Seismic constraints on the processes and consequences of secondary igneous evolution of Pacific oceanic lithosphere

This thesis examines the structure of Pacific oceanic lithosphere that has been modified by post-formation magmatism in order to better understand the processes of secondary magmatic evolution of the lithosphere, which can have global-scale implications for oceanic and atmospheric chemistry. In the western Pacific, widespread Cretaceous magmatism has modified oceanic lithosphere over hundreds of millions of square kilometers. Seismic models of the upper crust from within the Jurassic Quiet Zone and the crust and upper mantle near the Mariana Trench reveal crust that is locally thickened via focused extrusive volcanism and crust that is modestly but uniformly thickened over broad regions. These distinct modes of magmatic emplacement suggest the operation of both focused and diffuse modes of melt transport through the lithosphere. Analysis of seismic observations from Guaymas Basin, in the Gulf of California, endeavor to advance our understanding of sill-driven alteration of sediments, an important consequence of secondary magmatism. We show that seismically imaged physical disruption to sediments due to igneous sill intrusion can be related to changes in sediment physical properties that reflect alteration processes. We also show how sill thickness can be estimated, enabling alteration intensity to be related to sill thickness in a variety of settings.

Department dc:contributor.department

Joint Program in Oceanography/Applied Ocean Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2016

Author dc:creator

• Feng, Helen Shao-Hwa

Advisor dc:contributor.advisor

• Daniel Lizarralde.

• Joint Program in Oceanography/Applied Ocean Science and Engineering.
• Earth, Atmospheric, and Planetary Sciences.
• Woods Hole Oceanographic Institution.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/103166

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/103166