supplementary information - nature research · 2011-10-31 · supplementary information. doi:...

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NGEO1275

NATURE GEOSCIENCE | www.nature.com/naturegeoscience 11

Supplementary Material for Resing et al., 2011 Active Submarine Eruption of Boninite in the north-eastern Lau Basin

This document provides information about accompanying video footage, calculations

described in the paper, supplemental figures, supplemental data, additional methods not discussed in the main text, and supplemental references in support of the supplemental information. The supplemental figures referred to in the main and supplemental text are located at the end of the document.

SUPPLEMENTAL VIDEOS

Video imagery was collected in both high definition and digital formats from cameras on the Jason ROV. High definition footage was produced by William Lange at the Woods Hole Oceanographic Institution’s Advanced Imaging and Visualization Laboratory. SV1 Pyroclastic activity at Prometheus Vent. Pulses of magmatic gas produce abundant pebble and sand-size clastic materials. Additional magmatic gases escape to the seafloor through a large mound of clastic debris. Video collected on Jason dive 417. SV2 Pillow lavas forming at Hades Vent. Pillow lavas are actively formed at the base of Hades Vent. The largely degassed pillow lavas were formed within meters of the sites of active degassing. Video collected on Jason dive 414. SV3 Lava collection at Hades vent. A fresh lava sample is collected using a bent piece of metal rod. The active flow being sampled is ~0.3 m wide. Video and lava sample collected on Jason dive 420. SV4 Bubble formation with sound. Lava bubbles form as magmatic gasses push through molten lava. The lava bubbles generally ranged in size from 0.25 to 1 m in diameter but were occasionally larger. Note that as the lava bubbles burst they produce large clouds of fine-grained elemental sulfur and clastic debris. However, they do not produce any obvious gas bubbles in the surrounding water. A hydrophone placed nearby recorded a characteristic low-frequency sound produced by bursting bubbles that was distinct form the other explosive sounds. The video and sound were collected on Jason dive 413 at Hades. Sound is best heard using a woofer or subwoofer after elevating the bass on an equalizer. Without these adjustments the sound is unremarkable.

SV5 Cap rock pushed aside with sound. After a period of quiet, the seafloor opens,revealing molten lava and active degassing. The active efflux of hot volatiles buffers the glowing lava from the much colder surrounding seawater allowing prolonged viewing of the molten rock. The hot volatiles can be seen bubbling from the molten lava, producing a schlieren effect in the water immediately above the opening. Particulate sulfur forms just above the area of schlieren. Despite this active degassing, no visible gas bubbles are present in the surrounding water. Video and sound were collected on Jason dive 413 at Hades. Sound is best heard using a

© 2011 Macmillan Publishers Limited. All rights reserved.

2

woofer or subwoofer after elevating the bass on an equalizer. Without these adjustments the

sound is unremarkable.

SV 6 Flame-like degassing at Hades and Prometheus. The rapid escape of volcanic

gases through the molten lava produces a flickering, flame-like appearance as the gas entrains

molten lava and produces pyroclasts. The active efflux of hot volatiles buffers the glowing lava

from the colder surrounding seawater, allowing prolonged viewing of the molten rock. Despite

the active degassing, no visible gas bubbles are present in the surrounding water. Video was

collected on Jason dive 417.

SUPPLEMENTAL TEXT

This section provides information about the calcuations described in the paper and

additional methods not discussed in the main text.

Percent subducted carbon

The ratio of CO2 to 3He at West Mata is 8.6 – 20 × 10

9 mol mol

-1 which is similar to that

observed at other submarine arc volcanoes, for example, Suiyo Seamount (12 109 ; ref. 1) and

NW Eifuku Seamount (20 109; ref. 2). It is also falls within the wide range volcanic for gases

at subaerial arc volcanoes (6 – 34 109

Ra; ref. 3 and references therein). However, the ratio at

West Mata is much higher than the generally accepted upper mantle range of ~1 – 2 109

mol

mol-1

. Using the approach of Sano and Marty3, it is possible to calculate the percentage of CO2

that comes from a non-mantle source by accounting for the upper mantle carbon. Their

equations are simplified as follows:

%Subducted Carbon = [(CO2:3He(fluid) − CO2:

3He(mantle)/[ CO2:

3He(fluid)]% .

