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

2

3

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

2

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6

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