Geophysical and geochemical constraints on submarine volcanic processes
Jones, Meghan R.
MetadataShow full item record
KeywordSubmarine volcanoes; Ocean bottom; Biotic communities; Geochemistry; Volcanology; Water--Carbon dioxide content
Submarine volcanic systems form new oceanic crust, host unique chemosynthetic ecosystems, concentrate rare metals, and provide a conduit for chemical transfer from the Earth's interior to hydrosphere. Although our understanding of submarine volcanoes has been historically limited due to their relative inaccessibility, recent observations from active systems provide valuable opportunities to address key open questions in submarine volcanology. This thesis provides new insight into submarine volcanic processes using observations and samples from the 2011 Axial Seamount eruption, the 2012 Havre Volcano eruption, and the Mid-Atlantic Ridge near 14°N. In Chapter 2, I develop best practices for quantifying vesicle textures and reconstructing total CO2 concentrations in mid-ocean ridge basalts (MORB). Based on synthetic vesicle populations, 2D and 3D measurements, and Raman spectroscopy, I show that traditional methods overestimate MORB CO2 concentrations by as much as 50%, which has important implications for estimating ridge CO2 flux. In Chapter 3, I apply methods from Chapter 2, along with a bubble growth model, to samples from the 2011 Axial Seamount eruption in order to evaluate magma ascent and lava flow rates. I show that the variability in ascent rates during the 2011 eruption spans the range previously proposed over the global mid-ocean ridge system. I suggest that the variability in ascent rates relates to lateral dike propagation and evolving reservoir overpressures and that ascent rates influence flow morphology. In Chapter 4, I address the origin of highly vesicular MORB that pop upon recovery from the seafloor. I show that bubble accumulation produces the high volatile concentrations in these popping rocks and demonstrate that mantle carbon concentrations are lower and less heterogeneous than previously proposed. In Chapter 5, I evaluate models for the submarine dispersal of giant pumice clasts using observations from the 2012 Havre Volcano eruption. I show that the seafloor distribution of giant pumice is controlled by conductive cooling, the advective displacement of steam by water through highly permeable pathways, and clast breakup during transport and deposition. Together, these chapters provide critical constraints on the flux of volatiles at mid-ocean ridges and the processes governing the emplacement of volcanic products on the seafloor.
Submitted in partial fulfillment of the requirements for the degree of Degree of Doctor of Philosophy in Geological Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2019.
Suggested CitationThesis: Jones, Meghan R., "Geophysical and geochemical constraints on submarine volcanic processes", 2019-09, DOI:10.1575/1912/24375, https://hdl.handle.net/1912/24375
Showing items related by title, author, creator and subject.
Scientific results of the "Nautilus" Expedition, 1931 : under the command of Capt. Sir Hubert Wilkins. Parts I to III Sverdrup, Harald U.; Soule, Floyd M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1933-03)In 1930 Sir Hubert Wilkins announced his plan for exploring the Polar Sea by submarine. Thanks to the courtesy of the U. S. Navy Department and the U. S. Shipping Board the submarine 0 12 was placed at his disposal and ...
Magde, Laura S. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1997-03)The formation of new oceanic crust is the result of a complex geodynamic system in which mantle rises beneath spreading centers and undergoes decompression melting. The melt segregates from the matrix and is focused to ...
Detailed studies of the structure, tectonics, near bottom magnetic anomalies and microearthquake seismicity of the Mid-Atlantic Ridge near 37°N Macdonald, Ken C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1975-09)The Mid-Atlantic Ridge is one of the most well known and yet poorly understood spreading centers in the world. A detailed investigation of the Mid-Atlantic Ridge crest near 37°N (FAMOUS) was conducted using a deeply towed ...