Deep explosive volcanism on the Gakkel Ridge and seismological constraints on shallow recharge at TAG active mound
Deep explosive volcanism on the Gakkel Ridge and seismological constraints on shallow recharge at TAG active mound
Date
2013-02
Authors
Pontbriand, Claire W.
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Location
Gakkel Ridge
85°E
85°E
DOI
10.1575/1912/5761
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Keywords
Volcanic eruptions
Volcanology
Volcanology
Abstract
Seafloor digital imagery and bathymetric data are used to evaluate the volcanic
characteristics of the 85°E segment of the ultraslow spreading Gakkel Ridge (9 mm yr-1).
Imagery reveals that ridges and volcanic cones in the axial valley are covered by
numerous, small-volume lava flows, including a few flows fresh enough to have
potentially erupted during the 1999 seismic swarm at the site. The morphology and
distribution of volcaniclastic deposits observed on the seafloor at depths of ~3800 m,
greater than the critical point for steam generation, are consistent with having formed by
explosive discharge of magma and CO2 from source vents. Microearthquakes recorded on a 200 m aperture seismometer network deployed on the
Trans-Atlantic Geotraverse active mound, a seafloor massive sulfide on the Mid-Atlantic
Ridge at 26°N, are used to image subsurface processes at the hydrothermal system. Over
nine-months, 32,078 local microearthquakes (ML = -1) with single-phase arrivals cluster
on the southwest flank of the deposit at depths <125 m. Microearthquakes characteristics
are consistent with reaction-driven cracking driven by anhydrite deposition in the shallow
secondary circulation system. Exit fluid temperatures recorded at diffuse vents on the
mound during the microearthquake study are used to explore linkages between seismicity
and venting.
Description
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2013
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Citation
Pontbriand, C. W. (2013). Deep explosive volcanism on the Gakkel Ridge and seismological constraints on shallow recharge at TAG active mound [Doctoral thesis, Massachusetts Institute of Technology and Woods Hole Oceanographic Institution]. Woods Hole Open Access Server. https://doi.org/10.1575/1912/5761