Measuring marine self-potential using an autonomous underwater vehicle

Constable, Steven; Kowalczyk, Peter; Bloomer, Steve

doi:10.1093/gji/ggy263

Cited by 40 publications

(37 citation statements)

References 28 publications

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“…1) (Iizasa et al 1999). Earlier studies have demonstrated that the use of an AUV can yield information related to hydrothermal ore deposits more efficiently than deep-towed arrays can (Constable et al 2018;Sato et al 2017). In this study, we extend our research to observe turbidity, which is evidence of discharged plume fluids, and to observe self-potential signals, which might originate directly from ore deposits below the seafloor.…”

Section: Introductionmentioning

confidence: 59%

“…This estimation is probably the first-time result for the dipole moment of an electric current source for an ore deposit associated with a high-temperature hydrothermal system. Constable et al (2018) estimated the source intensity assuming subsurface monopole current sources with total intensity of zero.…”

Section: Modelingmentioning

confidence: 99%

“…The self-potential method is particularly efficient in marine environments because towing two or more non-polarized electrodes reveals in situ electrostatic fields. Although this method is not used very commonly in marine environments at present, it has been investigated continually since the 1970s (e.g., Beltenev et al 2009;Brewitt-Taylor 1975;Cherkashev et al 2013;Constable et al 2018;Corwin 1976;Francis 1985;Heinson et al 1999Heinson et al , 2005Kawada and Kasaya 2017;Petersen and Shipboard Scientific Party 2016;Safipour et al 2017;Von Herzen et al 1996). The use of autonomous underwater vehicles (AUVs) greatly improves the efficiency of the self-potential survey (Constable et al 2018;Sato et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Sato et al (2017) only measured self-potential. Constable et al (2018) conducted combined observations of self-potential and electromagnetic surveys. The main purpose of the present study is to map the difference in response between self-potential and turbidity using this high efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Self-potential mapping using an autonomous underwater vehicle for the Sunrise deposit, Izu-Ogasawara arc, southern Japan

Kawada

Kasaya

2018

Earth Planets Space

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We performed a simultaneous survey of self-potential and plume turbidity using an autonomous underwater vehicle (AUV) above the Sunrise deposit in the Myojin Knoll caldera of the Izu-Ogasawara arc. A 10-m-long electrode rod, on which five electrodes referenced with a common electrode were mounted, was connected at the tail of an AUV. The survey was conducted at a typical speed of 2 knots, covering the 1500 m × 1500 m area with a typical spacing of survey lines of 100 m. With AUV altitude of 100 m above the seafloor, a negative self-potential anomaly of a few millivolts was observed. The self-potential anomaly was found to spread 300 m × 300 m. The self-potential is probably attributable to the geo-battery mechanism: electric current is generated by redox reactions occurring around an ore body crossing a redox contrast. Assuming that the source of the self-potential is an electric current dipole, we can image a southward-dipping dipole with the moment of approximately 10 3 A m, approx. 30 m below the southern part of the ore deposit. Anomalies of turbidity, which are correlated to ambient temperature and which are signatures of discharged hydrothermal fluids, were distributed more broadly than the self-potential. Some turbidity anomalies were found without self-potential anomalies. They were probably transported by the ocean current. Spatial decoupling between the self-potential and turbidity anomalies suggests that the direct contribution of hydrothermal fluids to the self-potential anomalies is probably a secondary effect. The survey altitude of 100 m and the survey speed of 2 knots in the present study represent practical limitations for the self-potential survey when active hydrothermal fields are targeted. We have observed that the self-potential method responds exclusively to the presence of hydrothermal ore deposits. This behavior differs from other methods for exploring seafloor hydrothermal ore deposits: The geomagnetic method responds not only to ore deposits but also to volcanic bodies. The plume method can detect remote hydrothermal activities, but the source locations are not necessarily specified. The self-potential method is useful as an excellent exploration tool, particularly for initial surveys.

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Section: Introductionmentioning

confidence: 59%

Section: Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Self-potential mapping using an autonomous underwater vehicle for the Sunrise deposit, Izu-Ogasawara arc, southern Japan

Kawada

Kasaya

2018

Earth Planets Space

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“…Pore space saturation peaks at~0.2 and follows the same pattern as resistivity. Total hydrate volume is interpolated by using a linear inversion (Constable et al, 2018), which gives the smoothest hydrate saturation between the six lines at 10 m depth slices. The resulting 3-D model is used to calculate total hydrate volume and total gas in place.…”

Section: Hydrate Saturation and Volumementioning

confidence: 99%

Characterization and Quantification of Gas Hydrates in the California Borderlands

Kannberg

Constable

2020

Geophysical Research Letters

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Electromagnetic methods are directly sensitive to electrically resistive gas hydrates and can be used to characterize and quantify hydrate deposits. Using a 1 km long deep‐towed marine electromagnetic system, six survey lines were acquired coincident with legacy seismic reflection data in the Santa Cruz Basin in the Outer California Borderlands. While the strongest seismic indicators place hydrate in the central basin, resistors inferred to be hydrate are located predominantly on the flanks of the basin, coincident with gas migration pathways such as faults and steeply dipping strata. Two features consistent with the resistivity profile from previously imaged seafloor methane seeps were also found. Resistivity is related to hydrate saturation through Archie's law, and total hydrate volume of the Santa Cruz Basin is estimated to be 980 × 109 m3 of gas in place.

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Self-potential investigation of a deep-sea polymetallic sulfide deposit at the Southwest Indian Ridge (Indian Ocean)

Zhu

Tao

Shen

et al. 2020

Preprint

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Deep-sea polymetallic sulfides formed by hydrothermal activity are considered a potential resource for economically valuable base and precious metals.The Southwest Indian Ridge (SWIR, Indian Ocean) hosts active and inactive hydrothermal systems. Inactive hydrothermal fields are more abundant but difficult to characterize. We report a self-potential investigation to locate inactive ore deposits at the Yuhuang hydrothermal field on the ultraslow-spreading SWIR. A horizontal array of 6 AgCl electrodes were attached to a dual towed transient electromagnetic system to record the electrical field at a height of 40 m above the seafloor. The observed electrical field strength near the known sulfide drills reaches 0.5 mV/m. Negative self-potential anomalies (~ -25 mV, obtained by integrating the electrical field) were observed. High electrical conductivities (up to 12 S/m) of sulfide samples measured in the laboratory and the oxidize sulfides recovered at the outcrop of the deposit suggest that the selfpotential anomalies are due to sulfides mineralization and corrosion of the polymetallic sulfides. Tomography of the self-potential anomalies reveals a localized current source distribution with a thickness of ~65 m. Our field data demonstrate that the self-potential method is a useful exploration method to characterize seafloor sulfides localized in inactive hydrothermal fields at mid-ocean ridges.

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Measuring marine self-potential using an autonomous underwater vehicle

Cited by 40 publications

References 28 publications

Self-potential mapping using an autonomous underwater vehicle for the Sunrise deposit, Izu-Ogasawara arc, southern Japan

Self-potential mapping using an autonomous underwater vehicle for the Sunrise deposit, Izu-Ogasawara arc, southern Japan

Characterization and Quantification of Gas Hydrates in the California Borderlands

Self-potential investigation of a deep-sea polymetallic sulfide deposit at the Southwest Indian Ridge (Indian Ocean)

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