PRELIMINARY STRATIGRAPHIC INTEREPRETATION FROM BOREHOLE STRAINMETER DRLLING, YELLOWSTONE NATIONAL PARK
A preliminary stratigraphic interpretation of the geochemical analyses generally showed a correlation between borehole cuttings and previously mapped geology. Six of the boreholes encountered rhyolite lavas and explosive tuffs: the Canyon flow, the Gardner River flow, the Gibbon River flow, the Hayden flow, the Nez Perce flow, the West Thumb flow, the Tuff of Bluff Point, the Lava Creek Tuff. The borehole near the Panther Creek vent drilled through a sequence of Sheepeater Cliff basalts outside the Yellowstone caldera.
Data from the drilling of the borehole strainmeters improved the understanding of Yellowstone’s hydrothermal system: The boreholes encountered fluid flow at permeable boundaries between rhyolite lavas and fractures within the welded Lava Creek Tuff. Additionally, water flow rates during drilling support the interpretation that fractured rhyolite flows and tuffs are good aquifers.