V11E-03:
Hydrothermal Venting at Kick’Em Jenny Submarine Volcano (West Indies)
Monday, 15 December 2014: 8:30 AM
Steven Carey1, Katherine Lynn Croff Bell2, Frederic Jean-Yves Dondin3, Christopher Roman1, Clara Smart1, Marvin D Lilley4, John E Lupton5 and Robert D. Ballard2, (1)University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, United States, (2)Ocean Exploration Trust, Narragansett, RI, United States, (3)University of the West Indies, Seismic Research Center, St. Augustine, Trinidad and Tobago, (4)Univ Washington, Seattle, WA, United States, (5)NOAA/PMEL, Newport, OR, United States
Abstract:
Kick’em Jenny is a frequently-erupting, shallow submarine volcano located ~8 km off the northwest coast of Grenada in the West Indies. The last eruption took place in 2001 but did not breach the sea surface. Focused and diffuse hydrothermal venting is taking place mainly within a small (~100 x 100 m) depression within the 300 m diameter crater of the volcano at depths of about 265 meters. Near the center of the depression clear fluids are being discharged from a focused mound-like vent at a maximum temperature of 180o C with the simultaneous discharge of numerous bubble streams. The gas consists of 93-96% CO2 with trace amounts of methane and hydrogen. A sulfur component likely contributes 1-4% of the gas total. Gas flux measurements on individual bubble streams ranged from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5 to 35o C above ambient occurs throughout the depression and over large areas of the main crater. These zones are extensively colonized by reddish-yellow bacterial mats with the production of loose Fe-oxyhydroxides largely as a surface coating and in some cases, as fragile spires up to several meters in height. A high-resolution photo mosaic of the crater depression was constructed using the remotely operated vehicle Hercules on cruise NA039 of the E/V Nautilus. The image revealed prominent fluid flow patterns descending the sides of the depression towards the base. We speculate that the negatively buoyant fluid flow may be the result of second boiling of hydrothermal fluids at Kick’em Jenny generating a dense saline component that does not rise despite its elevated temperature. Increased density may also be the result of high dissolved CO2 content of the fluids, although we were not able to measure this directly. The low amount of sulphide mineralization on the crater floor suggests that deposition may be occurring mostly subsurface, in accord with models of second boiling mineralization from other hydrothermal vent systems.
