Table 1 Deep-sea serpentinization-associated geofluid fields

Location

13°47 ′N–146°00′E

11°40′N–140°03′E

30°07′N–42°07′W

36°14′N–33°54′W

Tectonics

Forearc seamount chain

Non-accretionary trench slope

Oceanic core complex, MAR

Non-transform offset, MAR

Driving force

Serpentine mud volcanism

(Hydrothermalism?)

Hydrothermalism

Hydrothermalism

Fluid source

Slab-derived fluid

Seawater penetration

Seawater penetration

Seawater penetration

Approach

ODP, CORK, Dive

Dive

Dive, IODP

Dive

Depth (m)

2960

5800

700–800

2300

T max

2

–

> 91

365

pH

12.5

(Brucite chimney)

10.7

2.8

H₂ (mM)

0.01 (possibly < 40)

–

15

16

CH₄ (mM)

37 (possibly < 65)

–

2

2.5

Note

The strongest alkaline deep-sea geofluid system so far identified. See text for details.

Active alkaline fluid seeping from brucite chimney surrounded by macrofauna colony.

Hot alkaline fluid discharging from tall carbonate chimney, only identified on the modern seafloor at this moment.

Black smoker acidic fluid discharging from sulfide chimney with abundant H2. Similar vent sites have already been found on the modrern seafloor.

Ref

See text

Ohara et al. 2012

Kelley et al. 2001

Charlou et al. 2002

Stern et al. 2014

Früh-Green et al. 2003

Okumura et al., 2016a

Onishi et al. 2018

Proskurowski et al. 2008