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Seminar: Dr. Andreas Teske, UNC Dept. of Marine Sciences
September 6, 2017 @ 3:35 pm - 4:35 pm
UNC Marine Sciences’ is proud to host a seminar by one of our own faculty Dr. Andreas Teske.
Presenter Affiliation: University of North Carolina at Chapel Hill, Department of Marine Sciences
Title: Exploring hot spots and cold seeps on the ridge flanks of Guaymas Basin
Abstract: The hydrothermal spreading center of Guaymas Basin in the Gulf of California is surrounded by extensive ridge flanks harboring numerous off-axis hot spots. These off-axis hot spots have been linked previously to methane and temperature anomalies in the overlying water column, and to magmatic emplacement in the form of deeply-buried volcanic sills. With increasing distance from the spreading center, these are more thickly sedimented and gradually cooling, but they remain capable of driving localized hydrothermal circulation. Two conspicuous sites, Ringvent and Octopus Mound, are located at a distance of 28.5 and 8.3 km northwest of the spreading center, respectively. These sites were mapped by AUV Sentry, and visited by two Alvin dives each, during a Guaymas Basin expedition with R/V Atlantis in December 2016. While both sites were dominated by classical cold seep fauna, in particular Lamellibrachia tubeworms resembling their counterparts in the Gulf of Mexico, they differed considerably from each other and from the hydrothermal vents at the Guaymas Basin spreading center. Ringvent turned out to be a massive ring-shaped seafloor edifice dominated by silica minerals, intersected and incised by craters and gullies that coincide with elevated heat flow, microbial mats, and even hydrothermal fauna. Octopus Mound was decidedly cooler, and hosted shallow hydrates, microbial mats, dense cold seep fauna, and carpet-like mats of amphitrid polychaetes that are otherwise known from cold seeps on the continental margins offshore New Zealand. Both off-axis sites, and the hydrothermal spreading center, illustrate a continuum where hydrothermal venting is increasingly attenuated until transitioning into de-facto cold seepage.