Phase separation and fluid mixing in subseafloor back arc hydrothermal systems: A microthermometric and oxygen isotope study of fluid inclusions in the barite‐sulfide chimneys of the Lau Basin

Lécuyer, Christophe; Dubois, Michel; Marignac, Christian; Gruau, Gérard; Fouquet, Yves; Ramboz, Claire

doi:10.1029/1999jb900121

Cited by 39 publications

(31 citation statements)

References 52 publications

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“…The calculated temperature of formation of nontronite in the Hine Hina field (46.2°C) is lower than its counterpart in the Mariner field but is consistent with the formation temperature of the Fe-Si oxide (see table 3) and the hydrothermal diffuse flow temperature in the Hine Hina field ($40°C; Fouquet et al, 1993;Lécuyer et al, 1999;Baker et al, 2005). Based on SEM observations (Fig.…”

Section: Formation Of Nontronite In Hydrothermal Fieldssupporting

confidence: 79%

“…At these two fields, there are numerous black and white smokers discharging fluids with temperatures up to 400°C at Vai Lili field and up to $365°C at the Mariner field (Takai et al, 2008). In addition, diffuse discharges depositing Fe-Mn oxides are also present in this area (Lécuyer et al, 1999). The White Church field (not shown in Fig.…”

Section: Geological Settingmentioning

confidence: 97%

“…The basin is composed of three major active spreading ridges: the Central Lau Spreading Center (CLSC), the Eastern Lau Spreading Center (ELSC), and the southernmost part of the ridge (21°20 0 S), which is referred to as the Valu Fa Ridge (VFR) (Jenner et al, 1987). This active back-arc basin has been opening over the past 6 Ma (Hawkins, 1995) whereas the Valu Fa spreading ridge (the southern part of the Lau Basin) began opening about one Ma ago (Lécuyer et al, 1999). The VFR extends for at least 165 km and is 5-6 km wide with the ridge flanks rising about 600 m above the surrounding seafloor (Taylor et al, 1996).…”

Section: Geological Settingmentioning

confidence: 98%

“…The White Church field (not shown in Fig. 1) in the northern portion VFR is at the tectonic stage but there is no evidence of widespread Fe-Mn oxide deposits (Fouquet et al, 1993;Lécuyer et al, 1999) except for the presence of numerous barite chimneys and small Mn-oxide chimneys controlled by major faults (Lécuyer et al, 1999).…”

Section: Geological Settingmentioning

confidence: 98%

“…According to Fouquet et al (1993), two different volcanic and tectonic stages have been recognized in the SVFR and NVFR. The Hine Hina hydrothermal field on the SVFR is in the volcanic stage and is characterized by diffuse discharge at $40°C (Fouquet et al, 1993;Lécuyer et al, 1999;Baker et al, 2005) through highly porous volcaniclastic material which was produced during the formation of extensive Fe-Mn-oxyhydroxide crusts covering sulfide deposits within the volcanic material (Fouquet et al, 1993;Lécuyer et al, 1999). The Vai Lili and Mariner fields were discovered on the CVFR (Fouquet et al, 1991;Baker et al, 2005Baker et al, , 2006Martinez et al, 2006) and are now at the volcanic/tectonic stage.…”

Section: Geological Settingmentioning

confidence: 98%

See 4 more Smart Citations

Formation of Fe–Mn–Si oxide and nontronite deposits in hydrothermal fields on the Valu Fa Ridge, Lau Basin

Sun

Zhou

Glasby

et al. 2012

Journal of Asian Earth Sciences

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Section: Formation Of Nontronite In Hydrothermal Fieldssupporting

confidence: 79%

Section: Geological Settingmentioning

confidence: 97%

Section: Geological Settingmentioning

confidence: 98%

Section: Geological Settingmentioning

confidence: 98%

Section: Geological Settingmentioning

confidence: 98%

See 3 more Smart Citations

Formation of Fe–Mn–Si oxide and nontronite deposits in hydrothermal fields on the Valu Fa Ridge, Lau Basin

