Hydrothermal activity and the evolution of the seismic properties of upper oceanic crust

Grevemeyer, Ingo; Kaul, Norbert E; Villinger, Heinrich; Weigel, W.

doi:10.1029/1998jb900096

Cited by 62 publications

(82 citation statements)

References 59 publications

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“…Using these relationships and the crustal densities from Table 1, we obtain the following crustal velocities; (a)for the upper 800 meters, Vp = 3.92 km/sec; (b) for 800 to 1300 meters, Vp = 4.81 km/sec. These Vp values are slightly higher than, but still consistent with previous studies of oceanic crust of about the same age (Carlson, 1998, Grevemeyer et al, 1999 and are a strong argument that crust exposed on the BFZ wall has not been severely impacted by fracture zone formation processes. The thickness of 800 meters for this upper crustal zone of low density and low Vp at the BFZ is also at the high end of thicknesses observed for Layer 2A, but is still of the fight scale (Grevemeyer et al, 1999).…”

Section: Conclusion and Interpretationsupporting

confidence: 76%

Density and porosity of the upper oceanic crust from seafloor gravity measurements

Johnson¹,

Pruis²,

Patten³

et al. 2000

Geophysical Research Letters

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Section: Conclusion and Interpretationsupporting

confidence: 76%

Density and porosity of the upper oceanic crust from seafloor gravity measurements

Johnson¹,

Pruis²,

Patten³

et al. 2000

Geophysical Research Letters

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“…Analysis of travel times and amplitudes of refraction data of CLASSIC deployment 2 at the eastern RTI of the Clipperton transform fault suggest partial melt may also be present under the northern segment [Begnaud eta/., 1996] [Carlson, 1998; Grevemeyer and Weigel, 1997; Grevemeyer et al, 1999]. We do not observe an increase in upper crustal velocity with age in our study area, although an increase of-0.5 km/s over the 1.5 Myr age span would be predicted by [Grevemeyer et al, 1999]. On the other hand, the scatter in global compilations of layer 2A velocities is also 0.5 km/s for crust younger than 2 Myr, and our seafloor seismic velocities -3.2 km/s are not exceptional.…”

Section: Transform Domaincontrasting

confidence: 38%

Contrast in crustal structure across the Clipperton transform fault from travel time tomography

Avendonk¹,

Harding²,

Orcutt³

et al. 2001

J. Geophys. Res.

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Abstract. A three-dimensional (3-D) seismic refraction study of the Clipperton transform fault, northern East Pacific Rise, reveals anomalously low compressional velocities from the seafloor to the Moho. We attribute this low-velocity anomaly to intensive brittle deformation, caused by transpression across this active strike-slip plate boundary. The seismic velocity structure south of the Clipperton transform appears unaffected by these tectonic forces, but to the north, seismic velocities are reduced over 10 km outside the zone of sheared seafloor. This contrast in seismic velocity structure corresponds well with the differences in mid-ocean ridge morphology across the Clipperton transform. We conclude that the amount of fracturing of the upper crust, which largely controls seismic velocity variations, is strongly dependent on the shallow temperature structure at the ridge axis. Intermittent supply of magma to the shallow crust north of the Clipperton transform allows seawater to penetrate deeper, and the cooler crust is brittle to a greater depth than south of the transform, where a steady state magma lens is known to exist. The crustal thickness averages 5.7 km, only slightly thinner than normal for oceanic crust, and variations in Moho depth in excess of-0.3 km are not required by our data. The absence of large crustal thickness variations and the general similarity in seismic structure imply that a steady state magma lens is not required to form normal East Pacific Rise type crust. Perhaps a significant portion of the lower crust is accreted in situ from a patchwork of short-lived gabbro sills or from ductile flow from a basal magma chamber as has been postulated in some recent ophiolite studies.

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“…Although there has been considerable work in the past few decades dedicated to characterizing the evolution of the upper crust, most studies have been based on sparse observations of seismic Layer 2A with little analysis of Layer 2B (e.g., Cudrak and Clowes, 1993;Harding et al, 1993;Rohr, 1994;Grevemeyer et al, 1999;Grevemeyer and Bartetzko, 2004;Christeson, 2007).…”

Section: Crustal Evolution After Formation and Ridge Flank Hydrothermmentioning

confidence: 99%

Recent Seismic Studies at the East Pacific Rise 8°20'–10°10'N and Endeavour Segment: Insights into Mid-Ocean Ridge Hydrothermal and Magmatic Processes

Carbotte¹,

Canales²,

Nedimović³

et al. 2012

oceanog

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Hydrothermal activity and the evolution of the seismic properties of upper oceanic crust

Cited by 62 publications

References 59 publications

Density and porosity of the upper oceanic crust from seafloor gravity measurements

Density and porosity of the upper oceanic crust from seafloor gravity measurements

Contrast in crustal structure across the Clipperton transform fault from travel time tomography

Recent Seismic Studies at the East Pacific Rise 8°20'–10°10'N and Endeavour Segment: Insights into Mid-Ocean Ridge Hydrothermal and Magmatic Processes

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