The physical characteristics of bottom sediment near Sur Ridge, California
Gabriel, Christopher L.
Greene, H. Gary
Collins, Curtis A.
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A study was conducted to determine the relationships between the geomorphology, sedimentology and acoustic properties surrounding Sur Ridge, California, in an effort to determine their effects on acoustic tomography. Eleven gravity cores were taken in the vicinity of Sur Ridge. Detailed acoustic and sedimentologial analyses were conducted on the sediment within each core. The acoustic characteristics of the sediment and the geomorphology of Sur slope were examined to determine their impact on the arrival times and structures of acoustic tomography signals sent from a source on Davidson Seamount to a receiver on Sur Ridge. Based on analyses of cores collected for this study, it was found that sediment along the western slope of Sur Ridge are composed primarily of hemipelagic silty clays. Sediment within the trough to the east of Sur Ridge are fine sands composed primarily of relict glauconite grains that appear to be a lag deposit created by a relatively strong bottom current. The in-situ compressional wave velocities and wet bulk densities from the cores taken along the lower part of Sur slope were then assimilated into an existing acoustic model in an attempt to improve the accuracy of the model. Results indicated that due to the presence of a sound channel in the surficial sediment, the cores taken did not penetrate deep enough into the sediment in order to obtain an accurate profile of the compressional wave velocity gradient within the sediment.
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