| Summary: | xiii, 92 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. Excess melt production due to the interaction between the northern Mid-Atlantic Ridge and the Iceland mantle plume generates anomalously thick oceanic crust. Observed V-shaped gravity anomalies on the Reykjanes Ridge south of Iceland are inferred to reflect changes in melting with a periodicity of 5-6 Ma. A 2-D tomographic inversion of travel times recorded on a seismic refraction line on the Kolbeinsey Ridge north of Iceland constrains crustal velocity and Moho depth. I do not find increased melt production on a 5-6 Ma period, but with a period of ~8-9 Ma, with Moho depth varying from 7.8 - 12.5 ± 0.5 km. Unlike the Reykjanes Ridge, the thickest crust does not correspond with a high gravity anomaly. However, it is a region of slow p-wave velocities and significant decay of magnetic signal. I interpret the V-shaped anomaly in this region to record the northward migration of a ridge segment offset. Committee in charge: Eugene Humphreys, Chair; Emilie Hooft; Mark Reed
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