Date of Award

Summer 2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Ocean and Earth Sciences

Committee Director

Jennifer Georgen

Committee Member

John Adam

Committee Member

Dennis A. Darby

Committee Member

Declan De Paor

Call Number for Print

Special Collections LD4331.O35 N468 201

Abstract

Similar to regions such as the Lau Basin and the Caribbean Sea, the eastern Scotia Sea is a geologically complex area that involves multiple plate boundary types. This study uses bathymetry and gravity data to infer upper mantle geodynamics in the eastern Scotia Sea region. Beneath this region is an intermediate-rate back-arc spreading center known as the East Scotia Ridge (ESR) that forms the boundary between the Scotia and Sandwich plates. To the east of the ESR are the South Sandwich island arc and the South Sandwich Trench. The ESR is a relatively young feature, with spreading estimated to have begun ~20 Ma (Livermore, 2003).

Earlier studies examining trends in bathymetry and geochemistry along the north-south striking ESR ( e.g., Livermore, 2003) suggested that westward-directed flow from the Bouvet plume, located approximately 2000 km to the east, may affect ridge magmatic processes at segments near the slab ends, particularly in the north. In this investigation mantle Bouguer anomaly (MBA) is calculated for the eastern Scotia Sea to evaluate the relative importance of magmatic and tectonic factors in controlling crustal accretion along the ESR.

MBA values do not indicate the presence of enhanced, plume-dominated upwelling beneath the northernmost and southernmost segments. Likewise, geochemical data from published sources do not show a clear thermal plume influence. Overall, a mechanism of geochemical source heterogeneity plus enhanced melting due to plate boundary geometry, rather than a "classic" thermal plume, is preferred to explain geophysical anomalies along the ESR.

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DOI

10.25777/hb4s-j551

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