Shaul Hurwitz John McGeehin Jacob B. Lowenstern 2016 <p><span>To explore the timing of hydrothermal activity at the Upper Geyser Basin (UGB) in Yellowstone National Park, we obtained seven new accelerator mass spectrometry (AMS) radiocarbon&nbsp;</span>¹⁴<span>C ages of carbonaceous material trapped within siliceous sinter. Five samples came from depths of 15&ndash;152&nbsp;cm within the Y-1 well, and two samples were from well Y-7 (depths of 24&nbsp;cm and 122&nbsp;cm). These two wells, at Black Sand and Biscuit Basins, respectively, were drilled in 1967 as part of a scientific drilling program by the U.S. Geological Survey (</span><span id="bbb0150"><a id="ancbbb0150" class="intra_ref" href="http://www.sciencedirect.com/science/article/pii/S0377027315004114#bb0150">White et al., 1975</a></span><span>). Even with samples as small as 15&nbsp;g, we obtained sufficient carbonaceous material (a mixture of thermophilic mats, pollen, and charcoal) for the&nbsp;</span>¹⁴<span>C analyses. Apparent time of deposition ranged from 3775&nbsp;&plusmn;&nbsp;25 and 2910&nbsp;&plusmn;&nbsp;30&nbsp;</span>¹⁴<span>C years BP at the top of the cores to about 8000&nbsp;years BP at the bottom. The dates are consistent with variable rates of sinter formation at individual sites within the UGB over the Holocene. On a basin-wide scale, though, these and other existing&nbsp;</span>¹⁴<span>C dates hint that hydrothermal activity at the UGB may have been continuous throughout the Holocene.</span></p> application/pdf 10.1016/j.jvolgeores.2015.12.005 en Elsevier Radiocarbon dating of silica sinter deposits in shallow drill cores from the Upper Geyser Basin, Yellowstone National Park article