For West Mata, CO2:3He ranges from 8.6 10

9 to 20 10

9 while upper mantle carbon ranges

from 1 109

to 2 109, yielding a range of ~77–95% subducted carbon at West Mata.

Decreases in salinity

The hydrothermal plume above West Mata showed clear decreases in salinity (Fig. S2),

which correlated well with changes in temperature. The freshening of the plume likely comes

from at least two sources: seawater vaporized by contact with molten lava and magmatic H2O.

The vaporization of seawater was evidenced by Scanning Electron Microscopic images of clasts

with halide deposits on them. The halide deposits have a flat platy morphology whereas drying

seawater forms cubic salt crystals.

Calculation of temperature anomaly (∆θ)

Increases in temperature above ambient (∆θ) must be calculated by correcting the

measured temperature increase above ambient (∆θ0) for local hydrography and entrainment. For


3

this area of the Lau basin these calculations are described by Baker et al., 4. They find that the

measured temperature anomaly (∆θ0) must be corrected as follows:

∆θ = 3.4 ∆θ0.

The values calculated this way are close to those calculated by measuring the deviation in the

relationship between temperature and salinity in background waters not affected by hydrothermal

activity. The resulting good agreement between the two methods suggests that the calculation of

∆θ shown above is robust.

Heat of cooling molten lava

The specific heat of cooling of molten basalt from 1300 C to 4 C is ~1.43 106

J kg-1

(ref. 5). This is a reasonable approximation for boninite as it lies within 10% of the specific heats

of its component mineral phases5. There have been a variety of estimates of the heat of fusion for

mafic basaltic compositions which range from 0.5 106

to 0.6 106J kg

-1 (refs., 6 and 7), with

the most reasonable value being 0.6 106J kg

-1. The formation of glass has a heat of fusion = 0.

Here we assume that heat that makes it into the plume comes from making a solid material that is

75% glass clasts and 25% crystals. Thus the total heat of cooling molten lava at West Mata from

1300 C to 4 C is ~1.56 106 J.

CO2 and H2O content in boninite glass

Despite the elevated gas contents driving explosive eruptions, it was found that lavas

from both vents have low S, CO2, and H2O concentrations in their glassy rinds (Table 1 in main

manuscript). These gas concentrations are consistent with their eruption depths as predicted by

equilibrium solubility models of H2O (0.84 to 0.93%) in boninites 8. Water contents in the glass

were modeled using H2OSOLvX1.xls from Moore8. The input values to the model were glass

composition taken from 413-R13 (Table 1), magma temperatures from 1200 to 1300 C, and the

molar fraction of water from 0.9 to 0.98. CO2 was estimated to be <20 ppm for basaltic

composition9 at 1200 m water depth and magma temperatures from 1100 to 1300 C.

Supplemental Methods

Discrete water samples were collected using a rosette package with 21 Niskin-type

bottles (18.5 L) with standard sampling spigots for gas collection, and Teflon stopcocks for trace

metal and trace particulate sample collection. Hydrocasts were conducted as vertical casts with a

single round trip between the ship and the depth of interest, and as towed hydrocasts in which the

CTD-rosette package was raised and lowered as the ship moved along a set course (see ref. 4).

