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Pruis & Johnson 2002
Pruis, M.J. and Johnson, H.P. (2002). Age dependent porosity of young upper oceanic crust: Insights from seafloor gravity studies of recent volcanic eruptions. Geophysical Research Letters 29: doi: 10.1029/2001GL013977. issn: 0094-8276.

An October 1997 ALVIN program collected a series of seafloor gravity stations over the February, 1996, volcanic eruption site on the northern Gorda Ridge (46¿41'N, 126¿47'W). These measurements yielded estimates of the density and porosity of mid-ocean ridge crust in the first few decades following formation. The estimated crustal density for this pillow eruption of 2270 ¿ 260 kg/m3 is very low, but in good agreement with the estimated densities of other recent seafloor volcanic flows. Rock matrix densities, measured from hand samples retrieved from the study area, give a bulk porosity for this flow of 34% ¿ 16%. This data, when included with similar estimates of upper crustal porosity, argue for a rapid evolution of upper crustal porosities from very high values (≥30%) for recent eruptions to much lower values (~10--15%) where the seafloor is older than 0.5 million years. These variations of density and porosity are of a magnitude consistent with previously observed changes in seismic compressional wave velocity and permeability of ocean crust.

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Abstract

Keywords
Marine Geology and Geophysics, Gravity, Marine Geology and Geophysics, Midocean ridge processes, Seismology, Oceanic crust, Tectonophysics, General or miscellaneous
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
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