Hydrothermal activity and metallogenesis in the Lau back-arc basin

Fouquet, Yves; Stackelberg, Ulrich von; Charlou, J. L.; Donval, Jean-Pierre; Erzinger, J.; Foucher, J.P.; Herzig, Peter; Mühe, Richard; Soakai, S.; Wiedicke, Michael; Whitechurch, Hubert

doi:10.1038/349778a0

Cited by 174 publications

(69 citation statements)

References 11 publications

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“…These values are significantly lower than Vienna Woods, but comparable to values previously reported for other arc/back-arc hydrothermal systems (Fouquet et al, 1991a;Fouquet et al, 1993;Gamo et al, 1997;Nakagawa et al, 2006;Takai et al, 2008).…”

Section: Phsupporting

confidence: 51%

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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This thesis presents the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at furthering our understanding of subsurface geochemical processes affecting hydrothermal fluid compositions. Chapters 2 and 3 concern the abiotic (nonbiological) formation of organic compounds in high temperature vent fluids, a process which has direct implications for the emergence of life in early Earth settings and sustainment of present day microbial populations in hydrothermal environments. Chapter 2 represents an experimental investigation of methane (CH 4 ) formation under hydrothermal conditions. The overall reduction of carbon dioxide (CO 2 ) to CH 4 , previously assumed to be kinetically inhibited in the absence of mineral catalysts, is shown to proceed on timescales pertinent to crustal residence times of hydrothermal fluids. In Chapter 3, the abundance of methanethiol (CH 3 SH), considered to be a crucial precursor for the emergence of primitive chemoautotrophic life, is characterized in vent fluids from ultramafic-, basalt-and sediment-hosted hydrothermal systems. Previous assumptions that CH 3 SH forms by reduction of CO 2 are not supported by the observed distribution in natural systems. Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding alkenes, which are feasible in natural systems. In Chapter 5, the controls on vent fluid composition in a backarc hydrothermal system are investigated. A comprehensive survey of the inorganic geochemistry of fluids from sites of hydrothermal activity in the eastern Manus Basin indicates that fluids there are influenced by input of acidic magmatic solutions at depth, and subsequently modified by variable extents of seawater entrainment and mixing-related secondary acidity production. CHAPTER 1 IntroductionSeafloor hydrothermal systems associated with the generation of oceanic crust represent a dramatic expression of heat and mass transfer from the interior of the Earth. In addition to profound effects on ocean chemistry, convective circulation of seawater through volcanically active oceanic crust leads to the formation of metal sulfide deposits. In addition, seafloor hot springs are often invoked as ideal settings from which early microbial life could have emerged.Since the initial discovery of low temperature venting at the Galápagos Spreading Center in 1977 (CORLISS et al., 1979), our understanding of the composition and diversity of hydrothermal solutions has expanded greatly. During convection through oceanic crust of basaltic composition, O 2 -replete seawater reacts with crustal rock, typically producin...

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Section: Phsupporting

confidence: 51%

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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“…Fouquet et al (1991) proposed seafloor massive sulfide deposits in a back-arc setting showed more resemblance to the Kuroko-type deposits compared with those in the midocean ridge. Halbach et al (1993) studied in detail mineralogy of sulfide ore samples collected from the Jade field in the Okinawa Trough, and concluded that the seafloor sulfide deposit is a modern analogue of the Kuroko-type deposits, based on strong similarities in the mineralogical and chemical composition of the polymetallic (zinc and lead enriched) sulfides present.…”

Section: Introductionmentioning

confidence: 97%

Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

Ishibashi

Ikegami

Tsuji

et al. 2014

Subseafloor Biosphere Linked to Hydrothermal Systems

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The Okinawa Trough is a back-arc basin behind the Ryukyu trench-arc system and located along the eastern margin of the Eurasian continent. Sulfide and sulfate mineralization associated with hydrothermal activity has been recognized in ten hydrothermal fields in the Okinawa Trough. Hydrothermal mineralization recognized in these fields is commonly represented by coexisting occurrence of zinc-and lead-enriched polymetallic sulfides and abundant sulfate minerals. The mineralogy and geochemical signatures present has led researchers to suggest these areas may be a modern analogue for the formation of ancient Kuroko-type volcanogenic massive sulfide (VMS) deposits. Recent seafloor drilling during IODP (Integrated Ocean Drilling Program) Expedition 331 documented the subseafloor structure of a hydrothermal system at the Iheya North Knoll. Mineral textures and hydrothermal assemblages present in the drilled cores obtained from a hydrothermal mound in the proximal area are consistent with Kuroko-type mineralization. Based on geochemical studies, the intra-field diversity of mineralization commonly recognized in the Okinawa Trough can be explained by subseafloor phase separation of the hydrothermal fluid, which reflects shallow water depth (from 700 to 1,600 m). The subseafloor phase separation may. play an important role to accumulate metal elements beneath the seafloor. Based on geophysical and geological studies, the Okinawa Trough is considered a back-arc basin in the rifting stage. Such a tectonic setting is characterized by development of normal faulting in brittle continental crust and frequent intrusion of a magma, which can be expected to provide favorable environment for development of a hydrothermal system Keywords

