Abstract
The northern Gorda Ridge is spreading at an intermediate rate but exhibits a deep, well-defined rift valley and petrologic diversity more like the slow-spreading Mid-Atlantic Ridge than other oceanic ridges with intermediate rates of spreading. A detailed investigation of a 10 km by 10 km area of the floor and eastern wall of the rift valley was conducted in order to define the geologic setting of active high-temperature hydrothermal vents regionally located using water column studies. High-temperature vents are apparently located on the east wall of the rift valley at the southern end of a linear ridge at a location where ridge-parallel and anomalous ridge-oblique tectonic trends intersect. Additional hydrothermal deposits were discovered along the axis of the valley floor near the shoal point of the axial valley of the northern Gorda Ridge, adjacent to an area of sheet flows. These deposits are of two types—a massive material, probably nontronite, and white coatings on talus that consist of mixed-layer clay and boehmite. These axial deposits do not appear to be actively forming. This study suggests that past and present hydrothermal activity occurs near the shallowest and volcanically most productive segment of the ridge, and the locations of the vents are controlled by the intersection of tectonic trends.
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Clague, D.A., Rona, P.A. (1990). Geology of the GR14 Site on Northern Gorda Ridge. In: McMurray, G.R. (eds) Gorda Ridge. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-3258-2_3
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DOI: https://doi.org/10.1007/978-1-4612-3258-2_3
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