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Crustal accretion and evolution at slow and ultra-slow spreading mid-ocean ridges
(Massachusetts Institute of Technology, 2001)
Half of the ocean crust is formed at spreading centers with total opening rates less than 40 km/Myr. The objective of this Thesis is to investigate temporal variations in active ridge processes and crustal aging at ...
Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
(Massachusetts Institute of Technology, 2009)
The radionuclides ²³¹Pa and ²³⁰Th, produced in the water column and removed from the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column ...
Isotopic constraints on the sources and associations of organic compounds in marine sediments
(Massachusetts Institute of Technology, 2006)
To provide a new perspective on the fate of both natural organic matter and hydrophobic organic contaminants (HOCs) in marine sediments, we have investigated the relationship between radiocarbon (14C) age and the different ...
Mechanisms of metal release from contaminated coastal sediments
(Massachusetts Institute of Technology, 2005)
The fate of trace metals in contaminated coastal sediments is poorly understood, yet critical for effective coastal management. The aim of this thesis is to investigate and quantify the mechanisms leading to the release ...
Structure and evolution of an oceanic megamullion on the Mid-Atlantic ridge at 27N̊
(Massachusetts Institute of Technology, 2001)
Megamullions in slow-spreading oceanic crust are characterized by smooth "turtle-back" morphology and are interpreted to be rotated footwalls of long-lived detachment faults. Megamullions have been analyzed in preliminary ...
Examining the effects of mid ocean ridge topography on 3D marine magnetometric resistivity model responses
(Massachusetts Institute of Technology, 2004)
Methods which measure seafloor resistivity are uniquely suited to studying hydrothermal circulation in the crust. The magnetometric resistivity (MMR) technique is a galvanic method which uses a bipole current source with ...
The distribution and history of nuclear weapons related contamination in sediments from the Ob River, Siberia as determined by isotopic ratios of Plutonium, Neptunium, and Cesium
(Massachusetts Institute of Technology, 2002)
This thesis addresses the sources and transport of nuclear weapons related contamination in the Ob River region, Siberia. In addition to being one of the largest rivers flowing into the Arctic Ocean, the bulk of the former ...
The effect of protozoan grazers on the cycling of polychlorinated biphenyls (PCBs) in marine systems
(Massachusetts Institute of Technology, 2000)
Processes affecting organic carbon distribution and composition can control the speciation of organic contaminants such as polychlorinated biphenyls (PCBs) and ultimately determine their residence time in a particular ...
Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity
(Massachusetts Institute of Technology, 2008)
Chapter 1 presents the first published measurements of Sr-isotope variability in olivine-hosted melt inclusions. Melt inclusions in just two Samoan basalt hand samples exhibit most of the total Sr-isotope variability ...
Tropical climate variability from the last glacial maximum to the present
(Massachusetts Institute of Technology, 2005)
This thesis evaluates the nature and magnitude of tropical climate variability from the Last Glacial Maximum to the present. The temporal variability of two specific tropical climate phenomena is examined. The first is the ...