Light scattering anomalies (dNTU) are the difference between the light scatter value measured in

a plume and that of the local background in nephelometric turbidity units (NTU). Samples for

total dissolvable Mn and Fe (TDMn and TDFe) were collected into 125 mL I-Chem polyethylene

bottles and acidified with 0.5 mL of sub-boiling quartz distilled 6N HCl. Mn was determined


4

with a precision of ~1 nM by modifying an existing direct-injection flow injection analysis (FIA)

method10

by adding 4 g of nitrilo-triacetic acid to each liter of buffer. Fe was determined with a

precision of ~2 nM by modifying an FIA pre-concentration method11

for direct injection

analysis. Total CO2 ( CO2) and alkalinity were sampled and determined by standard methods

with a precision of ± 1 M. pH samples were collected and analyzed as discussed previously12

.

Precision within individual hydrocasts is ±0.001 pH unit. Changes in pH ( pH), CO2 ( CO2),

and alkalinity ( alkalinity) were calculated by subtracting the regional background value of

each. pH has a precision of ~0.002 pH units and CO2 and alkalinity have precision of ± 3

M. The four parameters of the carbonate system (pCO2, pH, alkalinity, and CO2) are

thermodynamically related and only two of the parameters are required to fully describe the

carbonate system 13

. For sample 36 from V08C26, the alkalinity was determined using pH and

Total CO2 because the alkalinity was below the starting point for the titration and the actual

alkalinity could not determined.

Elemental composition of particulate matter was determined by x-ray primary- and

secondary-emission spectrometry with a Pd source and Mo, Ti, Ge, and Co secondary targets

using a non-destructive thin-film technique14

. Precision averaged 2% for major elements, 7% for

trace elements, 3.5% for total and non-volatile sulfur and 11.5% for elemental sulfur. Particulate

compositions are designated by a Ap@ in front of the element of interest (e.g., particulate Fe =

pFe). Total particulate Sulfur (pS) is a combination of elemental sulfur (pSEl) and non-volatile

sulfur (Snv) which include sulfides + sulfates. Total pS is analyzed under an atmosphere of

nitrogen and then analyzed again under a vacuum. Elemental sulfur sublimes under the vacuum

leaving pSNV; thus pSEl is the difference between total pS and Snv. Helium concentrations and

isotopic ratios were determined on samples sealed into copper tubing15

followed by analysis on a

21-cm radius, dual-collector mass spectrometer with a precision of 2 10-17

mol kg-1

in 3He

and 0.2% in 3He. Hydrogen concentrations were determined within hours of sampling using a

helium head-space technique by gas chromatography16

. Hydrogen samples were collected by

being drawn directly into 140 ml syringes.


5

ADDITIONAL REFERENCES

1. Tsunogai, U. et al. Peculiar features of Suiyo Seamount hydrothermal fluids, Izu-Bonin

Arc: differences from subaerial volcanism. Earth and Planetary Science Letters 126, 289–

301(1994).

2. Lupton, J. et al. Submarine venting of liquid carbon dioxide on a Mariana Arc volcano.

Geochem. Geophys. Geosyst. 7, Q08007(2006).

3. Sano, Y. & Marty, B. Origin of carbon in fumarolic gas from island arcs. Chemical

Geology 119, 265–274(1995).

4. Baker, E.T. et al. Unique event plumes from a 2008 eruption on the Northeast Lau

Spreading Center. Geochemistry Geophysics Geosystems 12, Q0AF02(2011).

5. Navrotsky, A. Thermodynamic properties of minerals. Mineral Physics and

Crystallography. A Handbook of Physical Constants. AGU Reference Shelf2 18-

28(1995).

6. Fukuyama, H. Heat of fusion of basaltic magma. Earth and Planetary Science Letters 73,

407-414(1985).

7. Kojitani, H. & Akaogi, M. Measurement of heat of fusion of model basalt in the system

diopside- forsteritc - anorthite. Geophysical Research Letters 22, 2329-2332(1995).

8. Moore, G., Vennemann, T. & Carmichael, I. Solubility of water in magmas to 2 kbar.

Geology 23, 1099-1102(1995).

