Geochemistry of low-temperature springs northwest of Yellowstone caldera: Seeking the link between seismicity, deformation, and fluid flow

A comprehensive geochemical survey of springs outside the northwest margin of the Yellowstone caldera was undertaken in 2003 and 2004. This survey was designed to detect: (1) active leakage from a huge reservoir of CO2 gas recently postulated to extend from beneath the caldera into this area; and (2) lingering evidence for subsurface flow of magmatic fluids into this area during the 1985 seismic swarm and concomitant caldera subsidence. Spring temperatures are low (< 15 °C), but two large-discharge springs contain 14C-dead carbon that can be identified as magmatic from calculated end-member values for δ13C(dead) and 3He/C(dead) of − 4‰ and 1 × 10− 10, respectively, similar to values for intra-caldera fumarolic and hot-spring gases. [...]