Structural evolution of the Norwegian-Greenland Sea: Results from detailed analysis of SeaMARC II side-scan sonar data.
Item
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Title
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Structural evolution of the Norwegian-Greenland Sea: Results from detailed analysis of SeaMARC II side-scan sonar data.
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Identifier
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AAI9720086
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identifier
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9720086
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Creator
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Doss, Hany S.
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Contributor
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Adviser: Kathleen Crane
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Geophysics | Geology
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Abstract
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In 1989-1990, the SeaMARC II side-scan sonar (11-12 kHz) and swath bathymetric system imaged more than 80,000 km{dollar}\sp2{dollar} of seafloor in the Norwegian-Greenland Sea and southern Arctic Ocean.;The SeaMARC II reveals that the Knipovich Ridge is segmented into predominantly distinct elongate basins; the bathymetric to most slow spreading mid-ocean ridges. Present day segment discontinuities coincide with some of the ancient fracture zone faults which are also the locus of large scale volcanism. It is possible that intermittent ponding and leaking of volcanic material occurred along these pre-existing faults creating anomalous belts of shallow bathymetry that cross obliquely onto both flanks of the rift valley. The influence of pre-existing faults on the evolution of the Knipovich Ridge is the primary reason that the segment discontinuities, rather than the centers of the basinal segments are predominantly volcanic. This contrasts both the punctiform basin and dome segmentation patterns found along most other spreading centers.;Off-axial ridge orientations of {dollar}{lcub}\sim{rcub}030\sp\circ{dollar} appear uniform on our SeaMARC II track between the Greenland Fracture Zone and the transitional zone of the Mohns-Knipovich system. This suggests that the ridges were formed under the stress of the Mohns and not the Knipovich Ridge. That these off-axial ridges occur along the entire northwestern flank of the Mohns Ridge up to the transition zone (Mohns-Knipovich bend) suggests that oblique spreading may not only be occurring across the Mohns Ridge, but additionally, substantial oblique spreading may also be occurring along the Knipovich Ridge.;Using data obtained from the SeaMARC II side-scan sonar system, a model that may help explain the numerous geophysical anomalies of the eastern Norwegian-Greenland Sea is presented. Numerous seamount chains which obliquely cross the Knipovich Ridge and lie nearly parallel to its spreading direction are interpreted to be the result of magma upwelling into an ancient splinter faults associated with the Paleo-Spitsbergen Shear Zone. This model suggests that the Knipovich Ridge evolved through time by propagating from the south into the ancient Spitsbergen Shear Zone and was trapped in one or more of the complex fault systems associated with the paleo-shear zone.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
