Indian Ocean Hydrothermal Systems: Seafloor Hydrothermal Activities, Physical and Chemical Characteristics of Hydrothermal Fluids, and Vent-Associated Biological Communities

Table 12.1 Location, host-rock type, and hydrothermal fluid chemistry of the four CIR hydrothermal vent fields

Hydrothermal field	Dodo	Solitaire	Edmond	Kairei
Location	CIR-segment16 on-axis	CIR-segment15 off-axis	CIR-segment4 off-axis	CIR-segment1 off-axis
Host-rock type	E-MORB	E-MORB	N-MORB	Troctolite + D-MORB
Depth (m)	2,745	2,606	3,270–3,303	2,420–2,452
Temperature (°C)	356	296	382	369
pH (25 °C)	3.2	4.8	≤2.97–3.3	3.35–3.60
Cl (mmol/L)	~680	~500	926–973	571–623
H₂ (mmol/L)	~2.4	0.46	0.0556–0.1116	2.48–8.50
CH₄ (mmol/L)	~0.02	~0.05	0.233–0.415	0.123–0.203
CO₂ (mmol/L)	~4	~8	7.19–15.8	4.53–10.1
References	1	1	2, 3	2, 3, 4

CIR central indian ridge, MORB mid-ocean ridge basalt, E-MORB enriched MORB, N-MORB normal MORB, D-MORB depleted MORB
1. Nakamura et al. (2012), 2. Gallant and Von Damm (2006), 3. Kumagai et al. (2008), 4. Van Dover et al. (2001)