Geological setting and mineralogical and geochemical investigations on sulfide deposits near 13°N on the East Pacific Rise

Fouquet, Yves; Auclair, Gilles; Cambon, Pierre; Étoubleau, Joël

doi:10.1016/0025-3227(88)90098-9

Cited by 88 publications

(44 citation statements)

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“…Combining the trace elements of the Fe-oxyhydroxide on the EPR near 13ºN with the content of As, Co, Ni, Cu, Zn, Ba, and Sr in the Fe-oxyhydroxide is compatible with the variable range of hydrothermal sulfide at this site in comparison with the average value of the sulfide here (Fe 29.88%, Cu 8.48%, Co 1172.52 × 10 −6 , Zn 11.06%, Pb 0.06%, Cd 315.16 × 10 −6 ) (19 samples) [16,17] , the contents of Fe, Co, and Cu are higher, and the contents of Zn, Pb, and Cd are lower ( Figure 4). This implies that sulfide is oxygenated in seawater to form Fe-oxyhydroxide.…”

Section: Discussionsupporting

confidence: 74%

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Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N: Evidence from mineralogical and geochemical data

Zeng

Wang

Zhang

et al. 2008

Sci. China Ser. D-Earth Sci.

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The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103°54.48′W, lat. 12°42.30′N, water depth 2655 m) on the East Pacific Rise near lat 13°N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%-1.85%) and Co (65×10 −6 -704×10 −6 ) contents, and contain Co+Cu+Zn+Ni> 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13°N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13°N are lower in ΣREE (5.44×10 −6 -17.01×10 −6 ), with a distinct negative Ce anomaly (0.12-0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13°N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples from the East Pacific Rise near 13°N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are lower, and their Fe, Co, and Cu contents are higher.

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Section: Discussionsupporting

confidence: 74%

“…The shaded areas show the range of concentrations of trace and major elements in the sulfides from the East Pacific Rise near 13°N[16,17] .…”

mentioning

confidence: 99%

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N: Evidence from mineralogical and geochemical data

Zeng

Wang

Zhang

et al. 2008

Sci. China Ser. D-Earth Sci.

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“…The site chosen for this study was the active TAG hydrothermal mound (26°N on the Mid-Atlantic Ridge) --a large, mature deposit composed of massive sulfides probably in excess of 5 N × 10 6 tons (Rona et al, 1986), making it equivalent in size to some of the ophiolite deposits in Cyprus, Oman, and elsewhere (e.g., Fouquet et al, 1988;Constantinou and Govett, 1973).…”

Section: Introductionmentioning

confidence: 99%

TAG: Drilling an Active Hydrothermal System on a Sediment-Free Slow-Spreading Ridge

Humphris¹,

Herzig²,

Stokking³

1994

ODP Preliminary Report

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Leg 158 investigated the fluid flow, geochemical fluxes and associated alteration and mineralization, microbiological processes, and the subsurface nature of an active hydrothermal system on a slow-spreading sediment-free mid-ocean ridge. The active mound within the TransAtlantic Geotraverse (TAG) hydrothermal field at 26°N latitude on the Mid-Atlantic Ridge (MAR) is a large, mature deposit of varying mineralogy with emanating fluids displaying a wide range of temperatures and two distinct, but related, chemistries.At Site 957, a northwest-southeast transect of holes in three major, distinct areas of the mound was drilled: the upper terrace east of the Black Smoker Complex (proposed TAG-1 area), the white smoker Kremlin area (proposed TAG-2 area), and the upper terrace west of the Black Smoker Complex (proposed TAG-4 area). In addition, holes were drilled on the south side of the lower terrace (proposed TAG-3 area) and on the northern edge of the upper terrace (proposed TAG-5 area) in an attempt to delineate lateral heterogeneity of the sulfide deposit, and the extent and nature of the underlying stockwork zone.Breccias of various types dominate the stratigraphy of the entire mound, not only within the sulfide section but also extending into the upper part of the stockwork. Within the sulfide mound, these different types are distinguished primarily on the basis of the relative abundances of pyrite, anhydrite, and silica, and therefore reflect different degrees of brecciation, cementation, hydrothermal reworking, and replacement of preexisting sulfides.Based on the sequence of rock types recovered from each area, four major lithologic types can be distinguished, all of which may or may not be present at a given location. Massive pyrites and pyrite breccias dominate the upper 10-20 m. This is followed by an anhydrite-rich zone, which is composed of matrix-supported pyrite-anhydrite breccias and pyrite-anhydrite-silica breccias. At depths of about 40-45 mbsf, the amount of quartz-pyrite mineralization and quartz veining increases and represents the top of the quartz-sulfide stockwork zone, which typically includes pyrite-silica breccias overlying silicified wall-rock breccias. A quartz-chlorite stockwork zone was sampled at depths greater than 100 mbsf in Hole 957E. This complex assemblage of rock types is a Leg 158 Preliminary Report Page 7product of the multistage development of the mound, and is reflected in the sequences of alteration and veining events that can be distinguished both in the sulfide breccias and in the silicified wallrock and chloritized basalt breccias.

