U-series Geochronology and the Age of Steep Cone, Sentinel Meadows, Yellowstone National Park

Hydrothermal systems have strong potential as sources of energy and mineral resources and as origins of geologic hazards, and thus they are important targets for scientific investigation. This study explores the temporal development of Steep Cone, a hydrothermal feature in the Sentinel Meadows region of Yellowstone National Park. Steep Cone was chosen for this experiment because domal mounds are the most common hydrothermal features in the park and are thought to have the best potential for long-term depositional records. Several hydrothermal silica sinter samples were collected from Steep Cone in July of 2015. Gamma ray spectrometry and multi-collector inductively coupled plasma mass spectrometry were used to detect activities and abundances of U-series radioisotopes in each sample. This data was used to date the approximate time of deposition of each sinter and to test the following hypothesis: Either, Steep Cone developed after the end of the Pleistocene Pinedale glaciation and thus formed within a period of no greater than 15,000 years, or its formation began before the recession of the glaciers in northwestern Wyoming.