Dissertation/Thesis Abstract

From pillow mound to lava pond: Identifying modes of volcanic emplacement by terrain modeling the 9 North Overlapping Spreading Centers
by Mason, Jessica Lynn, M.S., University of South Carolina, 2009, 92; 1463757
Abstract (Summary)

The 9°03’N Overlapping Spreading Centers (OSC) along the East Pacific Rise (EPR) are the only place along the mid-ocean ridge where we have hi-resolution bathymetric coverage, 3D seismic surveys of the mid-crustal melt lens (Kent 2000; Tong 2002; Tong, Barton et al. 2003; Singh, Harding et al. 2006) and tomographic images of the upper mantle (Toomey, Jousselin et al. 2007). Together with rock samples and seafloor photography, this provides the means to correlate the processes occurring on the seafloor with the mid-crustal magma lens. This research is a new approach to correlating the magma lens with seafloor morphology by using a classification model to locate terrain based provinces and establish uniqueness. High resolution (2m) backscatter imagery was collected by DSL-120a side-scan sonar over an area approximately 10 km wide by 25 km long, covering the OSC. Mounds, fissures and faults were later digitized from side-scan and graphed for comparison between provinces.

A bathymetric map was created from merging preexisting datasets (Kent 2000; Singh, Harding et al. 2006; White 2006; Combier 2008) and used to produce residual and median filtered bathymetric grids. Side-scan sonar backscatter, median filtered bathymetry and residual bathymetry were enhanced and input to a supervised and unsupervised classification to find and contrast terrain based provinces with bathymetric provinces. Using both classifications allowed us to compare results between a model that required computer learning and one that required user influence. The uniqueness of each province was tested using ground-reference data (rock samples, photography and digitized features) to find how the spatial distribution of features varied from province to province. Ultimately, we found unique terrain based provinces that differ from the bathymetric provinces, leading us to believe that the shape, depth and location of the magma lens has a great influence over the morphology of the terrain.

Indexing (document details)
Advisor: White, Scott M.
Commitee: Jensen, John R., Yogodzinski, Gene M.
School: University of South Carolina
Department: Geology
School Location: United States -- South Carolina
Source: MAI 47/05M, Masters Abstracts International
Subjects: Geology, Physical oceanography, Remote sensing
Keywords: East Pacific Rise, Image classification, Lava morphology, Overlapping spreading centers
Publication Number: 1463757
ISBN: 978-1-109-10972-6
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