Geology, sulfide geochemistry and supercritical venting at the <scp>B</scp>eebe <scp>H</scp>ydrothermal <scp>V</scp>ent <scp>F</scp>ield, <scp>C</scp>ayman <scp>T</scp>rough

Webber, Alexander P.; Roberts, Stephen; Murton, Bramley J.; Hodgkinson, Matthew R. S.

doi:10.1002/2015gc005879

Cited by 47 publications

(44 citation statements)

References 53 publications

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“…The Von Damm vent field lies on the Mt Dent oceanic core complex (OCC), west of the central axial valley. To the north, the Beebe vent field, which has also been named the Piccard vent field, is a black smoker vent system that discharges 400°C fluids at the seafloor of the axial valley [ Kinsey and German , ; Webber et al ., ]. Gravity and vintage seismic refraction data show that the MCSC crust may be as thin as 3 km [ Ewing et al ., ; ten Brink et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Seismic structure and segmentation of the axial valley of the Mid‐Cayman Spreading Center

Avendonk

Hayman

Harding

et al. 2017

Geochem Geophys Geosyst

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We report the results of a two‐dimensional tomographic inversion of marine seismic refraction data from an array of ocean‐bottom seismographs (OBSs), which produced an image of the crustal structure along the axial valley of the ultraslow spreading Mid‐Cayman Spreading Center (MCSC). The seismic velocity model shows variations in the thickness and properties of the young oceanic crust that are consistent with the existence of two magmatic‐tectonic segments along the 110 km long spreading center. Seismic wave speeds are consistent with exhumed mantle at the boundary between these two segments, but changes in the vertical gradient of seismic velocity suggest that volcanic crust occupies most of the axial valley seafloor along the seismic transect. The two spreading segments both have a low‐velocity zone (LVZ) several kilometers beneath the seafloor, which may indicate the presence of shallow melt. However, the northern segment also has low seismic velocities (3 km/s) in a thick upper crustal layer (1.5–2.0 km), which we interpret as an extrusive volcanic section with high porosity and permeability. This segment hosts the Beebe vent field, the deepest known high‐temperature black smoker hydrothermal vent system. In contrast, the southern spreading segment has seismic velocities as high as 4.0 km/s near the seafloor. We suggest that the porosity and permeability of the volcanic crust in the southern segment are much lower, thus limiting deep seawater penetration and hydrothermal recharge. This may explain why no hydrothermal vent system has been found in the southern half of the MCSC.

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Section: Introductionmentioning

confidence: 99%

Seismic structure and segmentation of the axial valley of the Mid‐Cayman Spreading Center

Avendonk

Hayman

Harding

et al. 2017

Geochem Geophys Geosyst

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“…In particular, the research findings of expeditions to the Trans-Atlantic Geotraverse [TAG], Manus Basin and Juan de Fuca Ridge have provided important insights into the nature of fluid rock interaction and fluid mixing in the development of seafloor hydrothermal systems in different tectonic settings (Barriga et al, 2000;Fouquet et al, 1997;Humphris et al, 1995Lackschewitz et al, 2004;Mottl et al, 1994;Paulick and Bach, 2006;Roberts et al, 2003;Teagle et al, 1998;Webber et al, 2011). This work has been complemented by countless other scientific and industry-funded cruises to hydrothermal fields worldwide (Connelly et al, 2012;de Ronde et al, 2005;Glasby et al, 2008;Hannington et al, 2005 and references therein; Ishibashi et al, 2015;McConachy et al, 2005;Petersen et al, 2014;Yeats et al, 2014;Webber et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, analogues for specific types of VHMS deposits are represented by different modern hydrothermal systems (e.g. Glasby et al, 2008;Hannington et al, 1998;Ishibashi and Urabe, 1995;Lüders et al, 2001;Webber et al, 2015). Active systems provide important insights into the formation of ancient VHMS deposits, allowing fluids to be directly sampled and mineralization to be studied without the effects of subsequent deformation and metamorphism.…”

Section: Introductionmentioning

confidence: 99%

Actively forming Kuroko-type volcanic-hosted massive sulfide (VHMS) mineralization at Iheya North, Okinawa Trough, Japan

Yeats

Hollis

Halfpenny

et al. 2017

Ore Geology Reviews

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“…The mid‐Cayman spreading center is ultraslow spreading, with one of the lowest melt thicknesses in the world [ Klein and Langmuir , ; White et al ., ] producing an extremely thin mafic crust just a few hundred meters thick [ Stroup and Fox , ; ten Brink et al ., ]. However, silica geothermobarometry indicates that the depth of hydrothermal circulation may be ∼1.8 km [ Webber et al ., ], much deeper than the inferred thickness of basaltic crust. This low crustal thickness and depth of hydrothermal circulation, together with indications from the sulfide geochemistry [ Webber et al ., ] and H 2 content of the fluids [ Seewald et al ., ], suggest that ultramafic lithologies may be present in the reaction zone beneath the BVF.…”

Section: Discussionmentioning

confidence: 99%

“…The black outline denotes the area covered by more detailed, 20 cm gridded bathymetry, available in Webber et al . [].…”

Section: Introductionmentioning

confidence: 99%

The formation of gold‐rich seafloor sulfide deposits: Evidence from the Beebe hydrothermal vent field, Cayman Trough

Webber

Roberts

Murton

et al. 2017

Geochem Geophys Geosyst

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The Beebe vent field (BVF) in the Cayman Trough has built an auriferous massive sulfide deposit on the ultraslow spreading mid‐Cayman spreading center. The genesis of auriferous sulfide deposits at mid‐ocean ridges is not fully understood, although there is a growing recognition that slow and ultraslow spreading centers are conducive to gold mineralization. Analysis of hydrothermal precipitates from the BVF indicates that the highest gold contents are present within “beehive diffusers,” which have developed a highly porous pyrrhotite framework. The beehive structure allows vent fluids to effuse slowly while allowing ingress of seawater to cool the fluid. The prevalence of pyrrhotite in the beehive samples, lack of sulfates, association between pyrrhotite and gold grains, and results of thermodynamic modeling suggest gold precipitation occurred under highly reduced conditions even during mixing with seawater. In contrast, high‐temperature chimneys, with a single orifice, maintain high temperatures to the primary vent orifice and much of the gold is lost to seawater. Despite this, both chimney types are relatively gold‐enriched, which points to a further underlying cause for high gold at the BVF such as interaction of hydrothermal fluids with ultramafic lithologies in the basement. The final gold composition of the deposit is partially controlled by loss of gold during mass‐wasting of the material, with gold depletion most prevalent in blocks formed at beehive‐type chimneys. The BVF demonstrates that the overall gold content of a massive sulfide deposit is the sum of basement, precipitation, and surface processes.

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Geology, sulfide geochemistry and supercritical venting at the Beebe Hydrothermal Vent Field, Cayman Trough

Cited by 47 publications

References 53 publications

Seismic structure and segmentation of the axial valley of the Mid‐Cayman Spreading Center

Seismic structure and segmentation of the axial valley of the Mid‐Cayman Spreading Center

Actively forming Kuroko-type volcanic-hosted massive sulfide (VHMS) mineralization at Iheya North, Okinawa Trough, Japan

The formation of gold‐rich seafloor sulfide deposits: Evidence from the Beebe hydrothermal vent field, Cayman Trough

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