Morphological and Geophysical Investigation of Western North Atlantic OceanCrustal Structure: Environmental Work in Support of the Acoustic Reverberation Special Research Program and Morphological and Geophysical Investigation of Western North Atlantic Oc

摘要

The Acoustic Reverberation Special Research Program required detailed knowledgeof large and small scale seafloor roughness, crustal structure, sediment distribution patterns, and material properties of the ocean floor on the MidAtlantic Ridge in order to advance fundamental research on acoustic wave scattering from the ocean bottom and subbottom at low frequencies and over long propagation paths. To provide this information and to improve our understanding of the fundamental geological processes that control formation and evolution of ocean crust and deposition of the overlying sediments, we conducted two geological/geophysical surveys in the Acoustic Reverberation Corridor within the ONR Atlantic Natural Laboratory at 25 deg 25' to 27 deg 10'N, 45 deg 00' to 49 deg 00'W. The initial survey acquired regional geological and geophysics data, and the second survey acquired fine scale, near bottom data at four seafloor sites identified by ARSRP researchers as prime acoustic study areas. This report summarizes the results of our geological and geophysical research on ridge flank tectonic segmentation; the structure, roughness, composition, thickness and magnetization of the ocean crust; gravity anomalies; sediment distribution; fault patterns and fault scarp denudation; and seamount construction and degradation.