Sun

Zhou

Glasby

et al. 2012

Journal of Asian Earth Sciences

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Halogens in Seawater, Marine Sediments and the Altered Oceanic Lithosphere

Kendrick

2018

Springer Geochemistry

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This chapter aims to provide a framework for understanding the distribution of halogens in the oceanic lithosphere. It reviews the concentration of F, Cl, Br and I in seawater, marine sediment pore waters, hydrothermal vent fluids, fluid inclusions from deeper in the crust, and the complementary solid-phase reservoirs of organic matter and minerals present in sediments and crustal rocks from varying depths. Seawater (3.4-3.5 wt. % salt) is depleted in F, weakly enriched in I and strongly enriched in Br and Cl compared to the primitive mantle. Sequestration of I and Br by phytoplankton lead to the storage of these elements in marine sediments which are the Earths dominant I reservoir. Regeneration of organic matter during diagenesis releases I and Br to marine sediment pore waters which can be advected into the underlying crust and lithosphere. In contrast, Cl is assumed to behave conservatively in pore waters and F is precipitated in sedimentary minerals meaning it is not significantly advected into the underlying basement. Vent fluids have salinities of 0.1-6 wt. % salts, which provide evidence for phase separation and segregation of vapours and brines in hydrothermal systems. The majority of vent fluids have Br/Cl ratios within 10% of the seawater value. However, elevated Br/Cl and I/Cl ratios indicate that some vent fluids interact with sediments, and depressed Br/Cl ratios suggest some vent fluids leach Cl from glassy volcanic rocks or halite. Vent fluids have F/Cl ratios scattered around the seawater value which reflects the generally low mobility of F during diagenesis and hydrothermal alteration. In comparison to vent fluids, fluid inclusions also provide evidence for phase separation but preserve a much greater range of salinity including brines with salinities as high as ~50 wt. % salt in many parts of the crust. The altered ocean crust has a F concentration of close to its initial value. In contrast, Cl is mobilised within layer 2 pillows and dykes and strongly enriched in layer 3 gabbros subjected to high temperature alteration. Amphibole is the dominant Cl host in the oceanic crust, with Cl concentrations of <500 ppm under greenschist conditions and up to wt. % levels under amphibolite conditions. The increasing Cl content of amphibole as a function of metamorphic grade most likely reflects a decreasing water/rock ratio and a general increase in fluid salinity as a function of depth in the crust. Amphibole preferentially incorporates Cl relative to Br and I; however, it is possible that I is enriched in absolute terms, and relative to Cl, in clay-rich alteration and biogenic alteration of glassy rocks in the upper crust. Serpentinites formed in the oceanic lithosphere can contain thousands of ppm Cl and some serpentinites preserve Br/Cl and I/Cl signatures very similar to sedimentary pore waters, indicating that all halogens have high compatibilities in serpentine. Fluorine is slightly enriched in serpentinites compared to peridotites which may indicate mobilisation of F from igneous lithologies in th...

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Hydrothermal fluids associated with seafloor mineralization at two southern Kermadec arc volcanoes, offshore New Zealand

et al. 2003

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Phase separation and fluid mixing in subseafloor back arc hydrothermal systems: A microthermometric and oxygen isotope study of fluid inclusions in the barite‐sulfide chimneys of the Lau Basin

Cited by 39 publications

References 52 publications

Formation of Fe–Mn–Si oxide and nontronite deposits in hydrothermal fields on the Valu Fa Ridge, Lau Basin

Formation of Fe–Mn–Si oxide and nontronite deposits in hydrothermal fields on the Valu Fa Ridge, Lau Basin

Halogens in Seawater, Marine Sediments and the Altered Oceanic Lithosphere

Hydrothermal fluids associated with seafloor mineralization at two southern Kermadec arc volcanoes, offshore New Zealand

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