Shaping an island arc: the influence of tectonic history and slab hydration at the lesser antilles subduction zone
File(s)
Author(s)
Allen, Robert William
Type
Thesis
Abstract
Island arc volcanism is driven by the release of water from the subducting slab. Over time
variations in the distribution of chemically bound water in the down-going lithosphere may influence an array of arc processes from rates of seismicity to arc structure. In slow spreading oceanic crust such as the Atlantic strong variations in crustal structure can lead to a pattern of hydration which changes across relatively short wavelengths along the slab front. As one of only two subduction zones to consume slow spreading lithosphere the Lesser Antilles is a key
location for understanding the influence that the distribution of subducting fluids may have on potentially hazardous arc processes. However, the tectonics of the Caribbean plate are complex, with a history of arc volcanism which extends over 100 My. As a result it is unclear to what degree along arc variations are result of the influence of recent subduction, and how much is
the result of inherited compositional and structural variations in the over-riding plate.
The VoiLA (Volatile Recycling in the Lesser Antilles) project collected an array of geophysical and geochemical data across the Lesser Antilles arc system in 2016 and 2017 in order to test the role that subducted volatiles have played in shaping the Lesser Antilles. In this thesis I present marine geophysical data including wide-angle and multichannel seismics, bathymetry
and potential field data, collected as part of two research cruises by the R.R.S. James Cook. These data are used to constrain the relative contributions of 1) the Tertiary history of the eastern Caribbean and 2) the degree of alteration in the down-going slab to shaping the modern arc. Results are combined with other key project findings to explain along strike variability in
the Lesser Antilles arc.
variations in the distribution of chemically bound water in the down-going lithosphere may influence an array of arc processes from rates of seismicity to arc structure. In slow spreading oceanic crust such as the Atlantic strong variations in crustal structure can lead to a pattern of hydration which changes across relatively short wavelengths along the slab front. As one of only two subduction zones to consume slow spreading lithosphere the Lesser Antilles is a key
location for understanding the influence that the distribution of subducting fluids may have on potentially hazardous arc processes. However, the tectonics of the Caribbean plate are complex, with a history of arc volcanism which extends over 100 My. As a result it is unclear to what degree along arc variations are result of the influence of recent subduction, and how much is
the result of inherited compositional and structural variations in the over-riding plate.
The VoiLA (Volatile Recycling in the Lesser Antilles) project collected an array of geophysical and geochemical data across the Lesser Antilles arc system in 2016 and 2017 in order to test the role that subducted volatiles have played in shaping the Lesser Antilles. In this thesis I present marine geophysical data including wide-angle and multichannel seismics, bathymetry
and potential field data, collected as part of two research cruises by the R.R.S. James Cook. These data are used to constrain the relative contributions of 1) the Tertiary history of the eastern Caribbean and 2) the degree of alteration in the down-going slab to shaping the modern arc. Results are combined with other key project findings to explain along strike variability in
the Lesser Antilles arc.
Version
Open Access
Date Issued
2020-09
Date Awarded
2021-02
Copyright Statement
Creative Commons Attribution-Non Commercial 4.0 International Licence
License URL
Advisor
Collier, Jennifer
Sponsor
Natural Environment Research Council (Great Britain)
Grant Number
1825825
Publisher Department
Department of Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)