GEOMORPHIC EVIDENCE FOR LONG-LIVED HYDROTHERMAL CIRCULATION AT HYDER HOT SPRINGS, NEVADA

Hot spring travertine and sinter deposits may preserve evidence of evolving hydrothermal regimes, paleohydrology, paleoclimate, and tectonism, if their records are sufficiently long. Geomorphic features at Hyder Hot Springs, Nevada, help constrain the minimum age of this deposit to at least ~12 ka. Hyder Hot Springs is an active, intrabasin, composite travertine mound measuring approximately 250 m in diameter and rising up to 18 m above the basin floor. The mound contains 9 active travertine cones or fans with discharge temperatures ranging from 59-83 °C, as well as numerous low-flow reedy seeps. Field observations, UAV acquired structure-from-motion topographic models, and sub-meter differential GPS surveys reveal a distinct notched and benched morphology cutting the uppermost travertine deposits at 1092.6 m AMSL, coincident with nearby beach bars that formed locally at 1092.7 m during the highstand of ancestral Lake Dixie. This relationship shows that the hydrothermal system at Hyder Hot Springs has persisted long enough to record syn- and post-depositional changes related to evolving climate, hydrology, and tectonism since at least the end of the last glacial period and the dawn of the Holocene.