Volcanic eruption and emplacement during the 2005-06 magmatic event at the East Pacific Rise R2K Integrated Study Site (Invited)
Abstract
The 2005-06 eruption of the East Pacific Rise (EPR) marks the first observed repeat volcanic eruption along the global mid-ocean ridge system. Intense study of the EPR ridge crest within the Ridge2000 integrated study site (8°-11° N) since the early 1990s has provided a uniquely well-characterized catalog of seafloor geology, crustal structure, hydrothermal circulation and discharge, magma distribution, and faunal abundance that can be used to critically examine the processes that controlled or were impacted by eruption dynamics and volcanic accretion during the most recent eruptive event. A variety of high-resolution, post-eruption data sets (near-bottom multibeam bathymetry, sidescan sonar backscatter, seafloor photography, seafloor magnetics) were used to fully characterize the extent, volume, and morphology of the erupted products. These data provide insight into the kinematics of the eruption including variations in magma supply to as many as five distinct eruptive vents along the ridge axis and the mechanisms controlling lava emplacement across the ridge crest. Correlative data sets including micro-seismicity, lava geochemistry, and radiometric eruption ages allow us to interpret the mapped lava flows as a time sequence of distinct units and relate the erupted products to potential along-axis variations within the underlying magmatic system. Within individual flow units, we utilize flow morphology and geochemical indicators (e.g., CO2 degassing) to examine rates of flow advance and eruption. In addition, we utilize spatially correlated pre-eruption data sets to examine how the seafloor has been modified by the 2005-06 eruption. We find only minor changes to the structure (width and depth) of the axial summit trough despite it being filled and overtopped by lava along much of the ~18 km length of the eruption. This suggests that fast-spreading ridge eruptions may disrupt active faunal communities, but maintain a nearly identical habitat for re-colonization. This detailed view of lava eruption and emplacement during the 2005-06 event and our evaluation of its duration and magnitude relative to past eruptions provides a context in which to interpret perturbations to the interconnected ridge-crest processes including precursory signals (e.g., microseismicity, vent fluid chemistry) that heralded an eruption and post-eruption changes (e.g., faunal communities, sites of fluid discharge) in the wake of the event.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMOS11B..03S
- Keywords:
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- 3035 MARINE GEOLOGY AND GEOPHYSICS / Midocean ridge processes;
- 3045 MARINE GEOLOGY AND GEOPHYSICS / Seafloor morphology;
- geology;
- and geophysics;
- 3075 MARINE GEOLOGY AND GEOPHYSICS / Submarine tectonics and volcanism;
- 8429 VOLCANOLOGY / Lava rheology and morphology