9. Dixon, J.E., Stolper, E.M. & Holloway, J.R. An experimental study of water and carbon

dioxide solubilities in mid-ocean ridge basaltic liquids. Part I: Calibration and solubility

models. Journal of Petrology 36, 1607-1633(1995).

10. Resing, J.A. & Mottl, M.J. Determination of Manganese in Seawater Using Flow Injection

Analysis with On-Line Preconcentration and Spectrophotometric Detection. Analytical

chemistry 64, 2682-2687(1992).

11. Measures, C.I., Yuan, J. & Resing, J.A. Determination of iron in seawater by flow

injection analysis using in-line preconcentration and spectrophotometric detection. Marine

Chemistry 50, 3-12(1995).

12. Resing, J.A. et al. CO2 and 3He in hydrothermal plumes: implications for mid-ocean ridge

CO2 flux. Earth and Planetary Science Letters 226, 449-464(2004).

13. Millero, F.J. The thermodynamics of the carbonate system in seawater. Geochim.

Cosmochim. Acta. 43, 1651-1661(1979).


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14. Feely, R.A., Massoth, G.J. & Lebon, G.T. Sampling of marine particulate matter and

analysis by x-ray fluorescence spectrometry. Marine Particles: Analysis and

Characterization, Geophysical Monograph Series 63 251-257(1991).

15. Young, C. & Lupton, J.E. An ultratight fluid sampling system using cold-welded copper

tubing. Eos Trans. AGU 64, 735(1983).

16. Kelley, D.S. et al. Enriched H2, CH4, and 3He concentrations in hydrothermal plumes

associated with the 1996 Gorda Ridge eruptive event. Deep-Sea Research II 45, 2665-

2682(1998).


7

SUPPLEMENTAL DATA

Data is also available in supplemental file “Resing et al 2011 Table S1.xlsx”.

Table S1. Chemical properties of the hydrothermal plume above West Mata gases.

Sample Longitude Latitude Depth dT%

dNTU pH pH

H2

(nM)

Total

CO2

CO

2

Alkali

nity

Alka

linity 3He

4He

Decimal

Degrees

Decimal

Degrees (m) nM M M Eq Eq fM nM

Vertical Hydrocast V08C26

2 -173.748 -15.0945 1043 0.011± 0.002 0.1059 7.714 0.045 482

3.9 1.93

8 -173.748 -15.0945 1062 0.229 ± 0.004 4.8736 6.942 0.817 10192 2399 131 2123 -222 17.6 3.29

9 -173.748 -15.0945 1101 0.216 ± 0.012 4.8736 7.025 0.730 6737 2391 121 2171 -174 16.3 3.17

13 -173.748 -15.0945 1172 0.170 ± 0.009 1.0029 7.275 0.478 2425 2383 112 2302 -44 14.5 2.99

14 -173.748 -15.0945 1083 0.263 ± .002 4.8734 6.869 0.889 10635

19.9 3.53

15 -173.748 -15.0945 1000 0.006 ± 0.003 0.0018 7.758 0.006 36

3.3 1.88

27 -173.748 -15.0945 1136 0.177± 0.004 2.0438 7.243 0.513 5666

12.2 2.77

30 -173.748 -15.0945 947 -0.002 ± 0.001 0.0004 7.769 -0.003 31

3.1 1.85

36 -173.748 -15.0945 1156 0.659 ± 0.053 4.8723 6.225 1.529 14566 2640 378 1535 -807#

47.2 6.26

38 -173.748 -15.0945 1020 0.013 ± 0.004 0.0035 7.747 0.013 39 2264 3.4 2340 -1 3.4 1.88

42 -173.748 -15.0945 1118 0.245 ± 0.015 3.803 7.119 0.637 8892 2375 105 2212 -134 14.3 2.97

Towed Hydrocast T08C17

27 -173.746 -15.0984 1059 0.090 ± 0.041 0.5025 7.611 0.150 2386 2281 16 2308 -35 5.1 2.07

