Investigation of the Hydrothermal System of Northern Yellowstone Lake Using Multi-Scale Magnetic Surveys
Abstract
Several high-resolution magnetic surveys of the northern basin of Yellowstone Lake were undertaken in 2016 as part of the Hydrothermal Dynamics of Yellowstone Lake project - a broad research effort to characterize the effect of hydrothermal activity on the lake floor. The surveys include lake-surface magnetic data, regional aeromagnetic data from the U.S. Geological Survey and data from a near-bottom autonomous underwater vehicle (AUV) survey. The objective was to identify the spatial relationship between hydrothermal activity and magnetic anomalies and provide insight into the subsurface structure and temporal nature of the vent activity. The magnetic data reveal that the northeastern part of the lake is weakly magnetic with a systematic pattern of discrete magnetic lows that correlates with the location of hydrothermal features. High heat flow in this part of the lake results in a shallow Curie isotherm and abundant hydrothermal activity. Magnetic lows are associated with the Mary Bay and Elliott hydrothermal explosion craters, various lake floor vents, and three linear NW-trending vent zones east of Stevenson Island. The AUV magnetic survey, which focused on these linear zones, shows decreased magnetization around the outside of the active Deep Hole vent. We postulate that lower magnetization in the outer zone results from enhanced hydrothermal alteration associated with strongly acidic conditions caused by the reaction of H2S with oxygen from lake waters and that the vapor-dominated center of the vent is less altered. West of Stevenson Island and along the western lake shoreline are sinuous high-amplitude magnetic anomaly highs, interpreted as flow fronts of the West Thumb rhyolite. An area of moderate magnetization, with lower heat flow, greater depth to Curie isotherm, and no obvious hydrothermal activity or magnetic lows, is found between these strong magnetic anomalies and the weakly magnetized northeastern basin. Its western boundary has steep magnetic and heat flow gradients and likely reflects a major structure within the currently active 17-km-long Eagle Bay-Lake Hotel fault zone that also possibly relates to the older ca 2.08 Ma Huckleberry Ridge caldera rim. In summary, we estimate the total area impacted by hydrothermal activity in the northern basin of the lake based on magnetics to be about 14 km2.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V24B..06B
- Keywords:
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- 4302 Geological;
- NATURAL HAZARDS;
- 7280 Volcano seismology;
- SEISMOLOGY;
- 8424 Hydrothermal systems;
- VOLCANOLOGY;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY