Actively forming polymetallic sulfide deposits associated with felsic volcanic rocks in the eastern Manus back-arc basin, Papua New Guinea

Binns, R. A.; Scott, S. D.

doi:10.2113/gsecongeo.88.8.2226

Cited by 204 publications

(147 citation statements)

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“…Backarc basin magmas in this study are characterised by olivine + clinopyroxene ± plagioclase-phyric basalts from the eastern Manus spreading ridge, near PACMANUS hydrothermal field (Binns and Scott, 1993;Kamenetsky et al, 2001), the New Hebrides Troughs, separating the Vanuatu island arc from the active North Fiji basin (Maillet et al, 1995), and the Okinawa Trough formed by extension of continental lithosphere behind the Ryukyu arc -trench system (Shinjo et al, 1999). A variety of primitive arc lavas (olivinebearing arc tholeiites and boninites) are from well known ophiolitic complexes, such as New Caledonia (Cameron, 1989) and Troodos (Sobolev et al, 1993;Portnyagin et al, 1997), and from the Hunter RidgeHunter Fracture Zone, an aborted embyonic intraoceanic arc along the southern margin of the North Fiji Basin (Sigurdsson et al, 1993).…”

Section: Samples and Methodsmentioning

confidence: 96%

Fluid bubbles in melt inclusions and pillow-rim glasses: high-temperature precursors to hydrothermal fluids?

et al. 2002

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Hypotheses for the formation of many types of hydrothermal ore deposits often involve the direct contribution of magmarelated fluids (e.g., Cu -Mo -Au porphyries) or their superimposition on barren hydrothermal cells (e.g., volcanic-hosted massive sulfide deposits). However, the chemical and phase compositions of such fluids remain largely unknown. We report preliminary results of a comprehensive study of fluid bubbles trapped inside glassy melt inclusions in primitive olivine phenocrysts and pillow-rim glasses from basaltic magmas from different tectonic environments, including mid-ocean ridges (Macquarie Island, SW Pacific and Mid-Atlantic Ridge 43°N Fracture Zone), ocean islands (Hawaii) and a variety of modern and ancient backarc -island arc settings (eastern Manus Basin, Okinawa and Vanuatu Troughs, Troodos, New Caledonia and Hunter Ridge -Hunter Fracture Zone). Fluid bubbles from all localities, studied using electron microscopy with EDS and laser Raman spectroscopy, are composed of CO 2 -( ± H 2 O ± sulfur)-bearing vapor and contain significant amounts of amorphous (Na -K -Ca -Fe alumino-silicates and dissorded carbon) and crystalline phases. The crystals are represented mainly by carbonates (magnesite, calcite, ankerite, dolomite, siderite, nahcolite and rhodochrosite), sulfates (anhydrite, gypsum, barite and anglesite), and sulfides (pyrite, arsenopyrite, chalcopyrite and marcasite), though other minerals (brukite, apatite, halite, clinoenstatite, kalsilite, nepheline, amphibole and mica) may occur as well. We argue that chemical components (e.g., C, H, S, Cl, Si, Al, Na, K, Fe, Mn, Cr, Ca, Mg, Ba, Pb and Cu) that later formed precipitates in fluid bubbles were originally dissolved in the magmatic fluid, and were not supplied by host glasses or phenocrysts after entrapment. Magma-related fluid rich in dissolved metals and other non-volatile elements may be a potential precursor to ore-forming solutions. D

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Section: Samples and Methodsmentioning

confidence: 96%

Fluid bubbles in melt inclusions and pillow-rim glasses: high-temperature precursors to hydrothermal fluids?

et al. 2002

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“…5.1b) and volcanic domes, known as the Eastern Manus Volcanic Zone (EMVZ, Fig. 5.1a), of basaltic to rhyodacitic composition (Binns and Scott, 1993;Kamenetsky et al, 2001;Sinton et al, 2003). These edifices possess isotopic, major and trace element characteristics similar to subaerial volcanoes of the New Britain Arc indicating strong arc affinities (Sinton et al, 2003;Pearce and Stern, 2006).…”

