBOW: Geological Context
Andreani et al., G3, 2014
RAINBOW: Geological Context
MGL1305 Multibeam Bathymetry and
Potential Fields Surveys
−42˚ −40˚ −38˚ −36˚ −34˚ −32˚ −30˚ −28˚ −26˚28˚
30˚
32˚
34˚
36˚
38˚
40˚
42˚
44˚
−6000 −4000 −2000 0Depth (m)
0 100 200
km
a)
−34˚20' −34˚10' −34˚00' −33˚50' −33˚40' −33˚30'
35˚50'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
0 10 20
km
1000 2000 3000Depth (m)
b)
Mid-Atla
ntic Ridge
Experiment siteRainbow
Azorestriple junction
S. A
MA
R
AM
AR
Min
or N
AM
AR
Min
or S
AM
AR
Rainbow massif
22 mm/yr
Pot of Gold massif
Clurichaun massif
basins
basins
Paulatto et al., G3, 2015
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
0 10 20
km
a)
0 5 10 15 20Sounding density (pings per grid cell)
b)
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
−20 0 20 40 60 80 100Free−air gravity anomaly (mGal)
c)
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
−1000 −500 0 500 1000Magnetic anomaly (nT)
d)
MGL1305 Multibeam Bathymetry and
Potential Fields Surveys
−42˚ −40˚ −38˚ −36˚ −34˚ −32˚ −30˚ −28˚ −26˚28˚
30˚
32˚
34˚
36˚
38˚
40˚
42˚
44˚
−6000 −4000 −2000 0Depth (m)
0 100 200
km
a)
−34˚20' −34˚10' −34˚00' −33˚50' −33˚40' −33˚30'
35˚50'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
0 10 20
km
1000 2000 3000Depth (m)
b)
Mid-Atla
ntic Ridge
Experiment siteRainbow
Azorestriple junction
S. A
MA
R
AM
AR
Min
or N
AM
AR
Min
or S
AM
AR
Rainbow massif
22 mm/yr
Pot of Gold massif
Clurichaun massif
basins
basins
Paulatto et al., G3, 2015
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
1
2
3
4
5
0 20 40 60Slope (degrees)
0 10 20km
a)
1
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5
0 10 20 30 40 50 60Roughness (m)b)
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
c)22 mm/yr
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
10 20 30 40Strike StD (degrees)d)
Morphometric parameters
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
−30 −20 −10 0 10 20 30Seabed magnetization (A/m)
b)
BMGa
M GaB
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
−20 −10 0 10 20RMBA (mGal)
0 10 20
km
a)
AM
AR
Min
or N
S. A
MA
R
AM
AR
Min
or S
AM
AR
1
2
3
4
5
MGL1305 Multibeam Bathymetry and Potential Fields Surveys
Paulatto et al., G3, 2015
MGL1305 Multibeam Bathymetry and Potential Fields Surveys
Paulatto et al., G3, 2015
30 km
60 km
Z=2 km bsf
Z=6 km bsf7.5
4.7
km/s
8.5
6.7
km/s
1.5
-1.5
km/s
0.8
-0.8
km/s
10 %
0 % Anisotro
py
Z=2 km bsf
Arai et al., in prep.
