Christophe Hemond
Anne Briais
Marcia Maia
Daniel S. Scheirer
Sharon L. Walker
Tingting Wang
Yongshun John Chen
Edward Baker
2014
<p><span>Multiple geological processes affect the distribution of hydrothermal venting along a mid-ocean ridge. Deciphering the role of a specific process is often frustrated by simultaneous changes in other influences. Here we take advantage of the almost constant spreading rate (65–71 mm/yr) along 2500 km of the Southeast Indian Ridge (SEIR) between 77°E and 99°E to examine the spatial density of hydrothermal venting relative to regional and segment-scale changes in the apparent magmatic budget. We use 227 vertical profiles of light backscatter and (on 41 profiles) oxidation-reduction potential along 27 first and second-order ridge segments on and adjacent to the Amsterdam-St. Paul (ASP) Plateau to map </span><i>p<span>h</span></i><span>, the fraction of casts detecting a plume. At the regional scale, venting on the five segments crossing the magma-thickened hot spot plateau is almost entirely suppressed (</span><i>p<span>h</span></i><span> = 0.02). Conversely, the combined </span><i>p<span>h</span></i><span> (0.34) from all other segments follows the global trend of </span><i>p<span>h</span></i><span> versus spreading rate. Off the ASP Plateau, multisegment trends in </span><i>p<span>h</span></i><span> track trends in the regional axial depth, high where regional depth increases and low where it decreases. At the individual segment scale, a robust correlation between </span><i>p<span>h</span></i><span> and cross-axis inflation for first-order segments shows that different magmatic budgets among first-order segments are expressed as different levels of hydrothermal spatial density. This correlation is absent among second-order segments. Eighty-five percent of the plumes occur in eight clusters totaling ∼350 km. We hypothesize that these clusters are a minimum estimate of the length of axial melt lenses underlying this section of the SEIR.</span></p>
application/pdf
10.1002/2014GC005344
en
American Geophysical Union
Correlated patterns in hydrothermal plume distribution and apparent magmatic budget along 2500 km of the Southeast Indian Ridge
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