Geofluids

Research Article

Organic, Gas, and Element Geochemistry of Hydrothermal Fluids of the Newly Discovered Extensive Hydrothermal Area in the Wallis and Futuna Region (SW Pacific)

Table 5

Endmember compositions in fluids from the Kulo Lasi and Fatu Kapa vent fields. Kulo Lasi endmembers cannot be extrapolated at Mg = 0. Values presented here for both brine and condensed vapour phases correspond to concentrations in the fluid with the lowest Mg. Elemental compositions in endmember fluids from the various sites of the Fatu Kapa vent field were calculated using the mixing lines (Figure S1) and assuming Mg = 0. Values of the purest fluid were used when linear regression was not possible (). Note that only one sample was available for the site .


Zone	Site	Depth		pH	NaCl	Cl	Si	SO4	Br	Na	K	Mg	Ca	Li	Rb	Sr	Fe	Mn	Cu	Zn	Na/Cl	Br/Cl	Na/K	CH4/Mn
Zone	Site	Depth	°C	pH	(wt%)	mM	mM	mM	µM	mM	mM	mM	mM	µM	µM	µM	µM	µM	µM	µM	Na/Cl	×10³	Na/K	CH4/Mn

Kulo Lasi	NaCl poor	1475	345	2.24	2.9	497	8.2	8.8	738	388	18.5	24.6	11.6	149	26	7.3	4796	862	14	45	0.78	1.48	21	0.007
Kulo Lasi	NaCl rich	1475	345	2.36	4.3	735	14.6	6.2	1135	612	29.5	26.5	10.9	238	46	3.4	9884	1416	2.5	175	0.83	1.54	21	0.001

Fatu Kapa	Stéphanie	1555	280	3.4	4.5	767	4.7	0.0	1569	532	54.5	0.0	98.9	708	114	282	655	268	6.6	<LOD	0.69	2.05	10	0.76
Fatu Kapa	Carla	1664	280	2.8	3.5	594	4.3	0.0	1132	477	59.9	0.0	31.4	691	105	114	287	53	nm	4.4	0.80	1.90	8	1.37
Fatu Kapa		1572	270	3.7	3.9	665	4.2	0.0	1282	518	66.4	0.0	44.3	751	113	160	28	60	nm	3.4	0.78	1.93	8	1.08
Fatu Kapa		1669	270	4.6	4.5	771	4.6	0.0	1458	580	71.0	0.0	85.9	777	nm	nm	nm	nm	nm	nm	0.75	1.89	8	-
Fatu Kapa		1540	265	4.4	4.1	693	3.7	1.0	1344	533	64.9	1.2	51.1	755	nm	nm	nm	nm	nm	nm	0.77	1.94	8	-
Fatu Kapa	Fati Ufu	1523	300	3.8	4.6	790	4.9	0.0	1589	580	48.2	0.0	85.4	722	nm	nm	nm	nm	nm	nm	0.73	2.01	12	-
Fatu Kapa	Fati Ufu	1503	280	3.3	4.1	700	4.9	0.0	1380	538	40.0	0.0	65.0	583	nm	nm	nm	nm	nm	nm	0.77	1.97	13	-
Fatu Kapa	Tutafi	1580	315	4.1	4.2	713	5.1	0.0	1405	535	52.9	0.0	65.1	635	nm	nm	nm	nm	nm	nm	0.75	1.97	10	-

IAPSO	Standard sw	-	-	-	3.2	546	0.0	28.2	839	468	10.2	53.2	10.3	27	1.3	90	<LOD	<LOD	<LOD	<LOD	0.9	1.5	46	-
Kulo Lasi	Reference sw	1150	-	-	3.2	551	0.1	29.0	833	457	9.8	53.2	10.6	25	4.4	93	<LOD	<LOD	<LOD	<LOD	0.83	1.5	47	-
Fatu Kapa	Reference sw	1488	-	-	3.3	565	0.0	28.8	841	483	10.4	54.5	10.7	22	5.8	<LOD	<LOD	<LOD	<LOD	<LOD	0.85	1.5	46	-
Fatu Kapa	Reference sw	1572	2	-	3.3	557	0.0	28.7	841	477	10.4	54.2	10.8	23	nm	nm	nm	nm	nm	nm	0.86	1.5	46	-

Maximum value when linear regression was not possible; only one sample.