MGL1305 3D OBS Tomography
Experiment
MGL1305 3D OBS Tomography Experiment
−42˚ −40˚ −38˚ −36˚ −34˚ −32˚ −30˚ −28˚ −26˚28˚
30˚
32˚
34˚
36˚
38˚
40˚
42˚
44˚
−6000 −4000 −2000 0Depth (m)
0 100 200
km
a)
−34˚20' −34˚10' −34˚00' −33˚50' −33˚40' −33˚30'
35˚50'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
0 10 20
km
1000 2000 3000Depth (m)
b)
Mid-Atla
ntic Ridge
Experiment siteRainbow
Azorestriple junction
S. A
MA
R
AM
AR
Min
or N
AM
AR
Min
or S
AM
AR
Rainbow massif
22 mm/yr
Pot of Gold massif
Clurichaun massif
basins
basins
Paulatto et
Dep
th (k
m)
−50 −40 −30 −20 −10 0 10 20 30 40
1
2
3
4
5
6
7
8
92
3
4
5
6
7
8
Distance (km)
Dep
th (k
m)
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1
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7
8
9−1.0−0.8−0.6−0.4−0.20.00.20.40.60.81.0
km/s
S. AMARAMAR
minor SAMAR
minor N AMAR
Processing 1. Pre-Migration Processing
• Geometry definition (6.25 m CMP bin, max. fold 106)
• Bandpass filtering• Spherical divergence correction• Spike noise suppression (LIFT method)• Surface-consistent amplitude balancing• Source wavelet deconvolution• Bottom mute below first free-surface multiple
2. Pre-Stack Depth Migration (wave equation-based FX using OBS-derived anisotropic Vp volume)3. Post-migration Image Enhancement
• Long-wavelength-pass filter (200-83 m)• F-K enhancement of flat or dipping events• Lateral running mean filter• Depth-dependent gain
MGL1305 2D Multichannel Seismic
Reflection Profiles
Data Acquisition • 8-km-long streamer, 636 channels,
12.5 m group spacing• Source volume: 6,600 cu.in. (36 units)• Source pressure: 2000 psi• Source interval: 37.5 m
m
2 km
4 km
6 km
8 km
10 km
km/s
m
2 km
4 km
6 km
8 km
10 km
km/s
m
2 km
4 km
6 km
8 km
10 km
m
2 km
4 km
6 km
8 km
10 km
m
2 km
4 km
6 km
8 km
10 km
km/s
101
112
110
2 km
4 km
6 km
8 km
10 km
101
114
110
2 km
4 km
6 km
8 km
10 km
101
116
110
2 km
4 km
6 km
8 km
10 km
101
118
110
4 km
6 km
8 km
10 km
8.0 km
4.6 km
2000
4000
6000
8000
10000
12000
0 20 40 60 80
Even
t dep
th (m
bsf
)
Number of events
0 200 400 600 800 100012001400 16000
40
80
120
160
Event extent (m)
Num
ber o
f ev
ents
6.8 7.0 7.2 7.4 7.6 7.8 8.00
20
40
60
80
100
Background Vp (km/s)
Num
ber o
f eve
nts
25 20 15 10 5 0Serpentinite (%)
35 30
gabbro
2000
4000
6000
8000
10000
12000
0 20 40 60 80
Even
t dep
th (m
bsf
)
Number of events
0 200 400 600 800 100012001400 16000
40
80
120
160
Event extent (m)
Num
ber o
f ev
ents
6.8 7.0 7.2 7.4 7.6 7.8 8.00
20
40
60
80
100
Background Vp (km/s)
Num
ber o
f eve
nts
25 20 15 10 5 0Serpentinite (%)
35 30
gabbro
Sills Statistics2000
4000
6000
8000
10000
12000
0 20 40 60 80
Even
t dep
th (m
bsf
)
Number of events
0 200 400 600 800 100012001400 16000
40
80
120
160
Event extent (m)
Num
ber o
f ev
ents
6.8 7.0 7.2 7.4 7.6 7.8 8.00
20
40
60
80
100
Background Vp (km/s)
Num
ber o
f eve
nts
25 20 15 10 5 0Serpentinite (%)
35 30
gabbro
2 km
4 km
6 km
8 km
10 km
2 km
4 km
6 km
8 km
10 kmkm/s
106 119
MGL1305 Passive Microseismicity Survey
X
X
• 9-month deployment• 15 OBS deployed, 13 recovered• >20,000 events (only 8,000 displayed)• Polarities do not fit double-couple mechanism
km/s
Summary of MGL1305 Datasets and Results
7.5
4.7
km/s
8.5
6.7
km/s
10 %
0 %
Anisotro
py
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
−30 −20 −10 0 10 20 30Seabed magnetization (A/m)
b)
BMGa
M GaB
−34˚30'
−34˚20'
−34˚10'
−34˚00'
−33˚50'
−33˚40'
36˚00'
36˚10'
36˚20'
36˚30'
36˚40'
−20 −10 0 10 20RMBA (mGal)
0 10 20
km
a)
AM
AR
Min
or N
S. A
MA
R
AM
AR
Min
or S
AM
AR
1
2
3
4
5
X
X