SHALLOW HYDROTHERMAL SYSTEM AT NEWBERRY VOLCANO, OREGON: A CONCEPTUAL MODEL.

Investigations at Newberry Volcano, Oregon, have resulted in a satisfactory account of the shallow hydrothermal system, but have not indicated the nature of a possible geothermal reservoir. Hot springs in the caldera probably represent the return of circulating meteoric water, warmed at shallow depths by high conductive heat flow and by steam rising from greater depths. Ground-water recharge to the hydrothermal system is at most 250 liters per second, of which about 20 liters per second reappears in the hot springs. Analysis of temperature anomalies in a Geological Survey drillhole indicates that ground-water flow totaling about 125 liters per second could be moving laterally at depths of less than 650 m at the drill site. Refs.