43 -173.747 -15.0976 1103 0.002 ± 0.001 0.1242 7.703 0.053 507

4.2 1.97

3 -173.747 -15.0975 1126 0.093 ± 0.002 0.4976 7.468 0.288 2071 2327 58 2306 -39 9.0 2.44

17 -173.747 -15.0965 1129 0.114 ± 0.010 0.558 7.503 0.252 2167

8.0 2.36

9 -173.748 -15.096 1095 0.124 ± 0.008 0.6981 7.412 0.345 1690 2343 76 2295 -48 10.7 2.61

25 -173.748 -15.0953 1060 0.156 ± 0.054 1.5349 7.516 0.242 4009 2293 29 2281 -62 6.5 2.19

8 -173.749 -15.0944 1041 0.314 ± 0.048 4.8746 6.940 0.820 14843 2398 135 2129 -214 17.7 3.31

49 -173.749 -15.0943 987 -0.005 ± 0.001 0.0572 7.750 0.014 38

3.4 1.94

7 -173.75 -15.0921 1097 0.001 ± 0.001 0.0042 7.735 0.022 6 2267 1.8 2341 -3

#Alkalinity calculated from pH and Total CO2; dT is Temperature anomaly; X is the change in X from background.

%dT is the average dT over 15 seconds prior to collecting a given discrete sample.


8

Table S1 continued. Chemical properties of the hydrothermal plume above

West Mata metals and particulate matter.

Nisken# TMn TFe pFe Total pS pSNV

Elemental pS

nM nM nM nM nM nM

Vertical Hydrocast V08C26

2 12 103 8 276 2272 931 L 2330

9 248 2567 995 L 2596 13 354 1942

14 308 3275 15 5 23 27 207 1609 665 5201 2285 2916

30 0 5 36 m m 4120 48246 6601 41646

38 4 30 42 247 2056 820 L 2202

Towed Hydrocast T08C17

27 25 175 43 34 157 3 169 1073 491 2044 950 1094

17 143 971 9 241 1333 666 2101 1210 891

25 61 351 178 1008 728 281 8 359 2157

49 4 65 7 4 27 40 8 24 14 4 17 33 1 11 5 1 42 L = samples that had elemental S >> than analytical capability (see

methods)


Mg Ca

Fe S

Si

a

b

Figure S1. a. Sharp edged clastic debris from the water column above the summit.

Most of the mineral shards (10–70 μm) were almost exclusively of Mg-silicates

(mainly orthopyroxene) and Ca-Mg-silicates (clinopyroxene). b. Elemental analysis of

shard by energy dispersive X-ray fluorescence spectrometry.

Supplemental Figures Resing et al., 2011

Active Submarine Eruption of Boninite in the north-eastern Lau Basin

9


Figure S2. Salinity and potential temperature versus depth. The green

line represents the regional background for salinity. The black line is

modeled salinity for entrainment of ambient seawater in a rising plume

with the following source characteristics: vent fluid salinity = ambient,

fluid temperature = 325 C, heat output = 55MW, vent size = 6 m × 6 m,

cross-flow = 2 cm/s. The model demonstrates that the increase in

salinity above the plume arises from entrainment of ambient seawater

from the same depth of the vent. Discrete samples were not collected

from the plume, so caution should be used in interpreting these results.



10


Figure S3 a. SEM image of fine particulate matter above Hades Vent.

The sulfur forms a dense mat on filter. b. Elemental analysis of material

by energy dispersive X-ray fluorescence spectrometry.



11


Figure S4. Four-month-long record of sound frequency and intensity from

a moored hydrophone deployed ~5 km from West Mata at 15 8.5′S 173

44.3′W from December 2009 to April 2010. a. Daily average of sound

intensity in dB relative to μPa from 1 to 125 Hz. Continuous explosion and

volcanic tremor signals from West Mata summit vents dominate the <30

Hz band. b. Daily average of sound intensity levels in 0–30 Hz band in

units of in dB relative to μPa2/Hz.



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