The role of seamounts in the transport of heat and fluids: Relations among seamount size, circulation patterns, and crustal heat flow

Kawada, Yoshifumi; Seama, Nobukazu; Urabe, Tetsuro

doi:10.1016/j.epsl.2011.03.029

Cited by 14 publications

(18 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Seamounts, which protrude through low-permeability sediments, serve as conduits enabling the transport of fluids into the basaltic basement in off-axis settings (Fisher et al, 2003;Villinger et al, 2017). In model studies, smallsized seamounts (with a radius of several hundred meters and a radius/height ratio < 0.5) can act either as fluid recharge or discharge sites at a crustal heat flow of 50-150 mW/m 2 , whereas large seamounts tend to form convection cells within their seamount structure (Kawada et al, 2011;Winslow and Fisher, 2015).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Kühn

Versteegh

Villinger

et al. 2017

Geology

View full text Add to dashboard Cite

On the basis of heat-flow measurements, seismic mapping, and sediment pore-water analysis, we demonstrate widespread and efficient ventilation of the 18-22 Ma oceanic crust of the northeast equatorial Pacific Ocean. Recharge and discharge appear to be associated with basement outcrops, including seamounts and north-south-trending faults, along which sediment cover thins out and volcanic rocks are exposed. Low-temperature hydrothermal circulation through the volcanic crust leads to the reduction of heat flow through overlying sediments, with measured heat-flow values that are well below those expected from conductive cooling curves for lithosphere of this age. Typically, dissolved pore-water oxygen decreases from the sediment surface downward, reaching minimum values at mid-depth and rising again in the lower part of the cores investigated, clearly indicating oxygen-rich seawater circulation through the oceanic crust underneath the sediments. If the residence time of the circulating fluids in the upper crust is short or the fluid flux is large, oxic conditions may be preserved, and oxygen can diffuse upwards into the sediments. This process, leading to widespread oxic conditions in the near-basement sediments, may cause the oxidation of residual reduced material stored in the deeper sediments, resulting in downward fluxes of the reaction products into the basement and from there back into the oceans. Considering the widespread existence of this type of off-axis ventilation, the net effect of the resulting return flow of reaction products on biogeochemical cycles and element fluxes (e.g., carbon and nitrogen) may be very large.

show abstract

Section: Discussionmentioning

confidence: 99%

“…All cores from the vicinity of small seamounts (after criteria of Kawada et al, 2011) have dissolved O 2 and Mn 2+ concentration profiles indicating the flow of seawater in the basaltic crust underneath the sediments at these locations.…”

Section: Discussionmentioning

confidence: 99%

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Kühn

Versteegh

Villinger

et al. 2017

Geology

View full text Add to dashboard Cite

show abstract

“…First, conductive refraction tends to generate a local, positive heat flow anomaly at the break in slope between the flat seafloor and the sloped basalt edifice. In addition, secondary hydrothermal convection within the outcrop generates local anomalies [elevated and suppressed values, e.g., Figure 22 of Hutnak et al ., ; Kawada et al ., ]. Some thermal transects around Grizzly Bare outcrop show a mixed thermal pattern, with small local anomalies superimposed on a broader pattern consistent with recharge [Figures 12–14 from Hutnak et al ., ]; one of the transects radiating from Grizzly Bare outcrop, to the northwest of the Site U1363 transect, shows evidence of discharge [Figure 15 from Hutnak et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Seawater recharge into oceanic crust: IODP Exp 327 Site U1363 Grizzly Bare outcrop

Wheat

Hulme

Fisher

et al. 2013

Geochem Geophys Geosyst

View full text Add to dashboard Cite

[1] Systematic differences in sediment thermal and pore water chemical profiles from Integrated Ocean Drilling Program Site U1363 document mixing and reaction within the basaltic crust adjacent to Grizzly Bare outcrop, a site of hydrothermal recharge into 3.6 My-old basaltic crust. A transect of seven holes was drilled~50 m to~750 m away from the base of the outcrop. Temperatures at the sediment-basement interface increase from~6 C to >30 C with increasing distance from the outcrop, and heat flow is suppressed within several hundred meters from the outcrop. Calculated fluid compositions at the sediment-basement interface are generally explained by mixing between bottom seawater and altered crustal basement fluids, with a composition similar but not identical to fluids from seeps at Baby Bare outcrop, located~45 km to the northeast. Reactions within upper basement and overlying sediment affect a variety of ions (Mn, Fe, Mo, Si, PO 4 3-, V, and U) and d 13 DIC, indicating a diagenetic influence and diffusive exchange with overlying sediment pore waters. The apparent 14 C age of basal pore fluids is much older than bottom seawater. Collectively, these results are consistent with seawater recharge at Grizzly Bare outcrop; however, there are strong gradients in fluid composition within 50 m of the outcrop, providing evidence for complex flow paths and vigorous mixing of young, recently recharged seawater with much older, more reacted basement fluid. The proximity of these altered fluids to the edge of the outcrop raises the possibility for fluid seepage from the outcrop in addition to seawater recharge.Components: 9,900 words, 7 figures, 3 tables.

show abstract

“…; Kawada et al . ). Topography has also been included in some black smoker modelling (Schardt et al .…”

Section: Introductionmentioning

confidence: 97%

Modelling the Lost City hydrothermal field: influence of topography and permeability structure

Titarenko

McCaig

2015

Geofluids

View full text Add to dashboard Cite

The Lost City hydrothermal field (LCHF) is hosted in serpentinite at the crest of the Atlantis Massif, an oceanic core complex close to the mid-Atlantic Ridge. It is remarkable for its longevity and for venting low-temperature (40-91°C) alkaline fluids rich in hydrogen and methane. IODP Hole U1309D, 5 km north of the LCHF, penetrated 1415 m of gabbroic rocks and contains a near-conductive thermal gradient close to 100°C km À1 . This is remarkable so close to an active hydrothermal field. We present hydrothermal modelling using a topographic profile through the vent field and IODP site U1309. Long-lived circulation with vent temperatures similar to the LCHF can be sustained at moderate permeabilities of 10 À14 to 10 À15 m 2 with a basal heatflow of 0.22 W m À2 .Seafloor topography is an important control, with vents tending to form and remain in higher topography. Models with a uniform permeability throughout the Massif cannot simultaneously maintain circulation at the LCHF and the near-conductive gradient in the borehole, where permeabilities <10 À16 m 2 are required. A steeply dipping permeability discontinuity between the LCHF and the drill hole is required to stabilize venting at the summit of the massif by creating a lateral conductive boundary layer. The discontinuity needs to be close to the vent site, supporting previous inferences that high permeability is most likely produced by faulting related to the transform fault. Rapid increases in modelled fluid temperatures with depth beneath the vent agree with previous estimates of reaction temperature based on geochemical modelling.

show abstract

The role of seamounts in the transport of heat and fluids: Relations among seamount size, circulation patterns, and crustal heat flow

Cited by 14 publications

References 24 publications

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Seawater recharge into oceanic crust: IODP Exp 327 Site U1363 Grizzly Bare outcrop

Modelling the Lost City hydrothermal field: influence of topography and permeability structure

Contact Info

Product

Resources

About