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“…The idea that crustal composition affects the concentration of Ba in hydrothermal fluids has been previously proposed (e.g., Hannington and Scott, 1988;Scott et al, 1990;Fouquet et al, 1991;Bendel et al, 1993;. However, high Ba concentrations (Ba > 67 μmol/L) in vent fluids from the ultramafic-hosted Rainbow vent field associated with Ba-poor sepentinized peridotites suggest that crustal lithology may not be the only factor controlling Ba concentrations Andreani et al, 2014).…”

Section: Dissolved Ba and Pbmentioning

confidence: 89%

Trace element proxies and mineral indicators of hydrothermal fluid composition and seafloor massive sulfide deposit formation processes

Evans¹

2017

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THESIS ABSTRACTThis thesis analyzes compositions of seafloor massive sulfide (SMS) deposits and related hydrothermal vent fluids to identify proxies of reaction zone conditions (host-rock lithology, hydrothermal fluid temperature and chemistry). Chapter 2 investigates the morphology, mineralogy, and geochemistry of SMS deposits from six vent fields along the Eastern Lau Spreading Center (ELSC), demonstrating that ELSC SMS deposits record differences in hydrothermal fluid temperature, pH, sulfur fugacity and host-rock lithology related to proximity to the nearby Tonga Subduction Zone. Chapters 3 and 4 focus on partitioning of Co, Ni, Ga, Ag, and In between hydrothermal vent fluids and chalcopyrite lining fluid conduits in black smoker chimneys. Chapter 3 develops secondary ion mass spectrometry (SIMS) as a technique to measure Co, Ni, Ga, Ag, and In in chalcopyrite and identifies a correlation between Ga and In in chalcopyrite and hydrothermal fluid pH. Chapter 4 presents new data on these elements in ELSC hydrothermal fluids that, combined with SIMS analyses of chalcopyrite chimney linings and previously published data on vent fluids from the Manus Basin, provide evidence that supports partitioning of Ag a lattice substitution for Cu. Together, concentrations of Ga, In, and Ag in chalcopyrite provide proxies of hydrothermal fluid pH and metal (i.e., Ag and Cu) contents. ACKNOWLEDGEMENTSThe work presented in this thesis could not have been accomplished without a network of professional and personal support. To that end, I would like to acknowledge my advisor, Dr. Margaret K. Tivey, for her mentorship and dedication, and members of my thesis committee: Dr. Jeffrey S. Seewald, Dr. Nobumichi Shimizu, Prof. Shuhei Ono, and Prof. Olivier J. Rouxel for their valuable input and advice to improve the contents of this thesis. Dr. Brian Monteleone's help in developing secondary ion mass spectrometry of trace elements in sulfide minerals and Margaret Sulanowska's help with sample preparation are also greatly acknowledged, as are Dr. Paul R. Craddock and Dr. Jill M. McDermott, my predecessors in the MIT/WHOI Joint Program, whose theses provided significant contributions to the work presented here.I would also like to acknowledge the captains and crews of the R/V Melville, the R/V Thompson, the R/V Atlantis III, and the R/V Roger Revelle, and the team of the ROV Jason II for their expertise in recovering fluid and SMS deposit samples from active vent fields, as well as chief scientists, Dr. Chris German (AT18-16) and Prof. Anna-Louise Reysenbach (RR1507) for welcoming my participation on research cruises to the Mid-Cayman Rise and Eastern Lau Spreading Center. Work presented in Chapter 2 of this thesis was supported by the National Science Foundation through grants OCE-1038135 to GNE and MKT, OCE-1038124, OCE-0241796, OCE-1233037 to JSS, and OCE-0242088 to CGW. Chapters 3 and 4 were supported by the National Science Foundation through grants OCE-1038135 and NSF Graduate Research Fellowship to GNE and funding from grant NSF O...

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Hydrothermal activity and metallogenesis in the Lau back-arc basin

Cited by 174 publications

References 11 publications

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Hydrothermal Activity in the Okinawa Trough Back-Arc Basin: Geological Background and Hydrothermal Mineralization

Trace element proxies and mineral indicators of hydrothermal fluid composition and seafloor massive sulfide deposit formation processes

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