Section: Geological Settingmentioning

confidence: 99%

“…Predominantly MORB-like basaltic lavas erupt along the MSC (Sinton et al, 2003) and numerous areas of hydrothermal activity have been reported, the largest of which is the unsedimented Vienna Woods field (Both et al, 1986;Tufar, 1990;Lisitsyn et al, 1993). In contrast, the eastern Manus Basin, between the Djual and Weitin transform faults, is an extensional transform zone within remnant Eocene-Oligocene island-arc crust that is thought to have formed during previous southwestward subduction along the Manus Trench (Binns and Scott, 1993;Binns et al, 2007). As such, it is probably the precursor of a back-arc spreading center like the MSC.…”

Section: Geological Settingmentioning

confidence: 99%

“…Several large areas of hydrothermal activity have been discovered in the EMVZ (Fig. 5.1a) in the last two decades, including the DESMOS caldera (Gamo et al, 1993;Gamo et al, 1997), SuSu Knolls (Binns et al, 1997;Moss and Scott, 2001;Tivey et al, 2006;Hrischeva et al, 2007) and PACMANUS vent fields (Binns and Scott, 1993).…”

Section: Geological Settingmentioning

confidence: 99%

“…5.1b, (Binns and Scott, 1993). Pual Ridge is a 20km long, Y-shaped neovolcanic edifice located 80km from Rabaul Volcano on the New Britain Arc (Fig.…”

Section: Pacmanus and Northeast Pualmentioning

confidence: 99%

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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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The competing effects of sulfide saturation versus degassing on the behavior of the chalcophile elements during the differentiation of hydrous melts

Jenner

Hauri

Bullock

et al. 2015

Geochem Geophys Geosyst

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There is a lack of consensus regarding the roles of sulfide saturation versus volatile degassing on the partitioning of Cu and Ag during differentiation and eruption of convergent margin magmas. Because of their oxidized character, volatile-rich magmas from the Eastern Manus Back-arc Basin (EMBB) only reach sulfide saturation following magnetite-driven reduction of the melt: the so-called ''magnetite crisis.'' If sulfide saturation typically precedes volatile saturation, the magnetite crisis will limit the proportion of Cu and Ag that can partition from the melt into an exsolving volatile-rich phase, which may contribute to the sporadic occurrence of magmatic-hydrothermal ore deposits at convergent margins. However, it is unclear whether the magnetite crisis is a common or rare event during differentiation of volatile-rich magmas. We report major and trace element data for submarine volcanic glasses from the Tonga arc-proximal Valu Fa Ridge (VFR; SW Pacific). Cu-Se-Ag systematics of samples erupting at the southern VFR suggest magnetite fractionation-triggered sulfide saturation. The similarity in chalcophile element systematics of the southern VFR and EMBB samples is unlikely to be coincidental, and may indicate that the magnetite crisis is a common event during differentiation of hydrous melts. However, unlike many convergent margin magmas, it is unlikely that the evolving VFR and EMBB were saturated in a S-bearing volatile phase prior to magnetite fractionation. Hence, the metal-depleting magnetite crisis may be restricted to back-arc basin magmas that do not degas volatiles prior to magnetite fractionation and potentially convergent margin magmas fractionating at high pressures in the continental crust.

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Actively forming polymetallic sulfide deposits associated with felsic volcanic rocks in the eastern Manus back-arc basin, Papua New Guinea

Cited by 204 publications

References 7 publications

Fluid bubbles in melt inclusions and pillow-rim glasses: high-temperature precursors to hydrothermal fluids?

Fluid bubbles in melt inclusions and pillow-rim glasses: high-temperature precursors to hydrothermal fluids?

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

The competing effects of sulfide saturation versus degassing on the behavior of the chalcophile elements during the differentiation of hydrous melts

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