Off Axis Volcanic Fields in an Ultraslow Spreading Ridge
DOEI Funded Project: 2008
We seek to
document the evidence for extensive explosive volcanic fields in the northern rift mountains of the ultraslow
spreading SW Indian Ridge (SWIR) 9° to 16°E. Explosive volcanism is only now
being recognized as a potentially widespread and important expression of
magmatic activity along the global mid-ocean ridge system, and many aspects of
how such processes occur remain unknown. We will examine the geochemical
characteristics of dredged pyroclastic and volcaniclastic rocks from the area in
order to verify that they were erupted locally, rather than being glacial
erratics originating at the South Sandwich Islands, as was previously supposed.
We will also characterize the petrologic and microtextural characteristics of
the rocks to provide insight into the nature of the explosive volcanic
processes. In concert with rock analyses, we will process and analyze
sea-surface collected multibeam bathymetry and backscatter data to characterize
the morphology of the explosive volcanic terrain and make comparisons to the adjacent
rift valley and conjugate seafloor south of the axis that show no evidence for explosive
volcanism. These data would then be used to write a preliminary paper documenting
this entirely unique form of volcanism previously thought to be restricted to terrestrial
sub aerial environments, and set the stage and provide the justification for a proposal
to investigate this region in detail with deep submergence vehicles and a more extensive
rock dredging program that we plan to submit to NSF-OCE upon the completion of
this work (August 15, 2008 or Jan 15 2009).
