Collaborative Research: Investigation of Volcanism and Tectonics in the Bight Transform Region (55.5N-57.0N, Mid-Atlantic Ridge)

University Of South Florida, Tampa FL

Investigators

Abstract

Volcanoes on the seafloor occur mostly along mid-ocean ridges or above mantle plumes. Iceland is an example of a place where ridges and plumes interact. The Bight transform fault is a sharp boundary between the Iceland plume-influenced Reykjanes Ridge to the north and the Mid-Atlantic Ridge to the south. This project will use deep sea robotic vehicles to map and sample submarine volcanoes near the Bight transform fault. The project team will analyze the sampled rocks to understand how oceanic crust and seafloor volcanoes form, and why there is such a sudden change in volcanism at this small-offset transform fault. These data will better constrain the conditions resulting in eruptions at other locations such as Hawaii. This work will also support early-career scientists at several institutions and international collaborations. Undergraduates and high school students will develop skills that are critical to beginning a successful science career. Large buoyant mantle upwellings associated with prominent gravity anomalies are thought to occur within a deep, low-viscosity, damp melting interval where volatile- and incompatible element-rich melts form and are efficiently transported to the surface through reactive flow channels. In contrast to the relative homogeneity of basalts erupted on or near the ridge axis, off-axis volcanoes can exhibit extreme compositional variations, reflecting fundamental but poorly understood processes that generate chemical heterogeneity. This project will sample a subset of off-axis volcanoes and axial rift sites near the Bight transform south of? Iceland to examine variations in volcanism relative to the Bight gravity anomaly. For the first time, the structure, morphology, and composition of these off-axis volcanoes will be characterized using the autonomous underwater vehicle Sentry combined with in situ sampling using the remotely operated vehicle Jason. The sampled lavas will undergo a full suite of geochemical analyses, including volatiles. Spatially resolved geochemical, volcanological, and geophysical data will test models for magmatic accretion differences across the Bight transform, constrain the distribution of mantle components, test the role of volatiles in volcano morphology and eruption dynamics, and help to explain why seamounts are so abundant in this area. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.