Show simple item record

dc.contributor.advisorMontesi, Laurent G. J.en_US
dc.contributor.authorBai, Hailongen_US
dc.date.accessioned2017-09-14T05:37:52Z
dc.date.available2017-09-14T05:37:52Z
dc.date.issued2017en_US
dc.identifierhttps://doi.org/10.13016/M2GT5FG2S
dc.identifier.urihttp://hdl.handle.net/1903/19912
dc.description.abstractMid-ocean ridges are underwater volcanic mountains extending more than 55,000 km in ocean basins worldwide, accounting for nearly 80% of the Earth’s volcanism. They are the birthplace of new seafloor, resurfacing two thirds of the planet over about 100 million years. At mid-ocean ridges, tectonic plates move away from each other, a phenomenon known as seafloor spreading, at rates ranging from slow (~10 cm/yr) to fast (~100 cm/yr). Plate divergence induces the underlying mantle to rise and melt. Buoyant melts segregate from the mantle and collect toward axes of mid-ocean ridges, where they are extracted and solidify into new oceanic crust. The thickness of oceanic crust, the final product of ridge magmatism, contains integrated information about plate motion, mantle flow, mantle temperature, melt generation, melt extraction and crustal accretion. In this dissertation, I investigate three types of crustal thickness variations at mid-ocean ridges to provide insights into the Earth’s deep, less accessible interior. Mid-ocean ridges are broken into segments bounded by transform faults. At fast-spreading ridges, transform faults exhibit thicker crust than adjacent ridge segments, while the crust along transform faults at slow-spreading ridges is thinner. I show that these observations are compatible with melt being extracted along fast-slipping transform faults, but not at the slow-slipping ones. The plates on either side of a ridge axis may move away from the ridge at different rates. I reveal a discrepancy between the expected and observed topography at such asymmetrically spreading ridges, and argue that the discrepancy is best explained by asymmetric crustal thickness, with thicker crust on the slower-moving plate and thinner crust on the faster-moving plate. Crustal thickness may differ between ridge segments separated by a transform fault, in a way that correlates with the relative motion between the ridge and the underlying mantle. I study the three-dimensional effects of background mantle flow, and demonstrate that the pattern of along-axis crustal thickness variations is controlled by the relative angle between ridge and background mantle flow. This dissertation systematically examines the origins of crustal thickness variations at mid-ocean ridges, and provides constraints on mantle and melt dynamics.en_US
dc.language.isoenen_US
dc.titleMelt extraction and crustal thickness variations at segmented mid-ocean ridgesen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentGeologyen_US
dc.subject.pqcontrolledMarine geologyen_US
dc.subject.pqcontrolledGeophysicsen_US
dc.subject.pqcontrolledPlate tectonicsen_US
dc.subject.pquncontrolledcrustal thicknessen_US
dc.subject.pquncontrolledmantle winden_US
dc.subject.pquncontrolledmelt extractionen_US
dc.subject.pquncontrolledmid-ocean ridgesen_US
dc.subject.pquncontrollednumerical modelen_US
dc.subject.pquncontrolledtransform faultsen_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record