Sediment Lithostratigraphy of the Galapagos Hydrothermal Mounds

Borella, P.E.

doi:10.2973/dsdp.proc.70.107.1983

Cited by 2 publications

(2 citation statements)

References 18 publications

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“…The results of the model-fitting are given in Tables 2 and 3 hydrothermal sediment [Borella, 1982] as well as the observed nonexponentially convex upward temperatures. Our preferred interpretation is that advective processes are active for the nine stations fit to the steady state, onedimensional advection model as well as for the exceptional stations, 507E and 509C.…”

Section: Data Interpretationmentioning

confidence: 99%

Heat transfer through the sediments of the Mounds Hydrothermal Area, Galapagos Spreading Center at 86°W

Becker¹,

Herzen²

1983

J. Geophys. Res.

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Heat transfer processes at the mounds area of the Galapagos Spreading Center at 86°W are revealed by temperatures measured at ≈ 10‐m intervals in the 30±10m sediment at each of 12 holes at DSDP Leg 70 Sites 506–509 and by temperatures of up to five thermistors on eleven 8–12 m long piston cores. The 325 needle‐probe values show a significant linear increase of thermal conductivity with depth in each core. About half of the temperature‐thermal resistance profiles are nonlinear and are fit to a steady state, vertical pore water advection model. Results indicate high and variable total heat flow and localized hydrothermal discharge at ≈ 10−8 m/s, associated with individual mounds. Recharge is indicated at similar rates in the low heat flow belt ≈ 5 km south of the mounds and is suggested at slower rates in the intermediate heat flow (0.17–0.42 W/m2) belt surrounding the mounds heat flow high. Possible slow entrained recharge within ≈ 100 m of discharging mounds is suggested. Also suggested is strong local discharge along the major fault bounding the mounds crustal block to the north. About 95 km north of the spreading axis, at DSDP Site 510, temperatures in the 114‐m sediment cover on 2.7‐m.y. crust are linear, consistent with the suggestion that the hydraulic resistance of this layer is sufficient to seal off free hydrothermal exchange between basement and bottom water. The combination of heat flow data and the physical properties data of Karato and Becker (this issue) suggests that ≈ 50 m of sediment may be a threshold thickness for sealing of hydrothermal circulation within basement, where the topography is smooth. We suggest that the formation of mounds may be associated with the forced localization of hydrothermal discharge through the sediment, as its thickness approaches this threshold value.

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Section: Data Interpretationmentioning

confidence: 99%

Heat transfer through the sediments of the Mounds Hydrothermal Area, Galapagos Spreading Center at 86°W

Becker¹,

Herzen²

1983

J. Geophys. Res.

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“…In this case, the zonal vertical distribution of low-temperature mineral phases is retained to a certain extent, as has been demonstrated by drilling of Mn and Fe-Mn mounds that are located to the south of the Galapagos Rift (Corliss et al, 1979;Hoffert et al, 1980;Borella, 1983;Migdisov et al, 1983).…”

Section: Discussionmentioning

confidence: 80%

Low-temperature hydrothermal deposits in the rift zone of the Mid-Atlantic Ridge

et al. 2008

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New data on the low-temperature hydrothermal deposits of the Snake Pit, TAG, Broken Spur, and Lucky Strike fields in the rift valley of the Mid-Atlantic Ridge (MAR) obtained during the 47th cruise of the R/V Akademik Mstislav Keldysh are reported. These deposits are related to focused and diffuse flows of hydrothermal solutions and the material precipitated from hydrothermal plumes. Electron microscopy study allowed us to identify protoferrihydrite, ferrihydrite, goethite, hematite, Mn-feroxyhyte, and Fe-vernadite. Fe-free vernadite, akaganeite, opal, nontronite, lepidocrocite, and jarosite occur in subordinate amounts. Bacteria-like forms made up of protoferrihydrite particles replaced with ferrihydrite, nontronite, and goethite along with particles of Fe-free vernadite and opal were found. The contents of major, minor, and noble metals were determined in samples with AAS, INAA, and the direct chromatographic method. Elevated PGE contents were established in the low-temperature hydrothermal deposits of the MAR for the first time. The highest PGE contents were detected in the inner zone of Fe-Mn crusts on the surface of a hydrothermal chimney in the Snake Pit field ((ppm) 0.13 Pd, 0.12 Rh, and 0.03 Pt, along with 16.5 Au, 642 Ag, and 355 Se) and in the Au-depleted crust on the surface of a sulfide ore fragment in the Lucky Strike field (0.12 ppm Pd and 0.04 ppm Rh along with 0.03 ppm Au, 683 ppm Se, and 1.5 wt % Ba).

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Sediment Lithostratigraphy of the Galapagos Hydrothermal Mounds

Cited by 2 publications

References 18 publications

Heat transfer through the sediments of the Mounds Hydrothermal Area, Galapagos Spreading Center at 86°W

Heat transfer through the sediments of the Mounds Hydrothermal Area, Galapagos Spreading Center at 86°W

Low-temperature hydrothermal deposits in the rift zone of the Mid-Atlantic Ridge

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