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Detailed Reference Information |
Hughes, S., Barton, P.J. and Harrison, D.J. (1997). Characterizing the Mid-Faeroe Ridge using seismic velocity measurements. Journal of Geophysical Research 102: doi: 10.1029/96JB03809. issn: 0148-0227. |
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The character of the basement and overlying sedimentary sequences in the vicinity of the Mid-Faeroe Ridge is investigated through a synthesis of seismic velocity measurements. A finite difference tomographic algorithm was applied to a wide-aperture seismic profile acquired across the center of the Faeroe Basin to produce a velocity model free from a priori artifacts. A series of parameterizations and smoothing constraints were run to assess the uniqueness of the final model. Uncertainties in the velocity structure were estimated at ¿5%. Comparison of the in situ velocity of the Mid-Faeroe Ridge with deterministic lithology-velocity data extracted from nearby boreholes strongly implies that Tertiary to Cretaceous shale and sandstone sequences extend to depths of 4.5 km. The occurrence of pre-Cretaceous sedimentary lithologies at 4.5--8.0 km depth is supported by in situ velocities of 4.0--4.5 km/s which are best explained by well-consolidated sediments and are incompatible with likely constituents of the basement. Evidence for a major structural discordance across the southeastern flank of the Mid-Faeroe Ridge is provided by a prominent fault whose location demarcates a lateral velocity variation of ~0.5 km/s. A rapid increase of the in situ velocity at 8 km depth is strongly suggestive of a transition into the basement, whose velocity (5.5 km/s) is comparable with high-pressure laboratory measurements of basalts from the Faeroe Islands. This basaltic basement in the center of the Faeroe Basin lies above a Moho depth of 18¿3 km which suggests cumulative stretching factors of about 3.0 and implies substantial igneous activity. We conclude that in the region of the Mid-Faeroe Ridge the prerift (Lewisian?) basement has been highly attenuated, pervasively intruded, and possibly wholly replaced by basaltic material.¿ 1997 American Geophysical Union |
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Abstract |
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Keywords
Tectonophysics, Earth's interior—composition and state, Seismology, Oceanic crust |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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