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“…Average mafic VMS 1-5 4.3 11.7 0.2 1.2 Herzig and Hannington (1995) Average mafic VMS (late phanerozoic) 3.3 2 1.1 100 1.7 Barrie and Hannington (1999) Fouquet (1985) and Fouquet (1988). ***Tonnage calculated assuming a cone of 200 m in diameter and 70 m of height (Fouquet et al 1996) and a density of 3 g.cm-3 (Henkininan and Fouquet 1985).…”

Section: Acknowledgmentsmentioning

confidence: 99%

Mobility of Au and related elements during the hydrothermal alteration of the oceanic crust: implications for the sources of metals in VMS deposits

et al. 2015

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10Volcanogenic Massive Sulphide (VMS) deposits are commonly enriched in Cu, Zn and 11Pb and can also be variably enriched in Au, As, Sb, Se and Te. The behaviour of these elements 12 during hydrothermal alteration of the oceanic crust is not well known. Ocean Drilling Program 13 (ODP) Hole 1256D penetrates a complete in-situ section of the upper oceanic crust providing a 14 unique sample suite to investigate the behaviour of metals during hydrothermal alteration. A 15 representative suite of samples was analysed for Au, As, Sb, Se and Te using low detection limit 16 methods, and a mass balance of metal mobility has been carried out through comparison with a 17 fresh Mid-Oceanic Ridge Basalt (MORB) glass database. The mass balance shows that Au, As, 18Se, Sb, S, Cu, Zn and Pb are depleted in the sheeted dyke and plutonic complexes with mobilities 19 of -46±12 %, -27±5 %, -2.5±0.5 %, -27±6 %, -8.4±0.7 %, -9.6±1.6 %, -7.9±0.5 % and -44±6 % 20 respectively. Arsenic and Sb are enriched in the volcanic section due to seawater-derived fluid 21Manuscript Click here to download Manuscript: MIDE-D-14-00144-1-Patten-revised.docx 2 circulation. Calculations suggest that large quantities of metal are mobilised from the oceanic 22 crust but only a small proportion is eventually trapped as VMS mineralisation. The quantity of 23 Au mobilised and the ratio Au to base metals are similar to that of mafic VMS and a ten times 24 enrichment of Au would be needed to form a Au-rich VMS. The Cu-rich affinity of mafic VMS 25 deposits could be explained by base metal fractionation both in the upper sheeted dykes and 26 during VMS deposit formation. 27Keywords: VMS deposit, Au-rich VMS, ODP Hole 1256D, hydrothermal alteration in the 28 oceanic crust 29

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Geological setting and mineralogical and geochemical investigations on sulfide deposits near 13°N on the East Pacific Rise

Cited by 88 publications

References 37 publications

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N: Evidence from mineralogical and geochemical data

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N: Evidence from mineralogical and geochemical data

TAG: Drilling an Active Hydrothermal System on a Sediment-Free Slow-Spreading Ridge

Mobility of Au and related elements during the hydrothermal alteration of the oceanic crust: implications for the sources of metals in VMS deposits

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